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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/percpu.c - percpu memory allocator
4 *
5 * Copyright (C) 2009 SUSE Linux Products GmbH
6 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 *
8 * Copyright (C) 2017 Facebook Inc.
9 * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org>
10 *
11 * The percpu allocator handles both static and dynamic areas. Percpu
12 * areas are allocated in chunks which are divided into units. There is
13 * a 1-to-1 mapping for units to possible cpus. These units are grouped
14 * based on NUMA properties of the machine.
15 *
16 * c0 c1 c2
17 * ------------------- ------------------- ------------
18 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
19 * ------------------- ...... ------------------- .... ------------
20 *
21 * Allocation is done by offsets into a unit's address space. Ie., an
22 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
23 * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
24 * and even sparse. Access is handled by configuring percpu base
25 * registers according to the cpu to unit mappings and offsetting the
26 * base address using pcpu_unit_size.
27 *
28 * There is special consideration for the first chunk which must handle
29 * the static percpu variables in the kernel image as allocation services
30 * are not online yet. In short, the first chunk is structured like so:
31 *
32 * <Static | [Reserved] | Dynamic>
33 *
34 * The static data is copied from the original section managed by the
35 * linker. The reserved section, if non-zero, primarily manages static
36 * percpu variables from kernel modules. Finally, the dynamic section
37 * takes care of normal allocations.
38 *
39 * The allocator organizes chunks into lists according to free size and
40 * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
41 * flag should be passed. All memcg-aware allocations are sharing one set
42 * of chunks and all unaccounted allocations and allocations performed
43 * by processes belonging to the root memory cgroup are using the second set.
44 *
45 * The allocator tries to allocate from the fullest chunk first. Each chunk
46 * is managed by a bitmap with metadata blocks. The allocation map is updated
47 * on every allocation and free to reflect the current state while the boundary
48 * map is only updated on allocation. Each metadata block contains
49 * information to help mitigate the need to iterate over large portions
50 * of the bitmap. The reverse mapping from page to chunk is stored in
51 * the page's index. Lastly, units are lazily backed and grow in unison.
52 *
53 * There is a unique conversion that goes on here between bytes and bits.
54 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
55 * tracks the number of pages it is responsible for in nr_pages. Helper
56 * functions are used to convert from between the bytes, bits, and blocks.
57 * All hints are managed in bits unless explicitly stated.
58 *
59 * To use this allocator, arch code should do the following:
60 *
61 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
62 * regular address to percpu pointer and back if they need to be
63 * different from the default
64 *
65 * - use pcpu_setup_first_chunk() during percpu area initialization to
66 * setup the first chunk containing the kernel static percpu area
67 */
68
69#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
70
71#include <linux/bitmap.h>
72#include <linux/cpumask.h>
73#include <linux/memblock.h>
74#include <linux/err.h>
75#include <linux/list.h>
76#include <linux/log2.h>
77#include <linux/mm.h>
78#include <linux/module.h>
79#include <linux/mutex.h>
80#include <linux/percpu.h>
81#include <linux/pfn.h>
82#include <linux/slab.h>
83#include <linux/spinlock.h>
84#include <linux/vmalloc.h>
85#include <linux/workqueue.h>
86#include <linux/kmemleak.h>
87#include <linux/sched.h>
88#include <linux/sched/mm.h>
89#include <linux/memcontrol.h>
90
91#include <asm/cacheflush.h>
92#include <asm/sections.h>
93#include <asm/tlbflush.h>
94#include <asm/io.h>
95
96#define CREATE_TRACE_POINTS
97#include <trace/events/percpu.h>
98
99#include "percpu-internal.h"
100
101/*
102 * The slots are sorted by the size of the biggest continuous free area.
103 * 1-31 bytes share the same slot.
104 */
105#define PCPU_SLOT_BASE_SHIFT 5
106/* chunks in slots below this are subject to being sidelined on failed alloc */
107#define PCPU_SLOT_FAIL_THRESHOLD 3
108
109#define PCPU_EMPTY_POP_PAGES_LOW 2
110#define PCPU_EMPTY_POP_PAGES_HIGH 4
111
112#ifdef CONFIG_SMP
113/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
114#ifndef __addr_to_pcpu_ptr
115#define __addr_to_pcpu_ptr(addr) \
116 (void __percpu *)((unsigned long)(addr) - \
117 (unsigned long)pcpu_base_addr + \
118 (unsigned long)__per_cpu_start)
119#endif
120#ifndef __pcpu_ptr_to_addr
121#define __pcpu_ptr_to_addr(ptr) \
122 (void __force *)((unsigned long)(ptr) + \
123 (unsigned long)pcpu_base_addr - \
124 (unsigned long)__per_cpu_start)
125#endif
126#else /* CONFIG_SMP */
127/* on UP, it's always identity mapped */
128#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
129#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
130#endif /* CONFIG_SMP */
131
132static int pcpu_unit_pages __ro_after_init;
133static int pcpu_unit_size __ro_after_init;
134static int pcpu_nr_units __ro_after_init;
135static int pcpu_atom_size __ro_after_init;
136int pcpu_nr_slots __ro_after_init;
137static int pcpu_free_slot __ro_after_init;
138int pcpu_sidelined_slot __ro_after_init;
139int pcpu_to_depopulate_slot __ro_after_init;
140static size_t pcpu_chunk_struct_size __ro_after_init;
141
142/* cpus with the lowest and highest unit addresses */
143static unsigned int pcpu_low_unit_cpu __ro_after_init;
144static unsigned int pcpu_high_unit_cpu __ro_after_init;
145
146/* the address of the first chunk which starts with the kernel static area */
147void *pcpu_base_addr __ro_after_init;
148
149static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
150const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
151
152/* group information, used for vm allocation */
153static int pcpu_nr_groups __ro_after_init;
154static const unsigned long *pcpu_group_offsets __ro_after_init;
155static const size_t *pcpu_group_sizes __ro_after_init;
156
157/*
158 * The first chunk which always exists. Note that unlike other
159 * chunks, this one can be allocated and mapped in several different
160 * ways and thus often doesn't live in the vmalloc area.
161 */
162struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
163
164/*
165 * Optional reserved chunk. This chunk reserves part of the first
166 * chunk and serves it for reserved allocations. When the reserved
167 * region doesn't exist, the following variable is NULL.
168 */
169struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
170
171DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
172static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
173
174struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
175
176/*
177 * The number of empty populated pages, protected by pcpu_lock.
178 * The reserved chunk doesn't contribute to the count.
179 */
180int pcpu_nr_empty_pop_pages;
181
182/*
183 * The number of populated pages in use by the allocator, protected by
184 * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets
185 * allocated/deallocated, it is allocated/deallocated in all units of a chunk
186 * and increments/decrements this count by 1).
187 */
188static unsigned long pcpu_nr_populated;
189
190/*
191 * Balance work is used to populate or destroy chunks asynchronously. We
192 * try to keep the number of populated free pages between
193 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
194 * empty chunk.
195 */
196static void pcpu_balance_workfn(struct work_struct *work);
197static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
198static bool pcpu_async_enabled __read_mostly;
199static bool pcpu_atomic_alloc_failed;
200
201static void pcpu_schedule_balance_work(void)
202{
203 if (pcpu_async_enabled)
204 schedule_work(&pcpu_balance_work);
205}
206
207/**
208 * pcpu_addr_in_chunk - check if the address is served from this chunk
209 * @chunk: chunk of interest
210 * @addr: percpu address
211 *
212 * RETURNS:
213 * True if the address is served from this chunk.
214 */
215static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
216{
217 void *start_addr, *end_addr;
218
219 if (!chunk)
220 return false;
221
222 start_addr = chunk->base_addr + chunk->start_offset;
223 end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
224 chunk->end_offset;
225
226 return addr >= start_addr && addr < end_addr;
227}
228
229static int __pcpu_size_to_slot(int size)
230{
231 int highbit = fls(size); /* size is in bytes */
232 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
233}
234
235static int pcpu_size_to_slot(int size)
236{
237 if (size == pcpu_unit_size)
238 return pcpu_free_slot;
239 return __pcpu_size_to_slot(size);
240}
241
242static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
243{
244 const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
245
246 if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
247 chunk_md->contig_hint == 0)
248 return 0;
249
250 return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
251}
252
253/* set the pointer to a chunk in a page struct */
254static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
255{
256 page->private = (unsigned long)pcpu;
257}
258
259/* obtain pointer to a chunk from a page struct */
260static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
261{
262 return (struct pcpu_chunk *)page->private;
263}
264
265static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
266{
267 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
268}
269
270static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
271{
272 return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
273}
274
275static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
276 unsigned int cpu, int page_idx)
277{
278 return (unsigned long)chunk->base_addr +
279 pcpu_unit_page_offset(cpu, page_idx);
280}
281
282/*
283 * The following are helper functions to help access bitmaps and convert
284 * between bitmap offsets to address offsets.
285 */
286static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
287{
288 return chunk->alloc_map +
289 (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
290}
291
292static unsigned long pcpu_off_to_block_index(int off)
293{
294 return off / PCPU_BITMAP_BLOCK_BITS;
295}
296
297static unsigned long pcpu_off_to_block_off(int off)
298{
299 return off & (PCPU_BITMAP_BLOCK_BITS - 1);
300}
301
302static unsigned long pcpu_block_off_to_off(int index, int off)
303{
304 return index * PCPU_BITMAP_BLOCK_BITS + off;
305}
306
307/**
308 * pcpu_check_block_hint - check against the contig hint
309 * @block: block of interest
310 * @bits: size of allocation
311 * @align: alignment of area (max PAGE_SIZE)
312 *
313 * Check to see if the allocation can fit in the block's contig hint.
314 * Note, a chunk uses the same hints as a block so this can also check against
315 * the chunk's contig hint.
316 */
317static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
318 size_t align)
319{
320 int bit_off = ALIGN(block->contig_hint_start, align) -
321 block->contig_hint_start;
322
323 return bit_off + bits <= block->contig_hint;
324}
325
326/*
327 * pcpu_next_hint - determine which hint to use
328 * @block: block of interest
329 * @alloc_bits: size of allocation
330 *
331 * This determines if we should scan based on the scan_hint or first_free.
332 * In general, we want to scan from first_free to fulfill allocations by
333 * first fit. However, if we know a scan_hint at position scan_hint_start
334 * cannot fulfill an allocation, we can begin scanning from there knowing
335 * the contig_hint will be our fallback.
336 */
337static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
338{
339 /*
340 * The three conditions below determine if we can skip past the
341 * scan_hint. First, does the scan hint exist. Second, is the
342 * contig_hint after the scan_hint (possibly not true iff
343 * contig_hint == scan_hint). Third, is the allocation request
344 * larger than the scan_hint.
345 */
346 if (block->scan_hint &&
347 block->contig_hint_start > block->scan_hint_start &&
348 alloc_bits > block->scan_hint)
349 return block->scan_hint_start + block->scan_hint;
350
351 return block->first_free;
352}
353
354/**
355 * pcpu_next_md_free_region - finds the next hint free area
356 * @chunk: chunk of interest
357 * @bit_off: chunk offset
358 * @bits: size of free area
359 *
360 * Helper function for pcpu_for_each_md_free_region. It checks
361 * block->contig_hint and performs aggregation across blocks to find the
362 * next hint. It modifies bit_off and bits in-place to be consumed in the
363 * loop.
364 */
365static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
366 int *bits)
367{
368 int i = pcpu_off_to_block_index(*bit_off);
369 int block_off = pcpu_off_to_block_off(*bit_off);
370 struct pcpu_block_md *block;
371
372 *bits = 0;
373 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
374 block++, i++) {
375 /* handles contig area across blocks */
376 if (*bits) {
377 *bits += block->left_free;
378 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
379 continue;
380 return;
381 }
382
383 /*
384 * This checks three things. First is there a contig_hint to
385 * check. Second, have we checked this hint before by
386 * comparing the block_off. Third, is this the same as the
387 * right contig hint. In the last case, it spills over into
388 * the next block and should be handled by the contig area
389 * across blocks code.
390 */
391 *bits = block->contig_hint;
392 if (*bits && block->contig_hint_start >= block_off &&
393 *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
394 *bit_off = pcpu_block_off_to_off(i,
395 block->contig_hint_start);
396 return;
397 }
398 /* reset to satisfy the second predicate above */
399 block_off = 0;
400
401 *bits = block->right_free;
402 *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
403 }
404}
405
406/**
407 * pcpu_next_fit_region - finds fit areas for a given allocation request
408 * @chunk: chunk of interest
409 * @alloc_bits: size of allocation
410 * @align: alignment of area (max PAGE_SIZE)
411 * @bit_off: chunk offset
412 * @bits: size of free area
413 *
414 * Finds the next free region that is viable for use with a given size and
415 * alignment. This only returns if there is a valid area to be used for this
416 * allocation. block->first_free is returned if the allocation request fits
417 * within the block to see if the request can be fulfilled prior to the contig
418 * hint.
419 */
420static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
421 int align, int *bit_off, int *bits)
422{
423 int i = pcpu_off_to_block_index(*bit_off);
424 int block_off = pcpu_off_to_block_off(*bit_off);
425 struct pcpu_block_md *block;
426
427 *bits = 0;
428 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
429 block++, i++) {
430 /* handles contig area across blocks */
431 if (*bits) {
432 *bits += block->left_free;
433 if (*bits >= alloc_bits)
434 return;
435 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
436 continue;
437 }
438
439 /* check block->contig_hint */
440 *bits = ALIGN(block->contig_hint_start, align) -
441 block->contig_hint_start;
442 /*
443 * This uses the block offset to determine if this has been
444 * checked in the prior iteration.
445 */
446 if (block->contig_hint &&
447 block->contig_hint_start >= block_off &&
448 block->contig_hint >= *bits + alloc_bits) {
449 int start = pcpu_next_hint(block, alloc_bits);
450
451 *bits += alloc_bits + block->contig_hint_start -
452 start;
453 *bit_off = pcpu_block_off_to_off(i, start);
454 return;
455 }
456 /* reset to satisfy the second predicate above */
457 block_off = 0;
458
459 *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
460 align);
461 *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
462 *bit_off = pcpu_block_off_to_off(i, *bit_off);
463 if (*bits >= alloc_bits)
464 return;
465 }
466
467 /* no valid offsets were found - fail condition */
468 *bit_off = pcpu_chunk_map_bits(chunk);
469}
470
471/*
472 * Metadata free area iterators. These perform aggregation of free areas
473 * based on the metadata blocks and return the offset @bit_off and size in
474 * bits of the free area @bits. pcpu_for_each_fit_region only returns when
475 * a fit is found for the allocation request.
476 */
477#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
478 for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
479 (bit_off) < pcpu_chunk_map_bits((chunk)); \
480 (bit_off) += (bits) + 1, \
481 pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
482
483#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
484 for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
485 &(bits)); \
486 (bit_off) < pcpu_chunk_map_bits((chunk)); \
487 (bit_off) += (bits), \
488 pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
489 &(bits)))
490
491/**
492 * pcpu_mem_zalloc - allocate memory
493 * @size: bytes to allocate
494 * @gfp: allocation flags
495 *
496 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
497 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
498 * This is to facilitate passing through whitelisted flags. The
499 * returned memory is always zeroed.
500 *
501 * RETURNS:
502 * Pointer to the allocated area on success, NULL on failure.
503 */
504static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
505{
506 if (WARN_ON_ONCE(!slab_is_available()))
507 return NULL;
508
509 if (size <= PAGE_SIZE)
510 return kzalloc(size, gfp);
511 else
512 return __vmalloc(size, gfp | __GFP_ZERO);
513}
514
515/**
516 * pcpu_mem_free - free memory
517 * @ptr: memory to free
518 *
519 * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
520 */
521static void pcpu_mem_free(void *ptr)
522{
523 kvfree(ptr);
524}
525
526static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
527 bool move_front)
528{
529 if (chunk != pcpu_reserved_chunk) {
530 if (move_front)
531 list_move(&chunk->list, &pcpu_chunk_lists[slot]);
532 else
533 list_move_tail(&chunk->list, &pcpu_chunk_lists[slot]);
534 }
535}
536
537static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
538{
539 __pcpu_chunk_move(chunk, slot, true);
540}
541
542/**
543 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
544 * @chunk: chunk of interest
545 * @oslot: the previous slot it was on
546 *
547 * This function is called after an allocation or free changed @chunk.
548 * New slot according to the changed state is determined and @chunk is
549 * moved to the slot. Note that the reserved chunk is never put on
550 * chunk slots.
551 *
552 * CONTEXT:
553 * pcpu_lock.
554 */
555static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
556{
557 int nslot = pcpu_chunk_slot(chunk);
558
559 /* leave isolated chunks in-place */
560 if (chunk->isolated)
561 return;
562
563 if (oslot != nslot)
564 __pcpu_chunk_move(chunk, nslot, oslot < nslot);
565}
566
567static void pcpu_isolate_chunk(struct pcpu_chunk *chunk)
568{
569 lockdep_assert_held(&pcpu_lock);
570
571 if (!chunk->isolated) {
572 chunk->isolated = true;
573 pcpu_nr_empty_pop_pages -= chunk->nr_empty_pop_pages;
574 }
575 list_move(&chunk->list, &pcpu_chunk_lists[pcpu_to_depopulate_slot]);
576}
577
578static void pcpu_reintegrate_chunk(struct pcpu_chunk *chunk)
579{
580 lockdep_assert_held(&pcpu_lock);
581
582 if (chunk->isolated) {
583 chunk->isolated = false;
584 pcpu_nr_empty_pop_pages += chunk->nr_empty_pop_pages;
585 pcpu_chunk_relocate(chunk, -1);
586 }
587}
588
589/*
590 * pcpu_update_empty_pages - update empty page counters
591 * @chunk: chunk of interest
592 * @nr: nr of empty pages
593 *
594 * This is used to keep track of the empty pages now based on the premise
595 * a md_block covers a page. The hint update functions recognize if a block
596 * is made full or broken to calculate deltas for keeping track of free pages.
597 */
598static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
599{
600 chunk->nr_empty_pop_pages += nr;
601 if (chunk != pcpu_reserved_chunk && !chunk->isolated)
602 pcpu_nr_empty_pop_pages += nr;
603}
604
605/*
606 * pcpu_region_overlap - determines if two regions overlap
607 * @a: start of first region, inclusive
608 * @b: end of first region, exclusive
609 * @x: start of second region, inclusive
610 * @y: end of second region, exclusive
611 *
612 * This is used to determine if the hint region [a, b) overlaps with the
613 * allocated region [x, y).
614 */
615static inline bool pcpu_region_overlap(int a, int b, int x, int y)
616{
617 return (a < y) && (x < b);
618}
619
620/**
621 * pcpu_block_update - updates a block given a free area
622 * @block: block of interest
623 * @start: start offset in block
624 * @end: end offset in block
625 *
626 * Updates a block given a known free area. The region [start, end) is
627 * expected to be the entirety of the free area within a block. Chooses
628 * the best starting offset if the contig hints are equal.
629 */
630static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
631{
632 int contig = end - start;
633
634 block->first_free = min(block->first_free, start);
635 if (start == 0)
636 block->left_free = contig;
637
638 if (end == block->nr_bits)
639 block->right_free = contig;
640
641 if (contig > block->contig_hint) {
642 /* promote the old contig_hint to be the new scan_hint */
643 if (start > block->contig_hint_start) {
644 if (block->contig_hint > block->scan_hint) {
645 block->scan_hint_start =
646 block->contig_hint_start;
647 block->scan_hint = block->contig_hint;
648 } else if (start < block->scan_hint_start) {
649 /*
650 * The old contig_hint == scan_hint. But, the
651 * new contig is larger so hold the invariant
652 * scan_hint_start < contig_hint_start.
653 */
654 block->scan_hint = 0;
655 }
656 } else {
657 block->scan_hint = 0;
658 }
659 block->contig_hint_start = start;
660 block->contig_hint = contig;
661 } else if (contig == block->contig_hint) {
662 if (block->contig_hint_start &&
663 (!start ||
664 __ffs(start) > __ffs(block->contig_hint_start))) {
665 /* start has a better alignment so use it */
666 block->contig_hint_start = start;
667 if (start < block->scan_hint_start &&
668 block->contig_hint > block->scan_hint)
669 block->scan_hint = 0;
670 } else if (start > block->scan_hint_start ||
671 block->contig_hint > block->scan_hint) {
672 /*
673 * Knowing contig == contig_hint, update the scan_hint
674 * if it is farther than or larger than the current
675 * scan_hint.
676 */
677 block->scan_hint_start = start;
678 block->scan_hint = contig;
679 }
680 } else {
681 /*
682 * The region is smaller than the contig_hint. So only update
683 * the scan_hint if it is larger than or equal and farther than
684 * the current scan_hint.
685 */
686 if ((start < block->contig_hint_start &&
687 (contig > block->scan_hint ||
688 (contig == block->scan_hint &&
689 start > block->scan_hint_start)))) {
690 block->scan_hint_start = start;
691 block->scan_hint = contig;
692 }
693 }
694}
695
696/*
697 * pcpu_block_update_scan - update a block given a free area from a scan
698 * @chunk: chunk of interest
699 * @bit_off: chunk offset
700 * @bits: size of free area
701 *
702 * Finding the final allocation spot first goes through pcpu_find_block_fit()
703 * to find a block that can hold the allocation and then pcpu_alloc_area()
704 * where a scan is used. When allocations require specific alignments,
705 * we can inadvertently create holes which will not be seen in the alloc
706 * or free paths.
707 *
708 * This takes a given free area hole and updates a block as it may change the
709 * scan_hint. We need to scan backwards to ensure we don't miss free bits
710 * from alignment.
711 */
712static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
713 int bits)
714{
715 int s_off = pcpu_off_to_block_off(bit_off);
716 int e_off = s_off + bits;
717 int s_index, l_bit;
718 struct pcpu_block_md *block;
719
720 if (e_off > PCPU_BITMAP_BLOCK_BITS)
721 return;
722
723 s_index = pcpu_off_to_block_index(bit_off);
724 block = chunk->md_blocks + s_index;
725
726 /* scan backwards in case of alignment skipping free bits */
727 l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
728 s_off = (s_off == l_bit) ? 0 : l_bit + 1;
729
730 pcpu_block_update(block, s_off, e_off);
731}
732
733/**
734 * pcpu_chunk_refresh_hint - updates metadata about a chunk
735 * @chunk: chunk of interest
736 * @full_scan: if we should scan from the beginning
737 *
738 * Iterates over the metadata blocks to find the largest contig area.
739 * A full scan can be avoided on the allocation path as this is triggered
740 * if we broke the contig_hint. In doing so, the scan_hint will be before
741 * the contig_hint or after if the scan_hint == contig_hint. This cannot
742 * be prevented on freeing as we want to find the largest area possibly
743 * spanning blocks.
744 */
745static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
746{
747 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
748 int bit_off, bits;
749
750 /* promote scan_hint to contig_hint */
751 if (!full_scan && chunk_md->scan_hint) {
752 bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
753 chunk_md->contig_hint_start = chunk_md->scan_hint_start;
754 chunk_md->contig_hint = chunk_md->scan_hint;
755 chunk_md->scan_hint = 0;
756 } else {
757 bit_off = chunk_md->first_free;
758 chunk_md->contig_hint = 0;
759 }
760
761 bits = 0;
762 pcpu_for_each_md_free_region(chunk, bit_off, bits)
763 pcpu_block_update(chunk_md, bit_off, bit_off + bits);
764}
765
766/**
767 * pcpu_block_refresh_hint
768 * @chunk: chunk of interest
769 * @index: index of the metadata block
770 *
771 * Scans over the block beginning at first_free and updates the block
772 * metadata accordingly.
773 */
774static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
775{
776 struct pcpu_block_md *block = chunk->md_blocks + index;
777 unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
778 unsigned int start, end; /* region start, region end */
779
780 /* promote scan_hint to contig_hint */
781 if (block->scan_hint) {
782 start = block->scan_hint_start + block->scan_hint;
783 block->contig_hint_start = block->scan_hint_start;
784 block->contig_hint = block->scan_hint;
785 block->scan_hint = 0;
786 } else {
787 start = block->first_free;
788 block->contig_hint = 0;
789 }
790
791 block->right_free = 0;
792
793 /* iterate over free areas and update the contig hints */
794 for_each_clear_bitrange_from(start, end, alloc_map, PCPU_BITMAP_BLOCK_BITS)
795 pcpu_block_update(block, start, end);
796}
797
798/**
799 * pcpu_block_update_hint_alloc - update hint on allocation path
800 * @chunk: chunk of interest
801 * @bit_off: chunk offset
802 * @bits: size of request
803 *
804 * Updates metadata for the allocation path. The metadata only has to be
805 * refreshed by a full scan iff the chunk's contig hint is broken. Block level
806 * scans are required if the block's contig hint is broken.
807 */
808static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
809 int bits)
810{
811 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
812 int nr_empty_pages = 0;
813 struct pcpu_block_md *s_block, *e_block, *block;
814 int s_index, e_index; /* block indexes of the freed allocation */
815 int s_off, e_off; /* block offsets of the freed allocation */
816
817 /*
818 * Calculate per block offsets.
819 * The calculation uses an inclusive range, but the resulting offsets
820 * are [start, end). e_index always points to the last block in the
821 * range.
822 */
823 s_index = pcpu_off_to_block_index(bit_off);
824 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
825 s_off = pcpu_off_to_block_off(bit_off);
826 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
827
828 s_block = chunk->md_blocks + s_index;
829 e_block = chunk->md_blocks + e_index;
830
831 /*
832 * Update s_block.
833 */
834 if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
835 nr_empty_pages++;
836
837 /*
838 * block->first_free must be updated if the allocation takes its place.
839 * If the allocation breaks the contig_hint, a scan is required to
840 * restore this hint.
841 */
842 if (s_off == s_block->first_free)
843 s_block->first_free = find_next_zero_bit(
844 pcpu_index_alloc_map(chunk, s_index),
845 PCPU_BITMAP_BLOCK_BITS,
846 s_off + bits);
847
848 if (pcpu_region_overlap(s_block->scan_hint_start,
849 s_block->scan_hint_start + s_block->scan_hint,
850 s_off,
851 s_off + bits))
852 s_block->scan_hint = 0;
853
854 if (pcpu_region_overlap(s_block->contig_hint_start,
855 s_block->contig_hint_start +
856 s_block->contig_hint,
857 s_off,
858 s_off + bits)) {
859 /* block contig hint is broken - scan to fix it */
860 if (!s_off)
861 s_block->left_free = 0;
862 pcpu_block_refresh_hint(chunk, s_index);
863 } else {
864 /* update left and right contig manually */
865 s_block->left_free = min(s_block->left_free, s_off);
866 if (s_index == e_index)
867 s_block->right_free = min_t(int, s_block->right_free,
868 PCPU_BITMAP_BLOCK_BITS - e_off);
869 else
870 s_block->right_free = 0;
871 }
872
873 /*
874 * Update e_block.
875 */
876 if (s_index != e_index) {
877 if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
878 nr_empty_pages++;
879
880 /*
881 * When the allocation is across blocks, the end is along
882 * the left part of the e_block.
883 */
884 e_block->first_free = find_next_zero_bit(
885 pcpu_index_alloc_map(chunk, e_index),
886 PCPU_BITMAP_BLOCK_BITS, e_off);
887
888 if (e_off == PCPU_BITMAP_BLOCK_BITS) {
889 /* reset the block */
890 e_block++;
891 } else {
892 if (e_off > e_block->scan_hint_start)
893 e_block->scan_hint = 0;
894
895 e_block->left_free = 0;
896 if (e_off > e_block->contig_hint_start) {
897 /* contig hint is broken - scan to fix it */
898 pcpu_block_refresh_hint(chunk, e_index);
899 } else {
900 e_block->right_free =
901 min_t(int, e_block->right_free,
902 PCPU_BITMAP_BLOCK_BITS - e_off);
903 }
904 }
905
906 /* update in-between md_blocks */
907 nr_empty_pages += (e_index - s_index - 1);
908 for (block = s_block + 1; block < e_block; block++) {
909 block->scan_hint = 0;
910 block->contig_hint = 0;
911 block->left_free = 0;
912 block->right_free = 0;
913 }
914 }
915
916 /*
917 * If the allocation is not atomic, some blocks may not be
918 * populated with pages, while we account it here. The number
919 * of pages will be added back with pcpu_chunk_populated()
920 * when populating pages.
921 */
922 if (nr_empty_pages)
923 pcpu_update_empty_pages(chunk, -nr_empty_pages);
924
925 if (pcpu_region_overlap(chunk_md->scan_hint_start,
926 chunk_md->scan_hint_start +
927 chunk_md->scan_hint,
928 bit_off,
929 bit_off + bits))
930 chunk_md->scan_hint = 0;
931
932 /*
933 * The only time a full chunk scan is required is if the chunk
934 * contig hint is broken. Otherwise, it means a smaller space
935 * was used and therefore the chunk contig hint is still correct.
936 */
937 if (pcpu_region_overlap(chunk_md->contig_hint_start,
938 chunk_md->contig_hint_start +
939 chunk_md->contig_hint,
940 bit_off,
941 bit_off + bits))
942 pcpu_chunk_refresh_hint(chunk, false);
943}
944
945/**
946 * pcpu_block_update_hint_free - updates the block hints on the free path
947 * @chunk: chunk of interest
948 * @bit_off: chunk offset
949 * @bits: size of request
950 *
951 * Updates metadata for the allocation path. This avoids a blind block
952 * refresh by making use of the block contig hints. If this fails, it scans
953 * forward and backward to determine the extent of the free area. This is
954 * capped at the boundary of blocks.
955 *
956 * A chunk update is triggered if a page becomes free, a block becomes free,
957 * or the free spans across blocks. This tradeoff is to minimize iterating
958 * over the block metadata to update chunk_md->contig_hint.
959 * chunk_md->contig_hint may be off by up to a page, but it will never be more
960 * than the available space. If the contig hint is contained in one block, it
961 * will be accurate.
962 */
963static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
964 int bits)
965{
966 int nr_empty_pages = 0;
967 struct pcpu_block_md *s_block, *e_block, *block;
968 int s_index, e_index; /* block indexes of the freed allocation */
969 int s_off, e_off; /* block offsets of the freed allocation */
970 int start, end; /* start and end of the whole free area */
971
972 /*
973 * Calculate per block offsets.
974 * The calculation uses an inclusive range, but the resulting offsets
975 * are [start, end). e_index always points to the last block in the
976 * range.
977 */
978 s_index = pcpu_off_to_block_index(bit_off);
979 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
980 s_off = pcpu_off_to_block_off(bit_off);
981 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
982
983 s_block = chunk->md_blocks + s_index;
984 e_block = chunk->md_blocks + e_index;
985
986 /*
987 * Check if the freed area aligns with the block->contig_hint.
988 * If it does, then the scan to find the beginning/end of the
989 * larger free area can be avoided.
990 *
991 * start and end refer to beginning and end of the free area
992 * within each their respective blocks. This is not necessarily
993 * the entire free area as it may span blocks past the beginning
994 * or end of the block.
995 */
996 start = s_off;
997 if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
998 start = s_block->contig_hint_start;
999 } else {
1000 /*
1001 * Scan backwards to find the extent of the free area.
1002 * find_last_bit returns the starting bit, so if the start bit
1003 * is returned, that means there was no last bit and the
1004 * remainder of the chunk is free.
1005 */
1006 int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
1007 start);
1008 start = (start == l_bit) ? 0 : l_bit + 1;
1009 }
1010
1011 end = e_off;
1012 if (e_off == e_block->contig_hint_start)
1013 end = e_block->contig_hint_start + e_block->contig_hint;
1014 else
1015 end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
1016 PCPU_BITMAP_BLOCK_BITS, end);
1017
1018 /* update s_block */
1019 e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
1020 if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
1021 nr_empty_pages++;
1022 pcpu_block_update(s_block, start, e_off);
1023
1024 /* freeing in the same block */
1025 if (s_index != e_index) {
1026 /* update e_block */
1027 if (end == PCPU_BITMAP_BLOCK_BITS)
1028 nr_empty_pages++;
1029 pcpu_block_update(e_block, 0, end);
1030
1031 /* reset md_blocks in the middle */
1032 nr_empty_pages += (e_index - s_index - 1);
1033 for (block = s_block + 1; block < e_block; block++) {
1034 block->first_free = 0;
1035 block->scan_hint = 0;
1036 block->contig_hint_start = 0;
1037 block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
1038 block->left_free = PCPU_BITMAP_BLOCK_BITS;
1039 block->right_free = PCPU_BITMAP_BLOCK_BITS;
1040 }
1041 }
1042
1043 if (nr_empty_pages)
1044 pcpu_update_empty_pages(chunk, nr_empty_pages);
1045
1046 /*
1047 * Refresh chunk metadata when the free makes a block free or spans
1048 * across blocks. The contig_hint may be off by up to a page, but if
1049 * the contig_hint is contained in a block, it will be accurate with
1050 * the else condition below.
1051 */
1052 if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1053 pcpu_chunk_refresh_hint(chunk, true);
1054 else
1055 pcpu_block_update(&chunk->chunk_md,
1056 pcpu_block_off_to_off(s_index, start),
1057 end);
1058}
1059
1060/**
1061 * pcpu_is_populated - determines if the region is populated
1062 * @chunk: chunk of interest
1063 * @bit_off: chunk offset
1064 * @bits: size of area
1065 * @next_off: return value for the next offset to start searching
1066 *
1067 * For atomic allocations, check if the backing pages are populated.
1068 *
1069 * RETURNS:
1070 * Bool if the backing pages are populated.
1071 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1072 */
1073static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1074 int *next_off)
1075{
1076 unsigned int start, end;
1077
1078 start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1079 end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1080
1081 start = find_next_zero_bit(chunk->populated, end, start);
1082 if (start >= end)
1083 return true;
1084
1085 end = find_next_bit(chunk->populated, end, start + 1);
1086
1087 *next_off = end * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1088 return false;
1089}
1090
1091/**
1092 * pcpu_find_block_fit - finds the block index to start searching
1093 * @chunk: chunk of interest
1094 * @alloc_bits: size of request in allocation units
1095 * @align: alignment of area (max PAGE_SIZE bytes)
1096 * @pop_only: use populated regions only
1097 *
1098 * Given a chunk and an allocation spec, find the offset to begin searching
1099 * for a free region. This iterates over the bitmap metadata blocks to
1100 * find an offset that will be guaranteed to fit the requirements. It is
1101 * not quite first fit as if the allocation does not fit in the contig hint
1102 * of a block or chunk, it is skipped. This errs on the side of caution
1103 * to prevent excess iteration. Poor alignment can cause the allocator to
1104 * skip over blocks and chunks that have valid free areas.
1105 *
1106 * RETURNS:
1107 * The offset in the bitmap to begin searching.
1108 * -1 if no offset is found.
1109 */
1110static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1111 size_t align, bool pop_only)
1112{
1113 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1114 int bit_off, bits, next_off;
1115
1116 /*
1117 * This is an optimization to prevent scanning by assuming if the
1118 * allocation cannot fit in the global hint, there is memory pressure
1119 * and creating a new chunk would happen soon.
1120 */
1121 if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
1122 return -1;
1123
1124 bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1125 bits = 0;
1126 pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1127 if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1128 &next_off))
1129 break;
1130
1131 bit_off = next_off;
1132 bits = 0;
1133 }
1134
1135 if (bit_off == pcpu_chunk_map_bits(chunk))
1136 return -1;
1137
1138 return bit_off;
1139}
1140
1141/*
1142 * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1143 * @map: the address to base the search on
1144 * @size: the bitmap size in bits
1145 * @start: the bitnumber to start searching at
1146 * @nr: the number of zeroed bits we're looking for
1147 * @align_mask: alignment mask for zero area
1148 * @largest_off: offset of the largest area skipped
1149 * @largest_bits: size of the largest area skipped
1150 *
1151 * The @align_mask should be one less than a power of 2.
1152 *
1153 * This is a modified version of bitmap_find_next_zero_area_off() to remember
1154 * the largest area that was skipped. This is imperfect, but in general is
1155 * good enough. The largest remembered region is the largest failed region
1156 * seen. This does not include anything we possibly skipped due to alignment.
1157 * pcpu_block_update_scan() does scan backwards to try and recover what was
1158 * lost to alignment. While this can cause scanning to miss earlier possible
1159 * free areas, smaller allocations will eventually fill those holes.
1160 */
1161static unsigned long pcpu_find_zero_area(unsigned long *map,
1162 unsigned long size,
1163 unsigned long start,
1164 unsigned long nr,
1165 unsigned long align_mask,
1166 unsigned long *largest_off,
1167 unsigned long *largest_bits)
1168{
1169 unsigned long index, end, i, area_off, area_bits;
1170again:
1171 index = find_next_zero_bit(map, size, start);
1172
1173 /* Align allocation */
1174 index = __ALIGN_MASK(index, align_mask);
1175 area_off = index;
1176
1177 end = index + nr;
1178 if (end > size)
1179 return end;
1180 i = find_next_bit(map, end, index);
1181 if (i < end) {
1182 area_bits = i - area_off;
1183 /* remember largest unused area with best alignment */
1184 if (area_bits > *largest_bits ||
1185 (area_bits == *largest_bits && *largest_off &&
1186 (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1187 *largest_off = area_off;
1188 *largest_bits = area_bits;
1189 }
1190
1191 start = i + 1;
1192 goto again;
1193 }
1194 return index;
1195}
1196
1197/**
1198 * pcpu_alloc_area - allocates an area from a pcpu_chunk
1199 * @chunk: chunk of interest
1200 * @alloc_bits: size of request in allocation units
1201 * @align: alignment of area (max PAGE_SIZE)
1202 * @start: bit_off to start searching
1203 *
1204 * This function takes in a @start offset to begin searching to fit an
1205 * allocation of @alloc_bits with alignment @align. It needs to scan
1206 * the allocation map because if it fits within the block's contig hint,
1207 * @start will be block->first_free. This is an attempt to fill the
1208 * allocation prior to breaking the contig hint. The allocation and
1209 * boundary maps are updated accordingly if it confirms a valid
1210 * free area.
1211 *
1212 * RETURNS:
1213 * Allocated addr offset in @chunk on success.
1214 * -1 if no matching area is found.
1215 */
1216static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1217 size_t align, int start)
1218{
1219 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1220 size_t align_mask = (align) ? (align - 1) : 0;
1221 unsigned long area_off = 0, area_bits = 0;
1222 int bit_off, end, oslot;
1223
1224 lockdep_assert_held(&pcpu_lock);
1225
1226 oslot = pcpu_chunk_slot(chunk);
1227
1228 /*
1229 * Search to find a fit.
1230 */
1231 end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1232 pcpu_chunk_map_bits(chunk));
1233 bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1234 align_mask, &area_off, &area_bits);
1235 if (bit_off >= end)
1236 return -1;
1237
1238 if (area_bits)
1239 pcpu_block_update_scan(chunk, area_off, area_bits);
1240
1241 /* update alloc map */
1242 bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1243
1244 /* update boundary map */
1245 set_bit(bit_off, chunk->bound_map);
1246 bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1247 set_bit(bit_off + alloc_bits, chunk->bound_map);
1248
1249 chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1250
1251 /* update first free bit */
1252 if (bit_off == chunk_md->first_free)
1253 chunk_md->first_free = find_next_zero_bit(
1254 chunk->alloc_map,
1255 pcpu_chunk_map_bits(chunk),
1256 bit_off + alloc_bits);
1257
1258 pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1259
1260 pcpu_chunk_relocate(chunk, oslot);
1261
1262 return bit_off * PCPU_MIN_ALLOC_SIZE;
1263}
1264
1265/**
1266 * pcpu_free_area - frees the corresponding offset
1267 * @chunk: chunk of interest
1268 * @off: addr offset into chunk
1269 *
1270 * This function determines the size of an allocation to free using
1271 * the boundary bitmap and clears the allocation map.
1272 *
1273 * RETURNS:
1274 * Number of freed bytes.
1275 */
1276static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
1277{
1278 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1279 int bit_off, bits, end, oslot, freed;
1280
1281 lockdep_assert_held(&pcpu_lock);
1282 pcpu_stats_area_dealloc(chunk);
1283
1284 oslot = pcpu_chunk_slot(chunk);
1285
1286 bit_off = off / PCPU_MIN_ALLOC_SIZE;
1287
1288 /* find end index */
1289 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1290 bit_off + 1);
1291 bits = end - bit_off;
1292 bitmap_clear(chunk->alloc_map, bit_off, bits);
1293
1294 freed = bits * PCPU_MIN_ALLOC_SIZE;
1295
1296 /* update metadata */
1297 chunk->free_bytes += freed;
1298
1299 /* update first free bit */
1300 chunk_md->first_free = min(chunk_md->first_free, bit_off);
1301
1302 pcpu_block_update_hint_free(chunk, bit_off, bits);
1303
1304 pcpu_chunk_relocate(chunk, oslot);
1305
1306 return freed;
1307}
1308
1309static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1310{
1311 block->scan_hint = 0;
1312 block->contig_hint = nr_bits;
1313 block->left_free = nr_bits;
1314 block->right_free = nr_bits;
1315 block->first_free = 0;
1316 block->nr_bits = nr_bits;
1317}
1318
1319static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1320{
1321 struct pcpu_block_md *md_block;
1322
1323 /* init the chunk's block */
1324 pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1325
1326 for (md_block = chunk->md_blocks;
1327 md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1328 md_block++)
1329 pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1330}
1331
1332/**
1333 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1334 * @tmp_addr: the start of the region served
1335 * @map_size: size of the region served
1336 *
1337 * This is responsible for creating the chunks that serve the first chunk. The
1338 * base_addr is page aligned down of @tmp_addr while the region end is page
1339 * aligned up. Offsets are kept track of to determine the region served. All
1340 * this is done to appease the bitmap allocator in avoiding partial blocks.
1341 *
1342 * RETURNS:
1343 * Chunk serving the region at @tmp_addr of @map_size.
1344 */
1345static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1346 int map_size)
1347{
1348 struct pcpu_chunk *chunk;
1349 unsigned long aligned_addr;
1350 int start_offset, offset_bits, region_size, region_bits;
1351 size_t alloc_size;
1352
1353 /* region calculations */
1354 aligned_addr = tmp_addr & PAGE_MASK;
1355
1356 start_offset = tmp_addr - aligned_addr;
1357 region_size = ALIGN(start_offset + map_size, PAGE_SIZE);
1358
1359 /* allocate chunk */
1360 alloc_size = struct_size(chunk, populated,
1361 BITS_TO_LONGS(region_size >> PAGE_SHIFT));
1362 chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1363 if (!chunk)
1364 panic("%s: Failed to allocate %zu bytes\n", __func__,
1365 alloc_size);
1366
1367 INIT_LIST_HEAD(&chunk->list);
1368
1369 chunk->base_addr = (void *)aligned_addr;
1370 chunk->start_offset = start_offset;
1371 chunk->end_offset = region_size - chunk->start_offset - map_size;
1372
1373 chunk->nr_pages = region_size >> PAGE_SHIFT;
1374 region_bits = pcpu_chunk_map_bits(chunk);
1375
1376 alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1377 chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1378 if (!chunk->alloc_map)
1379 panic("%s: Failed to allocate %zu bytes\n", __func__,
1380 alloc_size);
1381
1382 alloc_size =
1383 BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1384 chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1385 if (!chunk->bound_map)
1386 panic("%s: Failed to allocate %zu bytes\n", __func__,
1387 alloc_size);
1388
1389 alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1390 chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1391 if (!chunk->md_blocks)
1392 panic("%s: Failed to allocate %zu bytes\n", __func__,
1393 alloc_size);
1394
1395#ifdef NEED_PCPUOBJ_EXT
1396 /* first chunk is free to use */
1397 chunk->obj_exts = NULL;
1398#endif
1399 pcpu_init_md_blocks(chunk);
1400
1401 /* manage populated page bitmap */
1402 chunk->immutable = true;
1403 bitmap_fill(chunk->populated, chunk->nr_pages);
1404 chunk->nr_populated = chunk->nr_pages;
1405 chunk->nr_empty_pop_pages = chunk->nr_pages;
1406
1407 chunk->free_bytes = map_size;
1408
1409 if (chunk->start_offset) {
1410 /* hide the beginning of the bitmap */
1411 offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1412 bitmap_set(chunk->alloc_map, 0, offset_bits);
1413 set_bit(0, chunk->bound_map);
1414 set_bit(offset_bits, chunk->bound_map);
1415
1416 chunk->chunk_md.first_free = offset_bits;
1417
1418 pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1419 }
1420
1421 if (chunk->end_offset) {
1422 /* hide the end of the bitmap */
1423 offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1424 bitmap_set(chunk->alloc_map,
1425 pcpu_chunk_map_bits(chunk) - offset_bits,
1426 offset_bits);
1427 set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1428 chunk->bound_map);
1429 set_bit(region_bits, chunk->bound_map);
1430
1431 pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1432 - offset_bits, offset_bits);
1433 }
1434
1435 return chunk;
1436}
1437
1438static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
1439{
1440 struct pcpu_chunk *chunk;
1441 int region_bits;
1442
1443 chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1444 if (!chunk)
1445 return NULL;
1446
1447 INIT_LIST_HEAD(&chunk->list);
1448 chunk->nr_pages = pcpu_unit_pages;
1449 region_bits = pcpu_chunk_map_bits(chunk);
1450
1451 chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1452 sizeof(chunk->alloc_map[0]), gfp);
1453 if (!chunk->alloc_map)
1454 goto alloc_map_fail;
1455
1456 chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1457 sizeof(chunk->bound_map[0]), gfp);
1458 if (!chunk->bound_map)
1459 goto bound_map_fail;
1460
1461 chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1462 sizeof(chunk->md_blocks[0]), gfp);
1463 if (!chunk->md_blocks)
1464 goto md_blocks_fail;
1465
1466#ifdef NEED_PCPUOBJ_EXT
1467 if (need_pcpuobj_ext()) {
1468 chunk->obj_exts =
1469 pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
1470 sizeof(struct pcpuobj_ext), gfp);
1471 if (!chunk->obj_exts)
1472 goto objcg_fail;
1473 }
1474#endif
1475
1476 pcpu_init_md_blocks(chunk);
1477
1478 /* init metadata */
1479 chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1480
1481 return chunk;
1482
1483#ifdef NEED_PCPUOBJ_EXT
1484objcg_fail:
1485 pcpu_mem_free(chunk->md_blocks);
1486#endif
1487md_blocks_fail:
1488 pcpu_mem_free(chunk->bound_map);
1489bound_map_fail:
1490 pcpu_mem_free(chunk->alloc_map);
1491alloc_map_fail:
1492 pcpu_mem_free(chunk);
1493
1494 return NULL;
1495}
1496
1497static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1498{
1499 if (!chunk)
1500 return;
1501#ifdef NEED_PCPUOBJ_EXT
1502 pcpu_mem_free(chunk->obj_exts);
1503#endif
1504 pcpu_mem_free(chunk->md_blocks);
1505 pcpu_mem_free(chunk->bound_map);
1506 pcpu_mem_free(chunk->alloc_map);
1507 pcpu_mem_free(chunk);
1508}
1509
1510/**
1511 * pcpu_chunk_populated - post-population bookkeeping
1512 * @chunk: pcpu_chunk which got populated
1513 * @page_start: the start page
1514 * @page_end: the end page
1515 *
1516 * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1517 * the bookkeeping information accordingly. Must be called after each
1518 * successful population.
1519 */
1520static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1521 int page_end)
1522{
1523 int nr = page_end - page_start;
1524
1525 lockdep_assert_held(&pcpu_lock);
1526
1527 bitmap_set(chunk->populated, page_start, nr);
1528 chunk->nr_populated += nr;
1529 pcpu_nr_populated += nr;
1530
1531 pcpu_update_empty_pages(chunk, nr);
1532}
1533
1534/**
1535 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1536 * @chunk: pcpu_chunk which got depopulated
1537 * @page_start: the start page
1538 * @page_end: the end page
1539 *
1540 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1541 * Update the bookkeeping information accordingly. Must be called after
1542 * each successful depopulation.
1543 */
1544static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1545 int page_start, int page_end)
1546{
1547 int nr = page_end - page_start;
1548
1549 lockdep_assert_held(&pcpu_lock);
1550
1551 bitmap_clear(chunk->populated, page_start, nr);
1552 chunk->nr_populated -= nr;
1553 pcpu_nr_populated -= nr;
1554
1555 pcpu_update_empty_pages(chunk, -nr);
1556}
1557
1558/*
1559 * Chunk management implementation.
1560 *
1561 * To allow different implementations, chunk alloc/free and
1562 * [de]population are implemented in a separate file which is pulled
1563 * into this file and compiled together. The following functions
1564 * should be implemented.
1565 *
1566 * pcpu_populate_chunk - populate the specified range of a chunk
1567 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1568 * pcpu_post_unmap_tlb_flush - flush tlb for the specified range of a chunk
1569 * pcpu_create_chunk - create a new chunk
1570 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1571 * pcpu_addr_to_page - translate address to physical address
1572 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1573 */
1574static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1575 int page_start, int page_end, gfp_t gfp);
1576static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1577 int page_start, int page_end);
1578static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
1579 int page_start, int page_end);
1580static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
1581static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1582static struct page *pcpu_addr_to_page(void *addr);
1583static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1584
1585#ifdef CONFIG_NEED_PER_CPU_KM
1586#include "percpu-km.c"
1587#else
1588#include "percpu-vm.c"
1589#endif
1590
1591/**
1592 * pcpu_chunk_addr_search - determine chunk containing specified address
1593 * @addr: address for which the chunk needs to be determined.
1594 *
1595 * This is an internal function that handles all but static allocations.
1596 * Static percpu address values should never be passed into the allocator.
1597 *
1598 * RETURNS:
1599 * The address of the found chunk.
1600 */
1601static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1602{
1603 /* is it in the dynamic region (first chunk)? */
1604 if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1605 return pcpu_first_chunk;
1606
1607 /* is it in the reserved region? */
1608 if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1609 return pcpu_reserved_chunk;
1610
1611 /*
1612 * The address is relative to unit0 which might be unused and
1613 * thus unmapped. Offset the address to the unit space of the
1614 * current processor before looking it up in the vmalloc
1615 * space. Note that any possible cpu id can be used here, so
1616 * there's no need to worry about preemption or cpu hotplug.
1617 */
1618 addr += pcpu_unit_offsets[raw_smp_processor_id()];
1619 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1620}
1621
1622#ifdef CONFIG_MEMCG
1623static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
1624 struct obj_cgroup **objcgp)
1625{
1626 struct obj_cgroup *objcg;
1627
1628 if (!memcg_kmem_online() || !(gfp & __GFP_ACCOUNT))
1629 return true;
1630
1631 objcg = current_obj_cgroup();
1632 if (!objcg)
1633 return true;
1634
1635 if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size)))
1636 return false;
1637
1638 *objcgp = objcg;
1639 return true;
1640}
1641
1642static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1643 struct pcpu_chunk *chunk, int off,
1644 size_t size)
1645{
1646 if (!objcg)
1647 return;
1648
1649 if (likely(chunk && chunk->obj_exts)) {
1650 obj_cgroup_get(objcg);
1651 chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = objcg;
1652
1653 rcu_read_lock();
1654 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1655 pcpu_obj_full_size(size));
1656 rcu_read_unlock();
1657 } else {
1658 obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
1659 }
1660}
1661
1662static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1663{
1664 struct obj_cgroup *objcg;
1665
1666 if (unlikely(!chunk->obj_exts))
1667 return;
1668
1669 objcg = chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup;
1670 if (!objcg)
1671 return;
1672 chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = NULL;
1673
1674 obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
1675
1676 rcu_read_lock();
1677 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1678 -pcpu_obj_full_size(size));
1679 rcu_read_unlock();
1680
1681 obj_cgroup_put(objcg);
1682}
1683
1684#else /* CONFIG_MEMCG */
1685static bool
1686pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
1687{
1688 return true;
1689}
1690
1691static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1692 struct pcpu_chunk *chunk, int off,
1693 size_t size)
1694{
1695}
1696
1697static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1698{
1699}
1700#endif /* CONFIG_MEMCG */
1701
1702#ifdef CONFIG_MEM_ALLOC_PROFILING
1703static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk *chunk, int off,
1704 size_t size)
1705{
1706 if (mem_alloc_profiling_enabled() && likely(chunk->obj_exts)) {
1707 alloc_tag_add(&chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].tag,
1708 current->alloc_tag, size);
1709 }
1710}
1711
1712static void pcpu_alloc_tag_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1713{
1714 if (mem_alloc_profiling_enabled() && likely(chunk->obj_exts))
1715 alloc_tag_sub(&chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].tag, size);
1716}
1717#else
1718static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk *chunk, int off,
1719 size_t size)
1720{
1721}
1722
1723static void pcpu_alloc_tag_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1724{
1725}
1726#endif
1727
1728/**
1729 * pcpu_alloc - the percpu allocator
1730 * @size: size of area to allocate in bytes
1731 * @align: alignment of area (max PAGE_SIZE)
1732 * @reserved: allocate from the reserved chunk if available
1733 * @gfp: allocation flags
1734 *
1735 * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1736 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1737 * then no warning will be triggered on invalid or failed allocation
1738 * requests.
1739 *
1740 * RETURNS:
1741 * Percpu pointer to the allocated area on success, NULL on failure.
1742 */
1743void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
1744 gfp_t gfp)
1745{
1746 gfp_t pcpu_gfp;
1747 bool is_atomic;
1748 bool do_warn;
1749 struct obj_cgroup *objcg = NULL;
1750 static int warn_limit = 10;
1751 struct pcpu_chunk *chunk, *next;
1752 const char *err;
1753 int slot, off, cpu, ret;
1754 unsigned long flags;
1755 void __percpu *ptr;
1756 size_t bits, bit_align;
1757
1758 gfp = current_gfp_context(gfp);
1759 /* whitelisted flags that can be passed to the backing allocators */
1760 pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1761 is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1762 do_warn = !(gfp & __GFP_NOWARN);
1763
1764 /*
1765 * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1766 * therefore alignment must be a minimum of that many bytes.
1767 * An allocation may have internal fragmentation from rounding up
1768 * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1769 */
1770 if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1771 align = PCPU_MIN_ALLOC_SIZE;
1772
1773 size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1774 bits = size >> PCPU_MIN_ALLOC_SHIFT;
1775 bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1776
1777 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1778 !is_power_of_2(align))) {
1779 WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1780 size, align);
1781 return NULL;
1782 }
1783
1784 if (unlikely(!pcpu_memcg_pre_alloc_hook(size, gfp, &objcg)))
1785 return NULL;
1786
1787 if (!is_atomic) {
1788 /*
1789 * pcpu_balance_workfn() allocates memory under this mutex,
1790 * and it may wait for memory reclaim. Allow current task
1791 * to become OOM victim, in case of memory pressure.
1792 */
1793 if (gfp & __GFP_NOFAIL) {
1794 mutex_lock(&pcpu_alloc_mutex);
1795 } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
1796 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1797 return NULL;
1798 }
1799 }
1800
1801 spin_lock_irqsave(&pcpu_lock, flags);
1802
1803 /* serve reserved allocations from the reserved chunk if available */
1804 if (reserved && pcpu_reserved_chunk) {
1805 chunk = pcpu_reserved_chunk;
1806
1807 off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1808 if (off < 0) {
1809 err = "alloc from reserved chunk failed";
1810 goto fail_unlock;
1811 }
1812
1813 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1814 if (off >= 0)
1815 goto area_found;
1816
1817 err = "alloc from reserved chunk failed";
1818 goto fail_unlock;
1819 }
1820
1821restart:
1822 /* search through normal chunks */
1823 for (slot = pcpu_size_to_slot(size); slot <= pcpu_free_slot; slot++) {
1824 list_for_each_entry_safe(chunk, next, &pcpu_chunk_lists[slot],
1825 list) {
1826 off = pcpu_find_block_fit(chunk, bits, bit_align,
1827 is_atomic);
1828 if (off < 0) {
1829 if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1830 pcpu_chunk_move(chunk, 0);
1831 continue;
1832 }
1833
1834 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1835 if (off >= 0) {
1836 pcpu_reintegrate_chunk(chunk);
1837 goto area_found;
1838 }
1839 }
1840 }
1841
1842 spin_unlock_irqrestore(&pcpu_lock, flags);
1843
1844 if (is_atomic) {
1845 err = "atomic alloc failed, no space left";
1846 goto fail;
1847 }
1848
1849 /* No space left. Create a new chunk. */
1850 if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
1851 chunk = pcpu_create_chunk(pcpu_gfp);
1852 if (!chunk) {
1853 err = "failed to allocate new chunk";
1854 goto fail;
1855 }
1856
1857 spin_lock_irqsave(&pcpu_lock, flags);
1858 pcpu_chunk_relocate(chunk, -1);
1859 } else {
1860 spin_lock_irqsave(&pcpu_lock, flags);
1861 }
1862
1863 goto restart;
1864
1865area_found:
1866 pcpu_stats_area_alloc(chunk, size);
1867
1868 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1869 pcpu_schedule_balance_work();
1870
1871 spin_unlock_irqrestore(&pcpu_lock, flags);
1872
1873 /* populate if not all pages are already there */
1874 if (!is_atomic) {
1875 unsigned int page_end, rs, re;
1876
1877 rs = PFN_DOWN(off);
1878 page_end = PFN_UP(off + size);
1879
1880 for_each_clear_bitrange_from(rs, re, chunk->populated, page_end) {
1881 WARN_ON(chunk->immutable);
1882
1883 ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1884
1885 spin_lock_irqsave(&pcpu_lock, flags);
1886 if (ret) {
1887 pcpu_free_area(chunk, off);
1888 err = "failed to populate";
1889 goto fail_unlock;
1890 }
1891 pcpu_chunk_populated(chunk, rs, re);
1892 spin_unlock_irqrestore(&pcpu_lock, flags);
1893 }
1894
1895 mutex_unlock(&pcpu_alloc_mutex);
1896 }
1897
1898 /* clear the areas and return address relative to base address */
1899 for_each_possible_cpu(cpu)
1900 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1901
1902 ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1903 kmemleak_alloc_percpu(ptr, size, gfp);
1904
1905 trace_percpu_alloc_percpu(_RET_IP_, reserved, is_atomic, size, align,
1906 chunk->base_addr, off, ptr,
1907 pcpu_obj_full_size(size), gfp);
1908
1909 pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
1910
1911 pcpu_alloc_tag_alloc_hook(chunk, off, size);
1912
1913 return ptr;
1914
1915fail_unlock:
1916 spin_unlock_irqrestore(&pcpu_lock, flags);
1917fail:
1918 trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1919
1920 if (do_warn && warn_limit) {
1921 pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1922 size, align, is_atomic, err);
1923 if (!is_atomic)
1924 dump_stack();
1925 if (!--warn_limit)
1926 pr_info("limit reached, disable warning\n");
1927 }
1928
1929 if (is_atomic) {
1930 /* see the flag handling in pcpu_balance_workfn() */
1931 pcpu_atomic_alloc_failed = true;
1932 pcpu_schedule_balance_work();
1933 } else {
1934 mutex_unlock(&pcpu_alloc_mutex);
1935 }
1936
1937 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1938
1939 return NULL;
1940}
1941EXPORT_SYMBOL_GPL(pcpu_alloc_noprof);
1942
1943/**
1944 * pcpu_balance_free - manage the amount of free chunks
1945 * @empty_only: free chunks only if there are no populated pages
1946 *
1947 * If empty_only is %false, reclaim all fully free chunks regardless of the
1948 * number of populated pages. Otherwise, only reclaim chunks that have no
1949 * populated pages.
1950 *
1951 * CONTEXT:
1952 * pcpu_lock (can be dropped temporarily)
1953 */
1954static void pcpu_balance_free(bool empty_only)
1955{
1956 LIST_HEAD(to_free);
1957 struct list_head *free_head = &pcpu_chunk_lists[pcpu_free_slot];
1958 struct pcpu_chunk *chunk, *next;
1959
1960 lockdep_assert_held(&pcpu_lock);
1961
1962 /*
1963 * There's no reason to keep around multiple unused chunks and VM
1964 * areas can be scarce. Destroy all free chunks except for one.
1965 */
1966 list_for_each_entry_safe(chunk, next, free_head, list) {
1967 WARN_ON(chunk->immutable);
1968
1969 /* spare the first one */
1970 if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1971 continue;
1972
1973 if (!empty_only || chunk->nr_empty_pop_pages == 0)
1974 list_move(&chunk->list, &to_free);
1975 }
1976
1977 if (list_empty(&to_free))
1978 return;
1979
1980 spin_unlock_irq(&pcpu_lock);
1981 list_for_each_entry_safe(chunk, next, &to_free, list) {
1982 unsigned int rs, re;
1983
1984 for_each_set_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
1985 pcpu_depopulate_chunk(chunk, rs, re);
1986 spin_lock_irq(&pcpu_lock);
1987 pcpu_chunk_depopulated(chunk, rs, re);
1988 spin_unlock_irq(&pcpu_lock);
1989 }
1990 pcpu_destroy_chunk(chunk);
1991 cond_resched();
1992 }
1993 spin_lock_irq(&pcpu_lock);
1994}
1995
1996/**
1997 * pcpu_balance_populated - manage the amount of populated pages
1998 *
1999 * Maintain a certain amount of populated pages to satisfy atomic allocations.
2000 * It is possible that this is called when physical memory is scarce causing
2001 * OOM killer to be triggered. We should avoid doing so until an actual
2002 * allocation causes the failure as it is possible that requests can be
2003 * serviced from already backed regions.
2004 *
2005 * CONTEXT:
2006 * pcpu_lock (can be dropped temporarily)
2007 */
2008static void pcpu_balance_populated(void)
2009{
2010 /* gfp flags passed to underlying allocators */
2011 const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
2012 struct pcpu_chunk *chunk;
2013 int slot, nr_to_pop, ret;
2014
2015 lockdep_assert_held(&pcpu_lock);
2016
2017 /*
2018 * Ensure there are certain number of free populated pages for
2019 * atomic allocs. Fill up from the most packed so that atomic
2020 * allocs don't increase fragmentation. If atomic allocation
2021 * failed previously, always populate the maximum amount. This
2022 * should prevent atomic allocs larger than PAGE_SIZE from keeping
2023 * failing indefinitely; however, large atomic allocs are not
2024 * something we support properly and can be highly unreliable and
2025 * inefficient.
2026 */
2027retry_pop:
2028 if (pcpu_atomic_alloc_failed) {
2029 nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
2030 /* best effort anyway, don't worry about synchronization */
2031 pcpu_atomic_alloc_failed = false;
2032 } else {
2033 nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
2034 pcpu_nr_empty_pop_pages,
2035 0, PCPU_EMPTY_POP_PAGES_HIGH);
2036 }
2037
2038 for (slot = pcpu_size_to_slot(PAGE_SIZE); slot <= pcpu_free_slot; slot++) {
2039 unsigned int nr_unpop = 0, rs, re;
2040
2041 if (!nr_to_pop)
2042 break;
2043
2044 list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) {
2045 nr_unpop = chunk->nr_pages - chunk->nr_populated;
2046 if (nr_unpop)
2047 break;
2048 }
2049
2050 if (!nr_unpop)
2051 continue;
2052
2053 /* @chunk can't go away while pcpu_alloc_mutex is held */
2054 for_each_clear_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
2055 int nr = min_t(int, re - rs, nr_to_pop);
2056
2057 spin_unlock_irq(&pcpu_lock);
2058 ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
2059 cond_resched();
2060 spin_lock_irq(&pcpu_lock);
2061 if (!ret) {
2062 nr_to_pop -= nr;
2063 pcpu_chunk_populated(chunk, rs, rs + nr);
2064 } else {
2065 nr_to_pop = 0;
2066 }
2067
2068 if (!nr_to_pop)
2069 break;
2070 }
2071 }
2072
2073 if (nr_to_pop) {
2074 /* ran out of chunks to populate, create a new one and retry */
2075 spin_unlock_irq(&pcpu_lock);
2076 chunk = pcpu_create_chunk(gfp);
2077 cond_resched();
2078 spin_lock_irq(&pcpu_lock);
2079 if (chunk) {
2080 pcpu_chunk_relocate(chunk, -1);
2081 goto retry_pop;
2082 }
2083 }
2084}
2085
2086/**
2087 * pcpu_reclaim_populated - scan over to_depopulate chunks and free empty pages
2088 *
2089 * Scan over chunks in the depopulate list and try to release unused populated
2090 * pages back to the system. Depopulated chunks are sidelined to prevent
2091 * repopulating these pages unless required. Fully free chunks are reintegrated
2092 * and freed accordingly (1 is kept around). If we drop below the empty
2093 * populated pages threshold, reintegrate the chunk if it has empty free pages.
2094 * Each chunk is scanned in the reverse order to keep populated pages close to
2095 * the beginning of the chunk.
2096 *
2097 * CONTEXT:
2098 * pcpu_lock (can be dropped temporarily)
2099 *
2100 */
2101static void pcpu_reclaim_populated(void)
2102{
2103 struct pcpu_chunk *chunk;
2104 struct pcpu_block_md *block;
2105 int freed_page_start, freed_page_end;
2106 int i, end;
2107 bool reintegrate;
2108
2109 lockdep_assert_held(&pcpu_lock);
2110
2111 /*
2112 * Once a chunk is isolated to the to_depopulate list, the chunk is no
2113 * longer discoverable to allocations whom may populate pages. The only
2114 * other accessor is the free path which only returns area back to the
2115 * allocator not touching the populated bitmap.
2116 */
2117 while ((chunk = list_first_entry_or_null(
2118 &pcpu_chunk_lists[pcpu_to_depopulate_slot],
2119 struct pcpu_chunk, list))) {
2120 WARN_ON(chunk->immutable);
2121
2122 /*
2123 * Scan chunk's pages in the reverse order to keep populated
2124 * pages close to the beginning of the chunk.
2125 */
2126 freed_page_start = chunk->nr_pages;
2127 freed_page_end = 0;
2128 reintegrate = false;
2129 for (i = chunk->nr_pages - 1, end = -1; i >= 0; i--) {
2130 /* no more work to do */
2131 if (chunk->nr_empty_pop_pages == 0)
2132 break;
2133
2134 /* reintegrate chunk to prevent atomic alloc failures */
2135 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_HIGH) {
2136 reintegrate = true;
2137 break;
2138 }
2139
2140 /*
2141 * If the page is empty and populated, start or
2142 * extend the (i, end) range. If i == 0, decrease
2143 * i and perform the depopulation to cover the last
2144 * (first) page in the chunk.
2145 */
2146 block = chunk->md_blocks + i;
2147 if (block->contig_hint == PCPU_BITMAP_BLOCK_BITS &&
2148 test_bit(i, chunk->populated)) {
2149 if (end == -1)
2150 end = i;
2151 if (i > 0)
2152 continue;
2153 i--;
2154 }
2155
2156 /* depopulate if there is an active range */
2157 if (end == -1)
2158 continue;
2159
2160 spin_unlock_irq(&pcpu_lock);
2161 pcpu_depopulate_chunk(chunk, i + 1, end + 1);
2162 cond_resched();
2163 spin_lock_irq(&pcpu_lock);
2164
2165 pcpu_chunk_depopulated(chunk, i + 1, end + 1);
2166 freed_page_start = min(freed_page_start, i + 1);
2167 freed_page_end = max(freed_page_end, end + 1);
2168
2169 /* reset the range and continue */
2170 end = -1;
2171 }
2172
2173 /* batch tlb flush per chunk to amortize cost */
2174 if (freed_page_start < freed_page_end) {
2175 spin_unlock_irq(&pcpu_lock);
2176 pcpu_post_unmap_tlb_flush(chunk,
2177 freed_page_start,
2178 freed_page_end);
2179 cond_resched();
2180 spin_lock_irq(&pcpu_lock);
2181 }
2182
2183 if (reintegrate || chunk->free_bytes == pcpu_unit_size)
2184 pcpu_reintegrate_chunk(chunk);
2185 else
2186 list_move_tail(&chunk->list,
2187 &pcpu_chunk_lists[pcpu_sidelined_slot]);
2188 }
2189}
2190
2191/**
2192 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
2193 * @work: unused
2194 *
2195 * For each chunk type, manage the number of fully free chunks and the number of
2196 * populated pages. An important thing to consider is when pages are freed and
2197 * how they contribute to the global counts.
2198 */
2199static void pcpu_balance_workfn(struct work_struct *work)
2200{
2201 /*
2202 * pcpu_balance_free() is called twice because the first time we may
2203 * trim pages in the active pcpu_nr_empty_pop_pages which may cause us
2204 * to grow other chunks. This then gives pcpu_reclaim_populated() time
2205 * to move fully free chunks to the active list to be freed if
2206 * appropriate.
2207 */
2208 mutex_lock(&pcpu_alloc_mutex);
2209 spin_lock_irq(&pcpu_lock);
2210
2211 pcpu_balance_free(false);
2212 pcpu_reclaim_populated();
2213 pcpu_balance_populated();
2214 pcpu_balance_free(true);
2215
2216 spin_unlock_irq(&pcpu_lock);
2217 mutex_unlock(&pcpu_alloc_mutex);
2218}
2219
2220/**
2221 * free_percpu - free percpu area
2222 * @ptr: pointer to area to free
2223 *
2224 * Free percpu area @ptr.
2225 *
2226 * CONTEXT:
2227 * Can be called from atomic context.
2228 */
2229void free_percpu(void __percpu *ptr)
2230{
2231 void *addr;
2232 struct pcpu_chunk *chunk;
2233 unsigned long flags;
2234 int size, off;
2235 bool need_balance = false;
2236
2237 if (!ptr)
2238 return;
2239
2240 kmemleak_free_percpu(ptr);
2241
2242 addr = __pcpu_ptr_to_addr(ptr);
2243 chunk = pcpu_chunk_addr_search(addr);
2244 off = addr - chunk->base_addr;
2245
2246 spin_lock_irqsave(&pcpu_lock, flags);
2247 size = pcpu_free_area(chunk, off);
2248
2249 pcpu_alloc_tag_free_hook(chunk, off, size);
2250
2251 pcpu_memcg_free_hook(chunk, off, size);
2252
2253 /*
2254 * If there are more than one fully free chunks, wake up grim reaper.
2255 * If the chunk is isolated, it may be in the process of being
2256 * reclaimed. Let reclaim manage cleaning up of that chunk.
2257 */
2258 if (!chunk->isolated && chunk->free_bytes == pcpu_unit_size) {
2259 struct pcpu_chunk *pos;
2260
2261 list_for_each_entry(pos, &pcpu_chunk_lists[pcpu_free_slot], list)
2262 if (pos != chunk) {
2263 need_balance = true;
2264 break;
2265 }
2266 } else if (pcpu_should_reclaim_chunk(chunk)) {
2267 pcpu_isolate_chunk(chunk);
2268 need_balance = true;
2269 }
2270
2271 trace_percpu_free_percpu(chunk->base_addr, off, ptr);
2272
2273 spin_unlock_irqrestore(&pcpu_lock, flags);
2274
2275 if (need_balance)
2276 pcpu_schedule_balance_work();
2277}
2278EXPORT_SYMBOL_GPL(free_percpu);
2279
2280bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
2281{
2282#ifdef CONFIG_SMP
2283 const size_t static_size = __per_cpu_end - __per_cpu_start;
2284 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2285 unsigned int cpu;
2286
2287 for_each_possible_cpu(cpu) {
2288 void *start = per_cpu_ptr(base, cpu);
2289 void *va = (void *)addr;
2290
2291 if (va >= start && va < start + static_size) {
2292 if (can_addr) {
2293 *can_addr = (unsigned long) (va - start);
2294 *can_addr += (unsigned long)
2295 per_cpu_ptr(base, get_boot_cpu_id());
2296 }
2297 return true;
2298 }
2299 }
2300#endif
2301 /* on UP, can't distinguish from other static vars, always false */
2302 return false;
2303}
2304
2305/**
2306 * is_kernel_percpu_address - test whether address is from static percpu area
2307 * @addr: address to test
2308 *
2309 * Test whether @addr belongs to in-kernel static percpu area. Module
2310 * static percpu areas are not considered. For those, use
2311 * is_module_percpu_address().
2312 *
2313 * RETURNS:
2314 * %true if @addr is from in-kernel static percpu area, %false otherwise.
2315 */
2316bool is_kernel_percpu_address(unsigned long addr)
2317{
2318 return __is_kernel_percpu_address(addr, NULL);
2319}
2320
2321/**
2322 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2323 * @addr: the address to be converted to physical address
2324 *
2325 * Given @addr which is dereferenceable address obtained via one of
2326 * percpu access macros, this function translates it into its physical
2327 * address. The caller is responsible for ensuring @addr stays valid
2328 * until this function finishes.
2329 *
2330 * percpu allocator has special setup for the first chunk, which currently
2331 * supports either embedding in linear address space or vmalloc mapping,
2332 * and, from the second one, the backing allocator (currently either vm or
2333 * km) provides translation.
2334 *
2335 * The addr can be translated simply without checking if it falls into the
2336 * first chunk. But the current code reflects better how percpu allocator
2337 * actually works, and the verification can discover both bugs in percpu
2338 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2339 * code.
2340 *
2341 * RETURNS:
2342 * The physical address for @addr.
2343 */
2344phys_addr_t per_cpu_ptr_to_phys(void *addr)
2345{
2346 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2347 bool in_first_chunk = false;
2348 unsigned long first_low, first_high;
2349 unsigned int cpu;
2350
2351 /*
2352 * The following test on unit_low/high isn't strictly
2353 * necessary but will speed up lookups of addresses which
2354 * aren't in the first chunk.
2355 *
2356 * The address check is against full chunk sizes. pcpu_base_addr
2357 * points to the beginning of the first chunk including the
2358 * static region. Assumes good intent as the first chunk may
2359 * not be full (ie. < pcpu_unit_pages in size).
2360 */
2361 first_low = (unsigned long)pcpu_base_addr +
2362 pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2363 first_high = (unsigned long)pcpu_base_addr +
2364 pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2365 if ((unsigned long)addr >= first_low &&
2366 (unsigned long)addr < first_high) {
2367 for_each_possible_cpu(cpu) {
2368 void *start = per_cpu_ptr(base, cpu);
2369
2370 if (addr >= start && addr < start + pcpu_unit_size) {
2371 in_first_chunk = true;
2372 break;
2373 }
2374 }
2375 }
2376
2377 if (in_first_chunk) {
2378 if (!is_vmalloc_addr(addr))
2379 return __pa(addr);
2380 else
2381 return page_to_phys(vmalloc_to_page(addr)) +
2382 offset_in_page(addr);
2383 } else
2384 return page_to_phys(pcpu_addr_to_page(addr)) +
2385 offset_in_page(addr);
2386}
2387
2388/**
2389 * pcpu_alloc_alloc_info - allocate percpu allocation info
2390 * @nr_groups: the number of groups
2391 * @nr_units: the number of units
2392 *
2393 * Allocate ai which is large enough for @nr_groups groups containing
2394 * @nr_units units. The returned ai's groups[0].cpu_map points to the
2395 * cpu_map array which is long enough for @nr_units and filled with
2396 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
2397 * pointer of other groups.
2398 *
2399 * RETURNS:
2400 * Pointer to the allocated pcpu_alloc_info on success, NULL on
2401 * failure.
2402 */
2403struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2404 int nr_units)
2405{
2406 struct pcpu_alloc_info *ai;
2407 size_t base_size, ai_size;
2408 void *ptr;
2409 int unit;
2410
2411 base_size = ALIGN(struct_size(ai, groups, nr_groups),
2412 __alignof__(ai->groups[0].cpu_map[0]));
2413 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2414
2415 ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2416 if (!ptr)
2417 return NULL;
2418 ai = ptr;
2419 ptr += base_size;
2420
2421 ai->groups[0].cpu_map = ptr;
2422
2423 for (unit = 0; unit < nr_units; unit++)
2424 ai->groups[0].cpu_map[unit] = NR_CPUS;
2425
2426 ai->nr_groups = nr_groups;
2427 ai->__ai_size = PFN_ALIGN(ai_size);
2428
2429 return ai;
2430}
2431
2432/**
2433 * pcpu_free_alloc_info - free percpu allocation info
2434 * @ai: pcpu_alloc_info to free
2435 *
2436 * Free @ai which was allocated by pcpu_alloc_alloc_info().
2437 */
2438void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2439{
2440 memblock_free(ai, ai->__ai_size);
2441}
2442
2443/**
2444 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2445 * @lvl: loglevel
2446 * @ai: allocation info to dump
2447 *
2448 * Print out information about @ai using loglevel @lvl.
2449 */
2450static void pcpu_dump_alloc_info(const char *lvl,
2451 const struct pcpu_alloc_info *ai)
2452{
2453 int group_width = 1, cpu_width = 1, width;
2454 char empty_str[] = "--------";
2455 int alloc = 0, alloc_end = 0;
2456 int group, v;
2457 int upa, apl; /* units per alloc, allocs per line */
2458
2459 v = ai->nr_groups;
2460 while (v /= 10)
2461 group_width++;
2462
2463 v = num_possible_cpus();
2464 while (v /= 10)
2465 cpu_width++;
2466 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2467
2468 upa = ai->alloc_size / ai->unit_size;
2469 width = upa * (cpu_width + 1) + group_width + 3;
2470 apl = rounddown_pow_of_two(max(60 / width, 1));
2471
2472 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2473 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2474 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2475
2476 for (group = 0; group < ai->nr_groups; group++) {
2477 const struct pcpu_group_info *gi = &ai->groups[group];
2478 int unit = 0, unit_end = 0;
2479
2480 BUG_ON(gi->nr_units % upa);
2481 for (alloc_end += gi->nr_units / upa;
2482 alloc < alloc_end; alloc++) {
2483 if (!(alloc % apl)) {
2484 pr_cont("\n");
2485 printk("%spcpu-alloc: ", lvl);
2486 }
2487 pr_cont("[%0*d] ", group_width, group);
2488
2489 for (unit_end += upa; unit < unit_end; unit++)
2490 if (gi->cpu_map[unit] != NR_CPUS)
2491 pr_cont("%0*d ",
2492 cpu_width, gi->cpu_map[unit]);
2493 else
2494 pr_cont("%s ", empty_str);
2495 }
2496 }
2497 pr_cont("\n");
2498}
2499
2500/**
2501 * pcpu_setup_first_chunk - initialize the first percpu chunk
2502 * @ai: pcpu_alloc_info describing how to percpu area is shaped
2503 * @base_addr: mapped address
2504 *
2505 * Initialize the first percpu chunk which contains the kernel static
2506 * percpu area. This function is to be called from arch percpu area
2507 * setup path.
2508 *
2509 * @ai contains all information necessary to initialize the first
2510 * chunk and prime the dynamic percpu allocator.
2511 *
2512 * @ai->static_size is the size of static percpu area.
2513 *
2514 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2515 * reserve after the static area in the first chunk. This reserves
2516 * the first chunk such that it's available only through reserved
2517 * percpu allocation. This is primarily used to serve module percpu
2518 * static areas on architectures where the addressing model has
2519 * limited offset range for symbol relocations to guarantee module
2520 * percpu symbols fall inside the relocatable range.
2521 *
2522 * @ai->dyn_size determines the number of bytes available for dynamic
2523 * allocation in the first chunk. The area between @ai->static_size +
2524 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2525 *
2526 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2527 * and equal to or larger than @ai->static_size + @ai->reserved_size +
2528 * @ai->dyn_size.
2529 *
2530 * @ai->atom_size is the allocation atom size and used as alignment
2531 * for vm areas.
2532 *
2533 * @ai->alloc_size is the allocation size and always multiple of
2534 * @ai->atom_size. This is larger than @ai->atom_size if
2535 * @ai->unit_size is larger than @ai->atom_size.
2536 *
2537 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2538 * percpu areas. Units which should be colocated are put into the
2539 * same group. Dynamic VM areas will be allocated according to these
2540 * groupings. If @ai->nr_groups is zero, a single group containing
2541 * all units is assumed.
2542 *
2543 * The caller should have mapped the first chunk at @base_addr and
2544 * copied static data to each unit.
2545 *
2546 * The first chunk will always contain a static and a dynamic region.
2547 * However, the static region is not managed by any chunk. If the first
2548 * chunk also contains a reserved region, it is served by two chunks -
2549 * one for the reserved region and one for the dynamic region. They
2550 * share the same vm, but use offset regions in the area allocation map.
2551 * The chunk serving the dynamic region is circulated in the chunk slots
2552 * and available for dynamic allocation like any other chunk.
2553 */
2554void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2555 void *base_addr)
2556{
2557 size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2558 size_t static_size, dyn_size;
2559 unsigned long *group_offsets;
2560 size_t *group_sizes;
2561 unsigned long *unit_off;
2562 unsigned int cpu;
2563 int *unit_map;
2564 int group, unit, i;
2565 unsigned long tmp_addr;
2566 size_t alloc_size;
2567
2568#define PCPU_SETUP_BUG_ON(cond) do { \
2569 if (unlikely(cond)) { \
2570 pr_emerg("failed to initialize, %s\n", #cond); \
2571 pr_emerg("cpu_possible_mask=%*pb\n", \
2572 cpumask_pr_args(cpu_possible_mask)); \
2573 pcpu_dump_alloc_info(KERN_EMERG, ai); \
2574 BUG(); \
2575 } \
2576} while (0)
2577
2578 /* sanity checks */
2579 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2580#ifdef CONFIG_SMP
2581 PCPU_SETUP_BUG_ON(!ai->static_size);
2582 PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2583#endif
2584 PCPU_SETUP_BUG_ON(!base_addr);
2585 PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2586 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2587 PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2588 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2589 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2590 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2591 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2592 PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2593 IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2594 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2595
2596 /* process group information and build config tables accordingly */
2597 alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2598 group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2599 if (!group_offsets)
2600 panic("%s: Failed to allocate %zu bytes\n", __func__,
2601 alloc_size);
2602
2603 alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2604 group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2605 if (!group_sizes)
2606 panic("%s: Failed to allocate %zu bytes\n", __func__,
2607 alloc_size);
2608
2609 alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2610 unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2611 if (!unit_map)
2612 panic("%s: Failed to allocate %zu bytes\n", __func__,
2613 alloc_size);
2614
2615 alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2616 unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2617 if (!unit_off)
2618 panic("%s: Failed to allocate %zu bytes\n", __func__,
2619 alloc_size);
2620
2621 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2622 unit_map[cpu] = UINT_MAX;
2623
2624 pcpu_low_unit_cpu = NR_CPUS;
2625 pcpu_high_unit_cpu = NR_CPUS;
2626
2627 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2628 const struct pcpu_group_info *gi = &ai->groups[group];
2629
2630 group_offsets[group] = gi->base_offset;
2631 group_sizes[group] = gi->nr_units * ai->unit_size;
2632
2633 for (i = 0; i < gi->nr_units; i++) {
2634 cpu = gi->cpu_map[i];
2635 if (cpu == NR_CPUS)
2636 continue;
2637
2638 PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2639 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2640 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2641
2642 unit_map[cpu] = unit + i;
2643 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2644
2645 /* determine low/high unit_cpu */
2646 if (pcpu_low_unit_cpu == NR_CPUS ||
2647 unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2648 pcpu_low_unit_cpu = cpu;
2649 if (pcpu_high_unit_cpu == NR_CPUS ||
2650 unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2651 pcpu_high_unit_cpu = cpu;
2652 }
2653 }
2654 pcpu_nr_units = unit;
2655
2656 for_each_possible_cpu(cpu)
2657 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2658
2659 /* we're done parsing the input, undefine BUG macro and dump config */
2660#undef PCPU_SETUP_BUG_ON
2661 pcpu_dump_alloc_info(KERN_DEBUG, ai);
2662
2663 pcpu_nr_groups = ai->nr_groups;
2664 pcpu_group_offsets = group_offsets;
2665 pcpu_group_sizes = group_sizes;
2666 pcpu_unit_map = unit_map;
2667 pcpu_unit_offsets = unit_off;
2668
2669 /* determine basic parameters */
2670 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2671 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2672 pcpu_atom_size = ai->atom_size;
2673 pcpu_chunk_struct_size = struct_size((struct pcpu_chunk *)0, populated,
2674 BITS_TO_LONGS(pcpu_unit_pages));
2675
2676 pcpu_stats_save_ai(ai);
2677
2678 /*
2679 * Allocate chunk slots. The slots after the active slots are:
2680 * sidelined_slot - isolated, depopulated chunks
2681 * free_slot - fully free chunks
2682 * to_depopulate_slot - isolated, chunks to depopulate
2683 */
2684 pcpu_sidelined_slot = __pcpu_size_to_slot(pcpu_unit_size) + 1;
2685 pcpu_free_slot = pcpu_sidelined_slot + 1;
2686 pcpu_to_depopulate_slot = pcpu_free_slot + 1;
2687 pcpu_nr_slots = pcpu_to_depopulate_slot + 1;
2688 pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
2689 sizeof(pcpu_chunk_lists[0]),
2690 SMP_CACHE_BYTES);
2691 if (!pcpu_chunk_lists)
2692 panic("%s: Failed to allocate %zu bytes\n", __func__,
2693 pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]));
2694
2695 for (i = 0; i < pcpu_nr_slots; i++)
2696 INIT_LIST_HEAD(&pcpu_chunk_lists[i]);
2697
2698 /*
2699 * The end of the static region needs to be aligned with the
2700 * minimum allocation size as this offsets the reserved and
2701 * dynamic region. The first chunk ends page aligned by
2702 * expanding the dynamic region, therefore the dynamic region
2703 * can be shrunk to compensate while still staying above the
2704 * configured sizes.
2705 */
2706 static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2707 dyn_size = ai->dyn_size - (static_size - ai->static_size);
2708
2709 /*
2710 * Initialize first chunk:
2711 * This chunk is broken up into 3 parts:
2712 * < static | [reserved] | dynamic >
2713 * - static - there is no backing chunk because these allocations can
2714 * never be freed.
2715 * - reserved (pcpu_reserved_chunk) - exists primarily to serve
2716 * allocations from module load.
2717 * - dynamic (pcpu_first_chunk) - serves the dynamic part of the first
2718 * chunk.
2719 */
2720 tmp_addr = (unsigned long)base_addr + static_size;
2721 if (ai->reserved_size)
2722 pcpu_reserved_chunk = pcpu_alloc_first_chunk(tmp_addr,
2723 ai->reserved_size);
2724 tmp_addr = (unsigned long)base_addr + static_size + ai->reserved_size;
2725 pcpu_first_chunk = pcpu_alloc_first_chunk(tmp_addr, dyn_size);
2726
2727 pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2728 pcpu_chunk_relocate(pcpu_first_chunk, -1);
2729
2730 /* include all regions of the first chunk */
2731 pcpu_nr_populated += PFN_DOWN(size_sum);
2732
2733 pcpu_stats_chunk_alloc();
2734 trace_percpu_create_chunk(base_addr);
2735
2736 /* we're done */
2737 pcpu_base_addr = base_addr;
2738}
2739
2740#ifdef CONFIG_SMP
2741
2742const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2743 [PCPU_FC_AUTO] = "auto",
2744 [PCPU_FC_EMBED] = "embed",
2745 [PCPU_FC_PAGE] = "page",
2746};
2747
2748enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2749
2750static int __init percpu_alloc_setup(char *str)
2751{
2752 if (!str)
2753 return -EINVAL;
2754
2755 if (0)
2756 /* nada */;
2757#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2758 else if (!strcmp(str, "embed"))
2759 pcpu_chosen_fc = PCPU_FC_EMBED;
2760#endif
2761#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2762 else if (!strcmp(str, "page"))
2763 pcpu_chosen_fc = PCPU_FC_PAGE;
2764#endif
2765 else
2766 pr_warn("unknown allocator %s specified\n", str);
2767
2768 return 0;
2769}
2770early_param("percpu_alloc", percpu_alloc_setup);
2771
2772/*
2773 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2774 * Build it if needed by the arch config or the generic setup is going
2775 * to be used.
2776 */
2777#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2778 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2779#define BUILD_EMBED_FIRST_CHUNK
2780#endif
2781
2782/* build pcpu_page_first_chunk() iff needed by the arch config */
2783#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2784#define BUILD_PAGE_FIRST_CHUNK
2785#endif
2786
2787/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2788#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2789/**
2790 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2791 * @reserved_size: the size of reserved percpu area in bytes
2792 * @dyn_size: minimum free size for dynamic allocation in bytes
2793 * @atom_size: allocation atom size
2794 * @cpu_distance_fn: callback to determine distance between cpus, optional
2795 *
2796 * This function determines grouping of units, their mappings to cpus
2797 * and other parameters considering needed percpu size, allocation
2798 * atom size and distances between CPUs.
2799 *
2800 * Groups are always multiples of atom size and CPUs which are of
2801 * LOCAL_DISTANCE both ways are grouped together and share space for
2802 * units in the same group. The returned configuration is guaranteed
2803 * to have CPUs on different nodes on different groups and >=75% usage
2804 * of allocated virtual address space.
2805 *
2806 * RETURNS:
2807 * On success, pointer to the new allocation_info is returned. On
2808 * failure, ERR_PTR value is returned.
2809 */
2810static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
2811 size_t reserved_size, size_t dyn_size,
2812 size_t atom_size,
2813 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2814{
2815 static int group_map[NR_CPUS] __initdata;
2816 static int group_cnt[NR_CPUS] __initdata;
2817 static struct cpumask mask __initdata;
2818 const size_t static_size = __per_cpu_end - __per_cpu_start;
2819 int nr_groups = 1, nr_units = 0;
2820 size_t size_sum, min_unit_size, alloc_size;
2821 int upa, max_upa, best_upa; /* units_per_alloc */
2822 int last_allocs, group, unit;
2823 unsigned int cpu, tcpu;
2824 struct pcpu_alloc_info *ai;
2825 unsigned int *cpu_map;
2826
2827 /* this function may be called multiple times */
2828 memset(group_map, 0, sizeof(group_map));
2829 memset(group_cnt, 0, sizeof(group_cnt));
2830 cpumask_clear(&mask);
2831
2832 /* calculate size_sum and ensure dyn_size is enough for early alloc */
2833 size_sum = PFN_ALIGN(static_size + reserved_size +
2834 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2835 dyn_size = size_sum - static_size - reserved_size;
2836
2837 /*
2838 * Determine min_unit_size, alloc_size and max_upa such that
2839 * alloc_size is multiple of atom_size and is the smallest
2840 * which can accommodate 4k aligned segments which are equal to
2841 * or larger than min_unit_size.
2842 */
2843 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2844
2845 /* determine the maximum # of units that can fit in an allocation */
2846 alloc_size = roundup(min_unit_size, atom_size);
2847 upa = alloc_size / min_unit_size;
2848 while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2849 upa--;
2850 max_upa = upa;
2851
2852 cpumask_copy(&mask, cpu_possible_mask);
2853
2854 /* group cpus according to their proximity */
2855 for (group = 0; !cpumask_empty(&mask); group++) {
2856 /* pop the group's first cpu */
2857 cpu = cpumask_first(&mask);
2858 group_map[cpu] = group;
2859 group_cnt[group]++;
2860 cpumask_clear_cpu(cpu, &mask);
2861
2862 for_each_cpu(tcpu, &mask) {
2863 if (!cpu_distance_fn ||
2864 (cpu_distance_fn(cpu, tcpu) == LOCAL_DISTANCE &&
2865 cpu_distance_fn(tcpu, cpu) == LOCAL_DISTANCE)) {
2866 group_map[tcpu] = group;
2867 group_cnt[group]++;
2868 cpumask_clear_cpu(tcpu, &mask);
2869 }
2870 }
2871 }
2872 nr_groups = group;
2873
2874 /*
2875 * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2876 * Expand the unit_size until we use >= 75% of the units allocated.
2877 * Related to atom_size, which could be much larger than the unit_size.
2878 */
2879 last_allocs = INT_MAX;
2880 best_upa = 0;
2881 for (upa = max_upa; upa; upa--) {
2882 int allocs = 0, wasted = 0;
2883
2884 if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2885 continue;
2886
2887 for (group = 0; group < nr_groups; group++) {
2888 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2889 allocs += this_allocs;
2890 wasted += this_allocs * upa - group_cnt[group];
2891 }
2892
2893 /*
2894 * Don't accept if wastage is over 1/3. The
2895 * greater-than comparison ensures upa==1 always
2896 * passes the following check.
2897 */
2898 if (wasted > num_possible_cpus() / 3)
2899 continue;
2900
2901 /* and then don't consume more memory */
2902 if (allocs > last_allocs)
2903 break;
2904 last_allocs = allocs;
2905 best_upa = upa;
2906 }
2907 BUG_ON(!best_upa);
2908 upa = best_upa;
2909
2910 /* allocate and fill alloc_info */
2911 for (group = 0; group < nr_groups; group++)
2912 nr_units += roundup(group_cnt[group], upa);
2913
2914 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2915 if (!ai)
2916 return ERR_PTR(-ENOMEM);
2917 cpu_map = ai->groups[0].cpu_map;
2918
2919 for (group = 0; group < nr_groups; group++) {
2920 ai->groups[group].cpu_map = cpu_map;
2921 cpu_map += roundup(group_cnt[group], upa);
2922 }
2923
2924 ai->static_size = static_size;
2925 ai->reserved_size = reserved_size;
2926 ai->dyn_size = dyn_size;
2927 ai->unit_size = alloc_size / upa;
2928 ai->atom_size = atom_size;
2929 ai->alloc_size = alloc_size;
2930
2931 for (group = 0, unit = 0; group < nr_groups; group++) {
2932 struct pcpu_group_info *gi = &ai->groups[group];
2933
2934 /*
2935 * Initialize base_offset as if all groups are located
2936 * back-to-back. The caller should update this to
2937 * reflect actual allocation.
2938 */
2939 gi->base_offset = unit * ai->unit_size;
2940
2941 for_each_possible_cpu(cpu)
2942 if (group_map[cpu] == group)
2943 gi->cpu_map[gi->nr_units++] = cpu;
2944 gi->nr_units = roundup(gi->nr_units, upa);
2945 unit += gi->nr_units;
2946 }
2947 BUG_ON(unit != nr_units);
2948
2949 return ai;
2950}
2951
2952static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align,
2953 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
2954{
2955 const unsigned long goal = __pa(MAX_DMA_ADDRESS);
2956#ifdef CONFIG_NUMA
2957 int node = NUMA_NO_NODE;
2958 void *ptr;
2959
2960 if (cpu_to_nd_fn)
2961 node = cpu_to_nd_fn(cpu);
2962
2963 if (node == NUMA_NO_NODE || !node_online(node) || !NODE_DATA(node)) {
2964 ptr = memblock_alloc_from(size, align, goal);
2965 pr_info("cpu %d has no node %d or node-local memory\n",
2966 cpu, node);
2967 pr_debug("per cpu data for cpu%d %zu bytes at 0x%llx\n",
2968 cpu, size, (u64)__pa(ptr));
2969 } else {
2970 ptr = memblock_alloc_try_nid(size, align, goal,
2971 MEMBLOCK_ALLOC_ACCESSIBLE,
2972 node);
2973
2974 pr_debug("per cpu data for cpu%d %zu bytes on node%d at 0x%llx\n",
2975 cpu, size, node, (u64)__pa(ptr));
2976 }
2977 return ptr;
2978#else
2979 return memblock_alloc_from(size, align, goal);
2980#endif
2981}
2982
2983static void __init pcpu_fc_free(void *ptr, size_t size)
2984{
2985 memblock_free(ptr, size);
2986}
2987#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
2988
2989#if defined(BUILD_EMBED_FIRST_CHUNK)
2990/**
2991 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
2992 * @reserved_size: the size of reserved percpu area in bytes
2993 * @dyn_size: minimum free size for dynamic allocation in bytes
2994 * @atom_size: allocation atom size
2995 * @cpu_distance_fn: callback to determine distance between cpus, optional
2996 * @cpu_to_nd_fn: callback to convert cpu to it's node, optional
2997 *
2998 * This is a helper to ease setting up embedded first percpu chunk and
2999 * can be called where pcpu_setup_first_chunk() is expected.
3000 *
3001 * If this function is used to setup the first chunk, it is allocated
3002 * by calling pcpu_fc_alloc and used as-is without being mapped into
3003 * vmalloc area. Allocations are always whole multiples of @atom_size
3004 * aligned to @atom_size.
3005 *
3006 * This enables the first chunk to piggy back on the linear physical
3007 * mapping which often uses larger page size. Please note that this
3008 * can result in very sparse cpu->unit mapping on NUMA machines thus
3009 * requiring large vmalloc address space. Don't use this allocator if
3010 * vmalloc space is not orders of magnitude larger than distances
3011 * between node memory addresses (ie. 32bit NUMA machines).
3012 *
3013 * @dyn_size specifies the minimum dynamic area size.
3014 *
3015 * If the needed size is smaller than the minimum or specified unit
3016 * size, the leftover is returned using pcpu_fc_free.
3017 *
3018 * RETURNS:
3019 * 0 on success, -errno on failure.
3020 */
3021int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
3022 size_t atom_size,
3023 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
3024 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
3025{
3026 void *base = (void *)ULONG_MAX;
3027 void **areas = NULL;
3028 struct pcpu_alloc_info *ai;
3029 size_t size_sum, areas_size;
3030 unsigned long max_distance;
3031 int group, i, highest_group, rc = 0;
3032
3033 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
3034 cpu_distance_fn);
3035 if (IS_ERR(ai))
3036 return PTR_ERR(ai);
3037
3038 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
3039 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
3040
3041 areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
3042 if (!areas) {
3043 rc = -ENOMEM;
3044 goto out_free;
3045 }
3046
3047 /* allocate, copy and determine base address & max_distance */
3048 highest_group = 0;
3049 for (group = 0; group < ai->nr_groups; group++) {
3050 struct pcpu_group_info *gi = &ai->groups[group];
3051 unsigned int cpu = NR_CPUS;
3052 void *ptr;
3053
3054 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
3055 cpu = gi->cpu_map[i];
3056 BUG_ON(cpu == NR_CPUS);
3057
3058 /* allocate space for the whole group */
3059 ptr = pcpu_fc_alloc(cpu, gi->nr_units * ai->unit_size, atom_size, cpu_to_nd_fn);
3060 if (!ptr) {
3061 rc = -ENOMEM;
3062 goto out_free_areas;
3063 }
3064 /* kmemleak tracks the percpu allocations separately */
3065 kmemleak_ignore_phys(__pa(ptr));
3066 areas[group] = ptr;
3067
3068 base = min(ptr, base);
3069 if (ptr > areas[highest_group])
3070 highest_group = group;
3071 }
3072 max_distance = areas[highest_group] - base;
3073 max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
3074
3075 /* warn if maximum distance is further than 75% of vmalloc space */
3076 if (max_distance > VMALLOC_TOTAL * 3 / 4) {
3077 pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
3078 max_distance, VMALLOC_TOTAL);
3079#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
3080 /* and fail if we have fallback */
3081 rc = -EINVAL;
3082 goto out_free_areas;
3083#endif
3084 }
3085
3086 /*
3087 * Copy data and free unused parts. This should happen after all
3088 * allocations are complete; otherwise, we may end up with
3089 * overlapping groups.
3090 */
3091 for (group = 0; group < ai->nr_groups; group++) {
3092 struct pcpu_group_info *gi = &ai->groups[group];
3093 void *ptr = areas[group];
3094
3095 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
3096 if (gi->cpu_map[i] == NR_CPUS) {
3097 /* unused unit, free whole */
3098 pcpu_fc_free(ptr, ai->unit_size);
3099 continue;
3100 }
3101 /* copy and return the unused part */
3102 memcpy(ptr, __per_cpu_load, ai->static_size);
3103 pcpu_fc_free(ptr + size_sum, ai->unit_size - size_sum);
3104 }
3105 }
3106
3107 /* base address is now known, determine group base offsets */
3108 for (group = 0; group < ai->nr_groups; group++) {
3109 ai->groups[group].base_offset = areas[group] - base;
3110 }
3111
3112 pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
3113 PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
3114 ai->dyn_size, ai->unit_size);
3115
3116 pcpu_setup_first_chunk(ai, base);
3117 goto out_free;
3118
3119out_free_areas:
3120 for (group = 0; group < ai->nr_groups; group++)
3121 if (areas[group])
3122 pcpu_fc_free(areas[group],
3123 ai->groups[group].nr_units * ai->unit_size);
3124out_free:
3125 pcpu_free_alloc_info(ai);
3126 if (areas)
3127 memblock_free(areas, areas_size);
3128 return rc;
3129}
3130#endif /* BUILD_EMBED_FIRST_CHUNK */
3131
3132#ifdef BUILD_PAGE_FIRST_CHUNK
3133#include <asm/pgalloc.h>
3134
3135#ifndef P4D_TABLE_SIZE
3136#define P4D_TABLE_SIZE PAGE_SIZE
3137#endif
3138
3139#ifndef PUD_TABLE_SIZE
3140#define PUD_TABLE_SIZE PAGE_SIZE
3141#endif
3142
3143#ifndef PMD_TABLE_SIZE
3144#define PMD_TABLE_SIZE PAGE_SIZE
3145#endif
3146
3147#ifndef PTE_TABLE_SIZE
3148#define PTE_TABLE_SIZE PAGE_SIZE
3149#endif
3150void __init __weak pcpu_populate_pte(unsigned long addr)
3151{
3152 pgd_t *pgd = pgd_offset_k(addr);
3153 p4d_t *p4d;
3154 pud_t *pud;
3155 pmd_t *pmd;
3156
3157 if (pgd_none(*pgd)) {
3158 p4d = memblock_alloc(P4D_TABLE_SIZE, P4D_TABLE_SIZE);
3159 if (!p4d)
3160 goto err_alloc;
3161 pgd_populate(&init_mm, pgd, p4d);
3162 }
3163
3164 p4d = p4d_offset(pgd, addr);
3165 if (p4d_none(*p4d)) {
3166 pud = memblock_alloc(PUD_TABLE_SIZE, PUD_TABLE_SIZE);
3167 if (!pud)
3168 goto err_alloc;
3169 p4d_populate(&init_mm, p4d, pud);
3170 }
3171
3172 pud = pud_offset(p4d, addr);
3173 if (pud_none(*pud)) {
3174 pmd = memblock_alloc(PMD_TABLE_SIZE, PMD_TABLE_SIZE);
3175 if (!pmd)
3176 goto err_alloc;
3177 pud_populate(&init_mm, pud, pmd);
3178 }
3179
3180 pmd = pmd_offset(pud, addr);
3181 if (!pmd_present(*pmd)) {
3182 pte_t *new;
3183
3184 new = memblock_alloc(PTE_TABLE_SIZE, PTE_TABLE_SIZE);
3185 if (!new)
3186 goto err_alloc;
3187 pmd_populate_kernel(&init_mm, pmd, new);
3188 }
3189
3190 return;
3191
3192err_alloc:
3193 panic("%s: Failed to allocate memory\n", __func__);
3194}
3195
3196/**
3197 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
3198 * @reserved_size: the size of reserved percpu area in bytes
3199 * @cpu_to_nd_fn: callback to convert cpu to it's node, optional
3200 *
3201 * This is a helper to ease setting up page-remapped first percpu
3202 * chunk and can be called where pcpu_setup_first_chunk() is expected.
3203 *
3204 * This is the basic allocator. Static percpu area is allocated
3205 * page-by-page into vmalloc area.
3206 *
3207 * RETURNS:
3208 * 0 on success, -errno on failure.
3209 */
3210int __init pcpu_page_first_chunk(size_t reserved_size, pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
3211{
3212 static struct vm_struct vm;
3213 struct pcpu_alloc_info *ai;
3214 char psize_str[16];
3215 int unit_pages;
3216 size_t pages_size;
3217 struct page **pages;
3218 int unit, i, j, rc = 0;
3219 int upa;
3220 int nr_g0_units;
3221
3222 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
3223
3224 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
3225 if (IS_ERR(ai))
3226 return PTR_ERR(ai);
3227 BUG_ON(ai->nr_groups != 1);
3228 upa = ai->alloc_size/ai->unit_size;
3229 nr_g0_units = roundup(num_possible_cpus(), upa);
3230 if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
3231 pcpu_free_alloc_info(ai);
3232 return -EINVAL;
3233 }
3234
3235 unit_pages = ai->unit_size >> PAGE_SHIFT;
3236
3237 /* unaligned allocations can't be freed, round up to page size */
3238 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
3239 sizeof(pages[0]));
3240 pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
3241 if (!pages)
3242 panic("%s: Failed to allocate %zu bytes\n", __func__,
3243 pages_size);
3244
3245 /* allocate pages */
3246 j = 0;
3247 for (unit = 0; unit < num_possible_cpus(); unit++) {
3248 unsigned int cpu = ai->groups[0].cpu_map[unit];
3249 for (i = 0; i < unit_pages; i++) {
3250 void *ptr;
3251
3252 ptr = pcpu_fc_alloc(cpu, PAGE_SIZE, PAGE_SIZE, cpu_to_nd_fn);
3253 if (!ptr) {
3254 pr_warn("failed to allocate %s page for cpu%u\n",
3255 psize_str, cpu);
3256 goto enomem;
3257 }
3258 /* kmemleak tracks the percpu allocations separately */
3259 kmemleak_ignore_phys(__pa(ptr));
3260 pages[j++] = virt_to_page(ptr);
3261 }
3262 }
3263
3264 /* allocate vm area, map the pages and copy static data */
3265 vm.flags = VM_ALLOC;
3266 vm.size = num_possible_cpus() * ai->unit_size;
3267 vm_area_register_early(&vm, PAGE_SIZE);
3268
3269 for (unit = 0; unit < num_possible_cpus(); unit++) {
3270 unsigned long unit_addr =
3271 (unsigned long)vm.addr + unit * ai->unit_size;
3272
3273 for (i = 0; i < unit_pages; i++)
3274 pcpu_populate_pte(unit_addr + (i << PAGE_SHIFT));
3275
3276 /* pte already populated, the following shouldn't fail */
3277 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
3278 unit_pages);
3279 if (rc < 0)
3280 panic("failed to map percpu area, err=%d\n", rc);
3281
3282 flush_cache_vmap_early(unit_addr, unit_addr + ai->unit_size);
3283
3284 /* copy static data */
3285 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
3286 }
3287
3288 /* we're ready, commit */
3289 pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
3290 unit_pages, psize_str, ai->static_size,
3291 ai->reserved_size, ai->dyn_size);
3292
3293 pcpu_setup_first_chunk(ai, vm.addr);
3294 goto out_free_ar;
3295
3296enomem:
3297 while (--j >= 0)
3298 pcpu_fc_free(page_address(pages[j]), PAGE_SIZE);
3299 rc = -ENOMEM;
3300out_free_ar:
3301 memblock_free(pages, pages_size);
3302 pcpu_free_alloc_info(ai);
3303 return rc;
3304}
3305#endif /* BUILD_PAGE_FIRST_CHUNK */
3306
3307#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
3308/*
3309 * Generic SMP percpu area setup.
3310 *
3311 * The embedding helper is used because its behavior closely resembles
3312 * the original non-dynamic generic percpu area setup. This is
3313 * important because many archs have addressing restrictions and might
3314 * fail if the percpu area is located far away from the previous
3315 * location. As an added bonus, in non-NUMA cases, embedding is
3316 * generally a good idea TLB-wise because percpu area can piggy back
3317 * on the physical linear memory mapping which uses large page
3318 * mappings on applicable archs.
3319 */
3320unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
3321EXPORT_SYMBOL(__per_cpu_offset);
3322
3323void __init setup_per_cpu_areas(void)
3324{
3325 unsigned long delta;
3326 unsigned int cpu;
3327 int rc;
3328
3329 /*
3330 * Always reserve area for module percpu variables. That's
3331 * what the legacy allocator did.
3332 */
3333 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE, PERCPU_DYNAMIC_RESERVE,
3334 PAGE_SIZE, NULL, NULL);
3335 if (rc < 0)
3336 panic("Failed to initialize percpu areas.");
3337
3338 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
3339 for_each_possible_cpu(cpu)
3340 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
3341}
3342#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
3343
3344#else /* CONFIG_SMP */
3345
3346/*
3347 * UP percpu area setup.
3348 *
3349 * UP always uses km-based percpu allocator with identity mapping.
3350 * Static percpu variables are indistinguishable from the usual static
3351 * variables and don't require any special preparation.
3352 */
3353void __init setup_per_cpu_areas(void)
3354{
3355 const size_t unit_size =
3356 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
3357 PERCPU_DYNAMIC_RESERVE));
3358 struct pcpu_alloc_info *ai;
3359 void *fc;
3360
3361 ai = pcpu_alloc_alloc_info(1, 1);
3362 fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3363 if (!ai || !fc)
3364 panic("Failed to allocate memory for percpu areas.");
3365 /* kmemleak tracks the percpu allocations separately */
3366 kmemleak_ignore_phys(__pa(fc));
3367
3368 ai->dyn_size = unit_size;
3369 ai->unit_size = unit_size;
3370 ai->atom_size = unit_size;
3371 ai->alloc_size = unit_size;
3372 ai->groups[0].nr_units = 1;
3373 ai->groups[0].cpu_map[0] = 0;
3374
3375 pcpu_setup_first_chunk(ai, fc);
3376 pcpu_free_alloc_info(ai);
3377}
3378
3379#endif /* CONFIG_SMP */
3380
3381/*
3382 * pcpu_nr_pages - calculate total number of populated backing pages
3383 *
3384 * This reflects the number of pages populated to back chunks. Metadata is
3385 * excluded in the number exposed in meminfo as the number of backing pages
3386 * scales with the number of cpus and can quickly outweigh the memory used for
3387 * metadata. It also keeps this calculation nice and simple.
3388 *
3389 * RETURNS:
3390 * Total number of populated backing pages in use by the allocator.
3391 */
3392unsigned long pcpu_nr_pages(void)
3393{
3394 return pcpu_nr_populated * pcpu_nr_units;
3395}
3396
3397/*
3398 * Percpu allocator is initialized early during boot when neither slab or
3399 * workqueue is available. Plug async management until everything is up
3400 * and running.
3401 */
3402static int __init percpu_enable_async(void)
3403{
3404 pcpu_async_enabled = true;
3405 return 0;
3406}
3407subsys_initcall(percpu_enable_async);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/percpu.c - percpu memory allocator
4 *
5 * Copyright (C) 2009 SUSE Linux Products GmbH
6 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 *
8 * Copyright (C) 2017 Facebook Inc.
9 * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org>
10 *
11 * The percpu allocator handles both static and dynamic areas. Percpu
12 * areas are allocated in chunks which are divided into units. There is
13 * a 1-to-1 mapping for units to possible cpus. These units are grouped
14 * based on NUMA properties of the machine.
15 *
16 * c0 c1 c2
17 * ------------------- ------------------- ------------
18 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
19 * ------------------- ...... ------------------- .... ------------
20 *
21 * Allocation is done by offsets into a unit's address space. Ie., an
22 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
23 * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
24 * and even sparse. Access is handled by configuring percpu base
25 * registers according to the cpu to unit mappings and offsetting the
26 * base address using pcpu_unit_size.
27 *
28 * There is special consideration for the first chunk which must handle
29 * the static percpu variables in the kernel image as allocation services
30 * are not online yet. In short, the first chunk is structured like so:
31 *
32 * <Static | [Reserved] | Dynamic>
33 *
34 * The static data is copied from the original section managed by the
35 * linker. The reserved section, if non-zero, primarily manages static
36 * percpu variables from kernel modules. Finally, the dynamic section
37 * takes care of normal allocations.
38 *
39 * The allocator organizes chunks into lists according to free size and
40 * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
41 * flag should be passed. All memcg-aware allocations are sharing one set
42 * of chunks and all unaccounted allocations and allocations performed
43 * by processes belonging to the root memory cgroup are using the second set.
44 *
45 * The allocator tries to allocate from the fullest chunk first. Each chunk
46 * is managed by a bitmap with metadata blocks. The allocation map is updated
47 * on every allocation and free to reflect the current state while the boundary
48 * map is only updated on allocation. Each metadata block contains
49 * information to help mitigate the need to iterate over large portions
50 * of the bitmap. The reverse mapping from page to chunk is stored in
51 * the page's index. Lastly, units are lazily backed and grow in unison.
52 *
53 * There is a unique conversion that goes on here between bytes and bits.
54 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
55 * tracks the number of pages it is responsible for in nr_pages. Helper
56 * functions are used to convert from between the bytes, bits, and blocks.
57 * All hints are managed in bits unless explicitly stated.
58 *
59 * To use this allocator, arch code should do the following:
60 *
61 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
62 * regular address to percpu pointer and back if they need to be
63 * different from the default
64 *
65 * - use pcpu_setup_first_chunk() during percpu area initialization to
66 * setup the first chunk containing the kernel static percpu area
67 */
68
69#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
70
71#include <linux/bitmap.h>
72#include <linux/cpumask.h>
73#include <linux/memblock.h>
74#include <linux/err.h>
75#include <linux/lcm.h>
76#include <linux/list.h>
77#include <linux/log2.h>
78#include <linux/mm.h>
79#include <linux/module.h>
80#include <linux/mutex.h>
81#include <linux/percpu.h>
82#include <linux/pfn.h>
83#include <linux/slab.h>
84#include <linux/spinlock.h>
85#include <linux/vmalloc.h>
86#include <linux/workqueue.h>
87#include <linux/kmemleak.h>
88#include <linux/sched.h>
89#include <linux/sched/mm.h>
90#include <linux/memcontrol.h>
91
92#include <asm/cacheflush.h>
93#include <asm/sections.h>
94#include <asm/tlbflush.h>
95#include <asm/io.h>
96
97#define CREATE_TRACE_POINTS
98#include <trace/events/percpu.h>
99
100#include "percpu-internal.h"
101
102/*
103 * The slots are sorted by the size of the biggest continuous free area.
104 * 1-31 bytes share the same slot.
105 */
106#define PCPU_SLOT_BASE_SHIFT 5
107/* chunks in slots below this are subject to being sidelined on failed alloc */
108#define PCPU_SLOT_FAIL_THRESHOLD 3
109
110#define PCPU_EMPTY_POP_PAGES_LOW 2
111#define PCPU_EMPTY_POP_PAGES_HIGH 4
112
113#ifdef CONFIG_SMP
114/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
115#ifndef __addr_to_pcpu_ptr
116#define __addr_to_pcpu_ptr(addr) \
117 (void __percpu *)((unsigned long)(addr) - \
118 (unsigned long)pcpu_base_addr + \
119 (unsigned long)__per_cpu_start)
120#endif
121#ifndef __pcpu_ptr_to_addr
122#define __pcpu_ptr_to_addr(ptr) \
123 (void __force *)((unsigned long)(ptr) + \
124 (unsigned long)pcpu_base_addr - \
125 (unsigned long)__per_cpu_start)
126#endif
127#else /* CONFIG_SMP */
128/* on UP, it's always identity mapped */
129#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
130#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
131#endif /* CONFIG_SMP */
132
133static int pcpu_unit_pages __ro_after_init;
134static int pcpu_unit_size __ro_after_init;
135static int pcpu_nr_units __ro_after_init;
136static int pcpu_atom_size __ro_after_init;
137int pcpu_nr_slots __ro_after_init;
138static int pcpu_free_slot __ro_after_init;
139int pcpu_sidelined_slot __ro_after_init;
140int pcpu_to_depopulate_slot __ro_after_init;
141static size_t pcpu_chunk_struct_size __ro_after_init;
142
143/* cpus with the lowest and highest unit addresses */
144static unsigned int pcpu_low_unit_cpu __ro_after_init;
145static unsigned int pcpu_high_unit_cpu __ro_after_init;
146
147/* the address of the first chunk which starts with the kernel static area */
148void *pcpu_base_addr __ro_after_init;
149EXPORT_SYMBOL_GPL(pcpu_base_addr);
150
151static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
152const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
153
154/* group information, used for vm allocation */
155static int pcpu_nr_groups __ro_after_init;
156static const unsigned long *pcpu_group_offsets __ro_after_init;
157static const size_t *pcpu_group_sizes __ro_after_init;
158
159/*
160 * The first chunk which always exists. Note that unlike other
161 * chunks, this one can be allocated and mapped in several different
162 * ways and thus often doesn't live in the vmalloc area.
163 */
164struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
165
166/*
167 * Optional reserved chunk. This chunk reserves part of the first
168 * chunk and serves it for reserved allocations. When the reserved
169 * region doesn't exist, the following variable is NULL.
170 */
171struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
172
173DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
174static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
175
176struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
177
178/* chunks which need their map areas extended, protected by pcpu_lock */
179static LIST_HEAD(pcpu_map_extend_chunks);
180
181/*
182 * The number of empty populated pages, protected by pcpu_lock.
183 * The reserved chunk doesn't contribute to the count.
184 */
185int pcpu_nr_empty_pop_pages;
186
187/*
188 * The number of populated pages in use by the allocator, protected by
189 * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets
190 * allocated/deallocated, it is allocated/deallocated in all units of a chunk
191 * and increments/decrements this count by 1).
192 */
193static unsigned long pcpu_nr_populated;
194
195/*
196 * Balance work is used to populate or destroy chunks asynchronously. We
197 * try to keep the number of populated free pages between
198 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
199 * empty chunk.
200 */
201static void pcpu_balance_workfn(struct work_struct *work);
202static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
203static bool pcpu_async_enabled __read_mostly;
204static bool pcpu_atomic_alloc_failed;
205
206static void pcpu_schedule_balance_work(void)
207{
208 if (pcpu_async_enabled)
209 schedule_work(&pcpu_balance_work);
210}
211
212/**
213 * pcpu_addr_in_chunk - check if the address is served from this chunk
214 * @chunk: chunk of interest
215 * @addr: percpu address
216 *
217 * RETURNS:
218 * True if the address is served from this chunk.
219 */
220static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
221{
222 void *start_addr, *end_addr;
223
224 if (!chunk)
225 return false;
226
227 start_addr = chunk->base_addr + chunk->start_offset;
228 end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
229 chunk->end_offset;
230
231 return addr >= start_addr && addr < end_addr;
232}
233
234static int __pcpu_size_to_slot(int size)
235{
236 int highbit = fls(size); /* size is in bytes */
237 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
238}
239
240static int pcpu_size_to_slot(int size)
241{
242 if (size == pcpu_unit_size)
243 return pcpu_free_slot;
244 return __pcpu_size_to_slot(size);
245}
246
247static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
248{
249 const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
250
251 if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
252 chunk_md->contig_hint == 0)
253 return 0;
254
255 return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
256}
257
258/* set the pointer to a chunk in a page struct */
259static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
260{
261 page->index = (unsigned long)pcpu;
262}
263
264/* obtain pointer to a chunk from a page struct */
265static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
266{
267 return (struct pcpu_chunk *)page->index;
268}
269
270static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
271{
272 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
273}
274
275static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
276{
277 return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
278}
279
280static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
281 unsigned int cpu, int page_idx)
282{
283 return (unsigned long)chunk->base_addr +
284 pcpu_unit_page_offset(cpu, page_idx);
285}
286
287/*
288 * The following are helper functions to help access bitmaps and convert
289 * between bitmap offsets to address offsets.
290 */
291static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
292{
293 return chunk->alloc_map +
294 (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
295}
296
297static unsigned long pcpu_off_to_block_index(int off)
298{
299 return off / PCPU_BITMAP_BLOCK_BITS;
300}
301
302static unsigned long pcpu_off_to_block_off(int off)
303{
304 return off & (PCPU_BITMAP_BLOCK_BITS - 1);
305}
306
307static unsigned long pcpu_block_off_to_off(int index, int off)
308{
309 return index * PCPU_BITMAP_BLOCK_BITS + off;
310}
311
312/**
313 * pcpu_check_block_hint - check against the contig hint
314 * @block: block of interest
315 * @bits: size of allocation
316 * @align: alignment of area (max PAGE_SIZE)
317 *
318 * Check to see if the allocation can fit in the block's contig hint.
319 * Note, a chunk uses the same hints as a block so this can also check against
320 * the chunk's contig hint.
321 */
322static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
323 size_t align)
324{
325 int bit_off = ALIGN(block->contig_hint_start, align) -
326 block->contig_hint_start;
327
328 return bit_off + bits <= block->contig_hint;
329}
330
331/*
332 * pcpu_next_hint - determine which hint to use
333 * @block: block of interest
334 * @alloc_bits: size of allocation
335 *
336 * This determines if we should scan based on the scan_hint or first_free.
337 * In general, we want to scan from first_free to fulfill allocations by
338 * first fit. However, if we know a scan_hint at position scan_hint_start
339 * cannot fulfill an allocation, we can begin scanning from there knowing
340 * the contig_hint will be our fallback.
341 */
342static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
343{
344 /*
345 * The three conditions below determine if we can skip past the
346 * scan_hint. First, does the scan hint exist. Second, is the
347 * contig_hint after the scan_hint (possibly not true iff
348 * contig_hint == scan_hint). Third, is the allocation request
349 * larger than the scan_hint.
350 */
351 if (block->scan_hint &&
352 block->contig_hint_start > block->scan_hint_start &&
353 alloc_bits > block->scan_hint)
354 return block->scan_hint_start + block->scan_hint;
355
356 return block->first_free;
357}
358
359/**
360 * pcpu_next_md_free_region - finds the next hint free area
361 * @chunk: chunk of interest
362 * @bit_off: chunk offset
363 * @bits: size of free area
364 *
365 * Helper function for pcpu_for_each_md_free_region. It checks
366 * block->contig_hint and performs aggregation across blocks to find the
367 * next hint. It modifies bit_off and bits in-place to be consumed in the
368 * loop.
369 */
370static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
371 int *bits)
372{
373 int i = pcpu_off_to_block_index(*bit_off);
374 int block_off = pcpu_off_to_block_off(*bit_off);
375 struct pcpu_block_md *block;
376
377 *bits = 0;
378 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
379 block++, i++) {
380 /* handles contig area across blocks */
381 if (*bits) {
382 *bits += block->left_free;
383 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
384 continue;
385 return;
386 }
387
388 /*
389 * This checks three things. First is there a contig_hint to
390 * check. Second, have we checked this hint before by
391 * comparing the block_off. Third, is this the same as the
392 * right contig hint. In the last case, it spills over into
393 * the next block and should be handled by the contig area
394 * across blocks code.
395 */
396 *bits = block->contig_hint;
397 if (*bits && block->contig_hint_start >= block_off &&
398 *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
399 *bit_off = pcpu_block_off_to_off(i,
400 block->contig_hint_start);
401 return;
402 }
403 /* reset to satisfy the second predicate above */
404 block_off = 0;
405
406 *bits = block->right_free;
407 *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
408 }
409}
410
411/**
412 * pcpu_next_fit_region - finds fit areas for a given allocation request
413 * @chunk: chunk of interest
414 * @alloc_bits: size of allocation
415 * @align: alignment of area (max PAGE_SIZE)
416 * @bit_off: chunk offset
417 * @bits: size of free area
418 *
419 * Finds the next free region that is viable for use with a given size and
420 * alignment. This only returns if there is a valid area to be used for this
421 * allocation. block->first_free is returned if the allocation request fits
422 * within the block to see if the request can be fulfilled prior to the contig
423 * hint.
424 */
425static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
426 int align, int *bit_off, int *bits)
427{
428 int i = pcpu_off_to_block_index(*bit_off);
429 int block_off = pcpu_off_to_block_off(*bit_off);
430 struct pcpu_block_md *block;
431
432 *bits = 0;
433 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
434 block++, i++) {
435 /* handles contig area across blocks */
436 if (*bits) {
437 *bits += block->left_free;
438 if (*bits >= alloc_bits)
439 return;
440 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
441 continue;
442 }
443
444 /* check block->contig_hint */
445 *bits = ALIGN(block->contig_hint_start, align) -
446 block->contig_hint_start;
447 /*
448 * This uses the block offset to determine if this has been
449 * checked in the prior iteration.
450 */
451 if (block->contig_hint &&
452 block->contig_hint_start >= block_off &&
453 block->contig_hint >= *bits + alloc_bits) {
454 int start = pcpu_next_hint(block, alloc_bits);
455
456 *bits += alloc_bits + block->contig_hint_start -
457 start;
458 *bit_off = pcpu_block_off_to_off(i, start);
459 return;
460 }
461 /* reset to satisfy the second predicate above */
462 block_off = 0;
463
464 *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
465 align);
466 *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
467 *bit_off = pcpu_block_off_to_off(i, *bit_off);
468 if (*bits >= alloc_bits)
469 return;
470 }
471
472 /* no valid offsets were found - fail condition */
473 *bit_off = pcpu_chunk_map_bits(chunk);
474}
475
476/*
477 * Metadata free area iterators. These perform aggregation of free areas
478 * based on the metadata blocks and return the offset @bit_off and size in
479 * bits of the free area @bits. pcpu_for_each_fit_region only returns when
480 * a fit is found for the allocation request.
481 */
482#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
483 for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
484 (bit_off) < pcpu_chunk_map_bits((chunk)); \
485 (bit_off) += (bits) + 1, \
486 pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
487
488#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
489 for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
490 &(bits)); \
491 (bit_off) < pcpu_chunk_map_bits((chunk)); \
492 (bit_off) += (bits), \
493 pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
494 &(bits)))
495
496/**
497 * pcpu_mem_zalloc - allocate memory
498 * @size: bytes to allocate
499 * @gfp: allocation flags
500 *
501 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
502 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
503 * This is to facilitate passing through whitelisted flags. The
504 * returned memory is always zeroed.
505 *
506 * RETURNS:
507 * Pointer to the allocated area on success, NULL on failure.
508 */
509static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
510{
511 if (WARN_ON_ONCE(!slab_is_available()))
512 return NULL;
513
514 if (size <= PAGE_SIZE)
515 return kzalloc(size, gfp);
516 else
517 return __vmalloc(size, gfp | __GFP_ZERO);
518}
519
520/**
521 * pcpu_mem_free - free memory
522 * @ptr: memory to free
523 *
524 * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
525 */
526static void pcpu_mem_free(void *ptr)
527{
528 kvfree(ptr);
529}
530
531static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
532 bool move_front)
533{
534 if (chunk != pcpu_reserved_chunk) {
535 if (move_front)
536 list_move(&chunk->list, &pcpu_chunk_lists[slot]);
537 else
538 list_move_tail(&chunk->list, &pcpu_chunk_lists[slot]);
539 }
540}
541
542static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
543{
544 __pcpu_chunk_move(chunk, slot, true);
545}
546
547/**
548 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
549 * @chunk: chunk of interest
550 * @oslot: the previous slot it was on
551 *
552 * This function is called after an allocation or free changed @chunk.
553 * New slot according to the changed state is determined and @chunk is
554 * moved to the slot. Note that the reserved chunk is never put on
555 * chunk slots.
556 *
557 * CONTEXT:
558 * pcpu_lock.
559 */
560static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
561{
562 int nslot = pcpu_chunk_slot(chunk);
563
564 /* leave isolated chunks in-place */
565 if (chunk->isolated)
566 return;
567
568 if (oslot != nslot)
569 __pcpu_chunk_move(chunk, nslot, oslot < nslot);
570}
571
572static void pcpu_isolate_chunk(struct pcpu_chunk *chunk)
573{
574 lockdep_assert_held(&pcpu_lock);
575
576 if (!chunk->isolated) {
577 chunk->isolated = true;
578 pcpu_nr_empty_pop_pages -= chunk->nr_empty_pop_pages;
579 }
580 list_move(&chunk->list, &pcpu_chunk_lists[pcpu_to_depopulate_slot]);
581}
582
583static void pcpu_reintegrate_chunk(struct pcpu_chunk *chunk)
584{
585 lockdep_assert_held(&pcpu_lock);
586
587 if (chunk->isolated) {
588 chunk->isolated = false;
589 pcpu_nr_empty_pop_pages += chunk->nr_empty_pop_pages;
590 pcpu_chunk_relocate(chunk, -1);
591 }
592}
593
594/*
595 * pcpu_update_empty_pages - update empty page counters
596 * @chunk: chunk of interest
597 * @nr: nr of empty pages
598 *
599 * This is used to keep track of the empty pages now based on the premise
600 * a md_block covers a page. The hint update functions recognize if a block
601 * is made full or broken to calculate deltas for keeping track of free pages.
602 */
603static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
604{
605 chunk->nr_empty_pop_pages += nr;
606 if (chunk != pcpu_reserved_chunk && !chunk->isolated)
607 pcpu_nr_empty_pop_pages += nr;
608}
609
610/*
611 * pcpu_region_overlap - determines if two regions overlap
612 * @a: start of first region, inclusive
613 * @b: end of first region, exclusive
614 * @x: start of second region, inclusive
615 * @y: end of second region, exclusive
616 *
617 * This is used to determine if the hint region [a, b) overlaps with the
618 * allocated region [x, y).
619 */
620static inline bool pcpu_region_overlap(int a, int b, int x, int y)
621{
622 return (a < y) && (x < b);
623}
624
625/**
626 * pcpu_block_update - updates a block given a free area
627 * @block: block of interest
628 * @start: start offset in block
629 * @end: end offset in block
630 *
631 * Updates a block given a known free area. The region [start, end) is
632 * expected to be the entirety of the free area within a block. Chooses
633 * the best starting offset if the contig hints are equal.
634 */
635static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
636{
637 int contig = end - start;
638
639 block->first_free = min(block->first_free, start);
640 if (start == 0)
641 block->left_free = contig;
642
643 if (end == block->nr_bits)
644 block->right_free = contig;
645
646 if (contig > block->contig_hint) {
647 /* promote the old contig_hint to be the new scan_hint */
648 if (start > block->contig_hint_start) {
649 if (block->contig_hint > block->scan_hint) {
650 block->scan_hint_start =
651 block->contig_hint_start;
652 block->scan_hint = block->contig_hint;
653 } else if (start < block->scan_hint_start) {
654 /*
655 * The old contig_hint == scan_hint. But, the
656 * new contig is larger so hold the invariant
657 * scan_hint_start < contig_hint_start.
658 */
659 block->scan_hint = 0;
660 }
661 } else {
662 block->scan_hint = 0;
663 }
664 block->contig_hint_start = start;
665 block->contig_hint = contig;
666 } else if (contig == block->contig_hint) {
667 if (block->contig_hint_start &&
668 (!start ||
669 __ffs(start) > __ffs(block->contig_hint_start))) {
670 /* start has a better alignment so use it */
671 block->contig_hint_start = start;
672 if (start < block->scan_hint_start &&
673 block->contig_hint > block->scan_hint)
674 block->scan_hint = 0;
675 } else if (start > block->scan_hint_start ||
676 block->contig_hint > block->scan_hint) {
677 /*
678 * Knowing contig == contig_hint, update the scan_hint
679 * if it is farther than or larger than the current
680 * scan_hint.
681 */
682 block->scan_hint_start = start;
683 block->scan_hint = contig;
684 }
685 } else {
686 /*
687 * The region is smaller than the contig_hint. So only update
688 * the scan_hint if it is larger than or equal and farther than
689 * the current scan_hint.
690 */
691 if ((start < block->contig_hint_start &&
692 (contig > block->scan_hint ||
693 (contig == block->scan_hint &&
694 start > block->scan_hint_start)))) {
695 block->scan_hint_start = start;
696 block->scan_hint = contig;
697 }
698 }
699}
700
701/*
702 * pcpu_block_update_scan - update a block given a free area from a scan
703 * @chunk: chunk of interest
704 * @bit_off: chunk offset
705 * @bits: size of free area
706 *
707 * Finding the final allocation spot first goes through pcpu_find_block_fit()
708 * to find a block that can hold the allocation and then pcpu_alloc_area()
709 * where a scan is used. When allocations require specific alignments,
710 * we can inadvertently create holes which will not be seen in the alloc
711 * or free paths.
712 *
713 * This takes a given free area hole and updates a block as it may change the
714 * scan_hint. We need to scan backwards to ensure we don't miss free bits
715 * from alignment.
716 */
717static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
718 int bits)
719{
720 int s_off = pcpu_off_to_block_off(bit_off);
721 int e_off = s_off + bits;
722 int s_index, l_bit;
723 struct pcpu_block_md *block;
724
725 if (e_off > PCPU_BITMAP_BLOCK_BITS)
726 return;
727
728 s_index = pcpu_off_to_block_index(bit_off);
729 block = chunk->md_blocks + s_index;
730
731 /* scan backwards in case of alignment skipping free bits */
732 l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
733 s_off = (s_off == l_bit) ? 0 : l_bit + 1;
734
735 pcpu_block_update(block, s_off, e_off);
736}
737
738/**
739 * pcpu_chunk_refresh_hint - updates metadata about a chunk
740 * @chunk: chunk of interest
741 * @full_scan: if we should scan from the beginning
742 *
743 * Iterates over the metadata blocks to find the largest contig area.
744 * A full scan can be avoided on the allocation path as this is triggered
745 * if we broke the contig_hint. In doing so, the scan_hint will be before
746 * the contig_hint or after if the scan_hint == contig_hint. This cannot
747 * be prevented on freeing as we want to find the largest area possibly
748 * spanning blocks.
749 */
750static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
751{
752 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
753 int bit_off, bits;
754
755 /* promote scan_hint to contig_hint */
756 if (!full_scan && chunk_md->scan_hint) {
757 bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
758 chunk_md->contig_hint_start = chunk_md->scan_hint_start;
759 chunk_md->contig_hint = chunk_md->scan_hint;
760 chunk_md->scan_hint = 0;
761 } else {
762 bit_off = chunk_md->first_free;
763 chunk_md->contig_hint = 0;
764 }
765
766 bits = 0;
767 pcpu_for_each_md_free_region(chunk, bit_off, bits)
768 pcpu_block_update(chunk_md, bit_off, bit_off + bits);
769}
770
771/**
772 * pcpu_block_refresh_hint
773 * @chunk: chunk of interest
774 * @index: index of the metadata block
775 *
776 * Scans over the block beginning at first_free and updates the block
777 * metadata accordingly.
778 */
779static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
780{
781 struct pcpu_block_md *block = chunk->md_blocks + index;
782 unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
783 unsigned int rs, re, start; /* region start, region end */
784
785 /* promote scan_hint to contig_hint */
786 if (block->scan_hint) {
787 start = block->scan_hint_start + block->scan_hint;
788 block->contig_hint_start = block->scan_hint_start;
789 block->contig_hint = block->scan_hint;
790 block->scan_hint = 0;
791 } else {
792 start = block->first_free;
793 block->contig_hint = 0;
794 }
795
796 block->right_free = 0;
797
798 /* iterate over free areas and update the contig hints */
799 bitmap_for_each_clear_region(alloc_map, rs, re, start,
800 PCPU_BITMAP_BLOCK_BITS)
801 pcpu_block_update(block, rs, re);
802}
803
804/**
805 * pcpu_block_update_hint_alloc - update hint on allocation path
806 * @chunk: chunk of interest
807 * @bit_off: chunk offset
808 * @bits: size of request
809 *
810 * Updates metadata for the allocation path. The metadata only has to be
811 * refreshed by a full scan iff the chunk's contig hint is broken. Block level
812 * scans are required if the block's contig hint is broken.
813 */
814static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
815 int bits)
816{
817 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
818 int nr_empty_pages = 0;
819 struct pcpu_block_md *s_block, *e_block, *block;
820 int s_index, e_index; /* block indexes of the freed allocation */
821 int s_off, e_off; /* block offsets of the freed allocation */
822
823 /*
824 * Calculate per block offsets.
825 * The calculation uses an inclusive range, but the resulting offsets
826 * are [start, end). e_index always points to the last block in the
827 * range.
828 */
829 s_index = pcpu_off_to_block_index(bit_off);
830 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
831 s_off = pcpu_off_to_block_off(bit_off);
832 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
833
834 s_block = chunk->md_blocks + s_index;
835 e_block = chunk->md_blocks + e_index;
836
837 /*
838 * Update s_block.
839 * block->first_free must be updated if the allocation takes its place.
840 * If the allocation breaks the contig_hint, a scan is required to
841 * restore this hint.
842 */
843 if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
844 nr_empty_pages++;
845
846 if (s_off == s_block->first_free)
847 s_block->first_free = find_next_zero_bit(
848 pcpu_index_alloc_map(chunk, s_index),
849 PCPU_BITMAP_BLOCK_BITS,
850 s_off + bits);
851
852 if (pcpu_region_overlap(s_block->scan_hint_start,
853 s_block->scan_hint_start + s_block->scan_hint,
854 s_off,
855 s_off + bits))
856 s_block->scan_hint = 0;
857
858 if (pcpu_region_overlap(s_block->contig_hint_start,
859 s_block->contig_hint_start +
860 s_block->contig_hint,
861 s_off,
862 s_off + bits)) {
863 /* block contig hint is broken - scan to fix it */
864 if (!s_off)
865 s_block->left_free = 0;
866 pcpu_block_refresh_hint(chunk, s_index);
867 } else {
868 /* update left and right contig manually */
869 s_block->left_free = min(s_block->left_free, s_off);
870 if (s_index == e_index)
871 s_block->right_free = min_t(int, s_block->right_free,
872 PCPU_BITMAP_BLOCK_BITS - e_off);
873 else
874 s_block->right_free = 0;
875 }
876
877 /*
878 * Update e_block.
879 */
880 if (s_index != e_index) {
881 if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
882 nr_empty_pages++;
883
884 /*
885 * When the allocation is across blocks, the end is along
886 * the left part of the e_block.
887 */
888 e_block->first_free = find_next_zero_bit(
889 pcpu_index_alloc_map(chunk, e_index),
890 PCPU_BITMAP_BLOCK_BITS, e_off);
891
892 if (e_off == PCPU_BITMAP_BLOCK_BITS) {
893 /* reset the block */
894 e_block++;
895 } else {
896 if (e_off > e_block->scan_hint_start)
897 e_block->scan_hint = 0;
898
899 e_block->left_free = 0;
900 if (e_off > e_block->contig_hint_start) {
901 /* contig hint is broken - scan to fix it */
902 pcpu_block_refresh_hint(chunk, e_index);
903 } else {
904 e_block->right_free =
905 min_t(int, e_block->right_free,
906 PCPU_BITMAP_BLOCK_BITS - e_off);
907 }
908 }
909
910 /* update in-between md_blocks */
911 nr_empty_pages += (e_index - s_index - 1);
912 for (block = s_block + 1; block < e_block; block++) {
913 block->scan_hint = 0;
914 block->contig_hint = 0;
915 block->left_free = 0;
916 block->right_free = 0;
917 }
918 }
919
920 if (nr_empty_pages)
921 pcpu_update_empty_pages(chunk, -nr_empty_pages);
922
923 if (pcpu_region_overlap(chunk_md->scan_hint_start,
924 chunk_md->scan_hint_start +
925 chunk_md->scan_hint,
926 bit_off,
927 bit_off + bits))
928 chunk_md->scan_hint = 0;
929
930 /*
931 * The only time a full chunk scan is required is if the chunk
932 * contig hint is broken. Otherwise, it means a smaller space
933 * was used and therefore the chunk contig hint is still correct.
934 */
935 if (pcpu_region_overlap(chunk_md->contig_hint_start,
936 chunk_md->contig_hint_start +
937 chunk_md->contig_hint,
938 bit_off,
939 bit_off + bits))
940 pcpu_chunk_refresh_hint(chunk, false);
941}
942
943/**
944 * pcpu_block_update_hint_free - updates the block hints on the free path
945 * @chunk: chunk of interest
946 * @bit_off: chunk offset
947 * @bits: size of request
948 *
949 * Updates metadata for the allocation path. This avoids a blind block
950 * refresh by making use of the block contig hints. If this fails, it scans
951 * forward and backward to determine the extent of the free area. This is
952 * capped at the boundary of blocks.
953 *
954 * A chunk update is triggered if a page becomes free, a block becomes free,
955 * or the free spans across blocks. This tradeoff is to minimize iterating
956 * over the block metadata to update chunk_md->contig_hint.
957 * chunk_md->contig_hint may be off by up to a page, but it will never be more
958 * than the available space. If the contig hint is contained in one block, it
959 * will be accurate.
960 */
961static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
962 int bits)
963{
964 int nr_empty_pages = 0;
965 struct pcpu_block_md *s_block, *e_block, *block;
966 int s_index, e_index; /* block indexes of the freed allocation */
967 int s_off, e_off; /* block offsets of the freed allocation */
968 int start, end; /* start and end of the whole free area */
969
970 /*
971 * Calculate per block offsets.
972 * The calculation uses an inclusive range, but the resulting offsets
973 * are [start, end). e_index always points to the last block in the
974 * range.
975 */
976 s_index = pcpu_off_to_block_index(bit_off);
977 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
978 s_off = pcpu_off_to_block_off(bit_off);
979 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
980
981 s_block = chunk->md_blocks + s_index;
982 e_block = chunk->md_blocks + e_index;
983
984 /*
985 * Check if the freed area aligns with the block->contig_hint.
986 * If it does, then the scan to find the beginning/end of the
987 * larger free area can be avoided.
988 *
989 * start and end refer to beginning and end of the free area
990 * within each their respective blocks. This is not necessarily
991 * the entire free area as it may span blocks past the beginning
992 * or end of the block.
993 */
994 start = s_off;
995 if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
996 start = s_block->contig_hint_start;
997 } else {
998 /*
999 * Scan backwards to find the extent of the free area.
1000 * find_last_bit returns the starting bit, so if the start bit
1001 * is returned, that means there was no last bit and the
1002 * remainder of the chunk is free.
1003 */
1004 int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
1005 start);
1006 start = (start == l_bit) ? 0 : l_bit + 1;
1007 }
1008
1009 end = e_off;
1010 if (e_off == e_block->contig_hint_start)
1011 end = e_block->contig_hint_start + e_block->contig_hint;
1012 else
1013 end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
1014 PCPU_BITMAP_BLOCK_BITS, end);
1015
1016 /* update s_block */
1017 e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
1018 if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
1019 nr_empty_pages++;
1020 pcpu_block_update(s_block, start, e_off);
1021
1022 /* freeing in the same block */
1023 if (s_index != e_index) {
1024 /* update e_block */
1025 if (end == PCPU_BITMAP_BLOCK_BITS)
1026 nr_empty_pages++;
1027 pcpu_block_update(e_block, 0, end);
1028
1029 /* reset md_blocks in the middle */
1030 nr_empty_pages += (e_index - s_index - 1);
1031 for (block = s_block + 1; block < e_block; block++) {
1032 block->first_free = 0;
1033 block->scan_hint = 0;
1034 block->contig_hint_start = 0;
1035 block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
1036 block->left_free = PCPU_BITMAP_BLOCK_BITS;
1037 block->right_free = PCPU_BITMAP_BLOCK_BITS;
1038 }
1039 }
1040
1041 if (nr_empty_pages)
1042 pcpu_update_empty_pages(chunk, nr_empty_pages);
1043
1044 /*
1045 * Refresh chunk metadata when the free makes a block free or spans
1046 * across blocks. The contig_hint may be off by up to a page, but if
1047 * the contig_hint is contained in a block, it will be accurate with
1048 * the else condition below.
1049 */
1050 if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1051 pcpu_chunk_refresh_hint(chunk, true);
1052 else
1053 pcpu_block_update(&chunk->chunk_md,
1054 pcpu_block_off_to_off(s_index, start),
1055 end);
1056}
1057
1058/**
1059 * pcpu_is_populated - determines if the region is populated
1060 * @chunk: chunk of interest
1061 * @bit_off: chunk offset
1062 * @bits: size of area
1063 * @next_off: return value for the next offset to start searching
1064 *
1065 * For atomic allocations, check if the backing pages are populated.
1066 *
1067 * RETURNS:
1068 * Bool if the backing pages are populated.
1069 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1070 */
1071static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1072 int *next_off)
1073{
1074 unsigned int page_start, page_end, rs, re;
1075
1076 page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1077 page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1078
1079 rs = page_start;
1080 bitmap_next_clear_region(chunk->populated, &rs, &re, page_end);
1081 if (rs >= page_end)
1082 return true;
1083
1084 *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1085 return false;
1086}
1087
1088/**
1089 * pcpu_find_block_fit - finds the block index to start searching
1090 * @chunk: chunk of interest
1091 * @alloc_bits: size of request in allocation units
1092 * @align: alignment of area (max PAGE_SIZE bytes)
1093 * @pop_only: use populated regions only
1094 *
1095 * Given a chunk and an allocation spec, find the offset to begin searching
1096 * for a free region. This iterates over the bitmap metadata blocks to
1097 * find an offset that will be guaranteed to fit the requirements. It is
1098 * not quite first fit as if the allocation does not fit in the contig hint
1099 * of a block or chunk, it is skipped. This errs on the side of caution
1100 * to prevent excess iteration. Poor alignment can cause the allocator to
1101 * skip over blocks and chunks that have valid free areas.
1102 *
1103 * RETURNS:
1104 * The offset in the bitmap to begin searching.
1105 * -1 if no offset is found.
1106 */
1107static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1108 size_t align, bool pop_only)
1109{
1110 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1111 int bit_off, bits, next_off;
1112
1113 /*
1114 * This is an optimization to prevent scanning by assuming if the
1115 * allocation cannot fit in the global hint, there is memory pressure
1116 * and creating a new chunk would happen soon.
1117 */
1118 if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
1119 return -1;
1120
1121 bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1122 bits = 0;
1123 pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1124 if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1125 &next_off))
1126 break;
1127
1128 bit_off = next_off;
1129 bits = 0;
1130 }
1131
1132 if (bit_off == pcpu_chunk_map_bits(chunk))
1133 return -1;
1134
1135 return bit_off;
1136}
1137
1138/*
1139 * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1140 * @map: the address to base the search on
1141 * @size: the bitmap size in bits
1142 * @start: the bitnumber to start searching at
1143 * @nr: the number of zeroed bits we're looking for
1144 * @align_mask: alignment mask for zero area
1145 * @largest_off: offset of the largest area skipped
1146 * @largest_bits: size of the largest area skipped
1147 *
1148 * The @align_mask should be one less than a power of 2.
1149 *
1150 * This is a modified version of bitmap_find_next_zero_area_off() to remember
1151 * the largest area that was skipped. This is imperfect, but in general is
1152 * good enough. The largest remembered region is the largest failed region
1153 * seen. This does not include anything we possibly skipped due to alignment.
1154 * pcpu_block_update_scan() does scan backwards to try and recover what was
1155 * lost to alignment. While this can cause scanning to miss earlier possible
1156 * free areas, smaller allocations will eventually fill those holes.
1157 */
1158static unsigned long pcpu_find_zero_area(unsigned long *map,
1159 unsigned long size,
1160 unsigned long start,
1161 unsigned long nr,
1162 unsigned long align_mask,
1163 unsigned long *largest_off,
1164 unsigned long *largest_bits)
1165{
1166 unsigned long index, end, i, area_off, area_bits;
1167again:
1168 index = find_next_zero_bit(map, size, start);
1169
1170 /* Align allocation */
1171 index = __ALIGN_MASK(index, align_mask);
1172 area_off = index;
1173
1174 end = index + nr;
1175 if (end > size)
1176 return end;
1177 i = find_next_bit(map, end, index);
1178 if (i < end) {
1179 area_bits = i - area_off;
1180 /* remember largest unused area with best alignment */
1181 if (area_bits > *largest_bits ||
1182 (area_bits == *largest_bits && *largest_off &&
1183 (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1184 *largest_off = area_off;
1185 *largest_bits = area_bits;
1186 }
1187
1188 start = i + 1;
1189 goto again;
1190 }
1191 return index;
1192}
1193
1194/**
1195 * pcpu_alloc_area - allocates an area from a pcpu_chunk
1196 * @chunk: chunk of interest
1197 * @alloc_bits: size of request in allocation units
1198 * @align: alignment of area (max PAGE_SIZE)
1199 * @start: bit_off to start searching
1200 *
1201 * This function takes in a @start offset to begin searching to fit an
1202 * allocation of @alloc_bits with alignment @align. It needs to scan
1203 * the allocation map because if it fits within the block's contig hint,
1204 * @start will be block->first_free. This is an attempt to fill the
1205 * allocation prior to breaking the contig hint. The allocation and
1206 * boundary maps are updated accordingly if it confirms a valid
1207 * free area.
1208 *
1209 * RETURNS:
1210 * Allocated addr offset in @chunk on success.
1211 * -1 if no matching area is found.
1212 */
1213static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1214 size_t align, int start)
1215{
1216 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1217 size_t align_mask = (align) ? (align - 1) : 0;
1218 unsigned long area_off = 0, area_bits = 0;
1219 int bit_off, end, oslot;
1220
1221 lockdep_assert_held(&pcpu_lock);
1222
1223 oslot = pcpu_chunk_slot(chunk);
1224
1225 /*
1226 * Search to find a fit.
1227 */
1228 end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1229 pcpu_chunk_map_bits(chunk));
1230 bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1231 align_mask, &area_off, &area_bits);
1232 if (bit_off >= end)
1233 return -1;
1234
1235 if (area_bits)
1236 pcpu_block_update_scan(chunk, area_off, area_bits);
1237
1238 /* update alloc map */
1239 bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1240
1241 /* update boundary map */
1242 set_bit(bit_off, chunk->bound_map);
1243 bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1244 set_bit(bit_off + alloc_bits, chunk->bound_map);
1245
1246 chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1247
1248 /* update first free bit */
1249 if (bit_off == chunk_md->first_free)
1250 chunk_md->first_free = find_next_zero_bit(
1251 chunk->alloc_map,
1252 pcpu_chunk_map_bits(chunk),
1253 bit_off + alloc_bits);
1254
1255 pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1256
1257 pcpu_chunk_relocate(chunk, oslot);
1258
1259 return bit_off * PCPU_MIN_ALLOC_SIZE;
1260}
1261
1262/**
1263 * pcpu_free_area - frees the corresponding offset
1264 * @chunk: chunk of interest
1265 * @off: addr offset into chunk
1266 *
1267 * This function determines the size of an allocation to free using
1268 * the boundary bitmap and clears the allocation map.
1269 *
1270 * RETURNS:
1271 * Number of freed bytes.
1272 */
1273static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
1274{
1275 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1276 int bit_off, bits, end, oslot, freed;
1277
1278 lockdep_assert_held(&pcpu_lock);
1279 pcpu_stats_area_dealloc(chunk);
1280
1281 oslot = pcpu_chunk_slot(chunk);
1282
1283 bit_off = off / PCPU_MIN_ALLOC_SIZE;
1284
1285 /* find end index */
1286 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1287 bit_off + 1);
1288 bits = end - bit_off;
1289 bitmap_clear(chunk->alloc_map, bit_off, bits);
1290
1291 freed = bits * PCPU_MIN_ALLOC_SIZE;
1292
1293 /* update metadata */
1294 chunk->free_bytes += freed;
1295
1296 /* update first free bit */
1297 chunk_md->first_free = min(chunk_md->first_free, bit_off);
1298
1299 pcpu_block_update_hint_free(chunk, bit_off, bits);
1300
1301 pcpu_chunk_relocate(chunk, oslot);
1302
1303 return freed;
1304}
1305
1306static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1307{
1308 block->scan_hint = 0;
1309 block->contig_hint = nr_bits;
1310 block->left_free = nr_bits;
1311 block->right_free = nr_bits;
1312 block->first_free = 0;
1313 block->nr_bits = nr_bits;
1314}
1315
1316static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1317{
1318 struct pcpu_block_md *md_block;
1319
1320 /* init the chunk's block */
1321 pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1322
1323 for (md_block = chunk->md_blocks;
1324 md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1325 md_block++)
1326 pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1327}
1328
1329/**
1330 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1331 * @tmp_addr: the start of the region served
1332 * @map_size: size of the region served
1333 *
1334 * This is responsible for creating the chunks that serve the first chunk. The
1335 * base_addr is page aligned down of @tmp_addr while the region end is page
1336 * aligned up. Offsets are kept track of to determine the region served. All
1337 * this is done to appease the bitmap allocator in avoiding partial blocks.
1338 *
1339 * RETURNS:
1340 * Chunk serving the region at @tmp_addr of @map_size.
1341 */
1342static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1343 int map_size)
1344{
1345 struct pcpu_chunk *chunk;
1346 unsigned long aligned_addr, lcm_align;
1347 int start_offset, offset_bits, region_size, region_bits;
1348 size_t alloc_size;
1349
1350 /* region calculations */
1351 aligned_addr = tmp_addr & PAGE_MASK;
1352
1353 start_offset = tmp_addr - aligned_addr;
1354
1355 /*
1356 * Align the end of the region with the LCM of PAGE_SIZE and
1357 * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of
1358 * the other.
1359 */
1360 lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
1361 region_size = ALIGN(start_offset + map_size, lcm_align);
1362
1363 /* allocate chunk */
1364 alloc_size = struct_size(chunk, populated,
1365 BITS_TO_LONGS(region_size >> PAGE_SHIFT));
1366 chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1367 if (!chunk)
1368 panic("%s: Failed to allocate %zu bytes\n", __func__,
1369 alloc_size);
1370
1371 INIT_LIST_HEAD(&chunk->list);
1372
1373 chunk->base_addr = (void *)aligned_addr;
1374 chunk->start_offset = start_offset;
1375 chunk->end_offset = region_size - chunk->start_offset - map_size;
1376
1377 chunk->nr_pages = region_size >> PAGE_SHIFT;
1378 region_bits = pcpu_chunk_map_bits(chunk);
1379
1380 alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1381 chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1382 if (!chunk->alloc_map)
1383 panic("%s: Failed to allocate %zu bytes\n", __func__,
1384 alloc_size);
1385
1386 alloc_size =
1387 BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1388 chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1389 if (!chunk->bound_map)
1390 panic("%s: Failed to allocate %zu bytes\n", __func__,
1391 alloc_size);
1392
1393 alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1394 chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1395 if (!chunk->md_blocks)
1396 panic("%s: Failed to allocate %zu bytes\n", __func__,
1397 alloc_size);
1398
1399#ifdef CONFIG_MEMCG_KMEM
1400 /* first chunk is free to use */
1401 chunk->obj_cgroups = NULL;
1402#endif
1403 pcpu_init_md_blocks(chunk);
1404
1405 /* manage populated page bitmap */
1406 chunk->immutable = true;
1407 bitmap_fill(chunk->populated, chunk->nr_pages);
1408 chunk->nr_populated = chunk->nr_pages;
1409 chunk->nr_empty_pop_pages = chunk->nr_pages;
1410
1411 chunk->free_bytes = map_size;
1412
1413 if (chunk->start_offset) {
1414 /* hide the beginning of the bitmap */
1415 offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1416 bitmap_set(chunk->alloc_map, 0, offset_bits);
1417 set_bit(0, chunk->bound_map);
1418 set_bit(offset_bits, chunk->bound_map);
1419
1420 chunk->chunk_md.first_free = offset_bits;
1421
1422 pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1423 }
1424
1425 if (chunk->end_offset) {
1426 /* hide the end of the bitmap */
1427 offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1428 bitmap_set(chunk->alloc_map,
1429 pcpu_chunk_map_bits(chunk) - offset_bits,
1430 offset_bits);
1431 set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1432 chunk->bound_map);
1433 set_bit(region_bits, chunk->bound_map);
1434
1435 pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1436 - offset_bits, offset_bits);
1437 }
1438
1439 return chunk;
1440}
1441
1442static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
1443{
1444 struct pcpu_chunk *chunk;
1445 int region_bits;
1446
1447 chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1448 if (!chunk)
1449 return NULL;
1450
1451 INIT_LIST_HEAD(&chunk->list);
1452 chunk->nr_pages = pcpu_unit_pages;
1453 region_bits = pcpu_chunk_map_bits(chunk);
1454
1455 chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1456 sizeof(chunk->alloc_map[0]), gfp);
1457 if (!chunk->alloc_map)
1458 goto alloc_map_fail;
1459
1460 chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1461 sizeof(chunk->bound_map[0]), gfp);
1462 if (!chunk->bound_map)
1463 goto bound_map_fail;
1464
1465 chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1466 sizeof(chunk->md_blocks[0]), gfp);
1467 if (!chunk->md_blocks)
1468 goto md_blocks_fail;
1469
1470#ifdef CONFIG_MEMCG_KMEM
1471 if (!mem_cgroup_kmem_disabled()) {
1472 chunk->obj_cgroups =
1473 pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
1474 sizeof(struct obj_cgroup *), gfp);
1475 if (!chunk->obj_cgroups)
1476 goto objcg_fail;
1477 }
1478#endif
1479
1480 pcpu_init_md_blocks(chunk);
1481
1482 /* init metadata */
1483 chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1484
1485 return chunk;
1486
1487#ifdef CONFIG_MEMCG_KMEM
1488objcg_fail:
1489 pcpu_mem_free(chunk->md_blocks);
1490#endif
1491md_blocks_fail:
1492 pcpu_mem_free(chunk->bound_map);
1493bound_map_fail:
1494 pcpu_mem_free(chunk->alloc_map);
1495alloc_map_fail:
1496 pcpu_mem_free(chunk);
1497
1498 return NULL;
1499}
1500
1501static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1502{
1503 if (!chunk)
1504 return;
1505#ifdef CONFIG_MEMCG_KMEM
1506 pcpu_mem_free(chunk->obj_cgroups);
1507#endif
1508 pcpu_mem_free(chunk->md_blocks);
1509 pcpu_mem_free(chunk->bound_map);
1510 pcpu_mem_free(chunk->alloc_map);
1511 pcpu_mem_free(chunk);
1512}
1513
1514/**
1515 * pcpu_chunk_populated - post-population bookkeeping
1516 * @chunk: pcpu_chunk which got populated
1517 * @page_start: the start page
1518 * @page_end: the end page
1519 *
1520 * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1521 * the bookkeeping information accordingly. Must be called after each
1522 * successful population.
1523 *
1524 * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it
1525 * is to serve an allocation in that area.
1526 */
1527static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1528 int page_end)
1529{
1530 int nr = page_end - page_start;
1531
1532 lockdep_assert_held(&pcpu_lock);
1533
1534 bitmap_set(chunk->populated, page_start, nr);
1535 chunk->nr_populated += nr;
1536 pcpu_nr_populated += nr;
1537
1538 pcpu_update_empty_pages(chunk, nr);
1539}
1540
1541/**
1542 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1543 * @chunk: pcpu_chunk which got depopulated
1544 * @page_start: the start page
1545 * @page_end: the end page
1546 *
1547 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1548 * Update the bookkeeping information accordingly. Must be called after
1549 * each successful depopulation.
1550 */
1551static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1552 int page_start, int page_end)
1553{
1554 int nr = page_end - page_start;
1555
1556 lockdep_assert_held(&pcpu_lock);
1557
1558 bitmap_clear(chunk->populated, page_start, nr);
1559 chunk->nr_populated -= nr;
1560 pcpu_nr_populated -= nr;
1561
1562 pcpu_update_empty_pages(chunk, -nr);
1563}
1564
1565/*
1566 * Chunk management implementation.
1567 *
1568 * To allow different implementations, chunk alloc/free and
1569 * [de]population are implemented in a separate file which is pulled
1570 * into this file and compiled together. The following functions
1571 * should be implemented.
1572 *
1573 * pcpu_populate_chunk - populate the specified range of a chunk
1574 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1575 * pcpu_post_unmap_tlb_flush - flush tlb for the specified range of a chunk
1576 * pcpu_create_chunk - create a new chunk
1577 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1578 * pcpu_addr_to_page - translate address to physical address
1579 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1580 */
1581static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1582 int page_start, int page_end, gfp_t gfp);
1583static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1584 int page_start, int page_end);
1585static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
1586 int page_start, int page_end);
1587static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
1588static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1589static struct page *pcpu_addr_to_page(void *addr);
1590static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1591
1592#ifdef CONFIG_NEED_PER_CPU_KM
1593#include "percpu-km.c"
1594#else
1595#include "percpu-vm.c"
1596#endif
1597
1598/**
1599 * pcpu_chunk_addr_search - determine chunk containing specified address
1600 * @addr: address for which the chunk needs to be determined.
1601 *
1602 * This is an internal function that handles all but static allocations.
1603 * Static percpu address values should never be passed into the allocator.
1604 *
1605 * RETURNS:
1606 * The address of the found chunk.
1607 */
1608static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1609{
1610 /* is it in the dynamic region (first chunk)? */
1611 if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1612 return pcpu_first_chunk;
1613
1614 /* is it in the reserved region? */
1615 if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1616 return pcpu_reserved_chunk;
1617
1618 /*
1619 * The address is relative to unit0 which might be unused and
1620 * thus unmapped. Offset the address to the unit space of the
1621 * current processor before looking it up in the vmalloc
1622 * space. Note that any possible cpu id can be used here, so
1623 * there's no need to worry about preemption or cpu hotplug.
1624 */
1625 addr += pcpu_unit_offsets[raw_smp_processor_id()];
1626 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1627}
1628
1629#ifdef CONFIG_MEMCG_KMEM
1630static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
1631 struct obj_cgroup **objcgp)
1632{
1633 struct obj_cgroup *objcg;
1634
1635 if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT))
1636 return true;
1637
1638 objcg = get_obj_cgroup_from_current();
1639 if (!objcg)
1640 return true;
1641
1642 if (obj_cgroup_charge(objcg, gfp, size * num_possible_cpus())) {
1643 obj_cgroup_put(objcg);
1644 return false;
1645 }
1646
1647 *objcgp = objcg;
1648 return true;
1649}
1650
1651static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1652 struct pcpu_chunk *chunk, int off,
1653 size_t size)
1654{
1655 if (!objcg)
1656 return;
1657
1658 if (likely(chunk && chunk->obj_cgroups)) {
1659 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
1660
1661 rcu_read_lock();
1662 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1663 size * num_possible_cpus());
1664 rcu_read_unlock();
1665 } else {
1666 obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1667 obj_cgroup_put(objcg);
1668 }
1669}
1670
1671static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1672{
1673 struct obj_cgroup *objcg;
1674
1675 if (unlikely(!chunk->obj_cgroups))
1676 return;
1677
1678 objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
1679 if (!objcg)
1680 return;
1681 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
1682
1683 obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1684
1685 rcu_read_lock();
1686 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1687 -(size * num_possible_cpus()));
1688 rcu_read_unlock();
1689
1690 obj_cgroup_put(objcg);
1691}
1692
1693#else /* CONFIG_MEMCG_KMEM */
1694static bool
1695pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
1696{
1697 return true;
1698}
1699
1700static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1701 struct pcpu_chunk *chunk, int off,
1702 size_t size)
1703{
1704}
1705
1706static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1707{
1708}
1709#endif /* CONFIG_MEMCG_KMEM */
1710
1711/**
1712 * pcpu_alloc - the percpu allocator
1713 * @size: size of area to allocate in bytes
1714 * @align: alignment of area (max PAGE_SIZE)
1715 * @reserved: allocate from the reserved chunk if available
1716 * @gfp: allocation flags
1717 *
1718 * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1719 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1720 * then no warning will be triggered on invalid or failed allocation
1721 * requests.
1722 *
1723 * RETURNS:
1724 * Percpu pointer to the allocated area on success, NULL on failure.
1725 */
1726static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1727 gfp_t gfp)
1728{
1729 gfp_t pcpu_gfp;
1730 bool is_atomic;
1731 bool do_warn;
1732 struct obj_cgroup *objcg = NULL;
1733 static int warn_limit = 10;
1734 struct pcpu_chunk *chunk, *next;
1735 const char *err;
1736 int slot, off, cpu, ret;
1737 unsigned long flags;
1738 void __percpu *ptr;
1739 size_t bits, bit_align;
1740
1741 gfp = current_gfp_context(gfp);
1742 /* whitelisted flags that can be passed to the backing allocators */
1743 pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1744 is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1745 do_warn = !(gfp & __GFP_NOWARN);
1746
1747 /*
1748 * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1749 * therefore alignment must be a minimum of that many bytes.
1750 * An allocation may have internal fragmentation from rounding up
1751 * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1752 */
1753 if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1754 align = PCPU_MIN_ALLOC_SIZE;
1755
1756 size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1757 bits = size >> PCPU_MIN_ALLOC_SHIFT;
1758 bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1759
1760 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1761 !is_power_of_2(align))) {
1762 WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1763 size, align);
1764 return NULL;
1765 }
1766
1767 if (unlikely(!pcpu_memcg_pre_alloc_hook(size, gfp, &objcg)))
1768 return NULL;
1769
1770 if (!is_atomic) {
1771 /*
1772 * pcpu_balance_workfn() allocates memory under this mutex,
1773 * and it may wait for memory reclaim. Allow current task
1774 * to become OOM victim, in case of memory pressure.
1775 */
1776 if (gfp & __GFP_NOFAIL) {
1777 mutex_lock(&pcpu_alloc_mutex);
1778 } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
1779 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1780 return NULL;
1781 }
1782 }
1783
1784 spin_lock_irqsave(&pcpu_lock, flags);
1785
1786 /* serve reserved allocations from the reserved chunk if available */
1787 if (reserved && pcpu_reserved_chunk) {
1788 chunk = pcpu_reserved_chunk;
1789
1790 off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1791 if (off < 0) {
1792 err = "alloc from reserved chunk failed";
1793 goto fail_unlock;
1794 }
1795
1796 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1797 if (off >= 0)
1798 goto area_found;
1799
1800 err = "alloc from reserved chunk failed";
1801 goto fail_unlock;
1802 }
1803
1804restart:
1805 /* search through normal chunks */
1806 for (slot = pcpu_size_to_slot(size); slot <= pcpu_free_slot; slot++) {
1807 list_for_each_entry_safe(chunk, next, &pcpu_chunk_lists[slot],
1808 list) {
1809 off = pcpu_find_block_fit(chunk, bits, bit_align,
1810 is_atomic);
1811 if (off < 0) {
1812 if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1813 pcpu_chunk_move(chunk, 0);
1814 continue;
1815 }
1816
1817 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1818 if (off >= 0) {
1819 pcpu_reintegrate_chunk(chunk);
1820 goto area_found;
1821 }
1822 }
1823 }
1824
1825 spin_unlock_irqrestore(&pcpu_lock, flags);
1826
1827 /*
1828 * No space left. Create a new chunk. We don't want multiple
1829 * tasks to create chunks simultaneously. Serialize and create iff
1830 * there's still no empty chunk after grabbing the mutex.
1831 */
1832 if (is_atomic) {
1833 err = "atomic alloc failed, no space left";
1834 goto fail;
1835 }
1836
1837 if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
1838 chunk = pcpu_create_chunk(pcpu_gfp);
1839 if (!chunk) {
1840 err = "failed to allocate new chunk";
1841 goto fail;
1842 }
1843
1844 spin_lock_irqsave(&pcpu_lock, flags);
1845 pcpu_chunk_relocate(chunk, -1);
1846 } else {
1847 spin_lock_irqsave(&pcpu_lock, flags);
1848 }
1849
1850 goto restart;
1851
1852area_found:
1853 pcpu_stats_area_alloc(chunk, size);
1854 spin_unlock_irqrestore(&pcpu_lock, flags);
1855
1856 /* populate if not all pages are already there */
1857 if (!is_atomic) {
1858 unsigned int page_start, page_end, rs, re;
1859
1860 page_start = PFN_DOWN(off);
1861 page_end = PFN_UP(off + size);
1862
1863 bitmap_for_each_clear_region(chunk->populated, rs, re,
1864 page_start, page_end) {
1865 WARN_ON(chunk->immutable);
1866
1867 ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1868
1869 spin_lock_irqsave(&pcpu_lock, flags);
1870 if (ret) {
1871 pcpu_free_area(chunk, off);
1872 err = "failed to populate";
1873 goto fail_unlock;
1874 }
1875 pcpu_chunk_populated(chunk, rs, re);
1876 spin_unlock_irqrestore(&pcpu_lock, flags);
1877 }
1878
1879 mutex_unlock(&pcpu_alloc_mutex);
1880 }
1881
1882 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1883 pcpu_schedule_balance_work();
1884
1885 /* clear the areas and return address relative to base address */
1886 for_each_possible_cpu(cpu)
1887 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1888
1889 ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1890 kmemleak_alloc_percpu(ptr, size, gfp);
1891
1892 trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
1893 chunk->base_addr, off, ptr);
1894
1895 pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
1896
1897 return ptr;
1898
1899fail_unlock:
1900 spin_unlock_irqrestore(&pcpu_lock, flags);
1901fail:
1902 trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1903
1904 if (!is_atomic && do_warn && warn_limit) {
1905 pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1906 size, align, is_atomic, err);
1907 dump_stack();
1908 if (!--warn_limit)
1909 pr_info("limit reached, disable warning\n");
1910 }
1911 if (is_atomic) {
1912 /* see the flag handling in pcpu_balance_workfn() */
1913 pcpu_atomic_alloc_failed = true;
1914 pcpu_schedule_balance_work();
1915 } else {
1916 mutex_unlock(&pcpu_alloc_mutex);
1917 }
1918
1919 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1920
1921 return NULL;
1922}
1923
1924/**
1925 * __alloc_percpu_gfp - allocate dynamic percpu area
1926 * @size: size of area to allocate in bytes
1927 * @align: alignment of area (max PAGE_SIZE)
1928 * @gfp: allocation flags
1929 *
1930 * Allocate zero-filled percpu area of @size bytes aligned at @align. If
1931 * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1932 * be called from any context but is a lot more likely to fail. If @gfp
1933 * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1934 * allocation requests.
1935 *
1936 * RETURNS:
1937 * Percpu pointer to the allocated area on success, NULL on failure.
1938 */
1939void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1940{
1941 return pcpu_alloc(size, align, false, gfp);
1942}
1943EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1944
1945/**
1946 * __alloc_percpu - allocate dynamic percpu area
1947 * @size: size of area to allocate in bytes
1948 * @align: alignment of area (max PAGE_SIZE)
1949 *
1950 * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1951 */
1952void __percpu *__alloc_percpu(size_t size, size_t align)
1953{
1954 return pcpu_alloc(size, align, false, GFP_KERNEL);
1955}
1956EXPORT_SYMBOL_GPL(__alloc_percpu);
1957
1958/**
1959 * __alloc_reserved_percpu - allocate reserved percpu area
1960 * @size: size of area to allocate in bytes
1961 * @align: alignment of area (max PAGE_SIZE)
1962 *
1963 * Allocate zero-filled percpu area of @size bytes aligned at @align
1964 * from reserved percpu area if arch has set it up; otherwise,
1965 * allocation is served from the same dynamic area. Might sleep.
1966 * Might trigger writeouts.
1967 *
1968 * CONTEXT:
1969 * Does GFP_KERNEL allocation.
1970 *
1971 * RETURNS:
1972 * Percpu pointer to the allocated area on success, NULL on failure.
1973 */
1974void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1975{
1976 return pcpu_alloc(size, align, true, GFP_KERNEL);
1977}
1978
1979/**
1980 * pcpu_balance_free - manage the amount of free chunks
1981 * @empty_only: free chunks only if there are no populated pages
1982 *
1983 * If empty_only is %false, reclaim all fully free chunks regardless of the
1984 * number of populated pages. Otherwise, only reclaim chunks that have no
1985 * populated pages.
1986 *
1987 * CONTEXT:
1988 * pcpu_lock (can be dropped temporarily)
1989 */
1990static void pcpu_balance_free(bool empty_only)
1991{
1992 LIST_HEAD(to_free);
1993 struct list_head *free_head = &pcpu_chunk_lists[pcpu_free_slot];
1994 struct pcpu_chunk *chunk, *next;
1995
1996 lockdep_assert_held(&pcpu_lock);
1997
1998 /*
1999 * There's no reason to keep around multiple unused chunks and VM
2000 * areas can be scarce. Destroy all free chunks except for one.
2001 */
2002 list_for_each_entry_safe(chunk, next, free_head, list) {
2003 WARN_ON(chunk->immutable);
2004
2005 /* spare the first one */
2006 if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
2007 continue;
2008
2009 if (!empty_only || chunk->nr_empty_pop_pages == 0)
2010 list_move(&chunk->list, &to_free);
2011 }
2012
2013 if (list_empty(&to_free))
2014 return;
2015
2016 spin_unlock_irq(&pcpu_lock);
2017 list_for_each_entry_safe(chunk, next, &to_free, list) {
2018 unsigned int rs, re;
2019
2020 bitmap_for_each_set_region(chunk->populated, rs, re, 0,
2021 chunk->nr_pages) {
2022 pcpu_depopulate_chunk(chunk, rs, re);
2023 spin_lock_irq(&pcpu_lock);
2024 pcpu_chunk_depopulated(chunk, rs, re);
2025 spin_unlock_irq(&pcpu_lock);
2026 }
2027 pcpu_destroy_chunk(chunk);
2028 cond_resched();
2029 }
2030 spin_lock_irq(&pcpu_lock);
2031}
2032
2033/**
2034 * pcpu_balance_populated - manage the amount of populated pages
2035 *
2036 * Maintain a certain amount of populated pages to satisfy atomic allocations.
2037 * It is possible that this is called when physical memory is scarce causing
2038 * OOM killer to be triggered. We should avoid doing so until an actual
2039 * allocation causes the failure as it is possible that requests can be
2040 * serviced from already backed regions.
2041 *
2042 * CONTEXT:
2043 * pcpu_lock (can be dropped temporarily)
2044 */
2045static void pcpu_balance_populated(void)
2046{
2047 /* gfp flags passed to underlying allocators */
2048 const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
2049 struct pcpu_chunk *chunk;
2050 int slot, nr_to_pop, ret;
2051
2052 lockdep_assert_held(&pcpu_lock);
2053
2054 /*
2055 * Ensure there are certain number of free populated pages for
2056 * atomic allocs. Fill up from the most packed so that atomic
2057 * allocs don't increase fragmentation. If atomic allocation
2058 * failed previously, always populate the maximum amount. This
2059 * should prevent atomic allocs larger than PAGE_SIZE from keeping
2060 * failing indefinitely; however, large atomic allocs are not
2061 * something we support properly and can be highly unreliable and
2062 * inefficient.
2063 */
2064retry_pop:
2065 if (pcpu_atomic_alloc_failed) {
2066 nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
2067 /* best effort anyway, don't worry about synchronization */
2068 pcpu_atomic_alloc_failed = false;
2069 } else {
2070 nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
2071 pcpu_nr_empty_pop_pages,
2072 0, PCPU_EMPTY_POP_PAGES_HIGH);
2073 }
2074
2075 for (slot = pcpu_size_to_slot(PAGE_SIZE); slot <= pcpu_free_slot; slot++) {
2076 unsigned int nr_unpop = 0, rs, re;
2077
2078 if (!nr_to_pop)
2079 break;
2080
2081 list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) {
2082 nr_unpop = chunk->nr_pages - chunk->nr_populated;
2083 if (nr_unpop)
2084 break;
2085 }
2086
2087 if (!nr_unpop)
2088 continue;
2089
2090 /* @chunk can't go away while pcpu_alloc_mutex is held */
2091 bitmap_for_each_clear_region(chunk->populated, rs, re, 0,
2092 chunk->nr_pages) {
2093 int nr = min_t(int, re - rs, nr_to_pop);
2094
2095 spin_unlock_irq(&pcpu_lock);
2096 ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
2097 cond_resched();
2098 spin_lock_irq(&pcpu_lock);
2099 if (!ret) {
2100 nr_to_pop -= nr;
2101 pcpu_chunk_populated(chunk, rs, rs + nr);
2102 } else {
2103 nr_to_pop = 0;
2104 }
2105
2106 if (!nr_to_pop)
2107 break;
2108 }
2109 }
2110
2111 if (nr_to_pop) {
2112 /* ran out of chunks to populate, create a new one and retry */
2113 spin_unlock_irq(&pcpu_lock);
2114 chunk = pcpu_create_chunk(gfp);
2115 cond_resched();
2116 spin_lock_irq(&pcpu_lock);
2117 if (chunk) {
2118 pcpu_chunk_relocate(chunk, -1);
2119 goto retry_pop;
2120 }
2121 }
2122}
2123
2124/**
2125 * pcpu_reclaim_populated - scan over to_depopulate chunks and free empty pages
2126 *
2127 * Scan over chunks in the depopulate list and try to release unused populated
2128 * pages back to the system. Depopulated chunks are sidelined to prevent
2129 * repopulating these pages unless required. Fully free chunks are reintegrated
2130 * and freed accordingly (1 is kept around). If we drop below the empty
2131 * populated pages threshold, reintegrate the chunk if it has empty free pages.
2132 * Each chunk is scanned in the reverse order to keep populated pages close to
2133 * the beginning of the chunk.
2134 *
2135 * CONTEXT:
2136 * pcpu_lock (can be dropped temporarily)
2137 *
2138 */
2139static void pcpu_reclaim_populated(void)
2140{
2141 struct pcpu_chunk *chunk;
2142 struct pcpu_block_md *block;
2143 int freed_page_start, freed_page_end;
2144 int i, end;
2145 bool reintegrate;
2146
2147 lockdep_assert_held(&pcpu_lock);
2148
2149 /*
2150 * Once a chunk is isolated to the to_depopulate list, the chunk is no
2151 * longer discoverable to allocations whom may populate pages. The only
2152 * other accessor is the free path which only returns area back to the
2153 * allocator not touching the populated bitmap.
2154 */
2155 while (!list_empty(&pcpu_chunk_lists[pcpu_to_depopulate_slot])) {
2156 chunk = list_first_entry(&pcpu_chunk_lists[pcpu_to_depopulate_slot],
2157 struct pcpu_chunk, list);
2158 WARN_ON(chunk->immutable);
2159
2160 /*
2161 * Scan chunk's pages in the reverse order to keep populated
2162 * pages close to the beginning of the chunk.
2163 */
2164 freed_page_start = chunk->nr_pages;
2165 freed_page_end = 0;
2166 reintegrate = false;
2167 for (i = chunk->nr_pages - 1, end = -1; i >= 0; i--) {
2168 /* no more work to do */
2169 if (chunk->nr_empty_pop_pages == 0)
2170 break;
2171
2172 /* reintegrate chunk to prevent atomic alloc failures */
2173 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_HIGH) {
2174 reintegrate = true;
2175 goto end_chunk;
2176 }
2177
2178 /*
2179 * If the page is empty and populated, start or
2180 * extend the (i, end) range. If i == 0, decrease
2181 * i and perform the depopulation to cover the last
2182 * (first) page in the chunk.
2183 */
2184 block = chunk->md_blocks + i;
2185 if (block->contig_hint == PCPU_BITMAP_BLOCK_BITS &&
2186 test_bit(i, chunk->populated)) {
2187 if (end == -1)
2188 end = i;
2189 if (i > 0)
2190 continue;
2191 i--;
2192 }
2193
2194 /* depopulate if there is an active range */
2195 if (end == -1)
2196 continue;
2197
2198 spin_unlock_irq(&pcpu_lock);
2199 pcpu_depopulate_chunk(chunk, i + 1, end + 1);
2200 cond_resched();
2201 spin_lock_irq(&pcpu_lock);
2202
2203 pcpu_chunk_depopulated(chunk, i + 1, end + 1);
2204 freed_page_start = min(freed_page_start, i + 1);
2205 freed_page_end = max(freed_page_end, end + 1);
2206
2207 /* reset the range and continue */
2208 end = -1;
2209 }
2210
2211end_chunk:
2212 /* batch tlb flush per chunk to amortize cost */
2213 if (freed_page_start < freed_page_end) {
2214 spin_unlock_irq(&pcpu_lock);
2215 pcpu_post_unmap_tlb_flush(chunk,
2216 freed_page_start,
2217 freed_page_end);
2218 cond_resched();
2219 spin_lock_irq(&pcpu_lock);
2220 }
2221
2222 if (reintegrate || chunk->free_bytes == pcpu_unit_size)
2223 pcpu_reintegrate_chunk(chunk);
2224 else
2225 list_move_tail(&chunk->list,
2226 &pcpu_chunk_lists[pcpu_sidelined_slot]);
2227 }
2228}
2229
2230/**
2231 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
2232 * @work: unused
2233 *
2234 * For each chunk type, manage the number of fully free chunks and the number of
2235 * populated pages. An important thing to consider is when pages are freed and
2236 * how they contribute to the global counts.
2237 */
2238static void pcpu_balance_workfn(struct work_struct *work)
2239{
2240 /*
2241 * pcpu_balance_free() is called twice because the first time we may
2242 * trim pages in the active pcpu_nr_empty_pop_pages which may cause us
2243 * to grow other chunks. This then gives pcpu_reclaim_populated() time
2244 * to move fully free chunks to the active list to be freed if
2245 * appropriate.
2246 */
2247 mutex_lock(&pcpu_alloc_mutex);
2248 spin_lock_irq(&pcpu_lock);
2249
2250 pcpu_balance_free(false);
2251 pcpu_reclaim_populated();
2252 pcpu_balance_populated();
2253 pcpu_balance_free(true);
2254
2255 spin_unlock_irq(&pcpu_lock);
2256 mutex_unlock(&pcpu_alloc_mutex);
2257}
2258
2259/**
2260 * free_percpu - free percpu area
2261 * @ptr: pointer to area to free
2262 *
2263 * Free percpu area @ptr.
2264 *
2265 * CONTEXT:
2266 * Can be called from atomic context.
2267 */
2268void free_percpu(void __percpu *ptr)
2269{
2270 void *addr;
2271 struct pcpu_chunk *chunk;
2272 unsigned long flags;
2273 int size, off;
2274 bool need_balance = false;
2275
2276 if (!ptr)
2277 return;
2278
2279 kmemleak_free_percpu(ptr);
2280
2281 addr = __pcpu_ptr_to_addr(ptr);
2282
2283 spin_lock_irqsave(&pcpu_lock, flags);
2284
2285 chunk = pcpu_chunk_addr_search(addr);
2286 off = addr - chunk->base_addr;
2287
2288 size = pcpu_free_area(chunk, off);
2289
2290 pcpu_memcg_free_hook(chunk, off, size);
2291
2292 /*
2293 * If there are more than one fully free chunks, wake up grim reaper.
2294 * If the chunk is isolated, it may be in the process of being
2295 * reclaimed. Let reclaim manage cleaning up of that chunk.
2296 */
2297 if (!chunk->isolated && chunk->free_bytes == pcpu_unit_size) {
2298 struct pcpu_chunk *pos;
2299
2300 list_for_each_entry(pos, &pcpu_chunk_lists[pcpu_free_slot], list)
2301 if (pos != chunk) {
2302 need_balance = true;
2303 break;
2304 }
2305 } else if (pcpu_should_reclaim_chunk(chunk)) {
2306 pcpu_isolate_chunk(chunk);
2307 need_balance = true;
2308 }
2309
2310 trace_percpu_free_percpu(chunk->base_addr, off, ptr);
2311
2312 spin_unlock_irqrestore(&pcpu_lock, flags);
2313
2314 if (need_balance)
2315 pcpu_schedule_balance_work();
2316}
2317EXPORT_SYMBOL_GPL(free_percpu);
2318
2319bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
2320{
2321#ifdef CONFIG_SMP
2322 const size_t static_size = __per_cpu_end - __per_cpu_start;
2323 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2324 unsigned int cpu;
2325
2326 for_each_possible_cpu(cpu) {
2327 void *start = per_cpu_ptr(base, cpu);
2328 void *va = (void *)addr;
2329
2330 if (va >= start && va < start + static_size) {
2331 if (can_addr) {
2332 *can_addr = (unsigned long) (va - start);
2333 *can_addr += (unsigned long)
2334 per_cpu_ptr(base, get_boot_cpu_id());
2335 }
2336 return true;
2337 }
2338 }
2339#endif
2340 /* on UP, can't distinguish from other static vars, always false */
2341 return false;
2342}
2343
2344/**
2345 * is_kernel_percpu_address - test whether address is from static percpu area
2346 * @addr: address to test
2347 *
2348 * Test whether @addr belongs to in-kernel static percpu area. Module
2349 * static percpu areas are not considered. For those, use
2350 * is_module_percpu_address().
2351 *
2352 * RETURNS:
2353 * %true if @addr is from in-kernel static percpu area, %false otherwise.
2354 */
2355bool is_kernel_percpu_address(unsigned long addr)
2356{
2357 return __is_kernel_percpu_address(addr, NULL);
2358}
2359
2360/**
2361 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2362 * @addr: the address to be converted to physical address
2363 *
2364 * Given @addr which is dereferenceable address obtained via one of
2365 * percpu access macros, this function translates it into its physical
2366 * address. The caller is responsible for ensuring @addr stays valid
2367 * until this function finishes.
2368 *
2369 * percpu allocator has special setup for the first chunk, which currently
2370 * supports either embedding in linear address space or vmalloc mapping,
2371 * and, from the second one, the backing allocator (currently either vm or
2372 * km) provides translation.
2373 *
2374 * The addr can be translated simply without checking if it falls into the
2375 * first chunk. But the current code reflects better how percpu allocator
2376 * actually works, and the verification can discover both bugs in percpu
2377 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2378 * code.
2379 *
2380 * RETURNS:
2381 * The physical address for @addr.
2382 */
2383phys_addr_t per_cpu_ptr_to_phys(void *addr)
2384{
2385 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2386 bool in_first_chunk = false;
2387 unsigned long first_low, first_high;
2388 unsigned int cpu;
2389
2390 /*
2391 * The following test on unit_low/high isn't strictly
2392 * necessary but will speed up lookups of addresses which
2393 * aren't in the first chunk.
2394 *
2395 * The address check is against full chunk sizes. pcpu_base_addr
2396 * points to the beginning of the first chunk including the
2397 * static region. Assumes good intent as the first chunk may
2398 * not be full (ie. < pcpu_unit_pages in size).
2399 */
2400 first_low = (unsigned long)pcpu_base_addr +
2401 pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2402 first_high = (unsigned long)pcpu_base_addr +
2403 pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2404 if ((unsigned long)addr >= first_low &&
2405 (unsigned long)addr < first_high) {
2406 for_each_possible_cpu(cpu) {
2407 void *start = per_cpu_ptr(base, cpu);
2408
2409 if (addr >= start && addr < start + pcpu_unit_size) {
2410 in_first_chunk = true;
2411 break;
2412 }
2413 }
2414 }
2415
2416 if (in_first_chunk) {
2417 if (!is_vmalloc_addr(addr))
2418 return __pa(addr);
2419 else
2420 return page_to_phys(vmalloc_to_page(addr)) +
2421 offset_in_page(addr);
2422 } else
2423 return page_to_phys(pcpu_addr_to_page(addr)) +
2424 offset_in_page(addr);
2425}
2426
2427/**
2428 * pcpu_alloc_alloc_info - allocate percpu allocation info
2429 * @nr_groups: the number of groups
2430 * @nr_units: the number of units
2431 *
2432 * Allocate ai which is large enough for @nr_groups groups containing
2433 * @nr_units units. The returned ai's groups[0].cpu_map points to the
2434 * cpu_map array which is long enough for @nr_units and filled with
2435 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
2436 * pointer of other groups.
2437 *
2438 * RETURNS:
2439 * Pointer to the allocated pcpu_alloc_info on success, NULL on
2440 * failure.
2441 */
2442struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2443 int nr_units)
2444{
2445 struct pcpu_alloc_info *ai;
2446 size_t base_size, ai_size;
2447 void *ptr;
2448 int unit;
2449
2450 base_size = ALIGN(struct_size(ai, groups, nr_groups),
2451 __alignof__(ai->groups[0].cpu_map[0]));
2452 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2453
2454 ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2455 if (!ptr)
2456 return NULL;
2457 ai = ptr;
2458 ptr += base_size;
2459
2460 ai->groups[0].cpu_map = ptr;
2461
2462 for (unit = 0; unit < nr_units; unit++)
2463 ai->groups[0].cpu_map[unit] = NR_CPUS;
2464
2465 ai->nr_groups = nr_groups;
2466 ai->__ai_size = PFN_ALIGN(ai_size);
2467
2468 return ai;
2469}
2470
2471/**
2472 * pcpu_free_alloc_info - free percpu allocation info
2473 * @ai: pcpu_alloc_info to free
2474 *
2475 * Free @ai which was allocated by pcpu_alloc_alloc_info().
2476 */
2477void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2478{
2479 memblock_free_early(__pa(ai), ai->__ai_size);
2480}
2481
2482/**
2483 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2484 * @lvl: loglevel
2485 * @ai: allocation info to dump
2486 *
2487 * Print out information about @ai using loglevel @lvl.
2488 */
2489static void pcpu_dump_alloc_info(const char *lvl,
2490 const struct pcpu_alloc_info *ai)
2491{
2492 int group_width = 1, cpu_width = 1, width;
2493 char empty_str[] = "--------";
2494 int alloc = 0, alloc_end = 0;
2495 int group, v;
2496 int upa, apl; /* units per alloc, allocs per line */
2497
2498 v = ai->nr_groups;
2499 while (v /= 10)
2500 group_width++;
2501
2502 v = num_possible_cpus();
2503 while (v /= 10)
2504 cpu_width++;
2505 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2506
2507 upa = ai->alloc_size / ai->unit_size;
2508 width = upa * (cpu_width + 1) + group_width + 3;
2509 apl = rounddown_pow_of_two(max(60 / width, 1));
2510
2511 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2512 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2513 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2514
2515 for (group = 0; group < ai->nr_groups; group++) {
2516 const struct pcpu_group_info *gi = &ai->groups[group];
2517 int unit = 0, unit_end = 0;
2518
2519 BUG_ON(gi->nr_units % upa);
2520 for (alloc_end += gi->nr_units / upa;
2521 alloc < alloc_end; alloc++) {
2522 if (!(alloc % apl)) {
2523 pr_cont("\n");
2524 printk("%spcpu-alloc: ", lvl);
2525 }
2526 pr_cont("[%0*d] ", group_width, group);
2527
2528 for (unit_end += upa; unit < unit_end; unit++)
2529 if (gi->cpu_map[unit] != NR_CPUS)
2530 pr_cont("%0*d ",
2531 cpu_width, gi->cpu_map[unit]);
2532 else
2533 pr_cont("%s ", empty_str);
2534 }
2535 }
2536 pr_cont("\n");
2537}
2538
2539/**
2540 * pcpu_setup_first_chunk - initialize the first percpu chunk
2541 * @ai: pcpu_alloc_info describing how to percpu area is shaped
2542 * @base_addr: mapped address
2543 *
2544 * Initialize the first percpu chunk which contains the kernel static
2545 * percpu area. This function is to be called from arch percpu area
2546 * setup path.
2547 *
2548 * @ai contains all information necessary to initialize the first
2549 * chunk and prime the dynamic percpu allocator.
2550 *
2551 * @ai->static_size is the size of static percpu area.
2552 *
2553 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2554 * reserve after the static area in the first chunk. This reserves
2555 * the first chunk such that it's available only through reserved
2556 * percpu allocation. This is primarily used to serve module percpu
2557 * static areas on architectures where the addressing model has
2558 * limited offset range for symbol relocations to guarantee module
2559 * percpu symbols fall inside the relocatable range.
2560 *
2561 * @ai->dyn_size determines the number of bytes available for dynamic
2562 * allocation in the first chunk. The area between @ai->static_size +
2563 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2564 *
2565 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2566 * and equal to or larger than @ai->static_size + @ai->reserved_size +
2567 * @ai->dyn_size.
2568 *
2569 * @ai->atom_size is the allocation atom size and used as alignment
2570 * for vm areas.
2571 *
2572 * @ai->alloc_size is the allocation size and always multiple of
2573 * @ai->atom_size. This is larger than @ai->atom_size if
2574 * @ai->unit_size is larger than @ai->atom_size.
2575 *
2576 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2577 * percpu areas. Units which should be colocated are put into the
2578 * same group. Dynamic VM areas will be allocated according to these
2579 * groupings. If @ai->nr_groups is zero, a single group containing
2580 * all units is assumed.
2581 *
2582 * The caller should have mapped the first chunk at @base_addr and
2583 * copied static data to each unit.
2584 *
2585 * The first chunk will always contain a static and a dynamic region.
2586 * However, the static region is not managed by any chunk. If the first
2587 * chunk also contains a reserved region, it is served by two chunks -
2588 * one for the reserved region and one for the dynamic region. They
2589 * share the same vm, but use offset regions in the area allocation map.
2590 * The chunk serving the dynamic region is circulated in the chunk slots
2591 * and available for dynamic allocation like any other chunk.
2592 */
2593void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2594 void *base_addr)
2595{
2596 size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2597 size_t static_size, dyn_size;
2598 struct pcpu_chunk *chunk;
2599 unsigned long *group_offsets;
2600 size_t *group_sizes;
2601 unsigned long *unit_off;
2602 unsigned int cpu;
2603 int *unit_map;
2604 int group, unit, i;
2605 int map_size;
2606 unsigned long tmp_addr;
2607 size_t alloc_size;
2608
2609#define PCPU_SETUP_BUG_ON(cond) do { \
2610 if (unlikely(cond)) { \
2611 pr_emerg("failed to initialize, %s\n", #cond); \
2612 pr_emerg("cpu_possible_mask=%*pb\n", \
2613 cpumask_pr_args(cpu_possible_mask)); \
2614 pcpu_dump_alloc_info(KERN_EMERG, ai); \
2615 BUG(); \
2616 } \
2617} while (0)
2618
2619 /* sanity checks */
2620 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2621#ifdef CONFIG_SMP
2622 PCPU_SETUP_BUG_ON(!ai->static_size);
2623 PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2624#endif
2625 PCPU_SETUP_BUG_ON(!base_addr);
2626 PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2627 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2628 PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2629 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2630 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2631 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2632 PCPU_SETUP_BUG_ON(!ai->dyn_size);
2633 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2634 PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2635 IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2636 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2637
2638 /* process group information and build config tables accordingly */
2639 alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2640 group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2641 if (!group_offsets)
2642 panic("%s: Failed to allocate %zu bytes\n", __func__,
2643 alloc_size);
2644
2645 alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2646 group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2647 if (!group_sizes)
2648 panic("%s: Failed to allocate %zu bytes\n", __func__,
2649 alloc_size);
2650
2651 alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2652 unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2653 if (!unit_map)
2654 panic("%s: Failed to allocate %zu bytes\n", __func__,
2655 alloc_size);
2656
2657 alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2658 unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2659 if (!unit_off)
2660 panic("%s: Failed to allocate %zu bytes\n", __func__,
2661 alloc_size);
2662
2663 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2664 unit_map[cpu] = UINT_MAX;
2665
2666 pcpu_low_unit_cpu = NR_CPUS;
2667 pcpu_high_unit_cpu = NR_CPUS;
2668
2669 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2670 const struct pcpu_group_info *gi = &ai->groups[group];
2671
2672 group_offsets[group] = gi->base_offset;
2673 group_sizes[group] = gi->nr_units * ai->unit_size;
2674
2675 for (i = 0; i < gi->nr_units; i++) {
2676 cpu = gi->cpu_map[i];
2677 if (cpu == NR_CPUS)
2678 continue;
2679
2680 PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2681 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2682 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2683
2684 unit_map[cpu] = unit + i;
2685 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2686
2687 /* determine low/high unit_cpu */
2688 if (pcpu_low_unit_cpu == NR_CPUS ||
2689 unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2690 pcpu_low_unit_cpu = cpu;
2691 if (pcpu_high_unit_cpu == NR_CPUS ||
2692 unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2693 pcpu_high_unit_cpu = cpu;
2694 }
2695 }
2696 pcpu_nr_units = unit;
2697
2698 for_each_possible_cpu(cpu)
2699 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2700
2701 /* we're done parsing the input, undefine BUG macro and dump config */
2702#undef PCPU_SETUP_BUG_ON
2703 pcpu_dump_alloc_info(KERN_DEBUG, ai);
2704
2705 pcpu_nr_groups = ai->nr_groups;
2706 pcpu_group_offsets = group_offsets;
2707 pcpu_group_sizes = group_sizes;
2708 pcpu_unit_map = unit_map;
2709 pcpu_unit_offsets = unit_off;
2710
2711 /* determine basic parameters */
2712 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2713 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2714 pcpu_atom_size = ai->atom_size;
2715 pcpu_chunk_struct_size = struct_size(chunk, populated,
2716 BITS_TO_LONGS(pcpu_unit_pages));
2717
2718 pcpu_stats_save_ai(ai);
2719
2720 /*
2721 * Allocate chunk slots. The slots after the active slots are:
2722 * sidelined_slot - isolated, depopulated chunks
2723 * free_slot - fully free chunks
2724 * to_depopulate_slot - isolated, chunks to depopulate
2725 */
2726 pcpu_sidelined_slot = __pcpu_size_to_slot(pcpu_unit_size) + 1;
2727 pcpu_free_slot = pcpu_sidelined_slot + 1;
2728 pcpu_to_depopulate_slot = pcpu_free_slot + 1;
2729 pcpu_nr_slots = pcpu_to_depopulate_slot + 1;
2730 pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
2731 sizeof(pcpu_chunk_lists[0]),
2732 SMP_CACHE_BYTES);
2733 if (!pcpu_chunk_lists)
2734 panic("%s: Failed to allocate %zu bytes\n", __func__,
2735 pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]));
2736
2737 for (i = 0; i < pcpu_nr_slots; i++)
2738 INIT_LIST_HEAD(&pcpu_chunk_lists[i]);
2739
2740 /*
2741 * The end of the static region needs to be aligned with the
2742 * minimum allocation size as this offsets the reserved and
2743 * dynamic region. The first chunk ends page aligned by
2744 * expanding the dynamic region, therefore the dynamic region
2745 * can be shrunk to compensate while still staying above the
2746 * configured sizes.
2747 */
2748 static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2749 dyn_size = ai->dyn_size - (static_size - ai->static_size);
2750
2751 /*
2752 * Initialize first chunk.
2753 * If the reserved_size is non-zero, this initializes the reserved
2754 * chunk. If the reserved_size is zero, the reserved chunk is NULL
2755 * and the dynamic region is initialized here. The first chunk,
2756 * pcpu_first_chunk, will always point to the chunk that serves
2757 * the dynamic region.
2758 */
2759 tmp_addr = (unsigned long)base_addr + static_size;
2760 map_size = ai->reserved_size ?: dyn_size;
2761 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2762
2763 /* init dynamic chunk if necessary */
2764 if (ai->reserved_size) {
2765 pcpu_reserved_chunk = chunk;
2766
2767 tmp_addr = (unsigned long)base_addr + static_size +
2768 ai->reserved_size;
2769 map_size = dyn_size;
2770 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2771 }
2772
2773 /* link the first chunk in */
2774 pcpu_first_chunk = chunk;
2775 pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2776 pcpu_chunk_relocate(pcpu_first_chunk, -1);
2777
2778 /* include all regions of the first chunk */
2779 pcpu_nr_populated += PFN_DOWN(size_sum);
2780
2781 pcpu_stats_chunk_alloc();
2782 trace_percpu_create_chunk(base_addr);
2783
2784 /* we're done */
2785 pcpu_base_addr = base_addr;
2786}
2787
2788#ifdef CONFIG_SMP
2789
2790const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2791 [PCPU_FC_AUTO] = "auto",
2792 [PCPU_FC_EMBED] = "embed",
2793 [PCPU_FC_PAGE] = "page",
2794};
2795
2796enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2797
2798static int __init percpu_alloc_setup(char *str)
2799{
2800 if (!str)
2801 return -EINVAL;
2802
2803 if (0)
2804 /* nada */;
2805#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2806 else if (!strcmp(str, "embed"))
2807 pcpu_chosen_fc = PCPU_FC_EMBED;
2808#endif
2809#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2810 else if (!strcmp(str, "page"))
2811 pcpu_chosen_fc = PCPU_FC_PAGE;
2812#endif
2813 else
2814 pr_warn("unknown allocator %s specified\n", str);
2815
2816 return 0;
2817}
2818early_param("percpu_alloc", percpu_alloc_setup);
2819
2820/*
2821 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2822 * Build it if needed by the arch config or the generic setup is going
2823 * to be used.
2824 */
2825#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2826 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2827#define BUILD_EMBED_FIRST_CHUNK
2828#endif
2829
2830/* build pcpu_page_first_chunk() iff needed by the arch config */
2831#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2832#define BUILD_PAGE_FIRST_CHUNK
2833#endif
2834
2835/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2836#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2837/**
2838 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2839 * @reserved_size: the size of reserved percpu area in bytes
2840 * @dyn_size: minimum free size for dynamic allocation in bytes
2841 * @atom_size: allocation atom size
2842 * @cpu_distance_fn: callback to determine distance between cpus, optional
2843 *
2844 * This function determines grouping of units, their mappings to cpus
2845 * and other parameters considering needed percpu size, allocation
2846 * atom size and distances between CPUs.
2847 *
2848 * Groups are always multiples of atom size and CPUs which are of
2849 * LOCAL_DISTANCE both ways are grouped together and share space for
2850 * units in the same group. The returned configuration is guaranteed
2851 * to have CPUs on different nodes on different groups and >=75% usage
2852 * of allocated virtual address space.
2853 *
2854 * RETURNS:
2855 * On success, pointer to the new allocation_info is returned. On
2856 * failure, ERR_PTR value is returned.
2857 */
2858static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
2859 size_t reserved_size, size_t dyn_size,
2860 size_t atom_size,
2861 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2862{
2863 static int group_map[NR_CPUS] __initdata;
2864 static int group_cnt[NR_CPUS] __initdata;
2865 static struct cpumask mask __initdata;
2866 const size_t static_size = __per_cpu_end - __per_cpu_start;
2867 int nr_groups = 1, nr_units = 0;
2868 size_t size_sum, min_unit_size, alloc_size;
2869 int upa, max_upa, best_upa; /* units_per_alloc */
2870 int last_allocs, group, unit;
2871 unsigned int cpu, tcpu;
2872 struct pcpu_alloc_info *ai;
2873 unsigned int *cpu_map;
2874
2875 /* this function may be called multiple times */
2876 memset(group_map, 0, sizeof(group_map));
2877 memset(group_cnt, 0, sizeof(group_cnt));
2878 cpumask_clear(&mask);
2879
2880 /* calculate size_sum and ensure dyn_size is enough for early alloc */
2881 size_sum = PFN_ALIGN(static_size + reserved_size +
2882 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2883 dyn_size = size_sum - static_size - reserved_size;
2884
2885 /*
2886 * Determine min_unit_size, alloc_size and max_upa such that
2887 * alloc_size is multiple of atom_size and is the smallest
2888 * which can accommodate 4k aligned segments which are equal to
2889 * or larger than min_unit_size.
2890 */
2891 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2892
2893 /* determine the maximum # of units that can fit in an allocation */
2894 alloc_size = roundup(min_unit_size, atom_size);
2895 upa = alloc_size / min_unit_size;
2896 while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2897 upa--;
2898 max_upa = upa;
2899
2900 cpumask_copy(&mask, cpu_possible_mask);
2901
2902 /* group cpus according to their proximity */
2903 for (group = 0; !cpumask_empty(&mask); group++) {
2904 /* pop the group's first cpu */
2905 cpu = cpumask_first(&mask);
2906 group_map[cpu] = group;
2907 group_cnt[group]++;
2908 cpumask_clear_cpu(cpu, &mask);
2909
2910 for_each_cpu(tcpu, &mask) {
2911 if (!cpu_distance_fn ||
2912 (cpu_distance_fn(cpu, tcpu) == LOCAL_DISTANCE &&
2913 cpu_distance_fn(tcpu, cpu) == LOCAL_DISTANCE)) {
2914 group_map[tcpu] = group;
2915 group_cnt[group]++;
2916 cpumask_clear_cpu(tcpu, &mask);
2917 }
2918 }
2919 }
2920 nr_groups = group;
2921
2922 /*
2923 * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2924 * Expand the unit_size until we use >= 75% of the units allocated.
2925 * Related to atom_size, which could be much larger than the unit_size.
2926 */
2927 last_allocs = INT_MAX;
2928 best_upa = 0;
2929 for (upa = max_upa; upa; upa--) {
2930 int allocs = 0, wasted = 0;
2931
2932 if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2933 continue;
2934
2935 for (group = 0; group < nr_groups; group++) {
2936 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2937 allocs += this_allocs;
2938 wasted += this_allocs * upa - group_cnt[group];
2939 }
2940
2941 /*
2942 * Don't accept if wastage is over 1/3. The
2943 * greater-than comparison ensures upa==1 always
2944 * passes the following check.
2945 */
2946 if (wasted > num_possible_cpus() / 3)
2947 continue;
2948
2949 /* and then don't consume more memory */
2950 if (allocs > last_allocs)
2951 break;
2952 last_allocs = allocs;
2953 best_upa = upa;
2954 }
2955 BUG_ON(!best_upa);
2956 upa = best_upa;
2957
2958 /* allocate and fill alloc_info */
2959 for (group = 0; group < nr_groups; group++)
2960 nr_units += roundup(group_cnt[group], upa);
2961
2962 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2963 if (!ai)
2964 return ERR_PTR(-ENOMEM);
2965 cpu_map = ai->groups[0].cpu_map;
2966
2967 for (group = 0; group < nr_groups; group++) {
2968 ai->groups[group].cpu_map = cpu_map;
2969 cpu_map += roundup(group_cnt[group], upa);
2970 }
2971
2972 ai->static_size = static_size;
2973 ai->reserved_size = reserved_size;
2974 ai->dyn_size = dyn_size;
2975 ai->unit_size = alloc_size / upa;
2976 ai->atom_size = atom_size;
2977 ai->alloc_size = alloc_size;
2978
2979 for (group = 0, unit = 0; group < nr_groups; group++) {
2980 struct pcpu_group_info *gi = &ai->groups[group];
2981
2982 /*
2983 * Initialize base_offset as if all groups are located
2984 * back-to-back. The caller should update this to
2985 * reflect actual allocation.
2986 */
2987 gi->base_offset = unit * ai->unit_size;
2988
2989 for_each_possible_cpu(cpu)
2990 if (group_map[cpu] == group)
2991 gi->cpu_map[gi->nr_units++] = cpu;
2992 gi->nr_units = roundup(gi->nr_units, upa);
2993 unit += gi->nr_units;
2994 }
2995 BUG_ON(unit != nr_units);
2996
2997 return ai;
2998}
2999#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
3000
3001#if defined(BUILD_EMBED_FIRST_CHUNK)
3002/**
3003 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
3004 * @reserved_size: the size of reserved percpu area in bytes
3005 * @dyn_size: minimum free size for dynamic allocation in bytes
3006 * @atom_size: allocation atom size
3007 * @cpu_distance_fn: callback to determine distance between cpus, optional
3008 * @alloc_fn: function to allocate percpu page
3009 * @free_fn: function to free percpu page
3010 *
3011 * This is a helper to ease setting up embedded first percpu chunk and
3012 * can be called where pcpu_setup_first_chunk() is expected.
3013 *
3014 * If this function is used to setup the first chunk, it is allocated
3015 * by calling @alloc_fn and used as-is without being mapped into
3016 * vmalloc area. Allocations are always whole multiples of @atom_size
3017 * aligned to @atom_size.
3018 *
3019 * This enables the first chunk to piggy back on the linear physical
3020 * mapping which often uses larger page size. Please note that this
3021 * can result in very sparse cpu->unit mapping on NUMA machines thus
3022 * requiring large vmalloc address space. Don't use this allocator if
3023 * vmalloc space is not orders of magnitude larger than distances
3024 * between node memory addresses (ie. 32bit NUMA machines).
3025 *
3026 * @dyn_size specifies the minimum dynamic area size.
3027 *
3028 * If the needed size is smaller than the minimum or specified unit
3029 * size, the leftover is returned using @free_fn.
3030 *
3031 * RETURNS:
3032 * 0 on success, -errno on failure.
3033 */
3034int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
3035 size_t atom_size,
3036 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
3037 pcpu_fc_alloc_fn_t alloc_fn,
3038 pcpu_fc_free_fn_t free_fn)
3039{
3040 void *base = (void *)ULONG_MAX;
3041 void **areas = NULL;
3042 struct pcpu_alloc_info *ai;
3043 size_t size_sum, areas_size;
3044 unsigned long max_distance;
3045 int group, i, highest_group, rc = 0;
3046
3047 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
3048 cpu_distance_fn);
3049 if (IS_ERR(ai))
3050 return PTR_ERR(ai);
3051
3052 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
3053 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
3054
3055 areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
3056 if (!areas) {
3057 rc = -ENOMEM;
3058 goto out_free;
3059 }
3060
3061 /* allocate, copy and determine base address & max_distance */
3062 highest_group = 0;
3063 for (group = 0; group < ai->nr_groups; group++) {
3064 struct pcpu_group_info *gi = &ai->groups[group];
3065 unsigned int cpu = NR_CPUS;
3066 void *ptr;
3067
3068 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
3069 cpu = gi->cpu_map[i];
3070 BUG_ON(cpu == NR_CPUS);
3071
3072 /* allocate space for the whole group */
3073 ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
3074 if (!ptr) {
3075 rc = -ENOMEM;
3076 goto out_free_areas;
3077 }
3078 /* kmemleak tracks the percpu allocations separately */
3079 kmemleak_free(ptr);
3080 areas[group] = ptr;
3081
3082 base = min(ptr, base);
3083 if (ptr > areas[highest_group])
3084 highest_group = group;
3085 }
3086 max_distance = areas[highest_group] - base;
3087 max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
3088
3089 /* warn if maximum distance is further than 75% of vmalloc space */
3090 if (max_distance > VMALLOC_TOTAL * 3 / 4) {
3091 pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
3092 max_distance, VMALLOC_TOTAL);
3093#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
3094 /* and fail if we have fallback */
3095 rc = -EINVAL;
3096 goto out_free_areas;
3097#endif
3098 }
3099
3100 /*
3101 * Copy data and free unused parts. This should happen after all
3102 * allocations are complete; otherwise, we may end up with
3103 * overlapping groups.
3104 */
3105 for (group = 0; group < ai->nr_groups; group++) {
3106 struct pcpu_group_info *gi = &ai->groups[group];
3107 void *ptr = areas[group];
3108
3109 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
3110 if (gi->cpu_map[i] == NR_CPUS) {
3111 /* unused unit, free whole */
3112 free_fn(ptr, ai->unit_size);
3113 continue;
3114 }
3115 /* copy and return the unused part */
3116 memcpy(ptr, __per_cpu_load, ai->static_size);
3117 free_fn(ptr + size_sum, ai->unit_size - size_sum);
3118 }
3119 }
3120
3121 /* base address is now known, determine group base offsets */
3122 for (group = 0; group < ai->nr_groups; group++) {
3123 ai->groups[group].base_offset = areas[group] - base;
3124 }
3125
3126 pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
3127 PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
3128 ai->dyn_size, ai->unit_size);
3129
3130 pcpu_setup_first_chunk(ai, base);
3131 goto out_free;
3132
3133out_free_areas:
3134 for (group = 0; group < ai->nr_groups; group++)
3135 if (areas[group])
3136 free_fn(areas[group],
3137 ai->groups[group].nr_units * ai->unit_size);
3138out_free:
3139 pcpu_free_alloc_info(ai);
3140 if (areas)
3141 memblock_free_early(__pa(areas), areas_size);
3142 return rc;
3143}
3144#endif /* BUILD_EMBED_FIRST_CHUNK */
3145
3146#ifdef BUILD_PAGE_FIRST_CHUNK
3147/**
3148 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
3149 * @reserved_size: the size of reserved percpu area in bytes
3150 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
3151 * @free_fn: function to free percpu page, always called with PAGE_SIZE
3152 * @populate_pte_fn: function to populate pte
3153 *
3154 * This is a helper to ease setting up page-remapped first percpu
3155 * chunk and can be called where pcpu_setup_first_chunk() is expected.
3156 *
3157 * This is the basic allocator. Static percpu area is allocated
3158 * page-by-page into vmalloc area.
3159 *
3160 * RETURNS:
3161 * 0 on success, -errno on failure.
3162 */
3163int __init pcpu_page_first_chunk(size_t reserved_size,
3164 pcpu_fc_alloc_fn_t alloc_fn,
3165 pcpu_fc_free_fn_t free_fn,
3166 pcpu_fc_populate_pte_fn_t populate_pte_fn)
3167{
3168 static struct vm_struct vm;
3169 struct pcpu_alloc_info *ai;
3170 char psize_str[16];
3171 int unit_pages;
3172 size_t pages_size;
3173 struct page **pages;
3174 int unit, i, j, rc = 0;
3175 int upa;
3176 int nr_g0_units;
3177
3178 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
3179
3180 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
3181 if (IS_ERR(ai))
3182 return PTR_ERR(ai);
3183 BUG_ON(ai->nr_groups != 1);
3184 upa = ai->alloc_size/ai->unit_size;
3185 nr_g0_units = roundup(num_possible_cpus(), upa);
3186 if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
3187 pcpu_free_alloc_info(ai);
3188 return -EINVAL;
3189 }
3190
3191 unit_pages = ai->unit_size >> PAGE_SHIFT;
3192
3193 /* unaligned allocations can't be freed, round up to page size */
3194 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
3195 sizeof(pages[0]));
3196 pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
3197 if (!pages)
3198 panic("%s: Failed to allocate %zu bytes\n", __func__,
3199 pages_size);
3200
3201 /* allocate pages */
3202 j = 0;
3203 for (unit = 0; unit < num_possible_cpus(); unit++) {
3204 unsigned int cpu = ai->groups[0].cpu_map[unit];
3205 for (i = 0; i < unit_pages; i++) {
3206 void *ptr;
3207
3208 ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
3209 if (!ptr) {
3210 pr_warn("failed to allocate %s page for cpu%u\n",
3211 psize_str, cpu);
3212 goto enomem;
3213 }
3214 /* kmemleak tracks the percpu allocations separately */
3215 kmemleak_free(ptr);
3216 pages[j++] = virt_to_page(ptr);
3217 }
3218 }
3219
3220 /* allocate vm area, map the pages and copy static data */
3221 vm.flags = VM_ALLOC;
3222 vm.size = num_possible_cpus() * ai->unit_size;
3223 vm_area_register_early(&vm, PAGE_SIZE);
3224
3225 for (unit = 0; unit < num_possible_cpus(); unit++) {
3226 unsigned long unit_addr =
3227 (unsigned long)vm.addr + unit * ai->unit_size;
3228
3229 for (i = 0; i < unit_pages; i++)
3230 populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
3231
3232 /* pte already populated, the following shouldn't fail */
3233 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
3234 unit_pages);
3235 if (rc < 0)
3236 panic("failed to map percpu area, err=%d\n", rc);
3237
3238 /*
3239 * FIXME: Archs with virtual cache should flush local
3240 * cache for the linear mapping here - something
3241 * equivalent to flush_cache_vmap() on the local cpu.
3242 * flush_cache_vmap() can't be used as most supporting
3243 * data structures are not set up yet.
3244 */
3245
3246 /* copy static data */
3247 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
3248 }
3249
3250 /* we're ready, commit */
3251 pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
3252 unit_pages, psize_str, ai->static_size,
3253 ai->reserved_size, ai->dyn_size);
3254
3255 pcpu_setup_first_chunk(ai, vm.addr);
3256 goto out_free_ar;
3257
3258enomem:
3259 while (--j >= 0)
3260 free_fn(page_address(pages[j]), PAGE_SIZE);
3261 rc = -ENOMEM;
3262out_free_ar:
3263 memblock_free_early(__pa(pages), pages_size);
3264 pcpu_free_alloc_info(ai);
3265 return rc;
3266}
3267#endif /* BUILD_PAGE_FIRST_CHUNK */
3268
3269#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
3270/*
3271 * Generic SMP percpu area setup.
3272 *
3273 * The embedding helper is used because its behavior closely resembles
3274 * the original non-dynamic generic percpu area setup. This is
3275 * important because many archs have addressing restrictions and might
3276 * fail if the percpu area is located far away from the previous
3277 * location. As an added bonus, in non-NUMA cases, embedding is
3278 * generally a good idea TLB-wise because percpu area can piggy back
3279 * on the physical linear memory mapping which uses large page
3280 * mappings on applicable archs.
3281 */
3282unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
3283EXPORT_SYMBOL(__per_cpu_offset);
3284
3285static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
3286 size_t align)
3287{
3288 return memblock_alloc_from(size, align, __pa(MAX_DMA_ADDRESS));
3289}
3290
3291static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
3292{
3293 memblock_free_early(__pa(ptr), size);
3294}
3295
3296void __init setup_per_cpu_areas(void)
3297{
3298 unsigned long delta;
3299 unsigned int cpu;
3300 int rc;
3301
3302 /*
3303 * Always reserve area for module percpu variables. That's
3304 * what the legacy allocator did.
3305 */
3306 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
3307 PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
3308 pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
3309 if (rc < 0)
3310 panic("Failed to initialize percpu areas.");
3311
3312 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
3313 for_each_possible_cpu(cpu)
3314 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
3315}
3316#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
3317
3318#else /* CONFIG_SMP */
3319
3320/*
3321 * UP percpu area setup.
3322 *
3323 * UP always uses km-based percpu allocator with identity mapping.
3324 * Static percpu variables are indistinguishable from the usual static
3325 * variables and don't require any special preparation.
3326 */
3327void __init setup_per_cpu_areas(void)
3328{
3329 const size_t unit_size =
3330 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
3331 PERCPU_DYNAMIC_RESERVE));
3332 struct pcpu_alloc_info *ai;
3333 void *fc;
3334
3335 ai = pcpu_alloc_alloc_info(1, 1);
3336 fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3337 if (!ai || !fc)
3338 panic("Failed to allocate memory for percpu areas.");
3339 /* kmemleak tracks the percpu allocations separately */
3340 kmemleak_free(fc);
3341
3342 ai->dyn_size = unit_size;
3343 ai->unit_size = unit_size;
3344 ai->atom_size = unit_size;
3345 ai->alloc_size = unit_size;
3346 ai->groups[0].nr_units = 1;
3347 ai->groups[0].cpu_map[0] = 0;
3348
3349 pcpu_setup_first_chunk(ai, fc);
3350 pcpu_free_alloc_info(ai);
3351}
3352
3353#endif /* CONFIG_SMP */
3354
3355/*
3356 * pcpu_nr_pages - calculate total number of populated backing pages
3357 *
3358 * This reflects the number of pages populated to back chunks. Metadata is
3359 * excluded in the number exposed in meminfo as the number of backing pages
3360 * scales with the number of cpus and can quickly outweigh the memory used for
3361 * metadata. It also keeps this calculation nice and simple.
3362 *
3363 * RETURNS:
3364 * Total number of populated backing pages in use by the allocator.
3365 */
3366unsigned long pcpu_nr_pages(void)
3367{
3368 return pcpu_nr_populated * pcpu_nr_units;
3369}
3370
3371/*
3372 * Percpu allocator is initialized early during boot when neither slab or
3373 * workqueue is available. Plug async management until everything is up
3374 * and running.
3375 */
3376static int __init percpu_enable_async(void)
3377{
3378 pcpu_async_enabled = true;
3379 return 0;
3380}
3381subsys_initcall(percpu_enable_async);