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1/*
2 * Copyright (C) 2009 Red Hat, Inc.
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/mm.h>
11#include <linux/sched.h>
12#include <linux/sched/coredump.h>
13#include <linux/sched/numa_balancing.h>
14#include <linux/highmem.h>
15#include <linux/hugetlb.h>
16#include <linux/mmu_notifier.h>
17#include <linux/rmap.h>
18#include <linux/swap.h>
19#include <linux/shrinker.h>
20#include <linux/mm_inline.h>
21#include <linux/swapops.h>
22#include <linux/dax.h>
23#include <linux/khugepaged.h>
24#include <linux/freezer.h>
25#include <linux/pfn_t.h>
26#include <linux/mman.h>
27#include <linux/memremap.h>
28#include <linux/pagemap.h>
29#include <linux/debugfs.h>
30#include <linux/migrate.h>
31#include <linux/hashtable.h>
32#include <linux/userfaultfd_k.h>
33#include <linux/page_idle.h>
34#include <linux/shmem_fs.h>
35#include <linux/oom.h>
36
37#include <asm/tlb.h>
38#include <asm/pgalloc.h>
39#include "internal.h"
40
41/*
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
48 */
49unsigned long transparent_hugepage_flags __read_mostly =
50#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52#endif
53#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55#endif
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
59
60static struct shrinker deferred_split_shrinker;
61
62static atomic_t huge_zero_refcount;
63struct page *huge_zero_page __read_mostly;
64
65static struct page *get_huge_zero_page(void)
66{
67 struct page *zero_page;
68retry:
69 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
70 return READ_ONCE(huge_zero_page);
71
72 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
73 HPAGE_PMD_ORDER);
74 if (!zero_page) {
75 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
76 return NULL;
77 }
78 count_vm_event(THP_ZERO_PAGE_ALLOC);
79 preempt_disable();
80 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
81 preempt_enable();
82 __free_pages(zero_page, compound_order(zero_page));
83 goto retry;
84 }
85
86 /* We take additional reference here. It will be put back by shrinker */
87 atomic_set(&huge_zero_refcount, 2);
88 preempt_enable();
89 return READ_ONCE(huge_zero_page);
90}
91
92static void put_huge_zero_page(void)
93{
94 /*
95 * Counter should never go to zero here. Only shrinker can put
96 * last reference.
97 */
98 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
99}
100
101struct page *mm_get_huge_zero_page(struct mm_struct *mm)
102{
103 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
104 return READ_ONCE(huge_zero_page);
105
106 if (!get_huge_zero_page())
107 return NULL;
108
109 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
110 put_huge_zero_page();
111
112 return READ_ONCE(huge_zero_page);
113}
114
115void mm_put_huge_zero_page(struct mm_struct *mm)
116{
117 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
118 put_huge_zero_page();
119}
120
121static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
122 struct shrink_control *sc)
123{
124 /* we can free zero page only if last reference remains */
125 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
126}
127
128static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
129 struct shrink_control *sc)
130{
131 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
132 struct page *zero_page = xchg(&huge_zero_page, NULL);
133 BUG_ON(zero_page == NULL);
134 __free_pages(zero_page, compound_order(zero_page));
135 return HPAGE_PMD_NR;
136 }
137
138 return 0;
139}
140
141static struct shrinker huge_zero_page_shrinker = {
142 .count_objects = shrink_huge_zero_page_count,
143 .scan_objects = shrink_huge_zero_page_scan,
144 .seeks = DEFAULT_SEEKS,
145};
146
147#ifdef CONFIG_SYSFS
148static ssize_t enabled_show(struct kobject *kobj,
149 struct kobj_attribute *attr, char *buf)
150{
151 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
152 return sprintf(buf, "[always] madvise never\n");
153 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
154 return sprintf(buf, "always [madvise] never\n");
155 else
156 return sprintf(buf, "always madvise [never]\n");
157}
158
159static ssize_t enabled_store(struct kobject *kobj,
160 struct kobj_attribute *attr,
161 const char *buf, size_t count)
162{
163 ssize_t ret = count;
164
165 if (!memcmp("always", buf,
166 min(sizeof("always")-1, count))) {
167 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
168 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
169 } else if (!memcmp("madvise", buf,
170 min(sizeof("madvise")-1, count))) {
171 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
172 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
173 } else if (!memcmp("never", buf,
174 min(sizeof("never")-1, count))) {
175 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
177 } else
178 ret = -EINVAL;
179
180 if (ret > 0) {
181 int err = start_stop_khugepaged();
182 if (err)
183 ret = err;
184 }
185 return ret;
186}
187static struct kobj_attribute enabled_attr =
188 __ATTR(enabled, 0644, enabled_show, enabled_store);
189
190ssize_t single_hugepage_flag_show(struct kobject *kobj,
191 struct kobj_attribute *attr, char *buf,
192 enum transparent_hugepage_flag flag)
193{
194 return sprintf(buf, "%d\n",
195 !!test_bit(flag, &transparent_hugepage_flags));
196}
197
198ssize_t single_hugepage_flag_store(struct kobject *kobj,
199 struct kobj_attribute *attr,
200 const char *buf, size_t count,
201 enum transparent_hugepage_flag flag)
202{
203 unsigned long value;
204 int ret;
205
206 ret = kstrtoul(buf, 10, &value);
207 if (ret < 0)
208 return ret;
209 if (value > 1)
210 return -EINVAL;
211
212 if (value)
213 set_bit(flag, &transparent_hugepage_flags);
214 else
215 clear_bit(flag, &transparent_hugepage_flags);
216
217 return count;
218}
219
220static ssize_t defrag_show(struct kobject *kobj,
221 struct kobj_attribute *attr, char *buf)
222{
223 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
224 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
225 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
226 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
227 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
228 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
229 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
230 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
231 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
232}
233
234static ssize_t defrag_store(struct kobject *kobj,
235 struct kobj_attribute *attr,
236 const char *buf, size_t count)
237{
238 if (!memcmp("always", buf,
239 min(sizeof("always")-1, count))) {
240 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
241 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
242 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
243 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
244 } else if (!memcmp("defer+madvise", buf,
245 min(sizeof("defer+madvise")-1, count))) {
246 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
248 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
249 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
250 } else if (!memcmp("defer", buf,
251 min(sizeof("defer")-1, count))) {
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
255 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
256 } else if (!memcmp("madvise", buf,
257 min(sizeof("madvise")-1, count))) {
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
261 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
262 } else if (!memcmp("never", buf,
263 min(sizeof("never")-1, count))) {
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
268 } else
269 return -EINVAL;
270
271 return count;
272}
273static struct kobj_attribute defrag_attr =
274 __ATTR(defrag, 0644, defrag_show, defrag_store);
275
276static ssize_t use_zero_page_show(struct kobject *kobj,
277 struct kobj_attribute *attr, char *buf)
278{
279 return single_hugepage_flag_show(kobj, attr, buf,
280 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
281}
282static ssize_t use_zero_page_store(struct kobject *kobj,
283 struct kobj_attribute *attr, const char *buf, size_t count)
284{
285 return single_hugepage_flag_store(kobj, attr, buf, count,
286 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
287}
288static struct kobj_attribute use_zero_page_attr =
289 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
290
291static ssize_t hpage_pmd_size_show(struct kobject *kobj,
292 struct kobj_attribute *attr, char *buf)
293{
294 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
295}
296static struct kobj_attribute hpage_pmd_size_attr =
297 __ATTR_RO(hpage_pmd_size);
298
299#ifdef CONFIG_DEBUG_VM
300static ssize_t debug_cow_show(struct kobject *kobj,
301 struct kobj_attribute *attr, char *buf)
302{
303 return single_hugepage_flag_show(kobj, attr, buf,
304 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
305}
306static ssize_t debug_cow_store(struct kobject *kobj,
307 struct kobj_attribute *attr,
308 const char *buf, size_t count)
309{
310 return single_hugepage_flag_store(kobj, attr, buf, count,
311 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
312}
313static struct kobj_attribute debug_cow_attr =
314 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
315#endif /* CONFIG_DEBUG_VM */
316
317static struct attribute *hugepage_attr[] = {
318 &enabled_attr.attr,
319 &defrag_attr.attr,
320 &use_zero_page_attr.attr,
321 &hpage_pmd_size_attr.attr,
322#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
323 &shmem_enabled_attr.attr,
324#endif
325#ifdef CONFIG_DEBUG_VM
326 &debug_cow_attr.attr,
327#endif
328 NULL,
329};
330
331static const struct attribute_group hugepage_attr_group = {
332 .attrs = hugepage_attr,
333};
334
335static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
336{
337 int err;
338
339 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
340 if (unlikely(!*hugepage_kobj)) {
341 pr_err("failed to create transparent hugepage kobject\n");
342 return -ENOMEM;
343 }
344
345 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
346 if (err) {
347 pr_err("failed to register transparent hugepage group\n");
348 goto delete_obj;
349 }
350
351 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
352 if (err) {
353 pr_err("failed to register transparent hugepage group\n");
354 goto remove_hp_group;
355 }
356
357 return 0;
358
359remove_hp_group:
360 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
361delete_obj:
362 kobject_put(*hugepage_kobj);
363 return err;
364}
365
366static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
367{
368 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
369 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
370 kobject_put(hugepage_kobj);
371}
372#else
373static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
374{
375 return 0;
376}
377
378static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
379{
380}
381#endif /* CONFIG_SYSFS */
382
383static int __init hugepage_init(void)
384{
385 int err;
386 struct kobject *hugepage_kobj;
387
388 if (!has_transparent_hugepage()) {
389 transparent_hugepage_flags = 0;
390 return -EINVAL;
391 }
392
393 /*
394 * hugepages can't be allocated by the buddy allocator
395 */
396 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
397 /*
398 * we use page->mapping and page->index in second tail page
399 * as list_head: assuming THP order >= 2
400 */
401 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
402
403 err = hugepage_init_sysfs(&hugepage_kobj);
404 if (err)
405 goto err_sysfs;
406
407 err = khugepaged_init();
408 if (err)
409 goto err_slab;
410
411 err = register_shrinker(&huge_zero_page_shrinker);
412 if (err)
413 goto err_hzp_shrinker;
414 err = register_shrinker(&deferred_split_shrinker);
415 if (err)
416 goto err_split_shrinker;
417
418 /*
419 * By default disable transparent hugepages on smaller systems,
420 * where the extra memory used could hurt more than TLB overhead
421 * is likely to save. The admin can still enable it through /sys.
422 */
423 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
424 transparent_hugepage_flags = 0;
425 return 0;
426 }
427
428 err = start_stop_khugepaged();
429 if (err)
430 goto err_khugepaged;
431
432 return 0;
433err_khugepaged:
434 unregister_shrinker(&deferred_split_shrinker);
435err_split_shrinker:
436 unregister_shrinker(&huge_zero_page_shrinker);
437err_hzp_shrinker:
438 khugepaged_destroy();
439err_slab:
440 hugepage_exit_sysfs(hugepage_kobj);
441err_sysfs:
442 return err;
443}
444subsys_initcall(hugepage_init);
445
446static int __init setup_transparent_hugepage(char *str)
447{
448 int ret = 0;
449 if (!str)
450 goto out;
451 if (!strcmp(str, "always")) {
452 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
453 &transparent_hugepage_flags);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
455 &transparent_hugepage_flags);
456 ret = 1;
457 } else if (!strcmp(str, "madvise")) {
458 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
459 &transparent_hugepage_flags);
460 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
461 &transparent_hugepage_flags);
462 ret = 1;
463 } else if (!strcmp(str, "never")) {
464 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
465 &transparent_hugepage_flags);
466 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
467 &transparent_hugepage_flags);
468 ret = 1;
469 }
470out:
471 if (!ret)
472 pr_warn("transparent_hugepage= cannot parse, ignored\n");
473 return ret;
474}
475__setup("transparent_hugepage=", setup_transparent_hugepage);
476
477pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
478{
479 if (likely(vma->vm_flags & VM_WRITE))
480 pmd = pmd_mkwrite(pmd);
481 return pmd;
482}
483
484static inline struct list_head *page_deferred_list(struct page *page)
485{
486 /*
487 * ->lru in the tail pages is occupied by compound_head.
488 * Let's use ->mapping + ->index in the second tail page as list_head.
489 */
490 return (struct list_head *)&page[2].mapping;
491}
492
493void prep_transhuge_page(struct page *page)
494{
495 /*
496 * we use page->mapping and page->indexlru in second tail page
497 * as list_head: assuming THP order >= 2
498 */
499
500 INIT_LIST_HEAD(page_deferred_list(page));
501 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
502}
503
504unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
505 loff_t off, unsigned long flags, unsigned long size)
506{
507 unsigned long addr;
508 loff_t off_end = off + len;
509 loff_t off_align = round_up(off, size);
510 unsigned long len_pad;
511
512 if (off_end <= off_align || (off_end - off_align) < size)
513 return 0;
514
515 len_pad = len + size;
516 if (len_pad < len || (off + len_pad) < off)
517 return 0;
518
519 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
520 off >> PAGE_SHIFT, flags);
521 if (IS_ERR_VALUE(addr))
522 return 0;
523
524 addr += (off - addr) & (size - 1);
525 return addr;
526}
527
528unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
529 unsigned long len, unsigned long pgoff, unsigned long flags)
530{
531 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
532
533 if (addr)
534 goto out;
535 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
536 goto out;
537
538 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
539 if (addr)
540 return addr;
541
542 out:
543 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
544}
545EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
546
547static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
548 gfp_t gfp)
549{
550 struct vm_area_struct *vma = vmf->vma;
551 struct mem_cgroup *memcg;
552 pgtable_t pgtable;
553 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
554 int ret = 0;
555
556 VM_BUG_ON_PAGE(!PageCompound(page), page);
557
558 if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
559 put_page(page);
560 count_vm_event(THP_FAULT_FALLBACK);
561 return VM_FAULT_FALLBACK;
562 }
563
564 pgtable = pte_alloc_one(vma->vm_mm, haddr);
565 if (unlikely(!pgtable)) {
566 ret = VM_FAULT_OOM;
567 goto release;
568 }
569
570 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
571 /*
572 * The memory barrier inside __SetPageUptodate makes sure that
573 * clear_huge_page writes become visible before the set_pmd_at()
574 * write.
575 */
576 __SetPageUptodate(page);
577
578 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
579 if (unlikely(!pmd_none(*vmf->pmd))) {
580 goto unlock_release;
581 } else {
582 pmd_t entry;
583
584 ret = check_stable_address_space(vma->vm_mm);
585 if (ret)
586 goto unlock_release;
587
588 /* Deliver the page fault to userland */
589 if (userfaultfd_missing(vma)) {
590 int ret;
591
592 spin_unlock(vmf->ptl);
593 mem_cgroup_cancel_charge(page, memcg, true);
594 put_page(page);
595 pte_free(vma->vm_mm, pgtable);
596 ret = handle_userfault(vmf, VM_UFFD_MISSING);
597 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
598 return ret;
599 }
600
601 entry = mk_huge_pmd(page, vma->vm_page_prot);
602 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
603 page_add_new_anon_rmap(page, vma, haddr, true);
604 mem_cgroup_commit_charge(page, memcg, false, true);
605 lru_cache_add_active_or_unevictable(page, vma);
606 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
607 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
608 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
609 mm_inc_nr_ptes(vma->vm_mm);
610 spin_unlock(vmf->ptl);
611 count_vm_event(THP_FAULT_ALLOC);
612 }
613
614 return 0;
615unlock_release:
616 spin_unlock(vmf->ptl);
617release:
618 if (pgtable)
619 pte_free(vma->vm_mm, pgtable);
620 mem_cgroup_cancel_charge(page, memcg, true);
621 put_page(page);
622 return ret;
623
624}
625
626/*
627 * always: directly stall for all thp allocations
628 * defer: wake kswapd and fail if not immediately available
629 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
630 * fail if not immediately available
631 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
632 * available
633 * never: never stall for any thp allocation
634 */
635static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
636{
637 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
638
639 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
640 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
641 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
642 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
643 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
644 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
645 __GFP_KSWAPD_RECLAIM);
646 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
647 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
648 0);
649 return GFP_TRANSHUGE_LIGHT;
650}
651
652/* Caller must hold page table lock. */
653static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
654 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
655 struct page *zero_page)
656{
657 pmd_t entry;
658 if (!pmd_none(*pmd))
659 return false;
660 entry = mk_pmd(zero_page, vma->vm_page_prot);
661 entry = pmd_mkhuge(entry);
662 if (pgtable)
663 pgtable_trans_huge_deposit(mm, pmd, pgtable);
664 set_pmd_at(mm, haddr, pmd, entry);
665 mm_inc_nr_ptes(mm);
666 return true;
667}
668
669int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
670{
671 struct vm_area_struct *vma = vmf->vma;
672 gfp_t gfp;
673 struct page *page;
674 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
675
676 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
677 return VM_FAULT_FALLBACK;
678 if (unlikely(anon_vma_prepare(vma)))
679 return VM_FAULT_OOM;
680 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
681 return VM_FAULT_OOM;
682 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
683 !mm_forbids_zeropage(vma->vm_mm) &&
684 transparent_hugepage_use_zero_page()) {
685 pgtable_t pgtable;
686 struct page *zero_page;
687 bool set;
688 int ret;
689 pgtable = pte_alloc_one(vma->vm_mm, haddr);
690 if (unlikely(!pgtable))
691 return VM_FAULT_OOM;
692 zero_page = mm_get_huge_zero_page(vma->vm_mm);
693 if (unlikely(!zero_page)) {
694 pte_free(vma->vm_mm, pgtable);
695 count_vm_event(THP_FAULT_FALLBACK);
696 return VM_FAULT_FALLBACK;
697 }
698 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
699 ret = 0;
700 set = false;
701 if (pmd_none(*vmf->pmd)) {
702 ret = check_stable_address_space(vma->vm_mm);
703 if (ret) {
704 spin_unlock(vmf->ptl);
705 } else if (userfaultfd_missing(vma)) {
706 spin_unlock(vmf->ptl);
707 ret = handle_userfault(vmf, VM_UFFD_MISSING);
708 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
709 } else {
710 set_huge_zero_page(pgtable, vma->vm_mm, vma,
711 haddr, vmf->pmd, zero_page);
712 spin_unlock(vmf->ptl);
713 set = true;
714 }
715 } else
716 spin_unlock(vmf->ptl);
717 if (!set)
718 pte_free(vma->vm_mm, pgtable);
719 return ret;
720 }
721 gfp = alloc_hugepage_direct_gfpmask(vma);
722 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
723 if (unlikely(!page)) {
724 count_vm_event(THP_FAULT_FALLBACK);
725 return VM_FAULT_FALLBACK;
726 }
727 prep_transhuge_page(page);
728 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
729}
730
731static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
732 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
733 pgtable_t pgtable)
734{
735 struct mm_struct *mm = vma->vm_mm;
736 pmd_t entry;
737 spinlock_t *ptl;
738
739 ptl = pmd_lock(mm, pmd);
740 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
741 if (pfn_t_devmap(pfn))
742 entry = pmd_mkdevmap(entry);
743 if (write) {
744 entry = pmd_mkyoung(pmd_mkdirty(entry));
745 entry = maybe_pmd_mkwrite(entry, vma);
746 }
747
748 if (pgtable) {
749 pgtable_trans_huge_deposit(mm, pmd, pgtable);
750 mm_inc_nr_ptes(mm);
751 }
752
753 set_pmd_at(mm, addr, pmd, entry);
754 update_mmu_cache_pmd(vma, addr, pmd);
755 spin_unlock(ptl);
756}
757
758int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
759 pmd_t *pmd, pfn_t pfn, bool write)
760{
761 pgprot_t pgprot = vma->vm_page_prot;
762 pgtable_t pgtable = NULL;
763 /*
764 * If we had pmd_special, we could avoid all these restrictions,
765 * but we need to be consistent with PTEs and architectures that
766 * can't support a 'special' bit.
767 */
768 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
769 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
770 (VM_PFNMAP|VM_MIXEDMAP));
771 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
772 BUG_ON(!pfn_t_devmap(pfn));
773
774 if (addr < vma->vm_start || addr >= vma->vm_end)
775 return VM_FAULT_SIGBUS;
776
777 if (arch_needs_pgtable_deposit()) {
778 pgtable = pte_alloc_one(vma->vm_mm, addr);
779 if (!pgtable)
780 return VM_FAULT_OOM;
781 }
782
783 track_pfn_insert(vma, &pgprot, pfn);
784
785 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
786 return VM_FAULT_NOPAGE;
787}
788EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
789
790#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
791static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
792{
793 if (likely(vma->vm_flags & VM_WRITE))
794 pud = pud_mkwrite(pud);
795 return pud;
796}
797
798static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
799 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
800{
801 struct mm_struct *mm = vma->vm_mm;
802 pud_t entry;
803 spinlock_t *ptl;
804
805 ptl = pud_lock(mm, pud);
806 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
807 if (pfn_t_devmap(pfn))
808 entry = pud_mkdevmap(entry);
809 if (write) {
810 entry = pud_mkyoung(pud_mkdirty(entry));
811 entry = maybe_pud_mkwrite(entry, vma);
812 }
813 set_pud_at(mm, addr, pud, entry);
814 update_mmu_cache_pud(vma, addr, pud);
815 spin_unlock(ptl);
816}
817
818int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
819 pud_t *pud, pfn_t pfn, bool write)
820{
821 pgprot_t pgprot = vma->vm_page_prot;
822 /*
823 * If we had pud_special, we could avoid all these restrictions,
824 * but we need to be consistent with PTEs and architectures that
825 * can't support a 'special' bit.
826 */
827 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
828 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
829 (VM_PFNMAP|VM_MIXEDMAP));
830 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
831 BUG_ON(!pfn_t_devmap(pfn));
832
833 if (addr < vma->vm_start || addr >= vma->vm_end)
834 return VM_FAULT_SIGBUS;
835
836 track_pfn_insert(vma, &pgprot, pfn);
837
838 insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
839 return VM_FAULT_NOPAGE;
840}
841EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
842#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
843
844static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
845 pmd_t *pmd, int flags)
846{
847 pmd_t _pmd;
848
849 _pmd = pmd_mkyoung(*pmd);
850 if (flags & FOLL_WRITE)
851 _pmd = pmd_mkdirty(_pmd);
852 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
853 pmd, _pmd, flags & FOLL_WRITE))
854 update_mmu_cache_pmd(vma, addr, pmd);
855}
856
857struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
858 pmd_t *pmd, int flags)
859{
860 unsigned long pfn = pmd_pfn(*pmd);
861 struct mm_struct *mm = vma->vm_mm;
862 struct dev_pagemap *pgmap;
863 struct page *page;
864
865 assert_spin_locked(pmd_lockptr(mm, pmd));
866
867 /*
868 * When we COW a devmap PMD entry, we split it into PTEs, so we should
869 * not be in this function with `flags & FOLL_COW` set.
870 */
871 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
872
873 if (flags & FOLL_WRITE && !pmd_write(*pmd))
874 return NULL;
875
876 if (pmd_present(*pmd) && pmd_devmap(*pmd))
877 /* pass */;
878 else
879 return NULL;
880
881 if (flags & FOLL_TOUCH)
882 touch_pmd(vma, addr, pmd, flags);
883
884 /*
885 * device mapped pages can only be returned if the
886 * caller will manage the page reference count.
887 */
888 if (!(flags & FOLL_GET))
889 return ERR_PTR(-EEXIST);
890
891 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
892 pgmap = get_dev_pagemap(pfn, NULL);
893 if (!pgmap)
894 return ERR_PTR(-EFAULT);
895 page = pfn_to_page(pfn);
896 get_page(page);
897 put_dev_pagemap(pgmap);
898
899 return page;
900}
901
902int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
903 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
904 struct vm_area_struct *vma)
905{
906 spinlock_t *dst_ptl, *src_ptl;
907 struct page *src_page;
908 pmd_t pmd;
909 pgtable_t pgtable = NULL;
910 int ret = -ENOMEM;
911
912 /* Skip if can be re-fill on fault */
913 if (!vma_is_anonymous(vma))
914 return 0;
915
916 pgtable = pte_alloc_one(dst_mm, addr);
917 if (unlikely(!pgtable))
918 goto out;
919
920 dst_ptl = pmd_lock(dst_mm, dst_pmd);
921 src_ptl = pmd_lockptr(src_mm, src_pmd);
922 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
923
924 ret = -EAGAIN;
925 pmd = *src_pmd;
926
927#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
928 if (unlikely(is_swap_pmd(pmd))) {
929 swp_entry_t entry = pmd_to_swp_entry(pmd);
930
931 VM_BUG_ON(!is_pmd_migration_entry(pmd));
932 if (is_write_migration_entry(entry)) {
933 make_migration_entry_read(&entry);
934 pmd = swp_entry_to_pmd(entry);
935 if (pmd_swp_soft_dirty(*src_pmd))
936 pmd = pmd_swp_mksoft_dirty(pmd);
937 set_pmd_at(src_mm, addr, src_pmd, pmd);
938 }
939 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
940 mm_inc_nr_ptes(dst_mm);
941 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
942 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
943 ret = 0;
944 goto out_unlock;
945 }
946#endif
947
948 if (unlikely(!pmd_trans_huge(pmd))) {
949 pte_free(dst_mm, pgtable);
950 goto out_unlock;
951 }
952 /*
953 * When page table lock is held, the huge zero pmd should not be
954 * under splitting since we don't split the page itself, only pmd to
955 * a page table.
956 */
957 if (is_huge_zero_pmd(pmd)) {
958 struct page *zero_page;
959 /*
960 * get_huge_zero_page() will never allocate a new page here,
961 * since we already have a zero page to copy. It just takes a
962 * reference.
963 */
964 zero_page = mm_get_huge_zero_page(dst_mm);
965 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
966 zero_page);
967 ret = 0;
968 goto out_unlock;
969 }
970
971 src_page = pmd_page(pmd);
972 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
973 get_page(src_page);
974 page_dup_rmap(src_page, true);
975 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
976 mm_inc_nr_ptes(dst_mm);
977 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
978
979 pmdp_set_wrprotect(src_mm, addr, src_pmd);
980 pmd = pmd_mkold(pmd_wrprotect(pmd));
981 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
982
983 ret = 0;
984out_unlock:
985 spin_unlock(src_ptl);
986 spin_unlock(dst_ptl);
987out:
988 return ret;
989}
990
991#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
992static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
993 pud_t *pud, int flags)
994{
995 pud_t _pud;
996
997 _pud = pud_mkyoung(*pud);
998 if (flags & FOLL_WRITE)
999 _pud = pud_mkdirty(_pud);
1000 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1001 pud, _pud, flags & FOLL_WRITE))
1002 update_mmu_cache_pud(vma, addr, pud);
1003}
1004
1005struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1006 pud_t *pud, int flags)
1007{
1008 unsigned long pfn = pud_pfn(*pud);
1009 struct mm_struct *mm = vma->vm_mm;
1010 struct dev_pagemap *pgmap;
1011 struct page *page;
1012
1013 assert_spin_locked(pud_lockptr(mm, pud));
1014
1015 if (flags & FOLL_WRITE && !pud_write(*pud))
1016 return NULL;
1017
1018 if (pud_present(*pud) && pud_devmap(*pud))
1019 /* pass */;
1020 else
1021 return NULL;
1022
1023 if (flags & FOLL_TOUCH)
1024 touch_pud(vma, addr, pud, flags);
1025
1026 /*
1027 * device mapped pages can only be returned if the
1028 * caller will manage the page reference count.
1029 */
1030 if (!(flags & FOLL_GET))
1031 return ERR_PTR(-EEXIST);
1032
1033 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1034 pgmap = get_dev_pagemap(pfn, NULL);
1035 if (!pgmap)
1036 return ERR_PTR(-EFAULT);
1037 page = pfn_to_page(pfn);
1038 get_page(page);
1039 put_dev_pagemap(pgmap);
1040
1041 return page;
1042}
1043
1044int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1045 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1046 struct vm_area_struct *vma)
1047{
1048 spinlock_t *dst_ptl, *src_ptl;
1049 pud_t pud;
1050 int ret;
1051
1052 dst_ptl = pud_lock(dst_mm, dst_pud);
1053 src_ptl = pud_lockptr(src_mm, src_pud);
1054 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1055
1056 ret = -EAGAIN;
1057 pud = *src_pud;
1058 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1059 goto out_unlock;
1060
1061 /*
1062 * When page table lock is held, the huge zero pud should not be
1063 * under splitting since we don't split the page itself, only pud to
1064 * a page table.
1065 */
1066 if (is_huge_zero_pud(pud)) {
1067 /* No huge zero pud yet */
1068 }
1069
1070 pudp_set_wrprotect(src_mm, addr, src_pud);
1071 pud = pud_mkold(pud_wrprotect(pud));
1072 set_pud_at(dst_mm, addr, dst_pud, pud);
1073
1074 ret = 0;
1075out_unlock:
1076 spin_unlock(src_ptl);
1077 spin_unlock(dst_ptl);
1078 return ret;
1079}
1080
1081void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1082{
1083 pud_t entry;
1084 unsigned long haddr;
1085 bool write = vmf->flags & FAULT_FLAG_WRITE;
1086
1087 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1088 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1089 goto unlock;
1090
1091 entry = pud_mkyoung(orig_pud);
1092 if (write)
1093 entry = pud_mkdirty(entry);
1094 haddr = vmf->address & HPAGE_PUD_MASK;
1095 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1096 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1097
1098unlock:
1099 spin_unlock(vmf->ptl);
1100}
1101#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1102
1103void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1104{
1105 pmd_t entry;
1106 unsigned long haddr;
1107 bool write = vmf->flags & FAULT_FLAG_WRITE;
1108
1109 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1110 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1111 goto unlock;
1112
1113 entry = pmd_mkyoung(orig_pmd);
1114 if (write)
1115 entry = pmd_mkdirty(entry);
1116 haddr = vmf->address & HPAGE_PMD_MASK;
1117 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1118 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1119
1120unlock:
1121 spin_unlock(vmf->ptl);
1122}
1123
1124static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1125 struct page *page)
1126{
1127 struct vm_area_struct *vma = vmf->vma;
1128 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1129 struct mem_cgroup *memcg;
1130 pgtable_t pgtable;
1131 pmd_t _pmd;
1132 int ret = 0, i;
1133 struct page **pages;
1134 unsigned long mmun_start; /* For mmu_notifiers */
1135 unsigned long mmun_end; /* For mmu_notifiers */
1136
1137 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1138 GFP_KERNEL);
1139 if (unlikely(!pages)) {
1140 ret |= VM_FAULT_OOM;
1141 goto out;
1142 }
1143
1144 for (i = 0; i < HPAGE_PMD_NR; i++) {
1145 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1146 vmf->address, page_to_nid(page));
1147 if (unlikely(!pages[i] ||
1148 mem_cgroup_try_charge(pages[i], vma->vm_mm,
1149 GFP_KERNEL, &memcg, false))) {
1150 if (pages[i])
1151 put_page(pages[i]);
1152 while (--i >= 0) {
1153 memcg = (void *)page_private(pages[i]);
1154 set_page_private(pages[i], 0);
1155 mem_cgroup_cancel_charge(pages[i], memcg,
1156 false);
1157 put_page(pages[i]);
1158 }
1159 kfree(pages);
1160 ret |= VM_FAULT_OOM;
1161 goto out;
1162 }
1163 set_page_private(pages[i], (unsigned long)memcg);
1164 }
1165
1166 for (i = 0; i < HPAGE_PMD_NR; i++) {
1167 copy_user_highpage(pages[i], page + i,
1168 haddr + PAGE_SIZE * i, vma);
1169 __SetPageUptodate(pages[i]);
1170 cond_resched();
1171 }
1172
1173 mmun_start = haddr;
1174 mmun_end = haddr + HPAGE_PMD_SIZE;
1175 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1176
1177 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1178 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1179 goto out_free_pages;
1180 VM_BUG_ON_PAGE(!PageHead(page), page);
1181
1182 /*
1183 * Leave pmd empty until pte is filled note we must notify here as
1184 * concurrent CPU thread might write to new page before the call to
1185 * mmu_notifier_invalidate_range_end() happens which can lead to a
1186 * device seeing memory write in different order than CPU.
1187 *
1188 * See Documentation/vm/mmu_notifier.txt
1189 */
1190 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1191
1192 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1193 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1194
1195 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1196 pte_t entry;
1197 entry = mk_pte(pages[i], vma->vm_page_prot);
1198 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1199 memcg = (void *)page_private(pages[i]);
1200 set_page_private(pages[i], 0);
1201 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1202 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1203 lru_cache_add_active_or_unevictable(pages[i], vma);
1204 vmf->pte = pte_offset_map(&_pmd, haddr);
1205 VM_BUG_ON(!pte_none(*vmf->pte));
1206 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1207 pte_unmap(vmf->pte);
1208 }
1209 kfree(pages);
1210
1211 smp_wmb(); /* make pte visible before pmd */
1212 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1213 page_remove_rmap(page, true);
1214 spin_unlock(vmf->ptl);
1215
1216 /*
1217 * No need to double call mmu_notifier->invalidate_range() callback as
1218 * the above pmdp_huge_clear_flush_notify() did already call it.
1219 */
1220 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1221 mmun_end);
1222
1223 ret |= VM_FAULT_WRITE;
1224 put_page(page);
1225
1226out:
1227 return ret;
1228
1229out_free_pages:
1230 spin_unlock(vmf->ptl);
1231 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1232 for (i = 0; i < HPAGE_PMD_NR; i++) {
1233 memcg = (void *)page_private(pages[i]);
1234 set_page_private(pages[i], 0);
1235 mem_cgroup_cancel_charge(pages[i], memcg, false);
1236 put_page(pages[i]);
1237 }
1238 kfree(pages);
1239 goto out;
1240}
1241
1242int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1243{
1244 struct vm_area_struct *vma = vmf->vma;
1245 struct page *page = NULL, *new_page;
1246 struct mem_cgroup *memcg;
1247 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1248 unsigned long mmun_start; /* For mmu_notifiers */
1249 unsigned long mmun_end; /* For mmu_notifiers */
1250 gfp_t huge_gfp; /* for allocation and charge */
1251 int ret = 0;
1252
1253 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1254 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1255 if (is_huge_zero_pmd(orig_pmd))
1256 goto alloc;
1257 spin_lock(vmf->ptl);
1258 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1259 goto out_unlock;
1260
1261 page = pmd_page(orig_pmd);
1262 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1263 /*
1264 * We can only reuse the page if nobody else maps the huge page or it's
1265 * part.
1266 */
1267 if (!trylock_page(page)) {
1268 get_page(page);
1269 spin_unlock(vmf->ptl);
1270 lock_page(page);
1271 spin_lock(vmf->ptl);
1272 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1273 unlock_page(page);
1274 put_page(page);
1275 goto out_unlock;
1276 }
1277 put_page(page);
1278 }
1279 if (reuse_swap_page(page, NULL)) {
1280 pmd_t entry;
1281 entry = pmd_mkyoung(orig_pmd);
1282 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1283 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1284 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1285 ret |= VM_FAULT_WRITE;
1286 unlock_page(page);
1287 goto out_unlock;
1288 }
1289 unlock_page(page);
1290 get_page(page);
1291 spin_unlock(vmf->ptl);
1292alloc:
1293 if (transparent_hugepage_enabled(vma) &&
1294 !transparent_hugepage_debug_cow()) {
1295 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1296 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1297 } else
1298 new_page = NULL;
1299
1300 if (likely(new_page)) {
1301 prep_transhuge_page(new_page);
1302 } else {
1303 if (!page) {
1304 split_huge_pmd(vma, vmf->pmd, vmf->address);
1305 ret |= VM_FAULT_FALLBACK;
1306 } else {
1307 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1308 if (ret & VM_FAULT_OOM) {
1309 split_huge_pmd(vma, vmf->pmd, vmf->address);
1310 ret |= VM_FAULT_FALLBACK;
1311 }
1312 put_page(page);
1313 }
1314 count_vm_event(THP_FAULT_FALLBACK);
1315 goto out;
1316 }
1317
1318 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1319 huge_gfp, &memcg, true))) {
1320 put_page(new_page);
1321 split_huge_pmd(vma, vmf->pmd, vmf->address);
1322 if (page)
1323 put_page(page);
1324 ret |= VM_FAULT_FALLBACK;
1325 count_vm_event(THP_FAULT_FALLBACK);
1326 goto out;
1327 }
1328
1329 count_vm_event(THP_FAULT_ALLOC);
1330
1331 if (!page)
1332 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1333 else
1334 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1335 __SetPageUptodate(new_page);
1336
1337 mmun_start = haddr;
1338 mmun_end = haddr + HPAGE_PMD_SIZE;
1339 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1340
1341 spin_lock(vmf->ptl);
1342 if (page)
1343 put_page(page);
1344 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1345 spin_unlock(vmf->ptl);
1346 mem_cgroup_cancel_charge(new_page, memcg, true);
1347 put_page(new_page);
1348 goto out_mn;
1349 } else {
1350 pmd_t entry;
1351 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1352 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1353 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1354 page_add_new_anon_rmap(new_page, vma, haddr, true);
1355 mem_cgroup_commit_charge(new_page, memcg, false, true);
1356 lru_cache_add_active_or_unevictable(new_page, vma);
1357 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1358 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1359 if (!page) {
1360 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1361 } else {
1362 VM_BUG_ON_PAGE(!PageHead(page), page);
1363 page_remove_rmap(page, true);
1364 put_page(page);
1365 }
1366 ret |= VM_FAULT_WRITE;
1367 }
1368 spin_unlock(vmf->ptl);
1369out_mn:
1370 /*
1371 * No need to double call mmu_notifier->invalidate_range() callback as
1372 * the above pmdp_huge_clear_flush_notify() did already call it.
1373 */
1374 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1375 mmun_end);
1376out:
1377 return ret;
1378out_unlock:
1379 spin_unlock(vmf->ptl);
1380 return ret;
1381}
1382
1383/*
1384 * FOLL_FORCE can write to even unwritable pmd's, but only
1385 * after we've gone through a COW cycle and they are dirty.
1386 */
1387static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1388{
1389 return pmd_write(pmd) ||
1390 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1391}
1392
1393struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1394 unsigned long addr,
1395 pmd_t *pmd,
1396 unsigned int flags)
1397{
1398 struct mm_struct *mm = vma->vm_mm;
1399 struct page *page = NULL;
1400
1401 assert_spin_locked(pmd_lockptr(mm, pmd));
1402
1403 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1404 goto out;
1405
1406 /* Avoid dumping huge zero page */
1407 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1408 return ERR_PTR(-EFAULT);
1409
1410 /* Full NUMA hinting faults to serialise migration in fault paths */
1411 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1412 goto out;
1413
1414 page = pmd_page(*pmd);
1415 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1416 if (flags & FOLL_TOUCH)
1417 touch_pmd(vma, addr, pmd, flags);
1418 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1419 /*
1420 * We don't mlock() pte-mapped THPs. This way we can avoid
1421 * leaking mlocked pages into non-VM_LOCKED VMAs.
1422 *
1423 * For anon THP:
1424 *
1425 * In most cases the pmd is the only mapping of the page as we
1426 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1427 * writable private mappings in populate_vma_page_range().
1428 *
1429 * The only scenario when we have the page shared here is if we
1430 * mlocking read-only mapping shared over fork(). We skip
1431 * mlocking such pages.
1432 *
1433 * For file THP:
1434 *
1435 * We can expect PageDoubleMap() to be stable under page lock:
1436 * for file pages we set it in page_add_file_rmap(), which
1437 * requires page to be locked.
1438 */
1439
1440 if (PageAnon(page) && compound_mapcount(page) != 1)
1441 goto skip_mlock;
1442 if (PageDoubleMap(page) || !page->mapping)
1443 goto skip_mlock;
1444 if (!trylock_page(page))
1445 goto skip_mlock;
1446 lru_add_drain();
1447 if (page->mapping && !PageDoubleMap(page))
1448 mlock_vma_page(page);
1449 unlock_page(page);
1450 }
1451skip_mlock:
1452 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1453 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1454 if (flags & FOLL_GET)
1455 get_page(page);
1456
1457out:
1458 return page;
1459}
1460
1461/* NUMA hinting page fault entry point for trans huge pmds */
1462int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1463{
1464 struct vm_area_struct *vma = vmf->vma;
1465 struct anon_vma *anon_vma = NULL;
1466 struct page *page;
1467 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1468 int page_nid = -1, this_nid = numa_node_id();
1469 int target_nid, last_cpupid = -1;
1470 bool page_locked;
1471 bool migrated = false;
1472 bool was_writable;
1473 int flags = 0;
1474
1475 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1476 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1477 goto out_unlock;
1478
1479 /*
1480 * If there are potential migrations, wait for completion and retry
1481 * without disrupting NUMA hinting information. Do not relock and
1482 * check_same as the page may no longer be mapped.
1483 */
1484 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1485 page = pmd_page(*vmf->pmd);
1486 if (!get_page_unless_zero(page))
1487 goto out_unlock;
1488 spin_unlock(vmf->ptl);
1489 wait_on_page_locked(page);
1490 put_page(page);
1491 goto out;
1492 }
1493
1494 page = pmd_page(pmd);
1495 BUG_ON(is_huge_zero_page(page));
1496 page_nid = page_to_nid(page);
1497 last_cpupid = page_cpupid_last(page);
1498 count_vm_numa_event(NUMA_HINT_FAULTS);
1499 if (page_nid == this_nid) {
1500 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1501 flags |= TNF_FAULT_LOCAL;
1502 }
1503
1504 /* See similar comment in do_numa_page for explanation */
1505 if (!pmd_savedwrite(pmd))
1506 flags |= TNF_NO_GROUP;
1507
1508 /*
1509 * Acquire the page lock to serialise THP migrations but avoid dropping
1510 * page_table_lock if at all possible
1511 */
1512 page_locked = trylock_page(page);
1513 target_nid = mpol_misplaced(page, vma, haddr);
1514 if (target_nid == -1) {
1515 /* If the page was locked, there are no parallel migrations */
1516 if (page_locked)
1517 goto clear_pmdnuma;
1518 }
1519
1520 /* Migration could have started since the pmd_trans_migrating check */
1521 if (!page_locked) {
1522 page_nid = -1;
1523 if (!get_page_unless_zero(page))
1524 goto out_unlock;
1525 spin_unlock(vmf->ptl);
1526 wait_on_page_locked(page);
1527 put_page(page);
1528 goto out;
1529 }
1530
1531 /*
1532 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1533 * to serialises splits
1534 */
1535 get_page(page);
1536 spin_unlock(vmf->ptl);
1537 anon_vma = page_lock_anon_vma_read(page);
1538
1539 /* Confirm the PMD did not change while page_table_lock was released */
1540 spin_lock(vmf->ptl);
1541 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1542 unlock_page(page);
1543 put_page(page);
1544 page_nid = -1;
1545 goto out_unlock;
1546 }
1547
1548 /* Bail if we fail to protect against THP splits for any reason */
1549 if (unlikely(!anon_vma)) {
1550 put_page(page);
1551 page_nid = -1;
1552 goto clear_pmdnuma;
1553 }
1554
1555 /*
1556 * Since we took the NUMA fault, we must have observed the !accessible
1557 * bit. Make sure all other CPUs agree with that, to avoid them
1558 * modifying the page we're about to migrate.
1559 *
1560 * Must be done under PTL such that we'll observe the relevant
1561 * inc_tlb_flush_pending().
1562 *
1563 * We are not sure a pending tlb flush here is for a huge page
1564 * mapping or not. Hence use the tlb range variant
1565 */
1566 if (mm_tlb_flush_pending(vma->vm_mm))
1567 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1568
1569 /*
1570 * Migrate the THP to the requested node, returns with page unlocked
1571 * and access rights restored.
1572 */
1573 spin_unlock(vmf->ptl);
1574
1575 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1576 vmf->pmd, pmd, vmf->address, page, target_nid);
1577 if (migrated) {
1578 flags |= TNF_MIGRATED;
1579 page_nid = target_nid;
1580 } else
1581 flags |= TNF_MIGRATE_FAIL;
1582
1583 goto out;
1584clear_pmdnuma:
1585 BUG_ON(!PageLocked(page));
1586 was_writable = pmd_savedwrite(pmd);
1587 pmd = pmd_modify(pmd, vma->vm_page_prot);
1588 pmd = pmd_mkyoung(pmd);
1589 if (was_writable)
1590 pmd = pmd_mkwrite(pmd);
1591 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1592 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1593 unlock_page(page);
1594out_unlock:
1595 spin_unlock(vmf->ptl);
1596
1597out:
1598 if (anon_vma)
1599 page_unlock_anon_vma_read(anon_vma);
1600
1601 if (page_nid != -1)
1602 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1603 flags);
1604
1605 return 0;
1606}
1607
1608/*
1609 * Return true if we do MADV_FREE successfully on entire pmd page.
1610 * Otherwise, return false.
1611 */
1612bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1613 pmd_t *pmd, unsigned long addr, unsigned long next)
1614{
1615 spinlock_t *ptl;
1616 pmd_t orig_pmd;
1617 struct page *page;
1618 struct mm_struct *mm = tlb->mm;
1619 bool ret = false;
1620
1621 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1622
1623 ptl = pmd_trans_huge_lock(pmd, vma);
1624 if (!ptl)
1625 goto out_unlocked;
1626
1627 orig_pmd = *pmd;
1628 if (is_huge_zero_pmd(orig_pmd))
1629 goto out;
1630
1631 if (unlikely(!pmd_present(orig_pmd))) {
1632 VM_BUG_ON(thp_migration_supported() &&
1633 !is_pmd_migration_entry(orig_pmd));
1634 goto out;
1635 }
1636
1637 page = pmd_page(orig_pmd);
1638 /*
1639 * If other processes are mapping this page, we couldn't discard
1640 * the page unless they all do MADV_FREE so let's skip the page.
1641 */
1642 if (page_mapcount(page) != 1)
1643 goto out;
1644
1645 if (!trylock_page(page))
1646 goto out;
1647
1648 /*
1649 * If user want to discard part-pages of THP, split it so MADV_FREE
1650 * will deactivate only them.
1651 */
1652 if (next - addr != HPAGE_PMD_SIZE) {
1653 get_page(page);
1654 spin_unlock(ptl);
1655 split_huge_page(page);
1656 unlock_page(page);
1657 put_page(page);
1658 goto out_unlocked;
1659 }
1660
1661 if (PageDirty(page))
1662 ClearPageDirty(page);
1663 unlock_page(page);
1664
1665 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1666 pmdp_invalidate(vma, addr, pmd);
1667 orig_pmd = pmd_mkold(orig_pmd);
1668 orig_pmd = pmd_mkclean(orig_pmd);
1669
1670 set_pmd_at(mm, addr, pmd, orig_pmd);
1671 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1672 }
1673
1674 mark_page_lazyfree(page);
1675 ret = true;
1676out:
1677 spin_unlock(ptl);
1678out_unlocked:
1679 return ret;
1680}
1681
1682static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1683{
1684 pgtable_t pgtable;
1685
1686 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1687 pte_free(mm, pgtable);
1688 mm_dec_nr_ptes(mm);
1689}
1690
1691int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1692 pmd_t *pmd, unsigned long addr)
1693{
1694 pmd_t orig_pmd;
1695 spinlock_t *ptl;
1696
1697 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1698
1699 ptl = __pmd_trans_huge_lock(pmd, vma);
1700 if (!ptl)
1701 return 0;
1702 /*
1703 * For architectures like ppc64 we look at deposited pgtable
1704 * when calling pmdp_huge_get_and_clear. So do the
1705 * pgtable_trans_huge_withdraw after finishing pmdp related
1706 * operations.
1707 */
1708 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1709 tlb->fullmm);
1710 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1711 if (vma_is_dax(vma)) {
1712 if (arch_needs_pgtable_deposit())
1713 zap_deposited_table(tlb->mm, pmd);
1714 spin_unlock(ptl);
1715 if (is_huge_zero_pmd(orig_pmd))
1716 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1717 } else if (is_huge_zero_pmd(orig_pmd)) {
1718 zap_deposited_table(tlb->mm, pmd);
1719 spin_unlock(ptl);
1720 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1721 } else {
1722 struct page *page = NULL;
1723 int flush_needed = 1;
1724
1725 if (pmd_present(orig_pmd)) {
1726 page = pmd_page(orig_pmd);
1727 page_remove_rmap(page, true);
1728 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1729 VM_BUG_ON_PAGE(!PageHead(page), page);
1730 } else if (thp_migration_supported()) {
1731 swp_entry_t entry;
1732
1733 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1734 entry = pmd_to_swp_entry(orig_pmd);
1735 page = pfn_to_page(swp_offset(entry));
1736 flush_needed = 0;
1737 } else
1738 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1739
1740 if (PageAnon(page)) {
1741 zap_deposited_table(tlb->mm, pmd);
1742 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1743 } else {
1744 if (arch_needs_pgtable_deposit())
1745 zap_deposited_table(tlb->mm, pmd);
1746 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1747 }
1748
1749 spin_unlock(ptl);
1750 if (flush_needed)
1751 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1752 }
1753 return 1;
1754}
1755
1756#ifndef pmd_move_must_withdraw
1757static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1758 spinlock_t *old_pmd_ptl,
1759 struct vm_area_struct *vma)
1760{
1761 /*
1762 * With split pmd lock we also need to move preallocated
1763 * PTE page table if new_pmd is on different PMD page table.
1764 *
1765 * We also don't deposit and withdraw tables for file pages.
1766 */
1767 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1768}
1769#endif
1770
1771static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1772{
1773#ifdef CONFIG_MEM_SOFT_DIRTY
1774 if (unlikely(is_pmd_migration_entry(pmd)))
1775 pmd = pmd_swp_mksoft_dirty(pmd);
1776 else if (pmd_present(pmd))
1777 pmd = pmd_mksoft_dirty(pmd);
1778#endif
1779 return pmd;
1780}
1781
1782bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1783 unsigned long new_addr, unsigned long old_end,
1784 pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1785{
1786 spinlock_t *old_ptl, *new_ptl;
1787 pmd_t pmd;
1788 struct mm_struct *mm = vma->vm_mm;
1789 bool force_flush = false;
1790
1791 if ((old_addr & ~HPAGE_PMD_MASK) ||
1792 (new_addr & ~HPAGE_PMD_MASK) ||
1793 old_end - old_addr < HPAGE_PMD_SIZE)
1794 return false;
1795
1796 /*
1797 * The destination pmd shouldn't be established, free_pgtables()
1798 * should have release it.
1799 */
1800 if (WARN_ON(!pmd_none(*new_pmd))) {
1801 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1802 return false;
1803 }
1804
1805 /*
1806 * We don't have to worry about the ordering of src and dst
1807 * ptlocks because exclusive mmap_sem prevents deadlock.
1808 */
1809 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1810 if (old_ptl) {
1811 new_ptl = pmd_lockptr(mm, new_pmd);
1812 if (new_ptl != old_ptl)
1813 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1814 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1815 if (pmd_present(pmd) && pmd_dirty(pmd))
1816 force_flush = true;
1817 VM_BUG_ON(!pmd_none(*new_pmd));
1818
1819 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1820 pgtable_t pgtable;
1821 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1822 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1823 }
1824 pmd = move_soft_dirty_pmd(pmd);
1825 set_pmd_at(mm, new_addr, new_pmd, pmd);
1826 if (new_ptl != old_ptl)
1827 spin_unlock(new_ptl);
1828 if (force_flush)
1829 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1830 else
1831 *need_flush = true;
1832 spin_unlock(old_ptl);
1833 return true;
1834 }
1835 return false;
1836}
1837
1838/*
1839 * Returns
1840 * - 0 if PMD could not be locked
1841 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1842 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1843 */
1844int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1845 unsigned long addr, pgprot_t newprot, int prot_numa)
1846{
1847 struct mm_struct *mm = vma->vm_mm;
1848 spinlock_t *ptl;
1849 pmd_t entry;
1850 bool preserve_write;
1851 int ret;
1852
1853 ptl = __pmd_trans_huge_lock(pmd, vma);
1854 if (!ptl)
1855 return 0;
1856
1857 preserve_write = prot_numa && pmd_write(*pmd);
1858 ret = 1;
1859
1860#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1861 if (is_swap_pmd(*pmd)) {
1862 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1863
1864 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1865 if (is_write_migration_entry(entry)) {
1866 pmd_t newpmd;
1867 /*
1868 * A protection check is difficult so
1869 * just be safe and disable write
1870 */
1871 make_migration_entry_read(&entry);
1872 newpmd = swp_entry_to_pmd(entry);
1873 if (pmd_swp_soft_dirty(*pmd))
1874 newpmd = pmd_swp_mksoft_dirty(newpmd);
1875 set_pmd_at(mm, addr, pmd, newpmd);
1876 }
1877 goto unlock;
1878 }
1879#endif
1880
1881 /*
1882 * Avoid trapping faults against the zero page. The read-only
1883 * data is likely to be read-cached on the local CPU and
1884 * local/remote hits to the zero page are not interesting.
1885 */
1886 if (prot_numa && is_huge_zero_pmd(*pmd))
1887 goto unlock;
1888
1889 if (prot_numa && pmd_protnone(*pmd))
1890 goto unlock;
1891
1892 /*
1893 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1894 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1895 * which is also under down_read(mmap_sem):
1896 *
1897 * CPU0: CPU1:
1898 * change_huge_pmd(prot_numa=1)
1899 * pmdp_huge_get_and_clear_notify()
1900 * madvise_dontneed()
1901 * zap_pmd_range()
1902 * pmd_trans_huge(*pmd) == 0 (without ptl)
1903 * // skip the pmd
1904 * set_pmd_at();
1905 * // pmd is re-established
1906 *
1907 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1908 * which may break userspace.
1909 *
1910 * pmdp_invalidate() is required to make sure we don't miss
1911 * dirty/young flags set by hardware.
1912 */
1913 entry = pmdp_invalidate(vma, addr, pmd);
1914
1915 entry = pmd_modify(entry, newprot);
1916 if (preserve_write)
1917 entry = pmd_mk_savedwrite(entry);
1918 ret = HPAGE_PMD_NR;
1919 set_pmd_at(mm, addr, pmd, entry);
1920 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1921unlock:
1922 spin_unlock(ptl);
1923 return ret;
1924}
1925
1926/*
1927 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1928 *
1929 * Note that if it returns page table lock pointer, this routine returns without
1930 * unlocking page table lock. So callers must unlock it.
1931 */
1932spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1933{
1934 spinlock_t *ptl;
1935 ptl = pmd_lock(vma->vm_mm, pmd);
1936 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1937 pmd_devmap(*pmd)))
1938 return ptl;
1939 spin_unlock(ptl);
1940 return NULL;
1941}
1942
1943/*
1944 * Returns true if a given pud maps a thp, false otherwise.
1945 *
1946 * Note that if it returns true, this routine returns without unlocking page
1947 * table lock. So callers must unlock it.
1948 */
1949spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1950{
1951 spinlock_t *ptl;
1952
1953 ptl = pud_lock(vma->vm_mm, pud);
1954 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1955 return ptl;
1956 spin_unlock(ptl);
1957 return NULL;
1958}
1959
1960#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1961int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1962 pud_t *pud, unsigned long addr)
1963{
1964 pud_t orig_pud;
1965 spinlock_t *ptl;
1966
1967 ptl = __pud_trans_huge_lock(pud, vma);
1968 if (!ptl)
1969 return 0;
1970 /*
1971 * For architectures like ppc64 we look at deposited pgtable
1972 * when calling pudp_huge_get_and_clear. So do the
1973 * pgtable_trans_huge_withdraw after finishing pudp related
1974 * operations.
1975 */
1976 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1977 tlb->fullmm);
1978 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1979 if (vma_is_dax(vma)) {
1980 spin_unlock(ptl);
1981 /* No zero page support yet */
1982 } else {
1983 /* No support for anonymous PUD pages yet */
1984 BUG();
1985 }
1986 return 1;
1987}
1988
1989static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1990 unsigned long haddr)
1991{
1992 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1993 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1994 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1995 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1996
1997 count_vm_event(THP_SPLIT_PUD);
1998
1999 pudp_huge_clear_flush_notify(vma, haddr, pud);
2000}
2001
2002void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2003 unsigned long address)
2004{
2005 spinlock_t *ptl;
2006 struct mm_struct *mm = vma->vm_mm;
2007 unsigned long haddr = address & HPAGE_PUD_MASK;
2008
2009 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2010 ptl = pud_lock(mm, pud);
2011 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2012 goto out;
2013 __split_huge_pud_locked(vma, pud, haddr);
2014
2015out:
2016 spin_unlock(ptl);
2017 /*
2018 * No need to double call mmu_notifier->invalidate_range() callback as
2019 * the above pudp_huge_clear_flush_notify() did already call it.
2020 */
2021 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2022 HPAGE_PUD_SIZE);
2023}
2024#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2025
2026static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2027 unsigned long haddr, pmd_t *pmd)
2028{
2029 struct mm_struct *mm = vma->vm_mm;
2030 pgtable_t pgtable;
2031 pmd_t _pmd;
2032 int i;
2033
2034 /*
2035 * Leave pmd empty until pte is filled note that it is fine to delay
2036 * notification until mmu_notifier_invalidate_range_end() as we are
2037 * replacing a zero pmd write protected page with a zero pte write
2038 * protected page.
2039 *
2040 * See Documentation/vm/mmu_notifier.txt
2041 */
2042 pmdp_huge_clear_flush(vma, haddr, pmd);
2043
2044 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2045 pmd_populate(mm, &_pmd, pgtable);
2046
2047 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2048 pte_t *pte, entry;
2049 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2050 entry = pte_mkspecial(entry);
2051 pte = pte_offset_map(&_pmd, haddr);
2052 VM_BUG_ON(!pte_none(*pte));
2053 set_pte_at(mm, haddr, pte, entry);
2054 pte_unmap(pte);
2055 }
2056 smp_wmb(); /* make pte visible before pmd */
2057 pmd_populate(mm, pmd, pgtable);
2058}
2059
2060static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2061 unsigned long haddr, bool freeze)
2062{
2063 struct mm_struct *mm = vma->vm_mm;
2064 struct page *page;
2065 pgtable_t pgtable;
2066 pmd_t old_pmd, _pmd;
2067 bool young, write, soft_dirty, pmd_migration = false;
2068 unsigned long addr;
2069 int i;
2070
2071 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2072 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2073 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2074 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2075 && !pmd_devmap(*pmd));
2076
2077 count_vm_event(THP_SPLIT_PMD);
2078
2079 if (!vma_is_anonymous(vma)) {
2080 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2081 /*
2082 * We are going to unmap this huge page. So
2083 * just go ahead and zap it
2084 */
2085 if (arch_needs_pgtable_deposit())
2086 zap_deposited_table(mm, pmd);
2087 if (vma_is_dax(vma))
2088 return;
2089 page = pmd_page(_pmd);
2090 if (!PageReferenced(page) && pmd_young(_pmd))
2091 SetPageReferenced(page);
2092 page_remove_rmap(page, true);
2093 put_page(page);
2094 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2095 return;
2096 } else if (is_huge_zero_pmd(*pmd)) {
2097 /*
2098 * FIXME: Do we want to invalidate secondary mmu by calling
2099 * mmu_notifier_invalidate_range() see comments below inside
2100 * __split_huge_pmd() ?
2101 *
2102 * We are going from a zero huge page write protected to zero
2103 * small page also write protected so it does not seems useful
2104 * to invalidate secondary mmu at this time.
2105 */
2106 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2107 }
2108
2109 /*
2110 * Up to this point the pmd is present and huge and userland has the
2111 * whole access to the hugepage during the split (which happens in
2112 * place). If we overwrite the pmd with the not-huge version pointing
2113 * to the pte here (which of course we could if all CPUs were bug
2114 * free), userland could trigger a small page size TLB miss on the
2115 * small sized TLB while the hugepage TLB entry is still established in
2116 * the huge TLB. Some CPU doesn't like that.
2117 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2118 * 383 on page 93. Intel should be safe but is also warns that it's
2119 * only safe if the permission and cache attributes of the two entries
2120 * loaded in the two TLB is identical (which should be the case here).
2121 * But it is generally safer to never allow small and huge TLB entries
2122 * for the same virtual address to be loaded simultaneously. So instead
2123 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2124 * current pmd notpresent (atomically because here the pmd_trans_huge
2125 * must remain set at all times on the pmd until the split is complete
2126 * for this pmd), then we flush the SMP TLB and finally we write the
2127 * non-huge version of the pmd entry with pmd_populate.
2128 */
2129 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2130
2131#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2132 pmd_migration = is_pmd_migration_entry(old_pmd);
2133 if (pmd_migration) {
2134 swp_entry_t entry;
2135
2136 entry = pmd_to_swp_entry(old_pmd);
2137 page = pfn_to_page(swp_offset(entry));
2138 } else
2139#endif
2140 page = pmd_page(old_pmd);
2141 VM_BUG_ON_PAGE(!page_count(page), page);
2142 page_ref_add(page, HPAGE_PMD_NR - 1);
2143 if (pmd_dirty(old_pmd))
2144 SetPageDirty(page);
2145 write = pmd_write(old_pmd);
2146 young = pmd_young(old_pmd);
2147 soft_dirty = pmd_soft_dirty(old_pmd);
2148
2149 /*
2150 * Withdraw the table only after we mark the pmd entry invalid.
2151 * This's critical for some architectures (Power).
2152 */
2153 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2154 pmd_populate(mm, &_pmd, pgtable);
2155
2156 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2157 pte_t entry, *pte;
2158 /*
2159 * Note that NUMA hinting access restrictions are not
2160 * transferred to avoid any possibility of altering
2161 * permissions across VMAs.
2162 */
2163 if (freeze || pmd_migration) {
2164 swp_entry_t swp_entry;
2165 swp_entry = make_migration_entry(page + i, write);
2166 entry = swp_entry_to_pte(swp_entry);
2167 if (soft_dirty)
2168 entry = pte_swp_mksoft_dirty(entry);
2169 } else {
2170 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2171 entry = maybe_mkwrite(entry, vma);
2172 if (!write)
2173 entry = pte_wrprotect(entry);
2174 if (!young)
2175 entry = pte_mkold(entry);
2176 if (soft_dirty)
2177 entry = pte_mksoft_dirty(entry);
2178 }
2179 pte = pte_offset_map(&_pmd, addr);
2180 BUG_ON(!pte_none(*pte));
2181 set_pte_at(mm, addr, pte, entry);
2182 atomic_inc(&page[i]._mapcount);
2183 pte_unmap(pte);
2184 }
2185
2186 /*
2187 * Set PG_double_map before dropping compound_mapcount to avoid
2188 * false-negative page_mapped().
2189 */
2190 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2191 for (i = 0; i < HPAGE_PMD_NR; i++)
2192 atomic_inc(&page[i]._mapcount);
2193 }
2194
2195 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2196 /* Last compound_mapcount is gone. */
2197 __dec_node_page_state(page, NR_ANON_THPS);
2198 if (TestClearPageDoubleMap(page)) {
2199 /* No need in mapcount reference anymore */
2200 for (i = 0; i < HPAGE_PMD_NR; i++)
2201 atomic_dec(&page[i]._mapcount);
2202 }
2203 }
2204
2205 smp_wmb(); /* make pte visible before pmd */
2206 pmd_populate(mm, pmd, pgtable);
2207
2208 if (freeze) {
2209 for (i = 0; i < HPAGE_PMD_NR; i++) {
2210 page_remove_rmap(page + i, false);
2211 put_page(page + i);
2212 }
2213 }
2214}
2215
2216void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2217 unsigned long address, bool freeze, struct page *page)
2218{
2219 spinlock_t *ptl;
2220 struct mm_struct *mm = vma->vm_mm;
2221 unsigned long haddr = address & HPAGE_PMD_MASK;
2222
2223 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2224 ptl = pmd_lock(mm, pmd);
2225
2226 /*
2227 * If caller asks to setup a migration entries, we need a page to check
2228 * pmd against. Otherwise we can end up replacing wrong page.
2229 */
2230 VM_BUG_ON(freeze && !page);
2231 if (page && page != pmd_page(*pmd))
2232 goto out;
2233
2234 if (pmd_trans_huge(*pmd)) {
2235 page = pmd_page(*pmd);
2236 if (PageMlocked(page))
2237 clear_page_mlock(page);
2238 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2239 goto out;
2240 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2241out:
2242 spin_unlock(ptl);
2243 /*
2244 * No need to double call mmu_notifier->invalidate_range() callback.
2245 * They are 3 cases to consider inside __split_huge_pmd_locked():
2246 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2247 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2248 * fault will trigger a flush_notify before pointing to a new page
2249 * (it is fine if the secondary mmu keeps pointing to the old zero
2250 * page in the meantime)
2251 * 3) Split a huge pmd into pte pointing to the same page. No need
2252 * to invalidate secondary tlb entry they are all still valid.
2253 * any further changes to individual pte will notify. So no need
2254 * to call mmu_notifier->invalidate_range()
2255 */
2256 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2257 HPAGE_PMD_SIZE);
2258}
2259
2260void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2261 bool freeze, struct page *page)
2262{
2263 pgd_t *pgd;
2264 p4d_t *p4d;
2265 pud_t *pud;
2266 pmd_t *pmd;
2267
2268 pgd = pgd_offset(vma->vm_mm, address);
2269 if (!pgd_present(*pgd))
2270 return;
2271
2272 p4d = p4d_offset(pgd, address);
2273 if (!p4d_present(*p4d))
2274 return;
2275
2276 pud = pud_offset(p4d, address);
2277 if (!pud_present(*pud))
2278 return;
2279
2280 pmd = pmd_offset(pud, address);
2281
2282 __split_huge_pmd(vma, pmd, address, freeze, page);
2283}
2284
2285void vma_adjust_trans_huge(struct vm_area_struct *vma,
2286 unsigned long start,
2287 unsigned long end,
2288 long adjust_next)
2289{
2290 /*
2291 * If the new start address isn't hpage aligned and it could
2292 * previously contain an hugepage: check if we need to split
2293 * an huge pmd.
2294 */
2295 if (start & ~HPAGE_PMD_MASK &&
2296 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2297 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2298 split_huge_pmd_address(vma, start, false, NULL);
2299
2300 /*
2301 * If the new end address isn't hpage aligned and it could
2302 * previously contain an hugepage: check if we need to split
2303 * an huge pmd.
2304 */
2305 if (end & ~HPAGE_PMD_MASK &&
2306 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2307 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2308 split_huge_pmd_address(vma, end, false, NULL);
2309
2310 /*
2311 * If we're also updating the vma->vm_next->vm_start, if the new
2312 * vm_next->vm_start isn't page aligned and it could previously
2313 * contain an hugepage: check if we need to split an huge pmd.
2314 */
2315 if (adjust_next > 0) {
2316 struct vm_area_struct *next = vma->vm_next;
2317 unsigned long nstart = next->vm_start;
2318 nstart += adjust_next << PAGE_SHIFT;
2319 if (nstart & ~HPAGE_PMD_MASK &&
2320 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2321 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2322 split_huge_pmd_address(next, nstart, false, NULL);
2323 }
2324}
2325
2326static void freeze_page(struct page *page)
2327{
2328 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2329 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2330 bool unmap_success;
2331
2332 VM_BUG_ON_PAGE(!PageHead(page), page);
2333
2334 if (PageAnon(page))
2335 ttu_flags |= TTU_SPLIT_FREEZE;
2336
2337 unmap_success = try_to_unmap(page, ttu_flags);
2338 VM_BUG_ON_PAGE(!unmap_success, page);
2339}
2340
2341static void unfreeze_page(struct page *page)
2342{
2343 int i;
2344 if (PageTransHuge(page)) {
2345 remove_migration_ptes(page, page, true);
2346 } else {
2347 for (i = 0; i < HPAGE_PMD_NR; i++)
2348 remove_migration_ptes(page + i, page + i, true);
2349 }
2350}
2351
2352static void __split_huge_page_tail(struct page *head, int tail,
2353 struct lruvec *lruvec, struct list_head *list)
2354{
2355 struct page *page_tail = head + tail;
2356
2357 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2358
2359 /*
2360 * Clone page flags before unfreezing refcount.
2361 *
2362 * After successful get_page_unless_zero() might follow flags change,
2363 * for exmaple lock_page() which set PG_waiters.
2364 */
2365 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2366 page_tail->flags |= (head->flags &
2367 ((1L << PG_referenced) |
2368 (1L << PG_swapbacked) |
2369 (1L << PG_swapcache) |
2370 (1L << PG_mlocked) |
2371 (1L << PG_uptodate) |
2372 (1L << PG_active) |
2373 (1L << PG_locked) |
2374 (1L << PG_unevictable) |
2375 (1L << PG_dirty)));
2376
2377 /* Page flags must be visible before we make the page non-compound. */
2378 smp_wmb();
2379
2380 /*
2381 * Clear PageTail before unfreezing page refcount.
2382 *
2383 * After successful get_page_unless_zero() might follow put_page()
2384 * which needs correct compound_head().
2385 */
2386 clear_compound_head(page_tail);
2387
2388 /* Finally unfreeze refcount. Additional reference from page cache. */
2389 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2390 PageSwapCache(head)));
2391
2392 if (page_is_young(head))
2393 set_page_young(page_tail);
2394 if (page_is_idle(head))
2395 set_page_idle(page_tail);
2396
2397 /* ->mapping in first tail page is compound_mapcount */
2398 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2399 page_tail);
2400 page_tail->mapping = head->mapping;
2401
2402 page_tail->index = head->index + tail;
2403 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2404
2405 /*
2406 * always add to the tail because some iterators expect new
2407 * pages to show after the currently processed elements - e.g.
2408 * migrate_pages
2409 */
2410 lru_add_page_tail(head, page_tail, lruvec, list);
2411}
2412
2413static void __split_huge_page(struct page *page, struct list_head *list,
2414 unsigned long flags)
2415{
2416 struct page *head = compound_head(page);
2417 struct zone *zone = page_zone(head);
2418 struct lruvec *lruvec;
2419 pgoff_t end = -1;
2420 int i;
2421
2422 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2423
2424 /* complete memcg works before add pages to LRU */
2425 mem_cgroup_split_huge_fixup(head);
2426
2427 if (!PageAnon(page))
2428 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2429
2430 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2431 __split_huge_page_tail(head, i, lruvec, list);
2432 /* Some pages can be beyond i_size: drop them from page cache */
2433 if (head[i].index >= end) {
2434 ClearPageDirty(head + i);
2435 __delete_from_page_cache(head + i, NULL);
2436 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2437 shmem_uncharge(head->mapping->host, 1);
2438 put_page(head + i);
2439 }
2440 }
2441
2442 ClearPageCompound(head);
2443 /* See comment in __split_huge_page_tail() */
2444 if (PageAnon(head)) {
2445 /* Additional pin to radix tree of swap cache */
2446 if (PageSwapCache(head))
2447 page_ref_add(head, 2);
2448 else
2449 page_ref_inc(head);
2450 } else {
2451 /* Additional pin to radix tree */
2452 page_ref_add(head, 2);
2453 xa_unlock(&head->mapping->i_pages);
2454 }
2455
2456 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2457
2458 unfreeze_page(head);
2459
2460 for (i = 0; i < HPAGE_PMD_NR; i++) {
2461 struct page *subpage = head + i;
2462 if (subpage == page)
2463 continue;
2464 unlock_page(subpage);
2465
2466 /*
2467 * Subpages may be freed if there wasn't any mapping
2468 * like if add_to_swap() is running on a lru page that
2469 * had its mapping zapped. And freeing these pages
2470 * requires taking the lru_lock so we do the put_page
2471 * of the tail pages after the split is complete.
2472 */
2473 put_page(subpage);
2474 }
2475}
2476
2477int total_mapcount(struct page *page)
2478{
2479 int i, compound, ret;
2480
2481 VM_BUG_ON_PAGE(PageTail(page), page);
2482
2483 if (likely(!PageCompound(page)))
2484 return atomic_read(&page->_mapcount) + 1;
2485
2486 compound = compound_mapcount(page);
2487 if (PageHuge(page))
2488 return compound;
2489 ret = compound;
2490 for (i = 0; i < HPAGE_PMD_NR; i++)
2491 ret += atomic_read(&page[i]._mapcount) + 1;
2492 /* File pages has compound_mapcount included in _mapcount */
2493 if (!PageAnon(page))
2494 return ret - compound * HPAGE_PMD_NR;
2495 if (PageDoubleMap(page))
2496 ret -= HPAGE_PMD_NR;
2497 return ret;
2498}
2499
2500/*
2501 * This calculates accurately how many mappings a transparent hugepage
2502 * has (unlike page_mapcount() which isn't fully accurate). This full
2503 * accuracy is primarily needed to know if copy-on-write faults can
2504 * reuse the page and change the mapping to read-write instead of
2505 * copying them. At the same time this returns the total_mapcount too.
2506 *
2507 * The function returns the highest mapcount any one of the subpages
2508 * has. If the return value is one, even if different processes are
2509 * mapping different subpages of the transparent hugepage, they can
2510 * all reuse it, because each process is reusing a different subpage.
2511 *
2512 * The total_mapcount is instead counting all virtual mappings of the
2513 * subpages. If the total_mapcount is equal to "one", it tells the
2514 * caller all mappings belong to the same "mm" and in turn the
2515 * anon_vma of the transparent hugepage can become the vma->anon_vma
2516 * local one as no other process may be mapping any of the subpages.
2517 *
2518 * It would be more accurate to replace page_mapcount() with
2519 * page_trans_huge_mapcount(), however we only use
2520 * page_trans_huge_mapcount() in the copy-on-write faults where we
2521 * need full accuracy to avoid breaking page pinning, because
2522 * page_trans_huge_mapcount() is slower than page_mapcount().
2523 */
2524int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2525{
2526 int i, ret, _total_mapcount, mapcount;
2527
2528 /* hugetlbfs shouldn't call it */
2529 VM_BUG_ON_PAGE(PageHuge(page), page);
2530
2531 if (likely(!PageTransCompound(page))) {
2532 mapcount = atomic_read(&page->_mapcount) + 1;
2533 if (total_mapcount)
2534 *total_mapcount = mapcount;
2535 return mapcount;
2536 }
2537
2538 page = compound_head(page);
2539
2540 _total_mapcount = ret = 0;
2541 for (i = 0; i < HPAGE_PMD_NR; i++) {
2542 mapcount = atomic_read(&page[i]._mapcount) + 1;
2543 ret = max(ret, mapcount);
2544 _total_mapcount += mapcount;
2545 }
2546 if (PageDoubleMap(page)) {
2547 ret -= 1;
2548 _total_mapcount -= HPAGE_PMD_NR;
2549 }
2550 mapcount = compound_mapcount(page);
2551 ret += mapcount;
2552 _total_mapcount += mapcount;
2553 if (total_mapcount)
2554 *total_mapcount = _total_mapcount;
2555 return ret;
2556}
2557
2558/* Racy check whether the huge page can be split */
2559bool can_split_huge_page(struct page *page, int *pextra_pins)
2560{
2561 int extra_pins;
2562
2563 /* Additional pins from radix tree */
2564 if (PageAnon(page))
2565 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2566 else
2567 extra_pins = HPAGE_PMD_NR;
2568 if (pextra_pins)
2569 *pextra_pins = extra_pins;
2570 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2571}
2572
2573/*
2574 * This function splits huge page into normal pages. @page can point to any
2575 * subpage of huge page to split. Split doesn't change the position of @page.
2576 *
2577 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2578 * The huge page must be locked.
2579 *
2580 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2581 *
2582 * Both head page and tail pages will inherit mapping, flags, and so on from
2583 * the hugepage.
2584 *
2585 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2586 * they are not mapped.
2587 *
2588 * Returns 0 if the hugepage is split successfully.
2589 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2590 * us.
2591 */
2592int split_huge_page_to_list(struct page *page, struct list_head *list)
2593{
2594 struct page *head = compound_head(page);
2595 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2596 struct anon_vma *anon_vma = NULL;
2597 struct address_space *mapping = NULL;
2598 int count, mapcount, extra_pins, ret;
2599 bool mlocked;
2600 unsigned long flags;
2601
2602 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2603 VM_BUG_ON_PAGE(!PageLocked(page), page);
2604 VM_BUG_ON_PAGE(!PageCompound(page), page);
2605
2606 if (PageWriteback(page))
2607 return -EBUSY;
2608
2609 if (PageAnon(head)) {
2610 /*
2611 * The caller does not necessarily hold an mmap_sem that would
2612 * prevent the anon_vma disappearing so we first we take a
2613 * reference to it and then lock the anon_vma for write. This
2614 * is similar to page_lock_anon_vma_read except the write lock
2615 * is taken to serialise against parallel split or collapse
2616 * operations.
2617 */
2618 anon_vma = page_get_anon_vma(head);
2619 if (!anon_vma) {
2620 ret = -EBUSY;
2621 goto out;
2622 }
2623 mapping = NULL;
2624 anon_vma_lock_write(anon_vma);
2625 } else {
2626 mapping = head->mapping;
2627
2628 /* Truncated ? */
2629 if (!mapping) {
2630 ret = -EBUSY;
2631 goto out;
2632 }
2633
2634 anon_vma = NULL;
2635 i_mmap_lock_read(mapping);
2636 }
2637
2638 /*
2639 * Racy check if we can split the page, before freeze_page() will
2640 * split PMDs
2641 */
2642 if (!can_split_huge_page(head, &extra_pins)) {
2643 ret = -EBUSY;
2644 goto out_unlock;
2645 }
2646
2647 mlocked = PageMlocked(page);
2648 freeze_page(head);
2649 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2650
2651 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2652 if (mlocked)
2653 lru_add_drain();
2654
2655 /* prevent PageLRU to go away from under us, and freeze lru stats */
2656 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2657
2658 if (mapping) {
2659 void **pslot;
2660
2661 xa_lock(&mapping->i_pages);
2662 pslot = radix_tree_lookup_slot(&mapping->i_pages,
2663 page_index(head));
2664 /*
2665 * Check if the head page is present in radix tree.
2666 * We assume all tail are present too, if head is there.
2667 */
2668 if (radix_tree_deref_slot_protected(pslot,
2669 &mapping->i_pages.xa_lock) != head)
2670 goto fail;
2671 }
2672
2673 /* Prevent deferred_split_scan() touching ->_refcount */
2674 spin_lock(&pgdata->split_queue_lock);
2675 count = page_count(head);
2676 mapcount = total_mapcount(head);
2677 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2678 if (!list_empty(page_deferred_list(head))) {
2679 pgdata->split_queue_len--;
2680 list_del(page_deferred_list(head));
2681 }
2682 if (mapping)
2683 __dec_node_page_state(page, NR_SHMEM_THPS);
2684 spin_unlock(&pgdata->split_queue_lock);
2685 __split_huge_page(page, list, flags);
2686 if (PageSwapCache(head)) {
2687 swp_entry_t entry = { .val = page_private(head) };
2688
2689 ret = split_swap_cluster(entry);
2690 } else
2691 ret = 0;
2692 } else {
2693 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2694 pr_alert("total_mapcount: %u, page_count(): %u\n",
2695 mapcount, count);
2696 if (PageTail(page))
2697 dump_page(head, NULL);
2698 dump_page(page, "total_mapcount(head) > 0");
2699 BUG();
2700 }
2701 spin_unlock(&pgdata->split_queue_lock);
2702fail: if (mapping)
2703 xa_unlock(&mapping->i_pages);
2704 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2705 unfreeze_page(head);
2706 ret = -EBUSY;
2707 }
2708
2709out_unlock:
2710 if (anon_vma) {
2711 anon_vma_unlock_write(anon_vma);
2712 put_anon_vma(anon_vma);
2713 }
2714 if (mapping)
2715 i_mmap_unlock_read(mapping);
2716out:
2717 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2718 return ret;
2719}
2720
2721void free_transhuge_page(struct page *page)
2722{
2723 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2724 unsigned long flags;
2725
2726 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2727 if (!list_empty(page_deferred_list(page))) {
2728 pgdata->split_queue_len--;
2729 list_del(page_deferred_list(page));
2730 }
2731 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2732 free_compound_page(page);
2733}
2734
2735void deferred_split_huge_page(struct page *page)
2736{
2737 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2738 unsigned long flags;
2739
2740 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2741
2742 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2743 if (list_empty(page_deferred_list(page))) {
2744 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2745 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2746 pgdata->split_queue_len++;
2747 }
2748 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2749}
2750
2751static unsigned long deferred_split_count(struct shrinker *shrink,
2752 struct shrink_control *sc)
2753{
2754 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2755 return READ_ONCE(pgdata->split_queue_len);
2756}
2757
2758static unsigned long deferred_split_scan(struct shrinker *shrink,
2759 struct shrink_control *sc)
2760{
2761 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2762 unsigned long flags;
2763 LIST_HEAD(list), *pos, *next;
2764 struct page *page;
2765 int split = 0;
2766
2767 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2768 /* Take pin on all head pages to avoid freeing them under us */
2769 list_for_each_safe(pos, next, &pgdata->split_queue) {
2770 page = list_entry((void *)pos, struct page, mapping);
2771 page = compound_head(page);
2772 if (get_page_unless_zero(page)) {
2773 list_move(page_deferred_list(page), &list);
2774 } else {
2775 /* We lost race with put_compound_page() */
2776 list_del_init(page_deferred_list(page));
2777 pgdata->split_queue_len--;
2778 }
2779 if (!--sc->nr_to_scan)
2780 break;
2781 }
2782 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2783
2784 list_for_each_safe(pos, next, &list) {
2785 page = list_entry((void *)pos, struct page, mapping);
2786 if (!trylock_page(page))
2787 goto next;
2788 /* split_huge_page() removes page from list on success */
2789 if (!split_huge_page(page))
2790 split++;
2791 unlock_page(page);
2792next:
2793 put_page(page);
2794 }
2795
2796 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2797 list_splice_tail(&list, &pgdata->split_queue);
2798 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2799
2800 /*
2801 * Stop shrinker if we didn't split any page, but the queue is empty.
2802 * This can happen if pages were freed under us.
2803 */
2804 if (!split && list_empty(&pgdata->split_queue))
2805 return SHRINK_STOP;
2806 return split;
2807}
2808
2809static struct shrinker deferred_split_shrinker = {
2810 .count_objects = deferred_split_count,
2811 .scan_objects = deferred_split_scan,
2812 .seeks = DEFAULT_SEEKS,
2813 .flags = SHRINKER_NUMA_AWARE,
2814};
2815
2816#ifdef CONFIG_DEBUG_FS
2817static int split_huge_pages_set(void *data, u64 val)
2818{
2819 struct zone *zone;
2820 struct page *page;
2821 unsigned long pfn, max_zone_pfn;
2822 unsigned long total = 0, split = 0;
2823
2824 if (val != 1)
2825 return -EINVAL;
2826
2827 for_each_populated_zone(zone) {
2828 max_zone_pfn = zone_end_pfn(zone);
2829 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2830 if (!pfn_valid(pfn))
2831 continue;
2832
2833 page = pfn_to_page(pfn);
2834 if (!get_page_unless_zero(page))
2835 continue;
2836
2837 if (zone != page_zone(page))
2838 goto next;
2839
2840 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2841 goto next;
2842
2843 total++;
2844 lock_page(page);
2845 if (!split_huge_page(page))
2846 split++;
2847 unlock_page(page);
2848next:
2849 put_page(page);
2850 }
2851 }
2852
2853 pr_info("%lu of %lu THP split\n", split, total);
2854
2855 return 0;
2856}
2857DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2858 "%llu\n");
2859
2860static int __init split_huge_pages_debugfs(void)
2861{
2862 void *ret;
2863
2864 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2865 &split_huge_pages_fops);
2866 if (!ret)
2867 pr_warn("Failed to create split_huge_pages in debugfs");
2868 return 0;
2869}
2870late_initcall(split_huge_pages_debugfs);
2871#endif
2872
2873#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2874void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2875 struct page *page)
2876{
2877 struct vm_area_struct *vma = pvmw->vma;
2878 struct mm_struct *mm = vma->vm_mm;
2879 unsigned long address = pvmw->address;
2880 pmd_t pmdval;
2881 swp_entry_t entry;
2882 pmd_t pmdswp;
2883
2884 if (!(pvmw->pmd && !pvmw->pte))
2885 return;
2886
2887 mmu_notifier_invalidate_range_start(mm, address,
2888 address + HPAGE_PMD_SIZE);
2889
2890 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2891 pmdval = *pvmw->pmd;
2892 pmdp_invalidate(vma, address, pvmw->pmd);
2893 if (pmd_dirty(pmdval))
2894 set_page_dirty(page);
2895 entry = make_migration_entry(page, pmd_write(pmdval));
2896 pmdswp = swp_entry_to_pmd(entry);
2897 if (pmd_soft_dirty(pmdval))
2898 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2899 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2900 page_remove_rmap(page, true);
2901 put_page(page);
2902
2903 mmu_notifier_invalidate_range_end(mm, address,
2904 address + HPAGE_PMD_SIZE);
2905}
2906
2907void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2908{
2909 struct vm_area_struct *vma = pvmw->vma;
2910 struct mm_struct *mm = vma->vm_mm;
2911 unsigned long address = pvmw->address;
2912 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2913 pmd_t pmde;
2914 swp_entry_t entry;
2915
2916 if (!(pvmw->pmd && !pvmw->pte))
2917 return;
2918
2919 entry = pmd_to_swp_entry(*pvmw->pmd);
2920 get_page(new);
2921 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2922 if (pmd_swp_soft_dirty(*pvmw->pmd))
2923 pmde = pmd_mksoft_dirty(pmde);
2924 if (is_write_migration_entry(entry))
2925 pmde = maybe_pmd_mkwrite(pmde, vma);
2926
2927 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2928 if (PageAnon(new))
2929 page_add_anon_rmap(new, vma, mmun_start, true);
2930 else
2931 page_add_file_rmap(new, true);
2932 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2933 if (vma->vm_flags & VM_LOCKED)
2934 mlock_vma_page(new);
2935 update_mmu_cache_pmd(vma, address, pvmw->pmd);
2936}
2937#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2009 Red Hat, Inc.
4 */
5
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8#include <linux/mm.h>
9#include <linux/sched.h>
10#include <linux/sched/coredump.h>
11#include <linux/sched/numa_balancing.h>
12#include <linux/highmem.h>
13#include <linux/hugetlb.h>
14#include <linux/mmu_notifier.h>
15#include <linux/rmap.h>
16#include <linux/swap.h>
17#include <linux/shrinker.h>
18#include <linux/mm_inline.h>
19#include <linux/swapops.h>
20#include <linux/dax.h>
21#include <linux/khugepaged.h>
22#include <linux/freezer.h>
23#include <linux/pfn_t.h>
24#include <linux/mman.h>
25#include <linux/memremap.h>
26#include <linux/pagemap.h>
27#include <linux/debugfs.h>
28#include <linux/migrate.h>
29#include <linux/hashtable.h>
30#include <linux/userfaultfd_k.h>
31#include <linux/page_idle.h>
32#include <linux/shmem_fs.h>
33#include <linux/oom.h>
34#include <linux/numa.h>
35#include <linux/page_owner.h>
36
37#include <asm/tlb.h>
38#include <asm/pgalloc.h>
39#include "internal.h"
40
41/*
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
48 */
49unsigned long transparent_hugepage_flags __read_mostly =
50#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52#endif
53#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55#endif
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
59
60static struct shrinker deferred_split_shrinker;
61
62static atomic_t huge_zero_refcount;
63struct page *huge_zero_page __read_mostly;
64
65bool transparent_hugepage_enabled(struct vm_area_struct *vma)
66{
67 /* The addr is used to check if the vma size fits */
68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
69
70 if (!transhuge_vma_suitable(vma, addr))
71 return false;
72 if (vma_is_anonymous(vma))
73 return __transparent_hugepage_enabled(vma);
74 if (vma_is_shmem(vma))
75 return shmem_huge_enabled(vma);
76
77 return false;
78}
79
80static struct page *get_huge_zero_page(void)
81{
82 struct page *zero_page;
83retry:
84 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
85 return READ_ONCE(huge_zero_page);
86
87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
88 HPAGE_PMD_ORDER);
89 if (!zero_page) {
90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
91 return NULL;
92 }
93 count_vm_event(THP_ZERO_PAGE_ALLOC);
94 preempt_disable();
95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
96 preempt_enable();
97 __free_pages(zero_page, compound_order(zero_page));
98 goto retry;
99 }
100
101 /* We take additional reference here. It will be put back by shrinker */
102 atomic_set(&huge_zero_refcount, 2);
103 preempt_enable();
104 return READ_ONCE(huge_zero_page);
105}
106
107static void put_huge_zero_page(void)
108{
109 /*
110 * Counter should never go to zero here. Only shrinker can put
111 * last reference.
112 */
113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
114}
115
116struct page *mm_get_huge_zero_page(struct mm_struct *mm)
117{
118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 return READ_ONCE(huge_zero_page);
120
121 if (!get_huge_zero_page())
122 return NULL;
123
124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
125 put_huge_zero_page();
126
127 return READ_ONCE(huge_zero_page);
128}
129
130void mm_put_huge_zero_page(struct mm_struct *mm)
131{
132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
133 put_huge_zero_page();
134}
135
136static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
137 struct shrink_control *sc)
138{
139 /* we can free zero page only if last reference remains */
140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
141}
142
143static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
144 struct shrink_control *sc)
145{
146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
147 struct page *zero_page = xchg(&huge_zero_page, NULL);
148 BUG_ON(zero_page == NULL);
149 __free_pages(zero_page, compound_order(zero_page));
150 return HPAGE_PMD_NR;
151 }
152
153 return 0;
154}
155
156static struct shrinker huge_zero_page_shrinker = {
157 .count_objects = shrink_huge_zero_page_count,
158 .scan_objects = shrink_huge_zero_page_scan,
159 .seeks = DEFAULT_SEEKS,
160};
161
162#ifdef CONFIG_SYSFS
163static ssize_t enabled_show(struct kobject *kobj,
164 struct kobj_attribute *attr, char *buf)
165{
166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
167 return sprintf(buf, "[always] madvise never\n");
168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
169 return sprintf(buf, "always [madvise] never\n");
170 else
171 return sprintf(buf, "always madvise [never]\n");
172}
173
174static ssize_t enabled_store(struct kobject *kobj,
175 struct kobj_attribute *attr,
176 const char *buf, size_t count)
177{
178 ssize_t ret = count;
179
180 if (!memcmp("always", buf,
181 min(sizeof("always")-1, count))) {
182 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
183 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
184 } else if (!memcmp("madvise", buf,
185 min(sizeof("madvise")-1, count))) {
186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
187 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
188 } else if (!memcmp("never", buf,
189 min(sizeof("never")-1, count))) {
190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
192 } else
193 ret = -EINVAL;
194
195 if (ret > 0) {
196 int err = start_stop_khugepaged();
197 if (err)
198 ret = err;
199 }
200 return ret;
201}
202static struct kobj_attribute enabled_attr =
203 __ATTR(enabled, 0644, enabled_show, enabled_store);
204
205ssize_t single_hugepage_flag_show(struct kobject *kobj,
206 struct kobj_attribute *attr, char *buf,
207 enum transparent_hugepage_flag flag)
208{
209 return sprintf(buf, "%d\n",
210 !!test_bit(flag, &transparent_hugepage_flags));
211}
212
213ssize_t single_hugepage_flag_store(struct kobject *kobj,
214 struct kobj_attribute *attr,
215 const char *buf, size_t count,
216 enum transparent_hugepage_flag flag)
217{
218 unsigned long value;
219 int ret;
220
221 ret = kstrtoul(buf, 10, &value);
222 if (ret < 0)
223 return ret;
224 if (value > 1)
225 return -EINVAL;
226
227 if (value)
228 set_bit(flag, &transparent_hugepage_flags);
229 else
230 clear_bit(flag, &transparent_hugepage_flags);
231
232 return count;
233}
234
235static ssize_t defrag_show(struct kobject *kobj,
236 struct kobj_attribute *attr, char *buf)
237{
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
239 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
241 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
243 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
245 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
246 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
247}
248
249static ssize_t defrag_store(struct kobject *kobj,
250 struct kobj_attribute *attr,
251 const char *buf, size_t count)
252{
253 if (!memcmp("always", buf,
254 min(sizeof("always")-1, count))) {
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
259 } else if (!memcmp("defer+madvise", buf,
260 min(sizeof("defer+madvise")-1, count))) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
265 } else if (!memcmp("defer", buf,
266 min(sizeof("defer")-1, count))) {
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
271 } else if (!memcmp("madvise", buf,
272 min(sizeof("madvise")-1, count))) {
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
276 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
277 } else if (!memcmp("never", buf,
278 min(sizeof("never")-1, count))) {
279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
283 } else
284 return -EINVAL;
285
286 return count;
287}
288static struct kobj_attribute defrag_attr =
289 __ATTR(defrag, 0644, defrag_show, defrag_store);
290
291static ssize_t use_zero_page_show(struct kobject *kobj,
292 struct kobj_attribute *attr, char *buf)
293{
294 return single_hugepage_flag_show(kobj, attr, buf,
295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
296}
297static ssize_t use_zero_page_store(struct kobject *kobj,
298 struct kobj_attribute *attr, const char *buf, size_t count)
299{
300 return single_hugepage_flag_store(kobj, attr, buf, count,
301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
302}
303static struct kobj_attribute use_zero_page_attr =
304 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
305
306static ssize_t hpage_pmd_size_show(struct kobject *kobj,
307 struct kobj_attribute *attr, char *buf)
308{
309 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
310}
311static struct kobj_attribute hpage_pmd_size_attr =
312 __ATTR_RO(hpage_pmd_size);
313
314#ifdef CONFIG_DEBUG_VM
315static ssize_t debug_cow_show(struct kobject *kobj,
316 struct kobj_attribute *attr, char *buf)
317{
318 return single_hugepage_flag_show(kobj, attr, buf,
319 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
320}
321static ssize_t debug_cow_store(struct kobject *kobj,
322 struct kobj_attribute *attr,
323 const char *buf, size_t count)
324{
325 return single_hugepage_flag_store(kobj, attr, buf, count,
326 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
327}
328static struct kobj_attribute debug_cow_attr =
329 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
330#endif /* CONFIG_DEBUG_VM */
331
332static struct attribute *hugepage_attr[] = {
333 &enabled_attr.attr,
334 &defrag_attr.attr,
335 &use_zero_page_attr.attr,
336 &hpage_pmd_size_attr.attr,
337#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
338 &shmem_enabled_attr.attr,
339#endif
340#ifdef CONFIG_DEBUG_VM
341 &debug_cow_attr.attr,
342#endif
343 NULL,
344};
345
346static const struct attribute_group hugepage_attr_group = {
347 .attrs = hugepage_attr,
348};
349
350static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
351{
352 int err;
353
354 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
355 if (unlikely(!*hugepage_kobj)) {
356 pr_err("failed to create transparent hugepage kobject\n");
357 return -ENOMEM;
358 }
359
360 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
361 if (err) {
362 pr_err("failed to register transparent hugepage group\n");
363 goto delete_obj;
364 }
365
366 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
367 if (err) {
368 pr_err("failed to register transparent hugepage group\n");
369 goto remove_hp_group;
370 }
371
372 return 0;
373
374remove_hp_group:
375 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
376delete_obj:
377 kobject_put(*hugepage_kobj);
378 return err;
379}
380
381static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
382{
383 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
384 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
385 kobject_put(hugepage_kobj);
386}
387#else
388static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
389{
390 return 0;
391}
392
393static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
394{
395}
396#endif /* CONFIG_SYSFS */
397
398static int __init hugepage_init(void)
399{
400 int err;
401 struct kobject *hugepage_kobj;
402
403 if (!has_transparent_hugepage()) {
404 transparent_hugepage_flags = 0;
405 return -EINVAL;
406 }
407
408 /*
409 * hugepages can't be allocated by the buddy allocator
410 */
411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
412 /*
413 * we use page->mapping and page->index in second tail page
414 * as list_head: assuming THP order >= 2
415 */
416 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
417
418 err = hugepage_init_sysfs(&hugepage_kobj);
419 if (err)
420 goto err_sysfs;
421
422 err = khugepaged_init();
423 if (err)
424 goto err_slab;
425
426 err = register_shrinker(&huge_zero_page_shrinker);
427 if (err)
428 goto err_hzp_shrinker;
429 err = register_shrinker(&deferred_split_shrinker);
430 if (err)
431 goto err_split_shrinker;
432
433 /*
434 * By default disable transparent hugepages on smaller systems,
435 * where the extra memory used could hurt more than TLB overhead
436 * is likely to save. The admin can still enable it through /sys.
437 */
438 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
439 transparent_hugepage_flags = 0;
440 return 0;
441 }
442
443 err = start_stop_khugepaged();
444 if (err)
445 goto err_khugepaged;
446
447 return 0;
448err_khugepaged:
449 unregister_shrinker(&deferred_split_shrinker);
450err_split_shrinker:
451 unregister_shrinker(&huge_zero_page_shrinker);
452err_hzp_shrinker:
453 khugepaged_destroy();
454err_slab:
455 hugepage_exit_sysfs(hugepage_kobj);
456err_sysfs:
457 return err;
458}
459subsys_initcall(hugepage_init);
460
461static int __init setup_transparent_hugepage(char *str)
462{
463 int ret = 0;
464 if (!str)
465 goto out;
466 if (!strcmp(str, "always")) {
467 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
468 &transparent_hugepage_flags);
469 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
470 &transparent_hugepage_flags);
471 ret = 1;
472 } else if (!strcmp(str, "madvise")) {
473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
474 &transparent_hugepage_flags);
475 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
476 &transparent_hugepage_flags);
477 ret = 1;
478 } else if (!strcmp(str, "never")) {
479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
480 &transparent_hugepage_flags);
481 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
482 &transparent_hugepage_flags);
483 ret = 1;
484 }
485out:
486 if (!ret)
487 pr_warn("transparent_hugepage= cannot parse, ignored\n");
488 return ret;
489}
490__setup("transparent_hugepage=", setup_transparent_hugepage);
491
492pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
493{
494 if (likely(vma->vm_flags & VM_WRITE))
495 pmd = pmd_mkwrite(pmd);
496 return pmd;
497}
498
499#ifdef CONFIG_MEMCG
500static inline struct deferred_split *get_deferred_split_queue(struct page *page)
501{
502 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
503 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
504
505 if (memcg)
506 return &memcg->deferred_split_queue;
507 else
508 return &pgdat->deferred_split_queue;
509}
510#else
511static inline struct deferred_split *get_deferred_split_queue(struct page *page)
512{
513 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
514
515 return &pgdat->deferred_split_queue;
516}
517#endif
518
519void prep_transhuge_page(struct page *page)
520{
521 /*
522 * we use page->mapping and page->indexlru in second tail page
523 * as list_head: assuming THP order >= 2
524 */
525
526 INIT_LIST_HEAD(page_deferred_list(page));
527 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
528}
529
530static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
531 loff_t off, unsigned long flags, unsigned long size)
532{
533 unsigned long addr;
534 loff_t off_end = off + len;
535 loff_t off_align = round_up(off, size);
536 unsigned long len_pad;
537
538 if (off_end <= off_align || (off_end - off_align) < size)
539 return 0;
540
541 len_pad = len + size;
542 if (len_pad < len || (off + len_pad) < off)
543 return 0;
544
545 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
546 off >> PAGE_SHIFT, flags);
547 if (IS_ERR_VALUE(addr))
548 return 0;
549
550 addr += (off - addr) & (size - 1);
551 return addr;
552}
553
554unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
555 unsigned long len, unsigned long pgoff, unsigned long flags)
556{
557 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
558
559 if (addr)
560 goto out;
561 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
562 goto out;
563
564 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
565 if (addr)
566 return addr;
567
568 out:
569 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
570}
571EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
572
573static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
574 struct page *page, gfp_t gfp)
575{
576 struct vm_area_struct *vma = vmf->vma;
577 struct mem_cgroup *memcg;
578 pgtable_t pgtable;
579 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
580 vm_fault_t ret = 0;
581
582 VM_BUG_ON_PAGE(!PageCompound(page), page);
583
584 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
585 put_page(page);
586 count_vm_event(THP_FAULT_FALLBACK);
587 return VM_FAULT_FALLBACK;
588 }
589
590 pgtable = pte_alloc_one(vma->vm_mm);
591 if (unlikely(!pgtable)) {
592 ret = VM_FAULT_OOM;
593 goto release;
594 }
595
596 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
597 /*
598 * The memory barrier inside __SetPageUptodate makes sure that
599 * clear_huge_page writes become visible before the set_pmd_at()
600 * write.
601 */
602 __SetPageUptodate(page);
603
604 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
605 if (unlikely(!pmd_none(*vmf->pmd))) {
606 goto unlock_release;
607 } else {
608 pmd_t entry;
609
610 ret = check_stable_address_space(vma->vm_mm);
611 if (ret)
612 goto unlock_release;
613
614 /* Deliver the page fault to userland */
615 if (userfaultfd_missing(vma)) {
616 vm_fault_t ret2;
617
618 spin_unlock(vmf->ptl);
619 mem_cgroup_cancel_charge(page, memcg, true);
620 put_page(page);
621 pte_free(vma->vm_mm, pgtable);
622 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
623 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
624 return ret2;
625 }
626
627 entry = mk_huge_pmd(page, vma->vm_page_prot);
628 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
629 page_add_new_anon_rmap(page, vma, haddr, true);
630 mem_cgroup_commit_charge(page, memcg, false, true);
631 lru_cache_add_active_or_unevictable(page, vma);
632 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
633 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
634 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
635 mm_inc_nr_ptes(vma->vm_mm);
636 spin_unlock(vmf->ptl);
637 count_vm_event(THP_FAULT_ALLOC);
638 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
639 }
640
641 return 0;
642unlock_release:
643 spin_unlock(vmf->ptl);
644release:
645 if (pgtable)
646 pte_free(vma->vm_mm, pgtable);
647 mem_cgroup_cancel_charge(page, memcg, true);
648 put_page(page);
649 return ret;
650
651}
652
653/*
654 * always: directly stall for all thp allocations
655 * defer: wake kswapd and fail if not immediately available
656 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
657 * fail if not immediately available
658 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
659 * available
660 * never: never stall for any thp allocation
661 */
662static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
663{
664 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
665
666 /* Always do synchronous compaction */
667 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
668 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
669
670 /* Kick kcompactd and fail quickly */
671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
672 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
673
674 /* Synchronous compaction if madvised, otherwise kick kcompactd */
675 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
676 return GFP_TRANSHUGE_LIGHT |
677 (vma_madvised ? __GFP_DIRECT_RECLAIM :
678 __GFP_KSWAPD_RECLAIM);
679
680 /* Only do synchronous compaction if madvised */
681 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
682 return GFP_TRANSHUGE_LIGHT |
683 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
684
685 return GFP_TRANSHUGE_LIGHT;
686}
687
688/* Caller must hold page table lock. */
689static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
690 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
691 struct page *zero_page)
692{
693 pmd_t entry;
694 if (!pmd_none(*pmd))
695 return false;
696 entry = mk_pmd(zero_page, vma->vm_page_prot);
697 entry = pmd_mkhuge(entry);
698 if (pgtable)
699 pgtable_trans_huge_deposit(mm, pmd, pgtable);
700 set_pmd_at(mm, haddr, pmd, entry);
701 mm_inc_nr_ptes(mm);
702 return true;
703}
704
705vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
706{
707 struct vm_area_struct *vma = vmf->vma;
708 gfp_t gfp;
709 struct page *page;
710 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
711
712 if (!transhuge_vma_suitable(vma, haddr))
713 return VM_FAULT_FALLBACK;
714 if (unlikely(anon_vma_prepare(vma)))
715 return VM_FAULT_OOM;
716 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
717 return VM_FAULT_OOM;
718 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
719 !mm_forbids_zeropage(vma->vm_mm) &&
720 transparent_hugepage_use_zero_page()) {
721 pgtable_t pgtable;
722 struct page *zero_page;
723 bool set;
724 vm_fault_t ret;
725 pgtable = pte_alloc_one(vma->vm_mm);
726 if (unlikely(!pgtable))
727 return VM_FAULT_OOM;
728 zero_page = mm_get_huge_zero_page(vma->vm_mm);
729 if (unlikely(!zero_page)) {
730 pte_free(vma->vm_mm, pgtable);
731 count_vm_event(THP_FAULT_FALLBACK);
732 return VM_FAULT_FALLBACK;
733 }
734 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
735 ret = 0;
736 set = false;
737 if (pmd_none(*vmf->pmd)) {
738 ret = check_stable_address_space(vma->vm_mm);
739 if (ret) {
740 spin_unlock(vmf->ptl);
741 } else if (userfaultfd_missing(vma)) {
742 spin_unlock(vmf->ptl);
743 ret = handle_userfault(vmf, VM_UFFD_MISSING);
744 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
745 } else {
746 set_huge_zero_page(pgtable, vma->vm_mm, vma,
747 haddr, vmf->pmd, zero_page);
748 spin_unlock(vmf->ptl);
749 set = true;
750 }
751 } else
752 spin_unlock(vmf->ptl);
753 if (!set)
754 pte_free(vma->vm_mm, pgtable);
755 return ret;
756 }
757 gfp = alloc_hugepage_direct_gfpmask(vma);
758 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
759 if (unlikely(!page)) {
760 count_vm_event(THP_FAULT_FALLBACK);
761 return VM_FAULT_FALLBACK;
762 }
763 prep_transhuge_page(page);
764 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
765}
766
767static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
768 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
769 pgtable_t pgtable)
770{
771 struct mm_struct *mm = vma->vm_mm;
772 pmd_t entry;
773 spinlock_t *ptl;
774
775 ptl = pmd_lock(mm, pmd);
776 if (!pmd_none(*pmd)) {
777 if (write) {
778 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
779 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
780 goto out_unlock;
781 }
782 entry = pmd_mkyoung(*pmd);
783 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
784 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
785 update_mmu_cache_pmd(vma, addr, pmd);
786 }
787
788 goto out_unlock;
789 }
790
791 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
792 if (pfn_t_devmap(pfn))
793 entry = pmd_mkdevmap(entry);
794 if (write) {
795 entry = pmd_mkyoung(pmd_mkdirty(entry));
796 entry = maybe_pmd_mkwrite(entry, vma);
797 }
798
799 if (pgtable) {
800 pgtable_trans_huge_deposit(mm, pmd, pgtable);
801 mm_inc_nr_ptes(mm);
802 pgtable = NULL;
803 }
804
805 set_pmd_at(mm, addr, pmd, entry);
806 update_mmu_cache_pmd(vma, addr, pmd);
807
808out_unlock:
809 spin_unlock(ptl);
810 if (pgtable)
811 pte_free(mm, pgtable);
812}
813
814vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
815{
816 unsigned long addr = vmf->address & PMD_MASK;
817 struct vm_area_struct *vma = vmf->vma;
818 pgprot_t pgprot = vma->vm_page_prot;
819 pgtable_t pgtable = NULL;
820
821 /*
822 * If we had pmd_special, we could avoid all these restrictions,
823 * but we need to be consistent with PTEs and architectures that
824 * can't support a 'special' bit.
825 */
826 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
827 !pfn_t_devmap(pfn));
828 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
829 (VM_PFNMAP|VM_MIXEDMAP));
830 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
831
832 if (addr < vma->vm_start || addr >= vma->vm_end)
833 return VM_FAULT_SIGBUS;
834
835 if (arch_needs_pgtable_deposit()) {
836 pgtable = pte_alloc_one(vma->vm_mm);
837 if (!pgtable)
838 return VM_FAULT_OOM;
839 }
840
841 track_pfn_insert(vma, &pgprot, pfn);
842
843 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
844 return VM_FAULT_NOPAGE;
845}
846EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
847
848#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
849static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
850{
851 if (likely(vma->vm_flags & VM_WRITE))
852 pud = pud_mkwrite(pud);
853 return pud;
854}
855
856static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
857 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
858{
859 struct mm_struct *mm = vma->vm_mm;
860 pud_t entry;
861 spinlock_t *ptl;
862
863 ptl = pud_lock(mm, pud);
864 if (!pud_none(*pud)) {
865 if (write) {
866 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
867 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
868 goto out_unlock;
869 }
870 entry = pud_mkyoung(*pud);
871 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
872 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
873 update_mmu_cache_pud(vma, addr, pud);
874 }
875 goto out_unlock;
876 }
877
878 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
879 if (pfn_t_devmap(pfn))
880 entry = pud_mkdevmap(entry);
881 if (write) {
882 entry = pud_mkyoung(pud_mkdirty(entry));
883 entry = maybe_pud_mkwrite(entry, vma);
884 }
885 set_pud_at(mm, addr, pud, entry);
886 update_mmu_cache_pud(vma, addr, pud);
887
888out_unlock:
889 spin_unlock(ptl);
890}
891
892vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
893{
894 unsigned long addr = vmf->address & PUD_MASK;
895 struct vm_area_struct *vma = vmf->vma;
896 pgprot_t pgprot = vma->vm_page_prot;
897
898 /*
899 * If we had pud_special, we could avoid all these restrictions,
900 * but we need to be consistent with PTEs and architectures that
901 * can't support a 'special' bit.
902 */
903 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
904 !pfn_t_devmap(pfn));
905 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
906 (VM_PFNMAP|VM_MIXEDMAP));
907 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
908
909 if (addr < vma->vm_start || addr >= vma->vm_end)
910 return VM_FAULT_SIGBUS;
911
912 track_pfn_insert(vma, &pgprot, pfn);
913
914 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
915 return VM_FAULT_NOPAGE;
916}
917EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
918#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
919
920static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
921 pmd_t *pmd, int flags)
922{
923 pmd_t _pmd;
924
925 _pmd = pmd_mkyoung(*pmd);
926 if (flags & FOLL_WRITE)
927 _pmd = pmd_mkdirty(_pmd);
928 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
929 pmd, _pmd, flags & FOLL_WRITE))
930 update_mmu_cache_pmd(vma, addr, pmd);
931}
932
933struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
934 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
935{
936 unsigned long pfn = pmd_pfn(*pmd);
937 struct mm_struct *mm = vma->vm_mm;
938 struct page *page;
939
940 assert_spin_locked(pmd_lockptr(mm, pmd));
941
942 /*
943 * When we COW a devmap PMD entry, we split it into PTEs, so we should
944 * not be in this function with `flags & FOLL_COW` set.
945 */
946 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
947
948 if (flags & FOLL_WRITE && !pmd_write(*pmd))
949 return NULL;
950
951 if (pmd_present(*pmd) && pmd_devmap(*pmd))
952 /* pass */;
953 else
954 return NULL;
955
956 if (flags & FOLL_TOUCH)
957 touch_pmd(vma, addr, pmd, flags);
958
959 /*
960 * device mapped pages can only be returned if the
961 * caller will manage the page reference count.
962 */
963 if (!(flags & FOLL_GET))
964 return ERR_PTR(-EEXIST);
965
966 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
967 *pgmap = get_dev_pagemap(pfn, *pgmap);
968 if (!*pgmap)
969 return ERR_PTR(-EFAULT);
970 page = pfn_to_page(pfn);
971 get_page(page);
972
973 return page;
974}
975
976int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
977 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
978 struct vm_area_struct *vma)
979{
980 spinlock_t *dst_ptl, *src_ptl;
981 struct page *src_page;
982 pmd_t pmd;
983 pgtable_t pgtable = NULL;
984 int ret = -ENOMEM;
985
986 /* Skip if can be re-fill on fault */
987 if (!vma_is_anonymous(vma))
988 return 0;
989
990 pgtable = pte_alloc_one(dst_mm);
991 if (unlikely(!pgtable))
992 goto out;
993
994 dst_ptl = pmd_lock(dst_mm, dst_pmd);
995 src_ptl = pmd_lockptr(src_mm, src_pmd);
996 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
997
998 ret = -EAGAIN;
999 pmd = *src_pmd;
1000
1001#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1002 if (unlikely(is_swap_pmd(pmd))) {
1003 swp_entry_t entry = pmd_to_swp_entry(pmd);
1004
1005 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1006 if (is_write_migration_entry(entry)) {
1007 make_migration_entry_read(&entry);
1008 pmd = swp_entry_to_pmd(entry);
1009 if (pmd_swp_soft_dirty(*src_pmd))
1010 pmd = pmd_swp_mksoft_dirty(pmd);
1011 set_pmd_at(src_mm, addr, src_pmd, pmd);
1012 }
1013 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1014 mm_inc_nr_ptes(dst_mm);
1015 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1016 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1017 ret = 0;
1018 goto out_unlock;
1019 }
1020#endif
1021
1022 if (unlikely(!pmd_trans_huge(pmd))) {
1023 pte_free(dst_mm, pgtable);
1024 goto out_unlock;
1025 }
1026 /*
1027 * When page table lock is held, the huge zero pmd should not be
1028 * under splitting since we don't split the page itself, only pmd to
1029 * a page table.
1030 */
1031 if (is_huge_zero_pmd(pmd)) {
1032 struct page *zero_page;
1033 /*
1034 * get_huge_zero_page() will never allocate a new page here,
1035 * since we already have a zero page to copy. It just takes a
1036 * reference.
1037 */
1038 zero_page = mm_get_huge_zero_page(dst_mm);
1039 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1040 zero_page);
1041 ret = 0;
1042 goto out_unlock;
1043 }
1044
1045 src_page = pmd_page(pmd);
1046 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1047 get_page(src_page);
1048 page_dup_rmap(src_page, true);
1049 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1050 mm_inc_nr_ptes(dst_mm);
1051 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1052
1053 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1054 pmd = pmd_mkold(pmd_wrprotect(pmd));
1055 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1056
1057 ret = 0;
1058out_unlock:
1059 spin_unlock(src_ptl);
1060 spin_unlock(dst_ptl);
1061out:
1062 return ret;
1063}
1064
1065#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1066static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1067 pud_t *pud, int flags)
1068{
1069 pud_t _pud;
1070
1071 _pud = pud_mkyoung(*pud);
1072 if (flags & FOLL_WRITE)
1073 _pud = pud_mkdirty(_pud);
1074 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1075 pud, _pud, flags & FOLL_WRITE))
1076 update_mmu_cache_pud(vma, addr, pud);
1077}
1078
1079struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1080 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1081{
1082 unsigned long pfn = pud_pfn(*pud);
1083 struct mm_struct *mm = vma->vm_mm;
1084 struct page *page;
1085
1086 assert_spin_locked(pud_lockptr(mm, pud));
1087
1088 if (flags & FOLL_WRITE && !pud_write(*pud))
1089 return NULL;
1090
1091 if (pud_present(*pud) && pud_devmap(*pud))
1092 /* pass */;
1093 else
1094 return NULL;
1095
1096 if (flags & FOLL_TOUCH)
1097 touch_pud(vma, addr, pud, flags);
1098
1099 /*
1100 * device mapped pages can only be returned if the
1101 * caller will manage the page reference count.
1102 */
1103 if (!(flags & FOLL_GET))
1104 return ERR_PTR(-EEXIST);
1105
1106 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1107 *pgmap = get_dev_pagemap(pfn, *pgmap);
1108 if (!*pgmap)
1109 return ERR_PTR(-EFAULT);
1110 page = pfn_to_page(pfn);
1111 get_page(page);
1112
1113 return page;
1114}
1115
1116int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1117 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1118 struct vm_area_struct *vma)
1119{
1120 spinlock_t *dst_ptl, *src_ptl;
1121 pud_t pud;
1122 int ret;
1123
1124 dst_ptl = pud_lock(dst_mm, dst_pud);
1125 src_ptl = pud_lockptr(src_mm, src_pud);
1126 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1127
1128 ret = -EAGAIN;
1129 pud = *src_pud;
1130 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1131 goto out_unlock;
1132
1133 /*
1134 * When page table lock is held, the huge zero pud should not be
1135 * under splitting since we don't split the page itself, only pud to
1136 * a page table.
1137 */
1138 if (is_huge_zero_pud(pud)) {
1139 /* No huge zero pud yet */
1140 }
1141
1142 pudp_set_wrprotect(src_mm, addr, src_pud);
1143 pud = pud_mkold(pud_wrprotect(pud));
1144 set_pud_at(dst_mm, addr, dst_pud, pud);
1145
1146 ret = 0;
1147out_unlock:
1148 spin_unlock(src_ptl);
1149 spin_unlock(dst_ptl);
1150 return ret;
1151}
1152
1153void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1154{
1155 pud_t entry;
1156 unsigned long haddr;
1157 bool write = vmf->flags & FAULT_FLAG_WRITE;
1158
1159 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1160 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1161 goto unlock;
1162
1163 entry = pud_mkyoung(orig_pud);
1164 if (write)
1165 entry = pud_mkdirty(entry);
1166 haddr = vmf->address & HPAGE_PUD_MASK;
1167 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1168 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1169
1170unlock:
1171 spin_unlock(vmf->ptl);
1172}
1173#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1174
1175void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1176{
1177 pmd_t entry;
1178 unsigned long haddr;
1179 bool write = vmf->flags & FAULT_FLAG_WRITE;
1180
1181 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1182 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1183 goto unlock;
1184
1185 entry = pmd_mkyoung(orig_pmd);
1186 if (write)
1187 entry = pmd_mkdirty(entry);
1188 haddr = vmf->address & HPAGE_PMD_MASK;
1189 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1190 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1191
1192unlock:
1193 spin_unlock(vmf->ptl);
1194}
1195
1196static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1197 pmd_t orig_pmd, struct page *page)
1198{
1199 struct vm_area_struct *vma = vmf->vma;
1200 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1201 struct mem_cgroup *memcg;
1202 pgtable_t pgtable;
1203 pmd_t _pmd;
1204 int i;
1205 vm_fault_t ret = 0;
1206 struct page **pages;
1207 struct mmu_notifier_range range;
1208
1209 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1210 GFP_KERNEL);
1211 if (unlikely(!pages)) {
1212 ret |= VM_FAULT_OOM;
1213 goto out;
1214 }
1215
1216 for (i = 0; i < HPAGE_PMD_NR; i++) {
1217 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1218 vmf->address, page_to_nid(page));
1219 if (unlikely(!pages[i] ||
1220 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1221 GFP_KERNEL, &memcg, false))) {
1222 if (pages[i])
1223 put_page(pages[i]);
1224 while (--i >= 0) {
1225 memcg = (void *)page_private(pages[i]);
1226 set_page_private(pages[i], 0);
1227 mem_cgroup_cancel_charge(pages[i], memcg,
1228 false);
1229 put_page(pages[i]);
1230 }
1231 kfree(pages);
1232 ret |= VM_FAULT_OOM;
1233 goto out;
1234 }
1235 set_page_private(pages[i], (unsigned long)memcg);
1236 }
1237
1238 for (i = 0; i < HPAGE_PMD_NR; i++) {
1239 copy_user_highpage(pages[i], page + i,
1240 haddr + PAGE_SIZE * i, vma);
1241 __SetPageUptodate(pages[i]);
1242 cond_resched();
1243 }
1244
1245 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1246 haddr, haddr + HPAGE_PMD_SIZE);
1247 mmu_notifier_invalidate_range_start(&range);
1248
1249 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1250 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1251 goto out_free_pages;
1252 VM_BUG_ON_PAGE(!PageHead(page), page);
1253
1254 /*
1255 * Leave pmd empty until pte is filled note we must notify here as
1256 * concurrent CPU thread might write to new page before the call to
1257 * mmu_notifier_invalidate_range_end() happens which can lead to a
1258 * device seeing memory write in different order than CPU.
1259 *
1260 * See Documentation/vm/mmu_notifier.rst
1261 */
1262 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1263
1264 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1265 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1266
1267 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1268 pte_t entry;
1269 entry = mk_pte(pages[i], vma->vm_page_prot);
1270 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1271 memcg = (void *)page_private(pages[i]);
1272 set_page_private(pages[i], 0);
1273 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1274 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1275 lru_cache_add_active_or_unevictable(pages[i], vma);
1276 vmf->pte = pte_offset_map(&_pmd, haddr);
1277 VM_BUG_ON(!pte_none(*vmf->pte));
1278 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1279 pte_unmap(vmf->pte);
1280 }
1281 kfree(pages);
1282
1283 smp_wmb(); /* make pte visible before pmd */
1284 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1285 page_remove_rmap(page, true);
1286 spin_unlock(vmf->ptl);
1287
1288 /*
1289 * No need to double call mmu_notifier->invalidate_range() callback as
1290 * the above pmdp_huge_clear_flush_notify() did already call it.
1291 */
1292 mmu_notifier_invalidate_range_only_end(&range);
1293
1294 ret |= VM_FAULT_WRITE;
1295 put_page(page);
1296
1297out:
1298 return ret;
1299
1300out_free_pages:
1301 spin_unlock(vmf->ptl);
1302 mmu_notifier_invalidate_range_end(&range);
1303 for (i = 0; i < HPAGE_PMD_NR; i++) {
1304 memcg = (void *)page_private(pages[i]);
1305 set_page_private(pages[i], 0);
1306 mem_cgroup_cancel_charge(pages[i], memcg, false);
1307 put_page(pages[i]);
1308 }
1309 kfree(pages);
1310 goto out;
1311}
1312
1313vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1314{
1315 struct vm_area_struct *vma = vmf->vma;
1316 struct page *page = NULL, *new_page;
1317 struct mem_cgroup *memcg;
1318 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1319 struct mmu_notifier_range range;
1320 gfp_t huge_gfp; /* for allocation and charge */
1321 vm_fault_t ret = 0;
1322
1323 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1324 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1325 if (is_huge_zero_pmd(orig_pmd))
1326 goto alloc;
1327 spin_lock(vmf->ptl);
1328 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1329 goto out_unlock;
1330
1331 page = pmd_page(orig_pmd);
1332 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1333 /*
1334 * We can only reuse the page if nobody else maps the huge page or it's
1335 * part.
1336 */
1337 if (!trylock_page(page)) {
1338 get_page(page);
1339 spin_unlock(vmf->ptl);
1340 lock_page(page);
1341 spin_lock(vmf->ptl);
1342 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1343 unlock_page(page);
1344 put_page(page);
1345 goto out_unlock;
1346 }
1347 put_page(page);
1348 }
1349 if (reuse_swap_page(page, NULL)) {
1350 pmd_t entry;
1351 entry = pmd_mkyoung(orig_pmd);
1352 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1353 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1354 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1355 ret |= VM_FAULT_WRITE;
1356 unlock_page(page);
1357 goto out_unlock;
1358 }
1359 unlock_page(page);
1360 get_page(page);
1361 spin_unlock(vmf->ptl);
1362alloc:
1363 if (__transparent_hugepage_enabled(vma) &&
1364 !transparent_hugepage_debug_cow()) {
1365 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1366 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1367 } else
1368 new_page = NULL;
1369
1370 if (likely(new_page)) {
1371 prep_transhuge_page(new_page);
1372 } else {
1373 if (!page) {
1374 split_huge_pmd(vma, vmf->pmd, vmf->address);
1375 ret |= VM_FAULT_FALLBACK;
1376 } else {
1377 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1378 if (ret & VM_FAULT_OOM) {
1379 split_huge_pmd(vma, vmf->pmd, vmf->address);
1380 ret |= VM_FAULT_FALLBACK;
1381 }
1382 put_page(page);
1383 }
1384 count_vm_event(THP_FAULT_FALLBACK);
1385 goto out;
1386 }
1387
1388 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1389 huge_gfp, &memcg, true))) {
1390 put_page(new_page);
1391 split_huge_pmd(vma, vmf->pmd, vmf->address);
1392 if (page)
1393 put_page(page);
1394 ret |= VM_FAULT_FALLBACK;
1395 count_vm_event(THP_FAULT_FALLBACK);
1396 goto out;
1397 }
1398
1399 count_vm_event(THP_FAULT_ALLOC);
1400 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1401
1402 if (!page)
1403 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1404 else
1405 copy_user_huge_page(new_page, page, vmf->address,
1406 vma, HPAGE_PMD_NR);
1407 __SetPageUptodate(new_page);
1408
1409 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1410 haddr, haddr + HPAGE_PMD_SIZE);
1411 mmu_notifier_invalidate_range_start(&range);
1412
1413 spin_lock(vmf->ptl);
1414 if (page)
1415 put_page(page);
1416 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1417 spin_unlock(vmf->ptl);
1418 mem_cgroup_cancel_charge(new_page, memcg, true);
1419 put_page(new_page);
1420 goto out_mn;
1421 } else {
1422 pmd_t entry;
1423 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1424 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1425 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1426 page_add_new_anon_rmap(new_page, vma, haddr, true);
1427 mem_cgroup_commit_charge(new_page, memcg, false, true);
1428 lru_cache_add_active_or_unevictable(new_page, vma);
1429 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1430 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1431 if (!page) {
1432 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1433 } else {
1434 VM_BUG_ON_PAGE(!PageHead(page), page);
1435 page_remove_rmap(page, true);
1436 put_page(page);
1437 }
1438 ret |= VM_FAULT_WRITE;
1439 }
1440 spin_unlock(vmf->ptl);
1441out_mn:
1442 /*
1443 * No need to double call mmu_notifier->invalidate_range() callback as
1444 * the above pmdp_huge_clear_flush_notify() did already call it.
1445 */
1446 mmu_notifier_invalidate_range_only_end(&range);
1447out:
1448 return ret;
1449out_unlock:
1450 spin_unlock(vmf->ptl);
1451 return ret;
1452}
1453
1454/*
1455 * FOLL_FORCE can write to even unwritable pmd's, but only
1456 * after we've gone through a COW cycle and they are dirty.
1457 */
1458static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1459{
1460 return pmd_write(pmd) ||
1461 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1462}
1463
1464struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1465 unsigned long addr,
1466 pmd_t *pmd,
1467 unsigned int flags)
1468{
1469 struct mm_struct *mm = vma->vm_mm;
1470 struct page *page = NULL;
1471
1472 assert_spin_locked(pmd_lockptr(mm, pmd));
1473
1474 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1475 goto out;
1476
1477 /* Avoid dumping huge zero page */
1478 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1479 return ERR_PTR(-EFAULT);
1480
1481 /* Full NUMA hinting faults to serialise migration in fault paths */
1482 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1483 goto out;
1484
1485 page = pmd_page(*pmd);
1486 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1487 if (flags & FOLL_TOUCH)
1488 touch_pmd(vma, addr, pmd, flags);
1489 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1490 /*
1491 * We don't mlock() pte-mapped THPs. This way we can avoid
1492 * leaking mlocked pages into non-VM_LOCKED VMAs.
1493 *
1494 * For anon THP:
1495 *
1496 * In most cases the pmd is the only mapping of the page as we
1497 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1498 * writable private mappings in populate_vma_page_range().
1499 *
1500 * The only scenario when we have the page shared here is if we
1501 * mlocking read-only mapping shared over fork(). We skip
1502 * mlocking such pages.
1503 *
1504 * For file THP:
1505 *
1506 * We can expect PageDoubleMap() to be stable under page lock:
1507 * for file pages we set it in page_add_file_rmap(), which
1508 * requires page to be locked.
1509 */
1510
1511 if (PageAnon(page) && compound_mapcount(page) != 1)
1512 goto skip_mlock;
1513 if (PageDoubleMap(page) || !page->mapping)
1514 goto skip_mlock;
1515 if (!trylock_page(page))
1516 goto skip_mlock;
1517 lru_add_drain();
1518 if (page->mapping && !PageDoubleMap(page))
1519 mlock_vma_page(page);
1520 unlock_page(page);
1521 }
1522skip_mlock:
1523 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1524 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1525 if (flags & FOLL_GET)
1526 get_page(page);
1527
1528out:
1529 return page;
1530}
1531
1532/* NUMA hinting page fault entry point for trans huge pmds */
1533vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1534{
1535 struct vm_area_struct *vma = vmf->vma;
1536 struct anon_vma *anon_vma = NULL;
1537 struct page *page;
1538 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1539 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1540 int target_nid, last_cpupid = -1;
1541 bool page_locked;
1542 bool migrated = false;
1543 bool was_writable;
1544 int flags = 0;
1545
1546 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1547 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1548 goto out_unlock;
1549
1550 /*
1551 * If there are potential migrations, wait for completion and retry
1552 * without disrupting NUMA hinting information. Do not relock and
1553 * check_same as the page may no longer be mapped.
1554 */
1555 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1556 page = pmd_page(*vmf->pmd);
1557 if (!get_page_unless_zero(page))
1558 goto out_unlock;
1559 spin_unlock(vmf->ptl);
1560 put_and_wait_on_page_locked(page);
1561 goto out;
1562 }
1563
1564 page = pmd_page(pmd);
1565 BUG_ON(is_huge_zero_page(page));
1566 page_nid = page_to_nid(page);
1567 last_cpupid = page_cpupid_last(page);
1568 count_vm_numa_event(NUMA_HINT_FAULTS);
1569 if (page_nid == this_nid) {
1570 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1571 flags |= TNF_FAULT_LOCAL;
1572 }
1573
1574 /* See similar comment in do_numa_page for explanation */
1575 if (!pmd_savedwrite(pmd))
1576 flags |= TNF_NO_GROUP;
1577
1578 /*
1579 * Acquire the page lock to serialise THP migrations but avoid dropping
1580 * page_table_lock if at all possible
1581 */
1582 page_locked = trylock_page(page);
1583 target_nid = mpol_misplaced(page, vma, haddr);
1584 if (target_nid == NUMA_NO_NODE) {
1585 /* If the page was locked, there are no parallel migrations */
1586 if (page_locked)
1587 goto clear_pmdnuma;
1588 }
1589
1590 /* Migration could have started since the pmd_trans_migrating check */
1591 if (!page_locked) {
1592 page_nid = NUMA_NO_NODE;
1593 if (!get_page_unless_zero(page))
1594 goto out_unlock;
1595 spin_unlock(vmf->ptl);
1596 put_and_wait_on_page_locked(page);
1597 goto out;
1598 }
1599
1600 /*
1601 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1602 * to serialises splits
1603 */
1604 get_page(page);
1605 spin_unlock(vmf->ptl);
1606 anon_vma = page_lock_anon_vma_read(page);
1607
1608 /* Confirm the PMD did not change while page_table_lock was released */
1609 spin_lock(vmf->ptl);
1610 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1611 unlock_page(page);
1612 put_page(page);
1613 page_nid = NUMA_NO_NODE;
1614 goto out_unlock;
1615 }
1616
1617 /* Bail if we fail to protect against THP splits for any reason */
1618 if (unlikely(!anon_vma)) {
1619 put_page(page);
1620 page_nid = NUMA_NO_NODE;
1621 goto clear_pmdnuma;
1622 }
1623
1624 /*
1625 * Since we took the NUMA fault, we must have observed the !accessible
1626 * bit. Make sure all other CPUs agree with that, to avoid them
1627 * modifying the page we're about to migrate.
1628 *
1629 * Must be done under PTL such that we'll observe the relevant
1630 * inc_tlb_flush_pending().
1631 *
1632 * We are not sure a pending tlb flush here is for a huge page
1633 * mapping or not. Hence use the tlb range variant
1634 */
1635 if (mm_tlb_flush_pending(vma->vm_mm)) {
1636 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1637 /*
1638 * change_huge_pmd() released the pmd lock before
1639 * invalidating the secondary MMUs sharing the primary
1640 * MMU pagetables (with ->invalidate_range()). The
1641 * mmu_notifier_invalidate_range_end() (which
1642 * internally calls ->invalidate_range()) in
1643 * change_pmd_range() will run after us, so we can't
1644 * rely on it here and we need an explicit invalidate.
1645 */
1646 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1647 haddr + HPAGE_PMD_SIZE);
1648 }
1649
1650 /*
1651 * Migrate the THP to the requested node, returns with page unlocked
1652 * and access rights restored.
1653 */
1654 spin_unlock(vmf->ptl);
1655
1656 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1657 vmf->pmd, pmd, vmf->address, page, target_nid);
1658 if (migrated) {
1659 flags |= TNF_MIGRATED;
1660 page_nid = target_nid;
1661 } else
1662 flags |= TNF_MIGRATE_FAIL;
1663
1664 goto out;
1665clear_pmdnuma:
1666 BUG_ON(!PageLocked(page));
1667 was_writable = pmd_savedwrite(pmd);
1668 pmd = pmd_modify(pmd, vma->vm_page_prot);
1669 pmd = pmd_mkyoung(pmd);
1670 if (was_writable)
1671 pmd = pmd_mkwrite(pmd);
1672 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1673 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1674 unlock_page(page);
1675out_unlock:
1676 spin_unlock(vmf->ptl);
1677
1678out:
1679 if (anon_vma)
1680 page_unlock_anon_vma_read(anon_vma);
1681
1682 if (page_nid != NUMA_NO_NODE)
1683 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1684 flags);
1685
1686 return 0;
1687}
1688
1689/*
1690 * Return true if we do MADV_FREE successfully on entire pmd page.
1691 * Otherwise, return false.
1692 */
1693bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1694 pmd_t *pmd, unsigned long addr, unsigned long next)
1695{
1696 spinlock_t *ptl;
1697 pmd_t orig_pmd;
1698 struct page *page;
1699 struct mm_struct *mm = tlb->mm;
1700 bool ret = false;
1701
1702 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1703
1704 ptl = pmd_trans_huge_lock(pmd, vma);
1705 if (!ptl)
1706 goto out_unlocked;
1707
1708 orig_pmd = *pmd;
1709 if (is_huge_zero_pmd(orig_pmd))
1710 goto out;
1711
1712 if (unlikely(!pmd_present(orig_pmd))) {
1713 VM_BUG_ON(thp_migration_supported() &&
1714 !is_pmd_migration_entry(orig_pmd));
1715 goto out;
1716 }
1717
1718 page = pmd_page(orig_pmd);
1719 /*
1720 * If other processes are mapping this page, we couldn't discard
1721 * the page unless they all do MADV_FREE so let's skip the page.
1722 */
1723 if (page_mapcount(page) != 1)
1724 goto out;
1725
1726 if (!trylock_page(page))
1727 goto out;
1728
1729 /*
1730 * If user want to discard part-pages of THP, split it so MADV_FREE
1731 * will deactivate only them.
1732 */
1733 if (next - addr != HPAGE_PMD_SIZE) {
1734 get_page(page);
1735 spin_unlock(ptl);
1736 split_huge_page(page);
1737 unlock_page(page);
1738 put_page(page);
1739 goto out_unlocked;
1740 }
1741
1742 if (PageDirty(page))
1743 ClearPageDirty(page);
1744 unlock_page(page);
1745
1746 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1747 pmdp_invalidate(vma, addr, pmd);
1748 orig_pmd = pmd_mkold(orig_pmd);
1749 orig_pmd = pmd_mkclean(orig_pmd);
1750
1751 set_pmd_at(mm, addr, pmd, orig_pmd);
1752 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1753 }
1754
1755 mark_page_lazyfree(page);
1756 ret = true;
1757out:
1758 spin_unlock(ptl);
1759out_unlocked:
1760 return ret;
1761}
1762
1763static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1764{
1765 pgtable_t pgtable;
1766
1767 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1768 pte_free(mm, pgtable);
1769 mm_dec_nr_ptes(mm);
1770}
1771
1772int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1773 pmd_t *pmd, unsigned long addr)
1774{
1775 pmd_t orig_pmd;
1776 spinlock_t *ptl;
1777
1778 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1779
1780 ptl = __pmd_trans_huge_lock(pmd, vma);
1781 if (!ptl)
1782 return 0;
1783 /*
1784 * For architectures like ppc64 we look at deposited pgtable
1785 * when calling pmdp_huge_get_and_clear. So do the
1786 * pgtable_trans_huge_withdraw after finishing pmdp related
1787 * operations.
1788 */
1789 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1790 tlb->fullmm);
1791 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1792 if (vma_is_dax(vma)) {
1793 if (arch_needs_pgtable_deposit())
1794 zap_deposited_table(tlb->mm, pmd);
1795 spin_unlock(ptl);
1796 if (is_huge_zero_pmd(orig_pmd))
1797 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1798 } else if (is_huge_zero_pmd(orig_pmd)) {
1799 zap_deposited_table(tlb->mm, pmd);
1800 spin_unlock(ptl);
1801 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1802 } else {
1803 struct page *page = NULL;
1804 int flush_needed = 1;
1805
1806 if (pmd_present(orig_pmd)) {
1807 page = pmd_page(orig_pmd);
1808 page_remove_rmap(page, true);
1809 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1810 VM_BUG_ON_PAGE(!PageHead(page), page);
1811 } else if (thp_migration_supported()) {
1812 swp_entry_t entry;
1813
1814 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1815 entry = pmd_to_swp_entry(orig_pmd);
1816 page = pfn_to_page(swp_offset(entry));
1817 flush_needed = 0;
1818 } else
1819 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1820
1821 if (PageAnon(page)) {
1822 zap_deposited_table(tlb->mm, pmd);
1823 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1824 } else {
1825 if (arch_needs_pgtable_deposit())
1826 zap_deposited_table(tlb->mm, pmd);
1827 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1828 }
1829
1830 spin_unlock(ptl);
1831 if (flush_needed)
1832 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1833 }
1834 return 1;
1835}
1836
1837#ifndef pmd_move_must_withdraw
1838static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1839 spinlock_t *old_pmd_ptl,
1840 struct vm_area_struct *vma)
1841{
1842 /*
1843 * With split pmd lock we also need to move preallocated
1844 * PTE page table if new_pmd is on different PMD page table.
1845 *
1846 * We also don't deposit and withdraw tables for file pages.
1847 */
1848 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1849}
1850#endif
1851
1852static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1853{
1854#ifdef CONFIG_MEM_SOFT_DIRTY
1855 if (unlikely(is_pmd_migration_entry(pmd)))
1856 pmd = pmd_swp_mksoft_dirty(pmd);
1857 else if (pmd_present(pmd))
1858 pmd = pmd_mksoft_dirty(pmd);
1859#endif
1860 return pmd;
1861}
1862
1863bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1864 unsigned long new_addr, unsigned long old_end,
1865 pmd_t *old_pmd, pmd_t *new_pmd)
1866{
1867 spinlock_t *old_ptl, *new_ptl;
1868 pmd_t pmd;
1869 struct mm_struct *mm = vma->vm_mm;
1870 bool force_flush = false;
1871
1872 if ((old_addr & ~HPAGE_PMD_MASK) ||
1873 (new_addr & ~HPAGE_PMD_MASK) ||
1874 old_end - old_addr < HPAGE_PMD_SIZE)
1875 return false;
1876
1877 /*
1878 * The destination pmd shouldn't be established, free_pgtables()
1879 * should have release it.
1880 */
1881 if (WARN_ON(!pmd_none(*new_pmd))) {
1882 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1883 return false;
1884 }
1885
1886 /*
1887 * We don't have to worry about the ordering of src and dst
1888 * ptlocks because exclusive mmap_sem prevents deadlock.
1889 */
1890 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1891 if (old_ptl) {
1892 new_ptl = pmd_lockptr(mm, new_pmd);
1893 if (new_ptl != old_ptl)
1894 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1895 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1896 if (pmd_present(pmd))
1897 force_flush = true;
1898 VM_BUG_ON(!pmd_none(*new_pmd));
1899
1900 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1901 pgtable_t pgtable;
1902 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1903 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1904 }
1905 pmd = move_soft_dirty_pmd(pmd);
1906 set_pmd_at(mm, new_addr, new_pmd, pmd);
1907 if (force_flush)
1908 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1909 if (new_ptl != old_ptl)
1910 spin_unlock(new_ptl);
1911 spin_unlock(old_ptl);
1912 return true;
1913 }
1914 return false;
1915}
1916
1917/*
1918 * Returns
1919 * - 0 if PMD could not be locked
1920 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1921 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1922 */
1923int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1924 unsigned long addr, pgprot_t newprot, int prot_numa)
1925{
1926 struct mm_struct *mm = vma->vm_mm;
1927 spinlock_t *ptl;
1928 pmd_t entry;
1929 bool preserve_write;
1930 int ret;
1931
1932 ptl = __pmd_trans_huge_lock(pmd, vma);
1933 if (!ptl)
1934 return 0;
1935
1936 preserve_write = prot_numa && pmd_write(*pmd);
1937 ret = 1;
1938
1939#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1940 if (is_swap_pmd(*pmd)) {
1941 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1942
1943 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1944 if (is_write_migration_entry(entry)) {
1945 pmd_t newpmd;
1946 /*
1947 * A protection check is difficult so
1948 * just be safe and disable write
1949 */
1950 make_migration_entry_read(&entry);
1951 newpmd = swp_entry_to_pmd(entry);
1952 if (pmd_swp_soft_dirty(*pmd))
1953 newpmd = pmd_swp_mksoft_dirty(newpmd);
1954 set_pmd_at(mm, addr, pmd, newpmd);
1955 }
1956 goto unlock;
1957 }
1958#endif
1959
1960 /*
1961 * Avoid trapping faults against the zero page. The read-only
1962 * data is likely to be read-cached on the local CPU and
1963 * local/remote hits to the zero page are not interesting.
1964 */
1965 if (prot_numa && is_huge_zero_pmd(*pmd))
1966 goto unlock;
1967
1968 if (prot_numa && pmd_protnone(*pmd))
1969 goto unlock;
1970
1971 /*
1972 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1973 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1974 * which is also under down_read(mmap_sem):
1975 *
1976 * CPU0: CPU1:
1977 * change_huge_pmd(prot_numa=1)
1978 * pmdp_huge_get_and_clear_notify()
1979 * madvise_dontneed()
1980 * zap_pmd_range()
1981 * pmd_trans_huge(*pmd) == 0 (without ptl)
1982 * // skip the pmd
1983 * set_pmd_at();
1984 * // pmd is re-established
1985 *
1986 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1987 * which may break userspace.
1988 *
1989 * pmdp_invalidate() is required to make sure we don't miss
1990 * dirty/young flags set by hardware.
1991 */
1992 entry = pmdp_invalidate(vma, addr, pmd);
1993
1994 entry = pmd_modify(entry, newprot);
1995 if (preserve_write)
1996 entry = pmd_mk_savedwrite(entry);
1997 ret = HPAGE_PMD_NR;
1998 set_pmd_at(mm, addr, pmd, entry);
1999 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
2000unlock:
2001 spin_unlock(ptl);
2002 return ret;
2003}
2004
2005/*
2006 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2007 *
2008 * Note that if it returns page table lock pointer, this routine returns without
2009 * unlocking page table lock. So callers must unlock it.
2010 */
2011spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2012{
2013 spinlock_t *ptl;
2014 ptl = pmd_lock(vma->vm_mm, pmd);
2015 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2016 pmd_devmap(*pmd)))
2017 return ptl;
2018 spin_unlock(ptl);
2019 return NULL;
2020}
2021
2022/*
2023 * Returns true if a given pud maps a thp, false otherwise.
2024 *
2025 * Note that if it returns true, this routine returns without unlocking page
2026 * table lock. So callers must unlock it.
2027 */
2028spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2029{
2030 spinlock_t *ptl;
2031
2032 ptl = pud_lock(vma->vm_mm, pud);
2033 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2034 return ptl;
2035 spin_unlock(ptl);
2036 return NULL;
2037}
2038
2039#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2040int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2041 pud_t *pud, unsigned long addr)
2042{
2043 spinlock_t *ptl;
2044
2045 ptl = __pud_trans_huge_lock(pud, vma);
2046 if (!ptl)
2047 return 0;
2048 /*
2049 * For architectures like ppc64 we look at deposited pgtable
2050 * when calling pudp_huge_get_and_clear. So do the
2051 * pgtable_trans_huge_withdraw after finishing pudp related
2052 * operations.
2053 */
2054 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2055 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2056 if (vma_is_dax(vma)) {
2057 spin_unlock(ptl);
2058 /* No zero page support yet */
2059 } else {
2060 /* No support for anonymous PUD pages yet */
2061 BUG();
2062 }
2063 return 1;
2064}
2065
2066static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2067 unsigned long haddr)
2068{
2069 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2070 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2071 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2072 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2073
2074 count_vm_event(THP_SPLIT_PUD);
2075
2076 pudp_huge_clear_flush_notify(vma, haddr, pud);
2077}
2078
2079void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2080 unsigned long address)
2081{
2082 spinlock_t *ptl;
2083 struct mmu_notifier_range range;
2084
2085 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2086 address & HPAGE_PUD_MASK,
2087 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2088 mmu_notifier_invalidate_range_start(&range);
2089 ptl = pud_lock(vma->vm_mm, pud);
2090 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2091 goto out;
2092 __split_huge_pud_locked(vma, pud, range.start);
2093
2094out:
2095 spin_unlock(ptl);
2096 /*
2097 * No need to double call mmu_notifier->invalidate_range() callback as
2098 * the above pudp_huge_clear_flush_notify() did already call it.
2099 */
2100 mmu_notifier_invalidate_range_only_end(&range);
2101}
2102#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2103
2104static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2105 unsigned long haddr, pmd_t *pmd)
2106{
2107 struct mm_struct *mm = vma->vm_mm;
2108 pgtable_t pgtable;
2109 pmd_t _pmd;
2110 int i;
2111
2112 /*
2113 * Leave pmd empty until pte is filled note that it is fine to delay
2114 * notification until mmu_notifier_invalidate_range_end() as we are
2115 * replacing a zero pmd write protected page with a zero pte write
2116 * protected page.
2117 *
2118 * See Documentation/vm/mmu_notifier.rst
2119 */
2120 pmdp_huge_clear_flush(vma, haddr, pmd);
2121
2122 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2123 pmd_populate(mm, &_pmd, pgtable);
2124
2125 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2126 pte_t *pte, entry;
2127 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2128 entry = pte_mkspecial(entry);
2129 pte = pte_offset_map(&_pmd, haddr);
2130 VM_BUG_ON(!pte_none(*pte));
2131 set_pte_at(mm, haddr, pte, entry);
2132 pte_unmap(pte);
2133 }
2134 smp_wmb(); /* make pte visible before pmd */
2135 pmd_populate(mm, pmd, pgtable);
2136}
2137
2138static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2139 unsigned long haddr, bool freeze)
2140{
2141 struct mm_struct *mm = vma->vm_mm;
2142 struct page *page;
2143 pgtable_t pgtable;
2144 pmd_t old_pmd, _pmd;
2145 bool young, write, soft_dirty, pmd_migration = false;
2146 unsigned long addr;
2147 int i;
2148
2149 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2150 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2151 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2152 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2153 && !pmd_devmap(*pmd));
2154
2155 count_vm_event(THP_SPLIT_PMD);
2156
2157 if (!vma_is_anonymous(vma)) {
2158 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2159 /*
2160 * We are going to unmap this huge page. So
2161 * just go ahead and zap it
2162 */
2163 if (arch_needs_pgtable_deposit())
2164 zap_deposited_table(mm, pmd);
2165 if (vma_is_dax(vma))
2166 return;
2167 page = pmd_page(_pmd);
2168 if (!PageDirty(page) && pmd_dirty(_pmd))
2169 set_page_dirty(page);
2170 if (!PageReferenced(page) && pmd_young(_pmd))
2171 SetPageReferenced(page);
2172 page_remove_rmap(page, true);
2173 put_page(page);
2174 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2175 return;
2176 } else if (is_huge_zero_pmd(*pmd)) {
2177 /*
2178 * FIXME: Do we want to invalidate secondary mmu by calling
2179 * mmu_notifier_invalidate_range() see comments below inside
2180 * __split_huge_pmd() ?
2181 *
2182 * We are going from a zero huge page write protected to zero
2183 * small page also write protected so it does not seems useful
2184 * to invalidate secondary mmu at this time.
2185 */
2186 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2187 }
2188
2189 /*
2190 * Up to this point the pmd is present and huge and userland has the
2191 * whole access to the hugepage during the split (which happens in
2192 * place). If we overwrite the pmd with the not-huge version pointing
2193 * to the pte here (which of course we could if all CPUs were bug
2194 * free), userland could trigger a small page size TLB miss on the
2195 * small sized TLB while the hugepage TLB entry is still established in
2196 * the huge TLB. Some CPU doesn't like that.
2197 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2198 * 383 on page 93. Intel should be safe but is also warns that it's
2199 * only safe if the permission and cache attributes of the two entries
2200 * loaded in the two TLB is identical (which should be the case here).
2201 * But it is generally safer to never allow small and huge TLB entries
2202 * for the same virtual address to be loaded simultaneously. So instead
2203 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2204 * current pmd notpresent (atomically because here the pmd_trans_huge
2205 * must remain set at all times on the pmd until the split is complete
2206 * for this pmd), then we flush the SMP TLB and finally we write the
2207 * non-huge version of the pmd entry with pmd_populate.
2208 */
2209 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2210
2211 pmd_migration = is_pmd_migration_entry(old_pmd);
2212 if (unlikely(pmd_migration)) {
2213 swp_entry_t entry;
2214
2215 entry = pmd_to_swp_entry(old_pmd);
2216 page = pfn_to_page(swp_offset(entry));
2217 write = is_write_migration_entry(entry);
2218 young = false;
2219 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2220 } else {
2221 page = pmd_page(old_pmd);
2222 if (pmd_dirty(old_pmd))
2223 SetPageDirty(page);
2224 write = pmd_write(old_pmd);
2225 young = pmd_young(old_pmd);
2226 soft_dirty = pmd_soft_dirty(old_pmd);
2227 }
2228 VM_BUG_ON_PAGE(!page_count(page), page);
2229 page_ref_add(page, HPAGE_PMD_NR - 1);
2230
2231 /*
2232 * Withdraw the table only after we mark the pmd entry invalid.
2233 * This's critical for some architectures (Power).
2234 */
2235 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2236 pmd_populate(mm, &_pmd, pgtable);
2237
2238 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2239 pte_t entry, *pte;
2240 /*
2241 * Note that NUMA hinting access restrictions are not
2242 * transferred to avoid any possibility of altering
2243 * permissions across VMAs.
2244 */
2245 if (freeze || pmd_migration) {
2246 swp_entry_t swp_entry;
2247 swp_entry = make_migration_entry(page + i, write);
2248 entry = swp_entry_to_pte(swp_entry);
2249 if (soft_dirty)
2250 entry = pte_swp_mksoft_dirty(entry);
2251 } else {
2252 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2253 entry = maybe_mkwrite(entry, vma);
2254 if (!write)
2255 entry = pte_wrprotect(entry);
2256 if (!young)
2257 entry = pte_mkold(entry);
2258 if (soft_dirty)
2259 entry = pte_mksoft_dirty(entry);
2260 }
2261 pte = pte_offset_map(&_pmd, addr);
2262 BUG_ON(!pte_none(*pte));
2263 set_pte_at(mm, addr, pte, entry);
2264 atomic_inc(&page[i]._mapcount);
2265 pte_unmap(pte);
2266 }
2267
2268 /*
2269 * Set PG_double_map before dropping compound_mapcount to avoid
2270 * false-negative page_mapped().
2271 */
2272 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2273 for (i = 0; i < HPAGE_PMD_NR; i++)
2274 atomic_inc(&page[i]._mapcount);
2275 }
2276
2277 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2278 /* Last compound_mapcount is gone. */
2279 __dec_node_page_state(page, NR_ANON_THPS);
2280 if (TestClearPageDoubleMap(page)) {
2281 /* No need in mapcount reference anymore */
2282 for (i = 0; i < HPAGE_PMD_NR; i++)
2283 atomic_dec(&page[i]._mapcount);
2284 }
2285 }
2286
2287 smp_wmb(); /* make pte visible before pmd */
2288 pmd_populate(mm, pmd, pgtable);
2289
2290 if (freeze) {
2291 for (i = 0; i < HPAGE_PMD_NR; i++) {
2292 page_remove_rmap(page + i, false);
2293 put_page(page + i);
2294 }
2295 }
2296}
2297
2298void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2299 unsigned long address, bool freeze, struct page *page)
2300{
2301 spinlock_t *ptl;
2302 struct mmu_notifier_range range;
2303
2304 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2305 address & HPAGE_PMD_MASK,
2306 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2307 mmu_notifier_invalidate_range_start(&range);
2308 ptl = pmd_lock(vma->vm_mm, pmd);
2309
2310 /*
2311 * If caller asks to setup a migration entries, we need a page to check
2312 * pmd against. Otherwise we can end up replacing wrong page.
2313 */
2314 VM_BUG_ON(freeze && !page);
2315 if (page && page != pmd_page(*pmd))
2316 goto out;
2317
2318 if (pmd_trans_huge(*pmd)) {
2319 page = pmd_page(*pmd);
2320 if (PageMlocked(page))
2321 clear_page_mlock(page);
2322 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2323 goto out;
2324 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2325out:
2326 spin_unlock(ptl);
2327 /*
2328 * No need to double call mmu_notifier->invalidate_range() callback.
2329 * They are 3 cases to consider inside __split_huge_pmd_locked():
2330 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2331 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2332 * fault will trigger a flush_notify before pointing to a new page
2333 * (it is fine if the secondary mmu keeps pointing to the old zero
2334 * page in the meantime)
2335 * 3) Split a huge pmd into pte pointing to the same page. No need
2336 * to invalidate secondary tlb entry they are all still valid.
2337 * any further changes to individual pte will notify. So no need
2338 * to call mmu_notifier->invalidate_range()
2339 */
2340 mmu_notifier_invalidate_range_only_end(&range);
2341}
2342
2343void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2344 bool freeze, struct page *page)
2345{
2346 pgd_t *pgd;
2347 p4d_t *p4d;
2348 pud_t *pud;
2349 pmd_t *pmd;
2350
2351 pgd = pgd_offset(vma->vm_mm, address);
2352 if (!pgd_present(*pgd))
2353 return;
2354
2355 p4d = p4d_offset(pgd, address);
2356 if (!p4d_present(*p4d))
2357 return;
2358
2359 pud = pud_offset(p4d, address);
2360 if (!pud_present(*pud))
2361 return;
2362
2363 pmd = pmd_offset(pud, address);
2364
2365 __split_huge_pmd(vma, pmd, address, freeze, page);
2366}
2367
2368void vma_adjust_trans_huge(struct vm_area_struct *vma,
2369 unsigned long start,
2370 unsigned long end,
2371 long adjust_next)
2372{
2373 /*
2374 * If the new start address isn't hpage aligned and it could
2375 * previously contain an hugepage: check if we need to split
2376 * an huge pmd.
2377 */
2378 if (start & ~HPAGE_PMD_MASK &&
2379 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2380 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2381 split_huge_pmd_address(vma, start, false, NULL);
2382
2383 /*
2384 * If the new end address isn't hpage aligned and it could
2385 * previously contain an hugepage: check if we need to split
2386 * an huge pmd.
2387 */
2388 if (end & ~HPAGE_PMD_MASK &&
2389 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2390 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2391 split_huge_pmd_address(vma, end, false, NULL);
2392
2393 /*
2394 * If we're also updating the vma->vm_next->vm_start, if the new
2395 * vm_next->vm_start isn't page aligned and it could previously
2396 * contain an hugepage: check if we need to split an huge pmd.
2397 */
2398 if (adjust_next > 0) {
2399 struct vm_area_struct *next = vma->vm_next;
2400 unsigned long nstart = next->vm_start;
2401 nstart += adjust_next << PAGE_SHIFT;
2402 if (nstart & ~HPAGE_PMD_MASK &&
2403 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2404 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2405 split_huge_pmd_address(next, nstart, false, NULL);
2406 }
2407}
2408
2409static void unmap_page(struct page *page)
2410{
2411 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2412 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2413 bool unmap_success;
2414
2415 VM_BUG_ON_PAGE(!PageHead(page), page);
2416
2417 if (PageAnon(page))
2418 ttu_flags |= TTU_SPLIT_FREEZE;
2419
2420 unmap_success = try_to_unmap(page, ttu_flags);
2421 VM_BUG_ON_PAGE(!unmap_success, page);
2422}
2423
2424static void remap_page(struct page *page)
2425{
2426 int i;
2427 if (PageTransHuge(page)) {
2428 remove_migration_ptes(page, page, true);
2429 } else {
2430 for (i = 0; i < HPAGE_PMD_NR; i++)
2431 remove_migration_ptes(page + i, page + i, true);
2432 }
2433}
2434
2435static void __split_huge_page_tail(struct page *head, int tail,
2436 struct lruvec *lruvec, struct list_head *list)
2437{
2438 struct page *page_tail = head + tail;
2439
2440 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2441
2442 /*
2443 * Clone page flags before unfreezing refcount.
2444 *
2445 * After successful get_page_unless_zero() might follow flags change,
2446 * for exmaple lock_page() which set PG_waiters.
2447 */
2448 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2449 page_tail->flags |= (head->flags &
2450 ((1L << PG_referenced) |
2451 (1L << PG_swapbacked) |
2452 (1L << PG_swapcache) |
2453 (1L << PG_mlocked) |
2454 (1L << PG_uptodate) |
2455 (1L << PG_active) |
2456 (1L << PG_workingset) |
2457 (1L << PG_locked) |
2458 (1L << PG_unevictable) |
2459 (1L << PG_dirty)));
2460
2461 /* ->mapping in first tail page is compound_mapcount */
2462 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2463 page_tail);
2464 page_tail->mapping = head->mapping;
2465 page_tail->index = head->index + tail;
2466
2467 /* Page flags must be visible before we make the page non-compound. */
2468 smp_wmb();
2469
2470 /*
2471 * Clear PageTail before unfreezing page refcount.
2472 *
2473 * After successful get_page_unless_zero() might follow put_page()
2474 * which needs correct compound_head().
2475 */
2476 clear_compound_head(page_tail);
2477
2478 /* Finally unfreeze refcount. Additional reference from page cache. */
2479 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2480 PageSwapCache(head)));
2481
2482 if (page_is_young(head))
2483 set_page_young(page_tail);
2484 if (page_is_idle(head))
2485 set_page_idle(page_tail);
2486
2487 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2488
2489 /*
2490 * always add to the tail because some iterators expect new
2491 * pages to show after the currently processed elements - e.g.
2492 * migrate_pages
2493 */
2494 lru_add_page_tail(head, page_tail, lruvec, list);
2495}
2496
2497static void __split_huge_page(struct page *page, struct list_head *list,
2498 pgoff_t end, unsigned long flags)
2499{
2500 struct page *head = compound_head(page);
2501 pg_data_t *pgdat = page_pgdat(head);
2502 struct lruvec *lruvec;
2503 struct address_space *swap_cache = NULL;
2504 unsigned long offset = 0;
2505 int i;
2506
2507 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2508
2509 /* complete memcg works before add pages to LRU */
2510 mem_cgroup_split_huge_fixup(head);
2511
2512 if (PageAnon(head) && PageSwapCache(head)) {
2513 swp_entry_t entry = { .val = page_private(head) };
2514
2515 offset = swp_offset(entry);
2516 swap_cache = swap_address_space(entry);
2517 xa_lock(&swap_cache->i_pages);
2518 }
2519
2520 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2521 __split_huge_page_tail(head, i, lruvec, list);
2522 /* Some pages can be beyond i_size: drop them from page cache */
2523 if (head[i].index >= end) {
2524 ClearPageDirty(head + i);
2525 __delete_from_page_cache(head + i, NULL);
2526 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2527 shmem_uncharge(head->mapping->host, 1);
2528 put_page(head + i);
2529 } else if (!PageAnon(page)) {
2530 __xa_store(&head->mapping->i_pages, head[i].index,
2531 head + i, 0);
2532 } else if (swap_cache) {
2533 __xa_store(&swap_cache->i_pages, offset + i,
2534 head + i, 0);
2535 }
2536 }
2537
2538 ClearPageCompound(head);
2539
2540 split_page_owner(head, HPAGE_PMD_ORDER);
2541
2542 /* See comment in __split_huge_page_tail() */
2543 if (PageAnon(head)) {
2544 /* Additional pin to swap cache */
2545 if (PageSwapCache(head)) {
2546 page_ref_add(head, 2);
2547 xa_unlock(&swap_cache->i_pages);
2548 } else {
2549 page_ref_inc(head);
2550 }
2551 } else {
2552 /* Additional pin to page cache */
2553 page_ref_add(head, 2);
2554 xa_unlock(&head->mapping->i_pages);
2555 }
2556
2557 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2558
2559 remap_page(head);
2560
2561 for (i = 0; i < HPAGE_PMD_NR; i++) {
2562 struct page *subpage = head + i;
2563 if (subpage == page)
2564 continue;
2565 unlock_page(subpage);
2566
2567 /*
2568 * Subpages may be freed if there wasn't any mapping
2569 * like if add_to_swap() is running on a lru page that
2570 * had its mapping zapped. And freeing these pages
2571 * requires taking the lru_lock so we do the put_page
2572 * of the tail pages after the split is complete.
2573 */
2574 put_page(subpage);
2575 }
2576}
2577
2578int total_mapcount(struct page *page)
2579{
2580 int i, compound, ret;
2581
2582 VM_BUG_ON_PAGE(PageTail(page), page);
2583
2584 if (likely(!PageCompound(page)))
2585 return atomic_read(&page->_mapcount) + 1;
2586
2587 compound = compound_mapcount(page);
2588 if (PageHuge(page))
2589 return compound;
2590 ret = compound;
2591 for (i = 0; i < HPAGE_PMD_NR; i++)
2592 ret += atomic_read(&page[i]._mapcount) + 1;
2593 /* File pages has compound_mapcount included in _mapcount */
2594 if (!PageAnon(page))
2595 return ret - compound * HPAGE_PMD_NR;
2596 if (PageDoubleMap(page))
2597 ret -= HPAGE_PMD_NR;
2598 return ret;
2599}
2600
2601/*
2602 * This calculates accurately how many mappings a transparent hugepage
2603 * has (unlike page_mapcount() which isn't fully accurate). This full
2604 * accuracy is primarily needed to know if copy-on-write faults can
2605 * reuse the page and change the mapping to read-write instead of
2606 * copying them. At the same time this returns the total_mapcount too.
2607 *
2608 * The function returns the highest mapcount any one of the subpages
2609 * has. If the return value is one, even if different processes are
2610 * mapping different subpages of the transparent hugepage, they can
2611 * all reuse it, because each process is reusing a different subpage.
2612 *
2613 * The total_mapcount is instead counting all virtual mappings of the
2614 * subpages. If the total_mapcount is equal to "one", it tells the
2615 * caller all mappings belong to the same "mm" and in turn the
2616 * anon_vma of the transparent hugepage can become the vma->anon_vma
2617 * local one as no other process may be mapping any of the subpages.
2618 *
2619 * It would be more accurate to replace page_mapcount() with
2620 * page_trans_huge_mapcount(), however we only use
2621 * page_trans_huge_mapcount() in the copy-on-write faults where we
2622 * need full accuracy to avoid breaking page pinning, because
2623 * page_trans_huge_mapcount() is slower than page_mapcount().
2624 */
2625int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2626{
2627 int i, ret, _total_mapcount, mapcount;
2628
2629 /* hugetlbfs shouldn't call it */
2630 VM_BUG_ON_PAGE(PageHuge(page), page);
2631
2632 if (likely(!PageTransCompound(page))) {
2633 mapcount = atomic_read(&page->_mapcount) + 1;
2634 if (total_mapcount)
2635 *total_mapcount = mapcount;
2636 return mapcount;
2637 }
2638
2639 page = compound_head(page);
2640
2641 _total_mapcount = ret = 0;
2642 for (i = 0; i < HPAGE_PMD_NR; i++) {
2643 mapcount = atomic_read(&page[i]._mapcount) + 1;
2644 ret = max(ret, mapcount);
2645 _total_mapcount += mapcount;
2646 }
2647 if (PageDoubleMap(page)) {
2648 ret -= 1;
2649 _total_mapcount -= HPAGE_PMD_NR;
2650 }
2651 mapcount = compound_mapcount(page);
2652 ret += mapcount;
2653 _total_mapcount += mapcount;
2654 if (total_mapcount)
2655 *total_mapcount = _total_mapcount;
2656 return ret;
2657}
2658
2659/* Racy check whether the huge page can be split */
2660bool can_split_huge_page(struct page *page, int *pextra_pins)
2661{
2662 int extra_pins;
2663
2664 /* Additional pins from page cache */
2665 if (PageAnon(page))
2666 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2667 else
2668 extra_pins = HPAGE_PMD_NR;
2669 if (pextra_pins)
2670 *pextra_pins = extra_pins;
2671 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2672}
2673
2674/*
2675 * This function splits huge page into normal pages. @page can point to any
2676 * subpage of huge page to split. Split doesn't change the position of @page.
2677 *
2678 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2679 * The huge page must be locked.
2680 *
2681 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2682 *
2683 * Both head page and tail pages will inherit mapping, flags, and so on from
2684 * the hugepage.
2685 *
2686 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2687 * they are not mapped.
2688 *
2689 * Returns 0 if the hugepage is split successfully.
2690 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2691 * us.
2692 */
2693int split_huge_page_to_list(struct page *page, struct list_head *list)
2694{
2695 struct page *head = compound_head(page);
2696 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2697 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2698 struct anon_vma *anon_vma = NULL;
2699 struct address_space *mapping = NULL;
2700 int count, mapcount, extra_pins, ret;
2701 bool mlocked;
2702 unsigned long flags;
2703 pgoff_t end;
2704
2705 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2706 VM_BUG_ON_PAGE(!PageLocked(page), page);
2707 VM_BUG_ON_PAGE(!PageCompound(page), page);
2708
2709 if (PageWriteback(page))
2710 return -EBUSY;
2711
2712 if (PageAnon(head)) {
2713 /*
2714 * The caller does not necessarily hold an mmap_sem that would
2715 * prevent the anon_vma disappearing so we first we take a
2716 * reference to it and then lock the anon_vma for write. This
2717 * is similar to page_lock_anon_vma_read except the write lock
2718 * is taken to serialise against parallel split or collapse
2719 * operations.
2720 */
2721 anon_vma = page_get_anon_vma(head);
2722 if (!anon_vma) {
2723 ret = -EBUSY;
2724 goto out;
2725 }
2726 end = -1;
2727 mapping = NULL;
2728 anon_vma_lock_write(anon_vma);
2729 } else {
2730 mapping = head->mapping;
2731
2732 /* Truncated ? */
2733 if (!mapping) {
2734 ret = -EBUSY;
2735 goto out;
2736 }
2737
2738 anon_vma = NULL;
2739 i_mmap_lock_read(mapping);
2740
2741 /*
2742 *__split_huge_page() may need to trim off pages beyond EOF:
2743 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2744 * which cannot be nested inside the page tree lock. So note
2745 * end now: i_size itself may be changed at any moment, but
2746 * head page lock is good enough to serialize the trimming.
2747 */
2748 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2749 }
2750
2751 /*
2752 * Racy check if we can split the page, before unmap_page() will
2753 * split PMDs
2754 */
2755 if (!can_split_huge_page(head, &extra_pins)) {
2756 ret = -EBUSY;
2757 goto out_unlock;
2758 }
2759
2760 mlocked = PageMlocked(page);
2761 unmap_page(head);
2762 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2763
2764 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2765 if (mlocked)
2766 lru_add_drain();
2767
2768 /* prevent PageLRU to go away from under us, and freeze lru stats */
2769 spin_lock_irqsave(&pgdata->lru_lock, flags);
2770
2771 if (mapping) {
2772 XA_STATE(xas, &mapping->i_pages, page_index(head));
2773
2774 /*
2775 * Check if the head page is present in page cache.
2776 * We assume all tail are present too, if head is there.
2777 */
2778 xa_lock(&mapping->i_pages);
2779 if (xas_load(&xas) != head)
2780 goto fail;
2781 }
2782
2783 /* Prevent deferred_split_scan() touching ->_refcount */
2784 spin_lock(&ds_queue->split_queue_lock);
2785 count = page_count(head);
2786 mapcount = total_mapcount(head);
2787 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2788 if (!list_empty(page_deferred_list(head))) {
2789 ds_queue->split_queue_len--;
2790 list_del(page_deferred_list(head));
2791 }
2792 if (mapping) {
2793 if (PageSwapBacked(page))
2794 __dec_node_page_state(page, NR_SHMEM_THPS);
2795 else
2796 __dec_node_page_state(page, NR_FILE_THPS);
2797 }
2798
2799 spin_unlock(&ds_queue->split_queue_lock);
2800 __split_huge_page(page, list, end, flags);
2801 if (PageSwapCache(head)) {
2802 swp_entry_t entry = { .val = page_private(head) };
2803
2804 ret = split_swap_cluster(entry);
2805 } else
2806 ret = 0;
2807 } else {
2808 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2809 pr_alert("total_mapcount: %u, page_count(): %u\n",
2810 mapcount, count);
2811 if (PageTail(page))
2812 dump_page(head, NULL);
2813 dump_page(page, "total_mapcount(head) > 0");
2814 BUG();
2815 }
2816 spin_unlock(&ds_queue->split_queue_lock);
2817fail: if (mapping)
2818 xa_unlock(&mapping->i_pages);
2819 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2820 remap_page(head);
2821 ret = -EBUSY;
2822 }
2823
2824out_unlock:
2825 if (anon_vma) {
2826 anon_vma_unlock_write(anon_vma);
2827 put_anon_vma(anon_vma);
2828 }
2829 if (mapping)
2830 i_mmap_unlock_read(mapping);
2831out:
2832 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2833 return ret;
2834}
2835
2836void free_transhuge_page(struct page *page)
2837{
2838 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2839 unsigned long flags;
2840
2841 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2842 if (!list_empty(page_deferred_list(page))) {
2843 ds_queue->split_queue_len--;
2844 list_del(page_deferred_list(page));
2845 }
2846 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2847 free_compound_page(page);
2848}
2849
2850void deferred_split_huge_page(struct page *page)
2851{
2852 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2853#ifdef CONFIG_MEMCG
2854 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
2855#endif
2856 unsigned long flags;
2857
2858 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2859
2860 /*
2861 * The try_to_unmap() in page reclaim path might reach here too,
2862 * this may cause a race condition to corrupt deferred split queue.
2863 * And, if page reclaim is already handling the same page, it is
2864 * unnecessary to handle it again in shrinker.
2865 *
2866 * Check PageSwapCache to determine if the page is being
2867 * handled by page reclaim since THP swap would add the page into
2868 * swap cache before calling try_to_unmap().
2869 */
2870 if (PageSwapCache(page))
2871 return;
2872
2873 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2874 if (list_empty(page_deferred_list(page))) {
2875 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2876 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2877 ds_queue->split_queue_len++;
2878#ifdef CONFIG_MEMCG
2879 if (memcg)
2880 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2881 deferred_split_shrinker.id);
2882#endif
2883 }
2884 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2885}
2886
2887static unsigned long deferred_split_count(struct shrinker *shrink,
2888 struct shrink_control *sc)
2889{
2890 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2891 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2892
2893#ifdef CONFIG_MEMCG
2894 if (sc->memcg)
2895 ds_queue = &sc->memcg->deferred_split_queue;
2896#endif
2897 return READ_ONCE(ds_queue->split_queue_len);
2898}
2899
2900static unsigned long deferred_split_scan(struct shrinker *shrink,
2901 struct shrink_control *sc)
2902{
2903 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2904 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2905 unsigned long flags;
2906 LIST_HEAD(list), *pos, *next;
2907 struct page *page;
2908 int split = 0;
2909
2910#ifdef CONFIG_MEMCG
2911 if (sc->memcg)
2912 ds_queue = &sc->memcg->deferred_split_queue;
2913#endif
2914
2915 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2916 /* Take pin on all head pages to avoid freeing them under us */
2917 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2918 page = list_entry((void *)pos, struct page, mapping);
2919 page = compound_head(page);
2920 if (get_page_unless_zero(page)) {
2921 list_move(page_deferred_list(page), &list);
2922 } else {
2923 /* We lost race with put_compound_page() */
2924 list_del_init(page_deferred_list(page));
2925 ds_queue->split_queue_len--;
2926 }
2927 if (!--sc->nr_to_scan)
2928 break;
2929 }
2930 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2931
2932 list_for_each_safe(pos, next, &list) {
2933 page = list_entry((void *)pos, struct page, mapping);
2934 if (!trylock_page(page))
2935 goto next;
2936 /* split_huge_page() removes page from list on success */
2937 if (!split_huge_page(page))
2938 split++;
2939 unlock_page(page);
2940next:
2941 put_page(page);
2942 }
2943
2944 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2945 list_splice_tail(&list, &ds_queue->split_queue);
2946 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2947
2948 /*
2949 * Stop shrinker if we didn't split any page, but the queue is empty.
2950 * This can happen if pages were freed under us.
2951 */
2952 if (!split && list_empty(&ds_queue->split_queue))
2953 return SHRINK_STOP;
2954 return split;
2955}
2956
2957static struct shrinker deferred_split_shrinker = {
2958 .count_objects = deferred_split_count,
2959 .scan_objects = deferred_split_scan,
2960 .seeks = DEFAULT_SEEKS,
2961 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2962 SHRINKER_NONSLAB,
2963};
2964
2965#ifdef CONFIG_DEBUG_FS
2966static int split_huge_pages_set(void *data, u64 val)
2967{
2968 struct zone *zone;
2969 struct page *page;
2970 unsigned long pfn, max_zone_pfn;
2971 unsigned long total = 0, split = 0;
2972
2973 if (val != 1)
2974 return -EINVAL;
2975
2976 for_each_populated_zone(zone) {
2977 max_zone_pfn = zone_end_pfn(zone);
2978 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2979 if (!pfn_valid(pfn))
2980 continue;
2981
2982 page = pfn_to_page(pfn);
2983 if (!get_page_unless_zero(page))
2984 continue;
2985
2986 if (zone != page_zone(page))
2987 goto next;
2988
2989 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2990 goto next;
2991
2992 total++;
2993 lock_page(page);
2994 if (!split_huge_page(page))
2995 split++;
2996 unlock_page(page);
2997next:
2998 put_page(page);
2999 }
3000 }
3001
3002 pr_info("%lu of %lu THP split\n", split, total);
3003
3004 return 0;
3005}
3006DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
3007 "%llu\n");
3008
3009static int __init split_huge_pages_debugfs(void)
3010{
3011 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3012 &split_huge_pages_fops);
3013 return 0;
3014}
3015late_initcall(split_huge_pages_debugfs);
3016#endif
3017
3018#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3019void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3020 struct page *page)
3021{
3022 struct vm_area_struct *vma = pvmw->vma;
3023 struct mm_struct *mm = vma->vm_mm;
3024 unsigned long address = pvmw->address;
3025 pmd_t pmdval;
3026 swp_entry_t entry;
3027 pmd_t pmdswp;
3028
3029 if (!(pvmw->pmd && !pvmw->pte))
3030 return;
3031
3032 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3033 pmdval = *pvmw->pmd;
3034 pmdp_invalidate(vma, address, pvmw->pmd);
3035 if (pmd_dirty(pmdval))
3036 set_page_dirty(page);
3037 entry = make_migration_entry(page, pmd_write(pmdval));
3038 pmdswp = swp_entry_to_pmd(entry);
3039 if (pmd_soft_dirty(pmdval))
3040 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3041 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3042 page_remove_rmap(page, true);
3043 put_page(page);
3044}
3045
3046void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3047{
3048 struct vm_area_struct *vma = pvmw->vma;
3049 struct mm_struct *mm = vma->vm_mm;
3050 unsigned long address = pvmw->address;
3051 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3052 pmd_t pmde;
3053 swp_entry_t entry;
3054
3055 if (!(pvmw->pmd && !pvmw->pte))
3056 return;
3057
3058 entry = pmd_to_swp_entry(*pvmw->pmd);
3059 get_page(new);
3060 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3061 if (pmd_swp_soft_dirty(*pvmw->pmd))
3062 pmde = pmd_mksoft_dirty(pmde);
3063 if (is_write_migration_entry(entry))
3064 pmde = maybe_pmd_mkwrite(pmde, vma);
3065
3066 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3067 if (PageAnon(new))
3068 page_add_anon_rmap(new, vma, mmun_start, true);
3069 else
3070 page_add_file_rmap(new, true);
3071 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3072 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3073 mlock_vma_page(new);
3074 update_mmu_cache_pmd(vma, address, pvmw->pmd);
3075}
3076#endif