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1/*
2 * Copyright (C) 2008, 2009 Intel Corporation
3 * Authors: Andi Kleen, Fengguang Wu
4 *
5 * This software may be redistributed and/or modified under the terms of
6 * the GNU General Public License ("GPL") version 2 only as published by the
7 * Free Software Foundation.
8 *
9 * High level machine check handler. Handles pages reported by the
10 * hardware as being corrupted usually due to a multi-bit ECC memory or cache
11 * failure.
12 *
13 * In addition there is a "soft offline" entry point that allows stop using
14 * not-yet-corrupted-by-suspicious pages without killing anything.
15 *
16 * Handles page cache pages in various states. The tricky part
17 * here is that we can access any page asynchronously in respect to
18 * other VM users, because memory failures could happen anytime and
19 * anywhere. This could violate some of their assumptions. This is why
20 * this code has to be extremely careful. Generally it tries to use
21 * normal locking rules, as in get the standard locks, even if that means
22 * the error handling takes potentially a long time.
23 *
24 * There are several operations here with exponential complexity because
25 * of unsuitable VM data structures. For example the operation to map back
26 * from RMAP chains to processes has to walk the complete process list and
27 * has non linear complexity with the number. But since memory corruptions
28 * are rare we hope to get away with this. This avoids impacting the core
29 * VM.
30 */
31
32/*
33 * Notebook:
34 * - hugetlb needs more code
35 * - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
36 * - pass bad pages to kdump next kernel
37 */
38#include <linux/kernel.h>
39#include <linux/mm.h>
40#include <linux/page-flags.h>
41#include <linux/kernel-page-flags.h>
42#include <linux/sched.h>
43#include <linux/ksm.h>
44#include <linux/rmap.h>
45#include <linux/export.h>
46#include <linux/pagemap.h>
47#include <linux/swap.h>
48#include <linux/backing-dev.h>
49#include <linux/migrate.h>
50#include <linux/page-isolation.h>
51#include <linux/suspend.h>
52#include <linux/slab.h>
53#include <linux/swapops.h>
54#include <linux/hugetlb.h>
55#include <linux/memory_hotplug.h>
56#include <linux/mm_inline.h>
57#include <linux/kfifo.h>
58#include "internal.h"
59
60int sysctl_memory_failure_early_kill __read_mostly = 0;
61
62int sysctl_memory_failure_recovery __read_mostly = 1;
63
64atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
65
66#if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
67
68u32 hwpoison_filter_enable = 0;
69u32 hwpoison_filter_dev_major = ~0U;
70u32 hwpoison_filter_dev_minor = ~0U;
71u64 hwpoison_filter_flags_mask;
72u64 hwpoison_filter_flags_value;
73EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
74EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
75EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
76EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
77EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
78
79static int hwpoison_filter_dev(struct page *p)
80{
81 struct address_space *mapping;
82 dev_t dev;
83
84 if (hwpoison_filter_dev_major == ~0U &&
85 hwpoison_filter_dev_minor == ~0U)
86 return 0;
87
88 /*
89 * page_mapping() does not accept slab pages.
90 */
91 if (PageSlab(p))
92 return -EINVAL;
93
94 mapping = page_mapping(p);
95 if (mapping == NULL || mapping->host == NULL)
96 return -EINVAL;
97
98 dev = mapping->host->i_sb->s_dev;
99 if (hwpoison_filter_dev_major != ~0U &&
100 hwpoison_filter_dev_major != MAJOR(dev))
101 return -EINVAL;
102 if (hwpoison_filter_dev_minor != ~0U &&
103 hwpoison_filter_dev_minor != MINOR(dev))
104 return -EINVAL;
105
106 return 0;
107}
108
109static int hwpoison_filter_flags(struct page *p)
110{
111 if (!hwpoison_filter_flags_mask)
112 return 0;
113
114 if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
115 hwpoison_filter_flags_value)
116 return 0;
117 else
118 return -EINVAL;
119}
120
121/*
122 * This allows stress tests to limit test scope to a collection of tasks
123 * by putting them under some memcg. This prevents killing unrelated/important
124 * processes such as /sbin/init. Note that the target task may share clean
125 * pages with init (eg. libc text), which is harmless. If the target task
126 * share _dirty_ pages with another task B, the test scheme must make sure B
127 * is also included in the memcg. At last, due to race conditions this filter
128 * can only guarantee that the page either belongs to the memcg tasks, or is
129 * a freed page.
130 */
131#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
132u64 hwpoison_filter_memcg;
133EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
134static int hwpoison_filter_task(struct page *p)
135{
136 struct mem_cgroup *mem;
137 struct cgroup_subsys_state *css;
138 unsigned long ino;
139
140 if (!hwpoison_filter_memcg)
141 return 0;
142
143 mem = try_get_mem_cgroup_from_page(p);
144 if (!mem)
145 return -EINVAL;
146
147 css = mem_cgroup_css(mem);
148 /* root_mem_cgroup has NULL dentries */
149 if (!css->cgroup->dentry)
150 return -EINVAL;
151
152 ino = css->cgroup->dentry->d_inode->i_ino;
153 css_put(css);
154
155 if (ino != hwpoison_filter_memcg)
156 return -EINVAL;
157
158 return 0;
159}
160#else
161static int hwpoison_filter_task(struct page *p) { return 0; }
162#endif
163
164int hwpoison_filter(struct page *p)
165{
166 if (!hwpoison_filter_enable)
167 return 0;
168
169 if (hwpoison_filter_dev(p))
170 return -EINVAL;
171
172 if (hwpoison_filter_flags(p))
173 return -EINVAL;
174
175 if (hwpoison_filter_task(p))
176 return -EINVAL;
177
178 return 0;
179}
180#else
181int hwpoison_filter(struct page *p)
182{
183 return 0;
184}
185#endif
186
187EXPORT_SYMBOL_GPL(hwpoison_filter);
188
189/*
190 * Send all the processes who have the page mapped a signal.
191 * ``action optional'' if they are not immediately affected by the error
192 * ``action required'' if error happened in current execution context
193 */
194static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
195 unsigned long pfn, struct page *page, int flags)
196{
197 struct siginfo si;
198 int ret;
199
200 printk(KERN_ERR
201 "MCE %#lx: Killing %s:%d due to hardware memory corruption\n",
202 pfn, t->comm, t->pid);
203 si.si_signo = SIGBUS;
204 si.si_errno = 0;
205 si.si_addr = (void *)addr;
206#ifdef __ARCH_SI_TRAPNO
207 si.si_trapno = trapno;
208#endif
209 si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
210
211 if ((flags & MF_ACTION_REQUIRED) && t == current) {
212 si.si_code = BUS_MCEERR_AR;
213 ret = force_sig_info(SIGBUS, &si, t);
214 } else {
215 /*
216 * Don't use force here, it's convenient if the signal
217 * can be temporarily blocked.
218 * This could cause a loop when the user sets SIGBUS
219 * to SIG_IGN, but hopefully no one will do that?
220 */
221 si.si_code = BUS_MCEERR_AO;
222 ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
223 }
224 if (ret < 0)
225 printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
226 t->comm, t->pid, ret);
227 return ret;
228}
229
230/*
231 * When a unknown page type is encountered drain as many buffers as possible
232 * in the hope to turn the page into a LRU or free page, which we can handle.
233 */
234void shake_page(struct page *p, int access)
235{
236 if (!PageSlab(p)) {
237 lru_add_drain_all();
238 if (PageLRU(p))
239 return;
240 drain_all_pages();
241 if (PageLRU(p) || is_free_buddy_page(p))
242 return;
243 }
244
245 /*
246 * Only call shrink_slab here (which would also shrink other caches) if
247 * access is not potentially fatal.
248 */
249 if (access) {
250 int nr;
251 do {
252 struct shrink_control shrink = {
253 .gfp_mask = GFP_KERNEL,
254 };
255
256 nr = shrink_slab(&shrink, 1000, 1000);
257 if (page_count(p) == 1)
258 break;
259 } while (nr > 10);
260 }
261}
262EXPORT_SYMBOL_GPL(shake_page);
263
264/*
265 * Kill all processes that have a poisoned page mapped and then isolate
266 * the page.
267 *
268 * General strategy:
269 * Find all processes having the page mapped and kill them.
270 * But we keep a page reference around so that the page is not
271 * actually freed yet.
272 * Then stash the page away
273 *
274 * There's no convenient way to get back to mapped processes
275 * from the VMAs. So do a brute-force search over all
276 * running processes.
277 *
278 * Remember that machine checks are not common (or rather
279 * if they are common you have other problems), so this shouldn't
280 * be a performance issue.
281 *
282 * Also there are some races possible while we get from the
283 * error detection to actually handle it.
284 */
285
286struct to_kill {
287 struct list_head nd;
288 struct task_struct *tsk;
289 unsigned long addr;
290 char addr_valid;
291};
292
293/*
294 * Failure handling: if we can't find or can't kill a process there's
295 * not much we can do. We just print a message and ignore otherwise.
296 */
297
298/*
299 * Schedule a process for later kill.
300 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
301 * TBD would GFP_NOIO be enough?
302 */
303static void add_to_kill(struct task_struct *tsk, struct page *p,
304 struct vm_area_struct *vma,
305 struct list_head *to_kill,
306 struct to_kill **tkc)
307{
308 struct to_kill *tk;
309
310 if (*tkc) {
311 tk = *tkc;
312 *tkc = NULL;
313 } else {
314 tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
315 if (!tk) {
316 printk(KERN_ERR
317 "MCE: Out of memory while machine check handling\n");
318 return;
319 }
320 }
321 tk->addr = page_address_in_vma(p, vma);
322 tk->addr_valid = 1;
323
324 /*
325 * In theory we don't have to kill when the page was
326 * munmaped. But it could be also a mremap. Since that's
327 * likely very rare kill anyways just out of paranoia, but use
328 * a SIGKILL because the error is not contained anymore.
329 */
330 if (tk->addr == -EFAULT) {
331 pr_info("MCE: Unable to find user space address %lx in %s\n",
332 page_to_pfn(p), tsk->comm);
333 tk->addr_valid = 0;
334 }
335 get_task_struct(tsk);
336 tk->tsk = tsk;
337 list_add_tail(&tk->nd, to_kill);
338}
339
340/*
341 * Kill the processes that have been collected earlier.
342 *
343 * Only do anything when DOIT is set, otherwise just free the list
344 * (this is used for clean pages which do not need killing)
345 * Also when FAIL is set do a force kill because something went
346 * wrong earlier.
347 */
348static void kill_procs(struct list_head *to_kill, int forcekill, int trapno,
349 int fail, struct page *page, unsigned long pfn,
350 int flags)
351{
352 struct to_kill *tk, *next;
353
354 list_for_each_entry_safe (tk, next, to_kill, nd) {
355 if (forcekill) {
356 /*
357 * In case something went wrong with munmapping
358 * make sure the process doesn't catch the
359 * signal and then access the memory. Just kill it.
360 */
361 if (fail || tk->addr_valid == 0) {
362 printk(KERN_ERR
363 "MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
364 pfn, tk->tsk->comm, tk->tsk->pid);
365 force_sig(SIGKILL, tk->tsk);
366 }
367
368 /*
369 * In theory the process could have mapped
370 * something else on the address in-between. We could
371 * check for that, but we need to tell the
372 * process anyways.
373 */
374 else if (kill_proc(tk->tsk, tk->addr, trapno,
375 pfn, page, flags) < 0)
376 printk(KERN_ERR
377 "MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
378 pfn, tk->tsk->comm, tk->tsk->pid);
379 }
380 put_task_struct(tk->tsk);
381 kfree(tk);
382 }
383}
384
385static int task_early_kill(struct task_struct *tsk)
386{
387 if (!tsk->mm)
388 return 0;
389 if (tsk->flags & PF_MCE_PROCESS)
390 return !!(tsk->flags & PF_MCE_EARLY);
391 return sysctl_memory_failure_early_kill;
392}
393
394/*
395 * Collect processes when the error hit an anonymous page.
396 */
397static void collect_procs_anon(struct page *page, struct list_head *to_kill,
398 struct to_kill **tkc)
399{
400 struct vm_area_struct *vma;
401 struct task_struct *tsk;
402 struct anon_vma *av;
403
404 av = page_lock_anon_vma(page);
405 if (av == NULL) /* Not actually mapped anymore */
406 return;
407
408 read_lock(&tasklist_lock);
409 for_each_process (tsk) {
410 struct anon_vma_chain *vmac;
411
412 if (!task_early_kill(tsk))
413 continue;
414 list_for_each_entry(vmac, &av->head, same_anon_vma) {
415 vma = vmac->vma;
416 if (!page_mapped_in_vma(page, vma))
417 continue;
418 if (vma->vm_mm == tsk->mm)
419 add_to_kill(tsk, page, vma, to_kill, tkc);
420 }
421 }
422 read_unlock(&tasklist_lock);
423 page_unlock_anon_vma(av);
424}
425
426/*
427 * Collect processes when the error hit a file mapped page.
428 */
429static void collect_procs_file(struct page *page, struct list_head *to_kill,
430 struct to_kill **tkc)
431{
432 struct vm_area_struct *vma;
433 struct task_struct *tsk;
434 struct prio_tree_iter iter;
435 struct address_space *mapping = page->mapping;
436
437 mutex_lock(&mapping->i_mmap_mutex);
438 read_lock(&tasklist_lock);
439 for_each_process(tsk) {
440 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
441
442 if (!task_early_kill(tsk))
443 continue;
444
445 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff,
446 pgoff) {
447 /*
448 * Send early kill signal to tasks where a vma covers
449 * the page but the corrupted page is not necessarily
450 * mapped it in its pte.
451 * Assume applications who requested early kill want
452 * to be informed of all such data corruptions.
453 */
454 if (vma->vm_mm == tsk->mm)
455 add_to_kill(tsk, page, vma, to_kill, tkc);
456 }
457 }
458 read_unlock(&tasklist_lock);
459 mutex_unlock(&mapping->i_mmap_mutex);
460}
461
462/*
463 * Collect the processes who have the corrupted page mapped to kill.
464 * This is done in two steps for locking reasons.
465 * First preallocate one tokill structure outside the spin locks,
466 * so that we can kill at least one process reasonably reliable.
467 */
468static void collect_procs(struct page *page, struct list_head *tokill)
469{
470 struct to_kill *tk;
471
472 if (!page->mapping)
473 return;
474
475 tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
476 if (!tk)
477 return;
478 if (PageAnon(page))
479 collect_procs_anon(page, tokill, &tk);
480 else
481 collect_procs_file(page, tokill, &tk);
482 kfree(tk);
483}
484
485/*
486 * Error handlers for various types of pages.
487 */
488
489enum outcome {
490 IGNORED, /* Error: cannot be handled */
491 FAILED, /* Error: handling failed */
492 DELAYED, /* Will be handled later */
493 RECOVERED, /* Successfully recovered */
494};
495
496static const char *action_name[] = {
497 [IGNORED] = "Ignored",
498 [FAILED] = "Failed",
499 [DELAYED] = "Delayed",
500 [RECOVERED] = "Recovered",
501};
502
503/*
504 * XXX: It is possible that a page is isolated from LRU cache,
505 * and then kept in swap cache or failed to remove from page cache.
506 * The page count will stop it from being freed by unpoison.
507 * Stress tests should be aware of this memory leak problem.
508 */
509static int delete_from_lru_cache(struct page *p)
510{
511 if (!isolate_lru_page(p)) {
512 /*
513 * Clear sensible page flags, so that the buddy system won't
514 * complain when the page is unpoison-and-freed.
515 */
516 ClearPageActive(p);
517 ClearPageUnevictable(p);
518 /*
519 * drop the page count elevated by isolate_lru_page()
520 */
521 page_cache_release(p);
522 return 0;
523 }
524 return -EIO;
525}
526
527/*
528 * Error hit kernel page.
529 * Do nothing, try to be lucky and not touch this instead. For a few cases we
530 * could be more sophisticated.
531 */
532static int me_kernel(struct page *p, unsigned long pfn)
533{
534 return IGNORED;
535}
536
537/*
538 * Page in unknown state. Do nothing.
539 */
540static int me_unknown(struct page *p, unsigned long pfn)
541{
542 printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
543 return FAILED;
544}
545
546/*
547 * Clean (or cleaned) page cache page.
548 */
549static int me_pagecache_clean(struct page *p, unsigned long pfn)
550{
551 int err;
552 int ret = FAILED;
553 struct address_space *mapping;
554
555 delete_from_lru_cache(p);
556
557 /*
558 * For anonymous pages we're done the only reference left
559 * should be the one m_f() holds.
560 */
561 if (PageAnon(p))
562 return RECOVERED;
563
564 /*
565 * Now truncate the page in the page cache. This is really
566 * more like a "temporary hole punch"
567 * Don't do this for block devices when someone else
568 * has a reference, because it could be file system metadata
569 * and that's not safe to truncate.
570 */
571 mapping = page_mapping(p);
572 if (!mapping) {
573 /*
574 * Page has been teared down in the meanwhile
575 */
576 return FAILED;
577 }
578
579 /*
580 * Truncation is a bit tricky. Enable it per file system for now.
581 *
582 * Open: to take i_mutex or not for this? Right now we don't.
583 */
584 if (mapping->a_ops->error_remove_page) {
585 err = mapping->a_ops->error_remove_page(mapping, p);
586 if (err != 0) {
587 printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
588 pfn, err);
589 } else if (page_has_private(p) &&
590 !try_to_release_page(p, GFP_NOIO)) {
591 pr_info("MCE %#lx: failed to release buffers\n", pfn);
592 } else {
593 ret = RECOVERED;
594 }
595 } else {
596 /*
597 * If the file system doesn't support it just invalidate
598 * This fails on dirty or anything with private pages
599 */
600 if (invalidate_inode_page(p))
601 ret = RECOVERED;
602 else
603 printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
604 pfn);
605 }
606 return ret;
607}
608
609/*
610 * Dirty cache page page
611 * Issues: when the error hit a hole page the error is not properly
612 * propagated.
613 */
614static int me_pagecache_dirty(struct page *p, unsigned long pfn)
615{
616 struct address_space *mapping = page_mapping(p);
617
618 SetPageError(p);
619 /* TBD: print more information about the file. */
620 if (mapping) {
621 /*
622 * IO error will be reported by write(), fsync(), etc.
623 * who check the mapping.
624 * This way the application knows that something went
625 * wrong with its dirty file data.
626 *
627 * There's one open issue:
628 *
629 * The EIO will be only reported on the next IO
630 * operation and then cleared through the IO map.
631 * Normally Linux has two mechanisms to pass IO error
632 * first through the AS_EIO flag in the address space
633 * and then through the PageError flag in the page.
634 * Since we drop pages on memory failure handling the
635 * only mechanism open to use is through AS_AIO.
636 *
637 * This has the disadvantage that it gets cleared on
638 * the first operation that returns an error, while
639 * the PageError bit is more sticky and only cleared
640 * when the page is reread or dropped. If an
641 * application assumes it will always get error on
642 * fsync, but does other operations on the fd before
643 * and the page is dropped between then the error
644 * will not be properly reported.
645 *
646 * This can already happen even without hwpoisoned
647 * pages: first on metadata IO errors (which only
648 * report through AS_EIO) or when the page is dropped
649 * at the wrong time.
650 *
651 * So right now we assume that the application DTRT on
652 * the first EIO, but we're not worse than other parts
653 * of the kernel.
654 */
655 mapping_set_error(mapping, EIO);
656 }
657
658 return me_pagecache_clean(p, pfn);
659}
660
661/*
662 * Clean and dirty swap cache.
663 *
664 * Dirty swap cache page is tricky to handle. The page could live both in page
665 * cache and swap cache(ie. page is freshly swapped in). So it could be
666 * referenced concurrently by 2 types of PTEs:
667 * normal PTEs and swap PTEs. We try to handle them consistently by calling
668 * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
669 * and then
670 * - clear dirty bit to prevent IO
671 * - remove from LRU
672 * - but keep in the swap cache, so that when we return to it on
673 * a later page fault, we know the application is accessing
674 * corrupted data and shall be killed (we installed simple
675 * interception code in do_swap_page to catch it).
676 *
677 * Clean swap cache pages can be directly isolated. A later page fault will
678 * bring in the known good data from disk.
679 */
680static int me_swapcache_dirty(struct page *p, unsigned long pfn)
681{
682 ClearPageDirty(p);
683 /* Trigger EIO in shmem: */
684 ClearPageUptodate(p);
685
686 if (!delete_from_lru_cache(p))
687 return DELAYED;
688 else
689 return FAILED;
690}
691
692static int me_swapcache_clean(struct page *p, unsigned long pfn)
693{
694 delete_from_swap_cache(p);
695
696 if (!delete_from_lru_cache(p))
697 return RECOVERED;
698 else
699 return FAILED;
700}
701
702/*
703 * Huge pages. Needs work.
704 * Issues:
705 * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
706 * To narrow down kill region to one page, we need to break up pmd.
707 */
708static int me_huge_page(struct page *p, unsigned long pfn)
709{
710 int res = 0;
711 struct page *hpage = compound_head(p);
712 /*
713 * We can safely recover from error on free or reserved (i.e.
714 * not in-use) hugepage by dequeuing it from freelist.
715 * To check whether a hugepage is in-use or not, we can't use
716 * page->lru because it can be used in other hugepage operations,
717 * such as __unmap_hugepage_range() and gather_surplus_pages().
718 * So instead we use page_mapping() and PageAnon().
719 * We assume that this function is called with page lock held,
720 * so there is no race between isolation and mapping/unmapping.
721 */
722 if (!(page_mapping(hpage) || PageAnon(hpage))) {
723 res = dequeue_hwpoisoned_huge_page(hpage);
724 if (!res)
725 return RECOVERED;
726 }
727 return DELAYED;
728}
729
730/*
731 * Various page states we can handle.
732 *
733 * A page state is defined by its current page->flags bits.
734 * The table matches them in order and calls the right handler.
735 *
736 * This is quite tricky because we can access page at any time
737 * in its live cycle, so all accesses have to be extremely careful.
738 *
739 * This is not complete. More states could be added.
740 * For any missing state don't attempt recovery.
741 */
742
743#define dirty (1UL << PG_dirty)
744#define sc (1UL << PG_swapcache)
745#define unevict (1UL << PG_unevictable)
746#define mlock (1UL << PG_mlocked)
747#define writeback (1UL << PG_writeback)
748#define lru (1UL << PG_lru)
749#define swapbacked (1UL << PG_swapbacked)
750#define head (1UL << PG_head)
751#define tail (1UL << PG_tail)
752#define compound (1UL << PG_compound)
753#define slab (1UL << PG_slab)
754#define reserved (1UL << PG_reserved)
755
756static struct page_state {
757 unsigned long mask;
758 unsigned long res;
759 char *msg;
760 int (*action)(struct page *p, unsigned long pfn);
761} error_states[] = {
762 { reserved, reserved, "reserved kernel", me_kernel },
763 /*
764 * free pages are specially detected outside this table:
765 * PG_buddy pages only make a small fraction of all free pages.
766 */
767
768 /*
769 * Could in theory check if slab page is free or if we can drop
770 * currently unused objects without touching them. But just
771 * treat it as standard kernel for now.
772 */
773 { slab, slab, "kernel slab", me_kernel },
774
775#ifdef CONFIG_PAGEFLAGS_EXTENDED
776 { head, head, "huge", me_huge_page },
777 { tail, tail, "huge", me_huge_page },
778#else
779 { compound, compound, "huge", me_huge_page },
780#endif
781
782 { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty },
783 { sc|dirty, sc, "swapcache", me_swapcache_clean },
784
785 { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
786 { unevict, unevict, "unevictable LRU", me_pagecache_clean},
787
788 { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
789 { mlock, mlock, "mlocked LRU", me_pagecache_clean },
790
791 { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
792 { lru|dirty, lru, "clean LRU", me_pagecache_clean },
793
794 /*
795 * Catchall entry: must be at end.
796 */
797 { 0, 0, "unknown page state", me_unknown },
798};
799
800#undef dirty
801#undef sc
802#undef unevict
803#undef mlock
804#undef writeback
805#undef lru
806#undef swapbacked
807#undef head
808#undef tail
809#undef compound
810#undef slab
811#undef reserved
812
813static void action_result(unsigned long pfn, char *msg, int result)
814{
815 struct page *page = pfn_to_page(pfn);
816
817 printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
818 pfn,
819 PageDirty(page) ? "dirty " : "",
820 msg, action_name[result]);
821}
822
823static int page_action(struct page_state *ps, struct page *p,
824 unsigned long pfn)
825{
826 int result;
827 int count;
828
829 result = ps->action(p, pfn);
830 action_result(pfn, ps->msg, result);
831
832 count = page_count(p) - 1;
833 if (ps->action == me_swapcache_dirty && result == DELAYED)
834 count--;
835 if (count != 0) {
836 printk(KERN_ERR
837 "MCE %#lx: %s page still referenced by %d users\n",
838 pfn, ps->msg, count);
839 result = FAILED;
840 }
841
842 /* Could do more checks here if page looks ok */
843 /*
844 * Could adjust zone counters here to correct for the missing page.
845 */
846
847 return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
848}
849
850/*
851 * Do all that is necessary to remove user space mappings. Unmap
852 * the pages and send SIGBUS to the processes if the data was dirty.
853 */
854static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
855 int trapno, int flags)
856{
857 enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
858 struct address_space *mapping;
859 LIST_HEAD(tokill);
860 int ret;
861 int kill = 1, forcekill;
862 struct page *hpage = compound_head(p);
863 struct page *ppage;
864
865 if (PageReserved(p) || PageSlab(p))
866 return SWAP_SUCCESS;
867
868 /*
869 * This check implies we don't kill processes if their pages
870 * are in the swap cache early. Those are always late kills.
871 */
872 if (!page_mapped(hpage))
873 return SWAP_SUCCESS;
874
875 if (PageKsm(p))
876 return SWAP_FAIL;
877
878 if (PageSwapCache(p)) {
879 printk(KERN_ERR
880 "MCE %#lx: keeping poisoned page in swap cache\n", pfn);
881 ttu |= TTU_IGNORE_HWPOISON;
882 }
883
884 /*
885 * Propagate the dirty bit from PTEs to struct page first, because we
886 * need this to decide if we should kill or just drop the page.
887 * XXX: the dirty test could be racy: set_page_dirty() may not always
888 * be called inside page lock (it's recommended but not enforced).
889 */
890 mapping = page_mapping(hpage);
891 if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
892 mapping_cap_writeback_dirty(mapping)) {
893 if (page_mkclean(hpage)) {
894 SetPageDirty(hpage);
895 } else {
896 kill = 0;
897 ttu |= TTU_IGNORE_HWPOISON;
898 printk(KERN_INFO
899 "MCE %#lx: corrupted page was clean: dropped without side effects\n",
900 pfn);
901 }
902 }
903
904 /*
905 * ppage: poisoned page
906 * if p is regular page(4k page)
907 * ppage == real poisoned page;
908 * else p is hugetlb or THP, ppage == head page.
909 */
910 ppage = hpage;
911
912 if (PageTransHuge(hpage)) {
913 /*
914 * Verify that this isn't a hugetlbfs head page, the check for
915 * PageAnon is just for avoid tripping a split_huge_page
916 * internal debug check, as split_huge_page refuses to deal with
917 * anything that isn't an anon page. PageAnon can't go away fro
918 * under us because we hold a refcount on the hpage, without a
919 * refcount on the hpage. split_huge_page can't be safely called
920 * in the first place, having a refcount on the tail isn't
921 * enough * to be safe.
922 */
923 if (!PageHuge(hpage) && PageAnon(hpage)) {
924 if (unlikely(split_huge_page(hpage))) {
925 /*
926 * FIXME: if splitting THP is failed, it is
927 * better to stop the following operation rather
928 * than causing panic by unmapping. System might
929 * survive if the page is freed later.
930 */
931 printk(KERN_INFO
932 "MCE %#lx: failed to split THP\n", pfn);
933
934 BUG_ON(!PageHWPoison(p));
935 return SWAP_FAIL;
936 }
937 /* THP is split, so ppage should be the real poisoned page. */
938 ppage = p;
939 }
940 }
941
942 /*
943 * First collect all the processes that have the page
944 * mapped in dirty form. This has to be done before try_to_unmap,
945 * because ttu takes the rmap data structures down.
946 *
947 * Error handling: We ignore errors here because
948 * there's nothing that can be done.
949 */
950 if (kill)
951 collect_procs(ppage, &tokill);
952
953 if (hpage != ppage)
954 lock_page(ppage);
955
956 ret = try_to_unmap(ppage, ttu);
957 if (ret != SWAP_SUCCESS)
958 printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
959 pfn, page_mapcount(ppage));
960
961 if (hpage != ppage)
962 unlock_page(ppage);
963
964 /*
965 * Now that the dirty bit has been propagated to the
966 * struct page and all unmaps done we can decide if
967 * killing is needed or not. Only kill when the page
968 * was dirty or the process is not restartable,
969 * otherwise the tokill list is merely
970 * freed. When there was a problem unmapping earlier
971 * use a more force-full uncatchable kill to prevent
972 * any accesses to the poisoned memory.
973 */
974 forcekill = PageDirty(ppage) || (flags & MF_MUST_KILL);
975 kill_procs(&tokill, forcekill, trapno,
976 ret != SWAP_SUCCESS, p, pfn, flags);
977
978 return ret;
979}
980
981static void set_page_hwpoison_huge_page(struct page *hpage)
982{
983 int i;
984 int nr_pages = 1 << compound_trans_order(hpage);
985 for (i = 0; i < nr_pages; i++)
986 SetPageHWPoison(hpage + i);
987}
988
989static void clear_page_hwpoison_huge_page(struct page *hpage)
990{
991 int i;
992 int nr_pages = 1 << compound_trans_order(hpage);
993 for (i = 0; i < nr_pages; i++)
994 ClearPageHWPoison(hpage + i);
995}
996
997/**
998 * memory_failure - Handle memory failure of a page.
999 * @pfn: Page Number of the corrupted page
1000 * @trapno: Trap number reported in the signal to user space.
1001 * @flags: fine tune action taken
1002 *
1003 * This function is called by the low level machine check code
1004 * of an architecture when it detects hardware memory corruption
1005 * of a page. It tries its best to recover, which includes
1006 * dropping pages, killing processes etc.
1007 *
1008 * The function is primarily of use for corruptions that
1009 * happen outside the current execution context (e.g. when
1010 * detected by a background scrubber)
1011 *
1012 * Must run in process context (e.g. a work queue) with interrupts
1013 * enabled and no spinlocks hold.
1014 */
1015int memory_failure(unsigned long pfn, int trapno, int flags)
1016{
1017 struct page_state *ps;
1018 struct page *p;
1019 struct page *hpage;
1020 int res;
1021 unsigned int nr_pages;
1022
1023 if (!sysctl_memory_failure_recovery)
1024 panic("Memory failure from trap %d on page %lx", trapno, pfn);
1025
1026 if (!pfn_valid(pfn)) {
1027 printk(KERN_ERR
1028 "MCE %#lx: memory outside kernel control\n",
1029 pfn);
1030 return -ENXIO;
1031 }
1032
1033 p = pfn_to_page(pfn);
1034 hpage = compound_head(p);
1035 if (TestSetPageHWPoison(p)) {
1036 printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
1037 return 0;
1038 }
1039
1040 nr_pages = 1 << compound_trans_order(hpage);
1041 atomic_long_add(nr_pages, &mce_bad_pages);
1042
1043 /*
1044 * We need/can do nothing about count=0 pages.
1045 * 1) it's a free page, and therefore in safe hand:
1046 * prep_new_page() will be the gate keeper.
1047 * 2) it's a free hugepage, which is also safe:
1048 * an affected hugepage will be dequeued from hugepage freelist,
1049 * so there's no concern about reusing it ever after.
1050 * 3) it's part of a non-compound high order page.
1051 * Implies some kernel user: cannot stop them from
1052 * R/W the page; let's pray that the page has been
1053 * used and will be freed some time later.
1054 * In fact it's dangerous to directly bump up page count from 0,
1055 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
1056 */
1057 if (!(flags & MF_COUNT_INCREASED) &&
1058 !get_page_unless_zero(hpage)) {
1059 if (is_free_buddy_page(p)) {
1060 action_result(pfn, "free buddy", DELAYED);
1061 return 0;
1062 } else if (PageHuge(hpage)) {
1063 /*
1064 * Check "just unpoisoned", "filter hit", and
1065 * "race with other subpage."
1066 */
1067 lock_page(hpage);
1068 if (!PageHWPoison(hpage)
1069 || (hwpoison_filter(p) && TestClearPageHWPoison(p))
1070 || (p != hpage && TestSetPageHWPoison(hpage))) {
1071 atomic_long_sub(nr_pages, &mce_bad_pages);
1072 return 0;
1073 }
1074 set_page_hwpoison_huge_page(hpage);
1075 res = dequeue_hwpoisoned_huge_page(hpage);
1076 action_result(pfn, "free huge",
1077 res ? IGNORED : DELAYED);
1078 unlock_page(hpage);
1079 return res;
1080 } else {
1081 action_result(pfn, "high order kernel", IGNORED);
1082 return -EBUSY;
1083 }
1084 }
1085
1086 /*
1087 * We ignore non-LRU pages for good reasons.
1088 * - PG_locked is only well defined for LRU pages and a few others
1089 * - to avoid races with __set_page_locked()
1090 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
1091 * The check (unnecessarily) ignores LRU pages being isolated and
1092 * walked by the page reclaim code, however that's not a big loss.
1093 */
1094 if (!PageHuge(p) && !PageTransTail(p)) {
1095 if (!PageLRU(p))
1096 shake_page(p, 0);
1097 if (!PageLRU(p)) {
1098 /*
1099 * shake_page could have turned it free.
1100 */
1101 if (is_free_buddy_page(p)) {
1102 action_result(pfn, "free buddy, 2nd try",
1103 DELAYED);
1104 return 0;
1105 }
1106 action_result(pfn, "non LRU", IGNORED);
1107 put_page(p);
1108 return -EBUSY;
1109 }
1110 }
1111
1112 /*
1113 * Lock the page and wait for writeback to finish.
1114 * It's very difficult to mess with pages currently under IO
1115 * and in many cases impossible, so we just avoid it here.
1116 */
1117 lock_page(hpage);
1118
1119 /*
1120 * unpoison always clear PG_hwpoison inside page lock
1121 */
1122 if (!PageHWPoison(p)) {
1123 printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
1124 res = 0;
1125 goto out;
1126 }
1127 if (hwpoison_filter(p)) {
1128 if (TestClearPageHWPoison(p))
1129 atomic_long_sub(nr_pages, &mce_bad_pages);
1130 unlock_page(hpage);
1131 put_page(hpage);
1132 return 0;
1133 }
1134
1135 /*
1136 * For error on the tail page, we should set PG_hwpoison
1137 * on the head page to show that the hugepage is hwpoisoned
1138 */
1139 if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
1140 action_result(pfn, "hugepage already hardware poisoned",
1141 IGNORED);
1142 unlock_page(hpage);
1143 put_page(hpage);
1144 return 0;
1145 }
1146 /*
1147 * Set PG_hwpoison on all pages in an error hugepage,
1148 * because containment is done in hugepage unit for now.
1149 * Since we have done TestSetPageHWPoison() for the head page with
1150 * page lock held, we can safely set PG_hwpoison bits on tail pages.
1151 */
1152 if (PageHuge(p))
1153 set_page_hwpoison_huge_page(hpage);
1154
1155 wait_on_page_writeback(p);
1156
1157 /*
1158 * Now take care of user space mappings.
1159 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
1160 */
1161 if (hwpoison_user_mappings(p, pfn, trapno, flags) != SWAP_SUCCESS) {
1162 printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
1163 res = -EBUSY;
1164 goto out;
1165 }
1166
1167 /*
1168 * Torn down by someone else?
1169 */
1170 if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
1171 action_result(pfn, "already truncated LRU", IGNORED);
1172 res = -EBUSY;
1173 goto out;
1174 }
1175
1176 res = -EBUSY;
1177 for (ps = error_states;; ps++) {
1178 if ((p->flags & ps->mask) == ps->res) {
1179 res = page_action(ps, p, pfn);
1180 break;
1181 }
1182 }
1183out:
1184 unlock_page(hpage);
1185 return res;
1186}
1187EXPORT_SYMBOL_GPL(memory_failure);
1188
1189#define MEMORY_FAILURE_FIFO_ORDER 4
1190#define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER)
1191
1192struct memory_failure_entry {
1193 unsigned long pfn;
1194 int trapno;
1195 int flags;
1196};
1197
1198struct memory_failure_cpu {
1199 DECLARE_KFIFO(fifo, struct memory_failure_entry,
1200 MEMORY_FAILURE_FIFO_SIZE);
1201 spinlock_t lock;
1202 struct work_struct work;
1203};
1204
1205static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
1206
1207/**
1208 * memory_failure_queue - Schedule handling memory failure of a page.
1209 * @pfn: Page Number of the corrupted page
1210 * @trapno: Trap number reported in the signal to user space.
1211 * @flags: Flags for memory failure handling
1212 *
1213 * This function is called by the low level hardware error handler
1214 * when it detects hardware memory corruption of a page. It schedules
1215 * the recovering of error page, including dropping pages, killing
1216 * processes etc.
1217 *
1218 * The function is primarily of use for corruptions that
1219 * happen outside the current execution context (e.g. when
1220 * detected by a background scrubber)
1221 *
1222 * Can run in IRQ context.
1223 */
1224void memory_failure_queue(unsigned long pfn, int trapno, int flags)
1225{
1226 struct memory_failure_cpu *mf_cpu;
1227 unsigned long proc_flags;
1228 struct memory_failure_entry entry = {
1229 .pfn = pfn,
1230 .trapno = trapno,
1231 .flags = flags,
1232 };
1233
1234 mf_cpu = &get_cpu_var(memory_failure_cpu);
1235 spin_lock_irqsave(&mf_cpu->lock, proc_flags);
1236 if (kfifo_put(&mf_cpu->fifo, &entry))
1237 schedule_work_on(smp_processor_id(), &mf_cpu->work);
1238 else
1239 pr_err("Memory failure: buffer overflow when queuing memory failure at 0x%#lx\n",
1240 pfn);
1241 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
1242 put_cpu_var(memory_failure_cpu);
1243}
1244EXPORT_SYMBOL_GPL(memory_failure_queue);
1245
1246static void memory_failure_work_func(struct work_struct *work)
1247{
1248 struct memory_failure_cpu *mf_cpu;
1249 struct memory_failure_entry entry = { 0, };
1250 unsigned long proc_flags;
1251 int gotten;
1252
1253 mf_cpu = &__get_cpu_var(memory_failure_cpu);
1254 for (;;) {
1255 spin_lock_irqsave(&mf_cpu->lock, proc_flags);
1256 gotten = kfifo_get(&mf_cpu->fifo, &entry);
1257 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
1258 if (!gotten)
1259 break;
1260 memory_failure(entry.pfn, entry.trapno, entry.flags);
1261 }
1262}
1263
1264static int __init memory_failure_init(void)
1265{
1266 struct memory_failure_cpu *mf_cpu;
1267 int cpu;
1268
1269 for_each_possible_cpu(cpu) {
1270 mf_cpu = &per_cpu(memory_failure_cpu, cpu);
1271 spin_lock_init(&mf_cpu->lock);
1272 INIT_KFIFO(mf_cpu->fifo);
1273 INIT_WORK(&mf_cpu->work, memory_failure_work_func);
1274 }
1275
1276 return 0;
1277}
1278core_initcall(memory_failure_init);
1279
1280/**
1281 * unpoison_memory - Unpoison a previously poisoned page
1282 * @pfn: Page number of the to be unpoisoned page
1283 *
1284 * Software-unpoison a page that has been poisoned by
1285 * memory_failure() earlier.
1286 *
1287 * This is only done on the software-level, so it only works
1288 * for linux injected failures, not real hardware failures
1289 *
1290 * Returns 0 for success, otherwise -errno.
1291 */
1292int unpoison_memory(unsigned long pfn)
1293{
1294 struct page *page;
1295 struct page *p;
1296 int freeit = 0;
1297 unsigned int nr_pages;
1298
1299 if (!pfn_valid(pfn))
1300 return -ENXIO;
1301
1302 p = pfn_to_page(pfn);
1303 page = compound_head(p);
1304
1305 if (!PageHWPoison(p)) {
1306 pr_info("MCE: Page was already unpoisoned %#lx\n", pfn);
1307 return 0;
1308 }
1309
1310 nr_pages = 1 << compound_trans_order(page);
1311
1312 if (!get_page_unless_zero(page)) {
1313 /*
1314 * Since HWPoisoned hugepage should have non-zero refcount,
1315 * race between memory failure and unpoison seems to happen.
1316 * In such case unpoison fails and memory failure runs
1317 * to the end.
1318 */
1319 if (PageHuge(page)) {
1320 pr_info("MCE: Memory failure is now running on free hugepage %#lx\n", pfn);
1321 return 0;
1322 }
1323 if (TestClearPageHWPoison(p))
1324 atomic_long_sub(nr_pages, &mce_bad_pages);
1325 pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
1326 return 0;
1327 }
1328
1329 lock_page(page);
1330 /*
1331 * This test is racy because PG_hwpoison is set outside of page lock.
1332 * That's acceptable because that won't trigger kernel panic. Instead,
1333 * the PG_hwpoison page will be caught and isolated on the entrance to
1334 * the free buddy page pool.
1335 */
1336 if (TestClearPageHWPoison(page)) {
1337 pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
1338 atomic_long_sub(nr_pages, &mce_bad_pages);
1339 freeit = 1;
1340 if (PageHuge(page))
1341 clear_page_hwpoison_huge_page(page);
1342 }
1343 unlock_page(page);
1344
1345 put_page(page);
1346 if (freeit)
1347 put_page(page);
1348
1349 return 0;
1350}
1351EXPORT_SYMBOL(unpoison_memory);
1352
1353static struct page *new_page(struct page *p, unsigned long private, int **x)
1354{
1355 int nid = page_to_nid(p);
1356 if (PageHuge(p))
1357 return alloc_huge_page_node(page_hstate(compound_head(p)),
1358 nid);
1359 else
1360 return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
1361}
1362
1363/*
1364 * Safely get reference count of an arbitrary page.
1365 * Returns 0 for a free page, -EIO for a zero refcount page
1366 * that is not free, and 1 for any other page type.
1367 * For 1 the page is returned with increased page count, otherwise not.
1368 */
1369static int get_any_page(struct page *p, unsigned long pfn, int flags)
1370{
1371 int ret;
1372
1373 if (flags & MF_COUNT_INCREASED)
1374 return 1;
1375
1376 /*
1377 * The lock_memory_hotplug prevents a race with memory hotplug.
1378 * This is a big hammer, a better would be nicer.
1379 */
1380 lock_memory_hotplug();
1381
1382 /*
1383 * Isolate the page, so that it doesn't get reallocated if it
1384 * was free.
1385 */
1386 set_migratetype_isolate(p);
1387 /*
1388 * When the target page is a free hugepage, just remove it
1389 * from free hugepage list.
1390 */
1391 if (!get_page_unless_zero(compound_head(p))) {
1392 if (PageHuge(p)) {
1393 pr_info("%s: %#lx free huge page\n", __func__, pfn);
1394 ret = dequeue_hwpoisoned_huge_page(compound_head(p));
1395 } else if (is_free_buddy_page(p)) {
1396 pr_info("%s: %#lx free buddy page\n", __func__, pfn);
1397 /* Set hwpoison bit while page is still isolated */
1398 SetPageHWPoison(p);
1399 ret = 0;
1400 } else {
1401 pr_info("%s: %#lx: unknown zero refcount page type %lx\n",
1402 __func__, pfn, p->flags);
1403 ret = -EIO;
1404 }
1405 } else {
1406 /* Not a free page */
1407 ret = 1;
1408 }
1409 unset_migratetype_isolate(p, MIGRATE_MOVABLE);
1410 unlock_memory_hotplug();
1411 return ret;
1412}
1413
1414static int soft_offline_huge_page(struct page *page, int flags)
1415{
1416 int ret;
1417 unsigned long pfn = page_to_pfn(page);
1418 struct page *hpage = compound_head(page);
1419 LIST_HEAD(pagelist);
1420
1421 ret = get_any_page(page, pfn, flags);
1422 if (ret < 0)
1423 return ret;
1424 if (ret == 0)
1425 goto done;
1426
1427 if (PageHWPoison(hpage)) {
1428 put_page(hpage);
1429 pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
1430 return -EBUSY;
1431 }
1432
1433 /* Keep page count to indicate a given hugepage is isolated. */
1434
1435 list_add(&hpage->lru, &pagelist);
1436 ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, false,
1437 MIGRATE_SYNC);
1438 if (ret) {
1439 struct page *page1, *page2;
1440 list_for_each_entry_safe(page1, page2, &pagelist, lru)
1441 put_page(page1);
1442
1443 pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
1444 pfn, ret, page->flags);
1445 if (ret > 0)
1446 ret = -EIO;
1447 return ret;
1448 }
1449done:
1450 if (!PageHWPoison(hpage))
1451 atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
1452 set_page_hwpoison_huge_page(hpage);
1453 dequeue_hwpoisoned_huge_page(hpage);
1454 /* keep elevated page count for bad page */
1455 return ret;
1456}
1457
1458/**
1459 * soft_offline_page - Soft offline a page.
1460 * @page: page to offline
1461 * @flags: flags. Same as memory_failure().
1462 *
1463 * Returns 0 on success, otherwise negated errno.
1464 *
1465 * Soft offline a page, by migration or invalidation,
1466 * without killing anything. This is for the case when
1467 * a page is not corrupted yet (so it's still valid to access),
1468 * but has had a number of corrected errors and is better taken
1469 * out.
1470 *
1471 * The actual policy on when to do that is maintained by
1472 * user space.
1473 *
1474 * This should never impact any application or cause data loss,
1475 * however it might take some time.
1476 *
1477 * This is not a 100% solution for all memory, but tries to be
1478 * ``good enough'' for the majority of memory.
1479 */
1480int soft_offline_page(struct page *page, int flags)
1481{
1482 int ret;
1483 unsigned long pfn = page_to_pfn(page);
1484
1485 if (PageHuge(page))
1486 return soft_offline_huge_page(page, flags);
1487
1488 ret = get_any_page(page, pfn, flags);
1489 if (ret < 0)
1490 return ret;
1491 if (ret == 0)
1492 goto done;
1493
1494 /*
1495 * Page cache page we can handle?
1496 */
1497 if (!PageLRU(page)) {
1498 /*
1499 * Try to free it.
1500 */
1501 put_page(page);
1502 shake_page(page, 1);
1503
1504 /*
1505 * Did it turn free?
1506 */
1507 ret = get_any_page(page, pfn, 0);
1508 if (ret < 0)
1509 return ret;
1510 if (ret == 0)
1511 goto done;
1512 }
1513 if (!PageLRU(page)) {
1514 pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
1515 pfn, page->flags);
1516 return -EIO;
1517 }
1518
1519 lock_page(page);
1520 wait_on_page_writeback(page);
1521
1522 /*
1523 * Synchronized using the page lock with memory_failure()
1524 */
1525 if (PageHWPoison(page)) {
1526 unlock_page(page);
1527 put_page(page);
1528 pr_info("soft offline: %#lx page already poisoned\n", pfn);
1529 return -EBUSY;
1530 }
1531
1532 /*
1533 * Try to invalidate first. This should work for
1534 * non dirty unmapped page cache pages.
1535 */
1536 ret = invalidate_inode_page(page);
1537 unlock_page(page);
1538 /*
1539 * RED-PEN would be better to keep it isolated here, but we
1540 * would need to fix isolation locking first.
1541 */
1542 if (ret == 1) {
1543 put_page(page);
1544 ret = 0;
1545 pr_info("soft_offline: %#lx: invalidated\n", pfn);
1546 goto done;
1547 }
1548
1549 /*
1550 * Simple invalidation didn't work.
1551 * Try to migrate to a new page instead. migrate.c
1552 * handles a large number of cases for us.
1553 */
1554 ret = isolate_lru_page(page);
1555 /*
1556 * Drop page reference which is came from get_any_page()
1557 * successful isolate_lru_page() already took another one.
1558 */
1559 put_page(page);
1560 if (!ret) {
1561 LIST_HEAD(pagelist);
1562 inc_zone_page_state(page, NR_ISOLATED_ANON +
1563 page_is_file_cache(page));
1564 list_add(&page->lru, &pagelist);
1565 ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
1566 false, MIGRATE_SYNC);
1567 if (ret) {
1568 putback_lru_pages(&pagelist);
1569 pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
1570 pfn, ret, page->flags);
1571 if (ret > 0)
1572 ret = -EIO;
1573 }
1574 } else {
1575 pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
1576 pfn, ret, page_count(page), page->flags);
1577 }
1578 if (ret)
1579 return ret;
1580
1581done:
1582 atomic_long_add(1, &mce_bad_pages);
1583 SetPageHWPoison(page);
1584 /* keep elevated page count for bad page */
1585 return ret;
1586}