blob: 620b0b461593afb124fc3174508b55993fe1f782 [file] [log] [blame]
Andi Kleen6a460792009-09-16 11:50:15 +02001/*
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 2bit ECC memory or cache
11 * failure.
12 *
13 * Handles page cache pages in various states. The tricky part
14 * here is that we can access any page asynchronous to other VM
15 * users, because memory failures could happen anytime and anywhere,
16 * possibly violating some of their assumptions. This is why this code
17 * has to be extremely careful. Generally it tries to use normal locking
18 * rules, as in get the standard locks, even if that means the
19 * error handling takes potentially a long time.
20 *
21 * The operation to map back from RMAP chains to processes has to walk
22 * the complete process list and has non linear complexity with the number
23 * mappings. In short it can be quite slow. But since memory corruptions
24 * are rare we hope to get away with this.
25 */
26
27/*
28 * Notebook:
29 * - hugetlb needs more code
30 * - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
31 * - pass bad pages to kdump next kernel
32 */
33#define DEBUG 1 /* remove me in 2.6.34 */
34#include <linux/kernel.h>
35#include <linux/mm.h>
36#include <linux/page-flags.h>
Wu Fengguang478c5ff2009-12-16 12:19:59 +010037#include <linux/kernel-page-flags.h>
Andi Kleen6a460792009-09-16 11:50:15 +020038#include <linux/sched.h>
Hugh Dickins01e00f82009-10-13 15:02:11 +010039#include <linux/ksm.h>
Andi Kleen6a460792009-09-16 11:50:15 +020040#include <linux/rmap.h>
41#include <linux/pagemap.h>
42#include <linux/swap.h>
43#include <linux/backing-dev.h>
Andi Kleenfacb6012009-12-16 12:20:00 +010044#include <linux/migrate.h>
45#include <linux/page-isolation.h>
46#include <linux/suspend.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090047#include <linux/slab.h>
Andi Kleen6a460792009-09-16 11:50:15 +020048#include "internal.h"
49
50int sysctl_memory_failure_early_kill __read_mostly = 0;
51
52int sysctl_memory_failure_recovery __read_mostly = 1;
53
54atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
55
Andi Kleen27df5062009-12-21 19:56:42 +010056#if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
57
Haicheng Li1bfe5fe2009-12-16 12:19:59 +010058u32 hwpoison_filter_enable = 0;
Wu Fengguang7c116f22009-12-16 12:19:59 +010059u32 hwpoison_filter_dev_major = ~0U;
60u32 hwpoison_filter_dev_minor = ~0U;
Wu Fengguang478c5ff2009-12-16 12:19:59 +010061u64 hwpoison_filter_flags_mask;
62u64 hwpoison_filter_flags_value;
Haicheng Li1bfe5fe2009-12-16 12:19:59 +010063EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
Wu Fengguang7c116f22009-12-16 12:19:59 +010064EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
65EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
Wu Fengguang478c5ff2009-12-16 12:19:59 +010066EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
67EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
Wu Fengguang7c116f22009-12-16 12:19:59 +010068
69static int hwpoison_filter_dev(struct page *p)
70{
71 struct address_space *mapping;
72 dev_t dev;
73
74 if (hwpoison_filter_dev_major == ~0U &&
75 hwpoison_filter_dev_minor == ~0U)
76 return 0;
77
78 /*
79 * page_mapping() does not accept slab page
80 */
81 if (PageSlab(p))
82 return -EINVAL;
83
84 mapping = page_mapping(p);
85 if (mapping == NULL || mapping->host == NULL)
86 return -EINVAL;
87
88 dev = mapping->host->i_sb->s_dev;
89 if (hwpoison_filter_dev_major != ~0U &&
90 hwpoison_filter_dev_major != MAJOR(dev))
91 return -EINVAL;
92 if (hwpoison_filter_dev_minor != ~0U &&
93 hwpoison_filter_dev_minor != MINOR(dev))
94 return -EINVAL;
95
96 return 0;
97}
98
Wu Fengguang478c5ff2009-12-16 12:19:59 +010099static int hwpoison_filter_flags(struct page *p)
100{
101 if (!hwpoison_filter_flags_mask)
102 return 0;
103
104 if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
105 hwpoison_filter_flags_value)
106 return 0;
107 else
108 return -EINVAL;
109}
110
Andi Kleen4fd466e2009-12-16 12:19:59 +0100111/*
112 * This allows stress tests to limit test scope to a collection of tasks
113 * by putting them under some memcg. This prevents killing unrelated/important
114 * processes such as /sbin/init. Note that the target task may share clean
115 * pages with init (eg. libc text), which is harmless. If the target task
116 * share _dirty_ pages with another task B, the test scheme must make sure B
117 * is also included in the memcg. At last, due to race conditions this filter
118 * can only guarantee that the page either belongs to the memcg tasks, or is
119 * a freed page.
120 */
121#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
122u64 hwpoison_filter_memcg;
123EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
124static int hwpoison_filter_task(struct page *p)
125{
126 struct mem_cgroup *mem;
127 struct cgroup_subsys_state *css;
128 unsigned long ino;
129
130 if (!hwpoison_filter_memcg)
131 return 0;
132
133 mem = try_get_mem_cgroup_from_page(p);
134 if (!mem)
135 return -EINVAL;
136
137 css = mem_cgroup_css(mem);
138 /* root_mem_cgroup has NULL dentries */
139 if (!css->cgroup->dentry)
140 return -EINVAL;
141
142 ino = css->cgroup->dentry->d_inode->i_ino;
143 css_put(css);
144
145 if (ino != hwpoison_filter_memcg)
146 return -EINVAL;
147
148 return 0;
149}
150#else
151static int hwpoison_filter_task(struct page *p) { return 0; }
152#endif
153
Wu Fengguang7c116f22009-12-16 12:19:59 +0100154int hwpoison_filter(struct page *p)
155{
Haicheng Li1bfe5fe2009-12-16 12:19:59 +0100156 if (!hwpoison_filter_enable)
157 return 0;
158
Wu Fengguang7c116f22009-12-16 12:19:59 +0100159 if (hwpoison_filter_dev(p))
160 return -EINVAL;
161
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100162 if (hwpoison_filter_flags(p))
163 return -EINVAL;
164
Andi Kleen4fd466e2009-12-16 12:19:59 +0100165 if (hwpoison_filter_task(p))
166 return -EINVAL;
167
Wu Fengguang7c116f22009-12-16 12:19:59 +0100168 return 0;
169}
Andi Kleen27df5062009-12-21 19:56:42 +0100170#else
171int hwpoison_filter(struct page *p)
172{
173 return 0;
174}
175#endif
176
Wu Fengguang7c116f22009-12-16 12:19:59 +0100177EXPORT_SYMBOL_GPL(hwpoison_filter);
178
Andi Kleen6a460792009-09-16 11:50:15 +0200179/*
180 * Send all the processes who have the page mapped an ``action optional''
181 * signal.
182 */
183static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
184 unsigned long pfn)
185{
186 struct siginfo si;
187 int ret;
188
189 printk(KERN_ERR
190 "MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
191 pfn, t->comm, t->pid);
192 si.si_signo = SIGBUS;
193 si.si_errno = 0;
194 si.si_code = BUS_MCEERR_AO;
195 si.si_addr = (void *)addr;
196#ifdef __ARCH_SI_TRAPNO
197 si.si_trapno = trapno;
198#endif
199 si.si_addr_lsb = PAGE_SHIFT;
200 /*
201 * Don't use force here, it's convenient if the signal
202 * can be temporarily blocked.
203 * This could cause a loop when the user sets SIGBUS
204 * to SIG_IGN, but hopefully noone will do that?
205 */
206 ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
207 if (ret < 0)
208 printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
209 t->comm, t->pid, ret);
210 return ret;
211}
212
213/*
Andi Kleen588f9ce2009-12-16 12:19:57 +0100214 * When a unknown page type is encountered drain as many buffers as possible
215 * in the hope to turn the page into a LRU or free page, which we can handle.
216 */
Andi Kleenfacb6012009-12-16 12:20:00 +0100217void shake_page(struct page *p, int access)
Andi Kleen588f9ce2009-12-16 12:19:57 +0100218{
219 if (!PageSlab(p)) {
220 lru_add_drain_all();
221 if (PageLRU(p))
222 return;
223 drain_all_pages();
224 if (PageLRU(p) || is_free_buddy_page(p))
225 return;
226 }
Andi Kleenfacb6012009-12-16 12:20:00 +0100227
Andi Kleen588f9ce2009-12-16 12:19:57 +0100228 /*
Andi Kleenfacb6012009-12-16 12:20:00 +0100229 * Only all shrink_slab here (which would also
230 * shrink other caches) if access is not potentially fatal.
Andi Kleen588f9ce2009-12-16 12:19:57 +0100231 */
Andi Kleenfacb6012009-12-16 12:20:00 +0100232 if (access) {
233 int nr;
234 do {
235 nr = shrink_slab(1000, GFP_KERNEL, 1000);
236 if (page_count(p) == 0)
237 break;
238 } while (nr > 10);
239 }
Andi Kleen588f9ce2009-12-16 12:19:57 +0100240}
241EXPORT_SYMBOL_GPL(shake_page);
242
243/*
Andi Kleen6a460792009-09-16 11:50:15 +0200244 * Kill all processes that have a poisoned page mapped and then isolate
245 * the page.
246 *
247 * General strategy:
248 * Find all processes having the page mapped and kill them.
249 * But we keep a page reference around so that the page is not
250 * actually freed yet.
251 * Then stash the page away
252 *
253 * There's no convenient way to get back to mapped processes
254 * from the VMAs. So do a brute-force search over all
255 * running processes.
256 *
257 * Remember that machine checks are not common (or rather
258 * if they are common you have other problems), so this shouldn't
259 * be a performance issue.
260 *
261 * Also there are some races possible while we get from the
262 * error detection to actually handle it.
263 */
264
265struct to_kill {
266 struct list_head nd;
267 struct task_struct *tsk;
268 unsigned long addr;
269 unsigned addr_valid:1;
270};
271
272/*
273 * Failure handling: if we can't find or can't kill a process there's
274 * not much we can do. We just print a message and ignore otherwise.
275 */
276
277/*
278 * Schedule a process for later kill.
279 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
280 * TBD would GFP_NOIO be enough?
281 */
282static void add_to_kill(struct task_struct *tsk, struct page *p,
283 struct vm_area_struct *vma,
284 struct list_head *to_kill,
285 struct to_kill **tkc)
286{
287 struct to_kill *tk;
288
289 if (*tkc) {
290 tk = *tkc;
291 *tkc = NULL;
292 } else {
293 tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
294 if (!tk) {
295 printk(KERN_ERR
296 "MCE: Out of memory while machine check handling\n");
297 return;
298 }
299 }
300 tk->addr = page_address_in_vma(p, vma);
301 tk->addr_valid = 1;
302
303 /*
304 * In theory we don't have to kill when the page was
305 * munmaped. But it could be also a mremap. Since that's
306 * likely very rare kill anyways just out of paranoia, but use
307 * a SIGKILL because the error is not contained anymore.
308 */
309 if (tk->addr == -EFAULT) {
310 pr_debug("MCE: Unable to find user space address %lx in %s\n",
311 page_to_pfn(p), tsk->comm);
312 tk->addr_valid = 0;
313 }
314 get_task_struct(tsk);
315 tk->tsk = tsk;
316 list_add_tail(&tk->nd, to_kill);
317}
318
319/*
320 * Kill the processes that have been collected earlier.
321 *
322 * Only do anything when DOIT is set, otherwise just free the list
323 * (this is used for clean pages which do not need killing)
324 * Also when FAIL is set do a force kill because something went
325 * wrong earlier.
326 */
327static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
328 int fail, unsigned long pfn)
329{
330 struct to_kill *tk, *next;
331
332 list_for_each_entry_safe (tk, next, to_kill, nd) {
333 if (doit) {
334 /*
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200335 * In case something went wrong with munmapping
Andi Kleen6a460792009-09-16 11:50:15 +0200336 * make sure the process doesn't catch the
337 * signal and then access the memory. Just kill it.
Andi Kleen6a460792009-09-16 11:50:15 +0200338 */
339 if (fail || tk->addr_valid == 0) {
340 printk(KERN_ERR
341 "MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
342 pfn, tk->tsk->comm, tk->tsk->pid);
343 force_sig(SIGKILL, tk->tsk);
344 }
345
346 /*
347 * In theory the process could have mapped
348 * something else on the address in-between. We could
349 * check for that, but we need to tell the
350 * process anyways.
351 */
352 else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
353 pfn) < 0)
354 printk(KERN_ERR
355 "MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
356 pfn, tk->tsk->comm, tk->tsk->pid);
357 }
358 put_task_struct(tk->tsk);
359 kfree(tk);
360 }
361}
362
363static int task_early_kill(struct task_struct *tsk)
364{
365 if (!tsk->mm)
366 return 0;
367 if (tsk->flags & PF_MCE_PROCESS)
368 return !!(tsk->flags & PF_MCE_EARLY);
369 return sysctl_memory_failure_early_kill;
370}
371
372/*
373 * Collect processes when the error hit an anonymous page.
374 */
375static void collect_procs_anon(struct page *page, struct list_head *to_kill,
376 struct to_kill **tkc)
377{
378 struct vm_area_struct *vma;
379 struct task_struct *tsk;
380 struct anon_vma *av;
381
382 read_lock(&tasklist_lock);
383 av = page_lock_anon_vma(page);
384 if (av == NULL) /* Not actually mapped anymore */
385 goto out;
386 for_each_process (tsk) {
Rik van Riel5beb4932010-03-05 13:42:07 -0800387 struct anon_vma_chain *vmac;
388
Andi Kleen6a460792009-09-16 11:50:15 +0200389 if (!task_early_kill(tsk))
390 continue;
Rik van Riel5beb4932010-03-05 13:42:07 -0800391 list_for_each_entry(vmac, &av->head, same_anon_vma) {
392 vma = vmac->vma;
Andi Kleen6a460792009-09-16 11:50:15 +0200393 if (!page_mapped_in_vma(page, vma))
394 continue;
395 if (vma->vm_mm == tsk->mm)
396 add_to_kill(tsk, page, vma, to_kill, tkc);
397 }
398 }
399 page_unlock_anon_vma(av);
400out:
401 read_unlock(&tasklist_lock);
402}
403
404/*
405 * Collect processes when the error hit a file mapped page.
406 */
407static void collect_procs_file(struct page *page, struct list_head *to_kill,
408 struct to_kill **tkc)
409{
410 struct vm_area_struct *vma;
411 struct task_struct *tsk;
412 struct prio_tree_iter iter;
413 struct address_space *mapping = page->mapping;
414
415 /*
416 * A note on the locking order between the two locks.
417 * We don't rely on this particular order.
418 * If you have some other code that needs a different order
419 * feel free to switch them around. Or add a reverse link
420 * from mm_struct to task_struct, then this could be all
421 * done without taking tasklist_lock and looping over all tasks.
422 */
423
424 read_lock(&tasklist_lock);
425 spin_lock(&mapping->i_mmap_lock);
426 for_each_process(tsk) {
427 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
428
429 if (!task_early_kill(tsk))
430 continue;
431
432 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff,
433 pgoff) {
434 /*
435 * Send early kill signal to tasks where a vma covers
436 * the page but the corrupted page is not necessarily
437 * mapped it in its pte.
438 * Assume applications who requested early kill want
439 * to be informed of all such data corruptions.
440 */
441 if (vma->vm_mm == tsk->mm)
442 add_to_kill(tsk, page, vma, to_kill, tkc);
443 }
444 }
445 spin_unlock(&mapping->i_mmap_lock);
446 read_unlock(&tasklist_lock);
447}
448
449/*
450 * Collect the processes who have the corrupted page mapped to kill.
451 * This is done in two steps for locking reasons.
452 * First preallocate one tokill structure outside the spin locks,
453 * so that we can kill at least one process reasonably reliable.
454 */
455static void collect_procs(struct page *page, struct list_head *tokill)
456{
457 struct to_kill *tk;
458
459 if (!page->mapping)
460 return;
461
462 tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
463 if (!tk)
464 return;
465 if (PageAnon(page))
466 collect_procs_anon(page, tokill, &tk);
467 else
468 collect_procs_file(page, tokill, &tk);
469 kfree(tk);
470}
471
472/*
473 * Error handlers for various types of pages.
474 */
475
476enum outcome {
Wu Fengguangd95ea512009-12-16 12:19:58 +0100477 IGNORED, /* Error: cannot be handled */
478 FAILED, /* Error: handling failed */
Andi Kleen6a460792009-09-16 11:50:15 +0200479 DELAYED, /* Will be handled later */
Andi Kleen6a460792009-09-16 11:50:15 +0200480 RECOVERED, /* Successfully recovered */
481};
482
483static const char *action_name[] = {
Wu Fengguangd95ea512009-12-16 12:19:58 +0100484 [IGNORED] = "Ignored",
Andi Kleen6a460792009-09-16 11:50:15 +0200485 [FAILED] = "Failed",
486 [DELAYED] = "Delayed",
Andi Kleen6a460792009-09-16 11:50:15 +0200487 [RECOVERED] = "Recovered",
488};
489
490/*
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +0100491 * XXX: It is possible that a page is isolated from LRU cache,
492 * and then kept in swap cache or failed to remove from page cache.
493 * The page count will stop it from being freed by unpoison.
494 * Stress tests should be aware of this memory leak problem.
495 */
496static int delete_from_lru_cache(struct page *p)
497{
498 if (!isolate_lru_page(p)) {
499 /*
500 * Clear sensible page flags, so that the buddy system won't
501 * complain when the page is unpoison-and-freed.
502 */
503 ClearPageActive(p);
504 ClearPageUnevictable(p);
505 /*
506 * drop the page count elevated by isolate_lru_page()
507 */
508 page_cache_release(p);
509 return 0;
510 }
511 return -EIO;
512}
513
514/*
Andi Kleen6a460792009-09-16 11:50:15 +0200515 * Error hit kernel page.
516 * Do nothing, try to be lucky and not touch this instead. For a few cases we
517 * could be more sophisticated.
518 */
519static int me_kernel(struct page *p, unsigned long pfn)
520{
Andi Kleen6a460792009-09-16 11:50:15 +0200521 return IGNORED;
522}
523
524/*
525 * Page in unknown state. Do nothing.
526 */
527static int me_unknown(struct page *p, unsigned long pfn)
528{
529 printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
530 return FAILED;
531}
532
533/*
Andi Kleen6a460792009-09-16 11:50:15 +0200534 * Clean (or cleaned) page cache page.
535 */
536static int me_pagecache_clean(struct page *p, unsigned long pfn)
537{
538 int err;
539 int ret = FAILED;
540 struct address_space *mapping;
541
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +0100542 delete_from_lru_cache(p);
543
Andi Kleen6a460792009-09-16 11:50:15 +0200544 /*
545 * For anonymous pages we're done the only reference left
546 * should be the one m_f() holds.
547 */
548 if (PageAnon(p))
549 return RECOVERED;
550
551 /*
552 * Now truncate the page in the page cache. This is really
553 * more like a "temporary hole punch"
554 * Don't do this for block devices when someone else
555 * has a reference, because it could be file system metadata
556 * and that's not safe to truncate.
557 */
558 mapping = page_mapping(p);
559 if (!mapping) {
560 /*
561 * Page has been teared down in the meanwhile
562 */
563 return FAILED;
564 }
565
566 /*
567 * Truncation is a bit tricky. Enable it per file system for now.
568 *
569 * Open: to take i_mutex or not for this? Right now we don't.
570 */
571 if (mapping->a_ops->error_remove_page) {
572 err = mapping->a_ops->error_remove_page(mapping, p);
573 if (err != 0) {
574 printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
575 pfn, err);
576 } else if (page_has_private(p) &&
577 !try_to_release_page(p, GFP_NOIO)) {
578 pr_debug("MCE %#lx: failed to release buffers\n", pfn);
579 } else {
580 ret = RECOVERED;
581 }
582 } else {
583 /*
584 * If the file system doesn't support it just invalidate
585 * This fails on dirty or anything with private pages
586 */
587 if (invalidate_inode_page(p))
588 ret = RECOVERED;
589 else
590 printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
591 pfn);
592 }
593 return ret;
594}
595
596/*
597 * Dirty cache page page
598 * Issues: when the error hit a hole page the error is not properly
599 * propagated.
600 */
601static int me_pagecache_dirty(struct page *p, unsigned long pfn)
602{
603 struct address_space *mapping = page_mapping(p);
604
605 SetPageError(p);
606 /* TBD: print more information about the file. */
607 if (mapping) {
608 /*
609 * IO error will be reported by write(), fsync(), etc.
610 * who check the mapping.
611 * This way the application knows that something went
612 * wrong with its dirty file data.
613 *
614 * There's one open issue:
615 *
616 * The EIO will be only reported on the next IO
617 * operation and then cleared through the IO map.
618 * Normally Linux has two mechanisms to pass IO error
619 * first through the AS_EIO flag in the address space
620 * and then through the PageError flag in the page.
621 * Since we drop pages on memory failure handling the
622 * only mechanism open to use is through AS_AIO.
623 *
624 * This has the disadvantage that it gets cleared on
625 * the first operation that returns an error, while
626 * the PageError bit is more sticky and only cleared
627 * when the page is reread or dropped. If an
628 * application assumes it will always get error on
629 * fsync, but does other operations on the fd before
630 * and the page is dropped inbetween then the error
631 * will not be properly reported.
632 *
633 * This can already happen even without hwpoisoned
634 * pages: first on metadata IO errors (which only
635 * report through AS_EIO) or when the page is dropped
636 * at the wrong time.
637 *
638 * So right now we assume that the application DTRT on
639 * the first EIO, but we're not worse than other parts
640 * of the kernel.
641 */
642 mapping_set_error(mapping, EIO);
643 }
644
645 return me_pagecache_clean(p, pfn);
646}
647
648/*
649 * Clean and dirty swap cache.
650 *
651 * Dirty swap cache page is tricky to handle. The page could live both in page
652 * cache and swap cache(ie. page is freshly swapped in). So it could be
653 * referenced concurrently by 2 types of PTEs:
654 * normal PTEs and swap PTEs. We try to handle them consistently by calling
655 * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
656 * and then
657 * - clear dirty bit to prevent IO
658 * - remove from LRU
659 * - but keep in the swap cache, so that when we return to it on
660 * a later page fault, we know the application is accessing
661 * corrupted data and shall be killed (we installed simple
662 * interception code in do_swap_page to catch it).
663 *
664 * Clean swap cache pages can be directly isolated. A later page fault will
665 * bring in the known good data from disk.
666 */
667static int me_swapcache_dirty(struct page *p, unsigned long pfn)
668{
Andi Kleen6a460792009-09-16 11:50:15 +0200669 ClearPageDirty(p);
670 /* Trigger EIO in shmem: */
671 ClearPageUptodate(p);
672
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +0100673 if (!delete_from_lru_cache(p))
674 return DELAYED;
675 else
676 return FAILED;
Andi Kleen6a460792009-09-16 11:50:15 +0200677}
678
679static int me_swapcache_clean(struct page *p, unsigned long pfn)
680{
Andi Kleen6a460792009-09-16 11:50:15 +0200681 delete_from_swap_cache(p);
Wu Fengguange43c3af2009-09-29 13:16:20 +0800682
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +0100683 if (!delete_from_lru_cache(p))
684 return RECOVERED;
685 else
686 return FAILED;
Andi Kleen6a460792009-09-16 11:50:15 +0200687}
688
689/*
690 * Huge pages. Needs work.
691 * Issues:
692 * No rmap support so we cannot find the original mapper. In theory could walk
693 * all MMs and look for the mappings, but that would be non atomic and racy.
694 * Need rmap for hugepages for this. Alternatively we could employ a heuristic,
695 * like just walking the current process and hoping it has it mapped (that
696 * should be usually true for the common "shared database cache" case)
697 * Should handle free huge pages and dequeue them too, but this needs to
698 * handle huge page accounting correctly.
699 */
700static int me_huge_page(struct page *p, unsigned long pfn)
701{
702 return FAILED;
703}
704
705/*
706 * Various page states we can handle.
707 *
708 * A page state is defined by its current page->flags bits.
709 * The table matches them in order and calls the right handler.
710 *
711 * This is quite tricky because we can access page at any time
712 * in its live cycle, so all accesses have to be extremly careful.
713 *
714 * This is not complete. More states could be added.
715 * For any missing state don't attempt recovery.
716 */
717
718#define dirty (1UL << PG_dirty)
719#define sc (1UL << PG_swapcache)
720#define unevict (1UL << PG_unevictable)
721#define mlock (1UL << PG_mlocked)
722#define writeback (1UL << PG_writeback)
723#define lru (1UL << PG_lru)
724#define swapbacked (1UL << PG_swapbacked)
725#define head (1UL << PG_head)
726#define tail (1UL << PG_tail)
727#define compound (1UL << PG_compound)
728#define slab (1UL << PG_slab)
Andi Kleen6a460792009-09-16 11:50:15 +0200729#define reserved (1UL << PG_reserved)
730
731static struct page_state {
732 unsigned long mask;
733 unsigned long res;
734 char *msg;
735 int (*action)(struct page *p, unsigned long pfn);
736} error_states[] = {
Wu Fengguangd95ea512009-12-16 12:19:58 +0100737 { reserved, reserved, "reserved kernel", me_kernel },
Wu Fengguang95d01fc2009-12-16 12:19:58 +0100738 /*
739 * free pages are specially detected outside this table:
740 * PG_buddy pages only make a small fraction of all free pages.
741 */
Andi Kleen6a460792009-09-16 11:50:15 +0200742
743 /*
744 * Could in theory check if slab page is free or if we can drop
745 * currently unused objects without touching them. But just
746 * treat it as standard kernel for now.
747 */
748 { slab, slab, "kernel slab", me_kernel },
749
750#ifdef CONFIG_PAGEFLAGS_EXTENDED
751 { head, head, "huge", me_huge_page },
752 { tail, tail, "huge", me_huge_page },
753#else
754 { compound, compound, "huge", me_huge_page },
755#endif
756
757 { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty },
758 { sc|dirty, sc, "swapcache", me_swapcache_clean },
759
760 { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
761 { unevict, unevict, "unevictable LRU", me_pagecache_clean},
762
Andi Kleen6a460792009-09-16 11:50:15 +0200763 { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
764 { mlock, mlock, "mlocked LRU", me_pagecache_clean },
Andi Kleen6a460792009-09-16 11:50:15 +0200765
766 { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
767 { lru|dirty, lru, "clean LRU", me_pagecache_clean },
Andi Kleen6a460792009-09-16 11:50:15 +0200768
769 /*
770 * Catchall entry: must be at end.
771 */
772 { 0, 0, "unknown page state", me_unknown },
773};
774
Andi Kleen2326c462009-12-16 12:20:00 +0100775#undef dirty
776#undef sc
777#undef unevict
778#undef mlock
779#undef writeback
780#undef lru
781#undef swapbacked
782#undef head
783#undef tail
784#undef compound
785#undef slab
786#undef reserved
787
Andi Kleen6a460792009-09-16 11:50:15 +0200788static void action_result(unsigned long pfn, char *msg, int result)
789{
Wu Fengguanga7560fc2009-12-16 12:19:57 +0100790 struct page *page = pfn_to_page(pfn);
Andi Kleen6a460792009-09-16 11:50:15 +0200791
792 printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
793 pfn,
Wu Fengguanga7560fc2009-12-16 12:19:57 +0100794 PageDirty(page) ? "dirty " : "",
Andi Kleen6a460792009-09-16 11:50:15 +0200795 msg, action_name[result]);
796}
797
798static int page_action(struct page_state *ps, struct page *p,
Wu Fengguangbd1ce5f2009-12-16 12:19:57 +0100799 unsigned long pfn)
Andi Kleen6a460792009-09-16 11:50:15 +0200800{
801 int result;
Wu Fengguang7456b042009-10-19 08:15:01 +0200802 int count;
Andi Kleen6a460792009-09-16 11:50:15 +0200803
804 result = ps->action(p, pfn);
805 action_result(pfn, ps->msg, result);
Wu Fengguang7456b042009-10-19 08:15:01 +0200806
Wu Fengguangbd1ce5f2009-12-16 12:19:57 +0100807 count = page_count(p) - 1;
Wu Fengguang138ce282009-12-16 12:19:58 +0100808 if (ps->action == me_swapcache_dirty && result == DELAYED)
809 count--;
810 if (count != 0) {
Andi Kleen6a460792009-09-16 11:50:15 +0200811 printk(KERN_ERR
812 "MCE %#lx: %s page still referenced by %d users\n",
Wu Fengguang7456b042009-10-19 08:15:01 +0200813 pfn, ps->msg, count);
Wu Fengguang138ce282009-12-16 12:19:58 +0100814 result = FAILED;
815 }
Andi Kleen6a460792009-09-16 11:50:15 +0200816
817 /* Could do more checks here if page looks ok */
818 /*
819 * Could adjust zone counters here to correct for the missing page.
820 */
821
Wu Fengguang138ce282009-12-16 12:19:58 +0100822 return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
Andi Kleen6a460792009-09-16 11:50:15 +0200823}
824
825#define N_UNMAP_TRIES 5
826
827/*
828 * Do all that is necessary to remove user space mappings. Unmap
829 * the pages and send SIGBUS to the processes if the data was dirty.
830 */
Wu Fengguang1668bfd2009-12-16 12:19:58 +0100831static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
Andi Kleen6a460792009-09-16 11:50:15 +0200832 int trapno)
833{
834 enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
835 struct address_space *mapping;
836 LIST_HEAD(tokill);
837 int ret;
838 int i;
839 int kill = 1;
840
Wu Fengguang1668bfd2009-12-16 12:19:58 +0100841 if (PageReserved(p) || PageSlab(p))
842 return SWAP_SUCCESS;
Andi Kleen6a460792009-09-16 11:50:15 +0200843
Andi Kleen6a460792009-09-16 11:50:15 +0200844 /*
845 * This check implies we don't kill processes if their pages
846 * are in the swap cache early. Those are always late kills.
847 */
848 if (!page_mapped(p))
Wu Fengguang1668bfd2009-12-16 12:19:58 +0100849 return SWAP_SUCCESS;
850
851 if (PageCompound(p) || PageKsm(p))
852 return SWAP_FAIL;
Andi Kleen6a460792009-09-16 11:50:15 +0200853
854 if (PageSwapCache(p)) {
855 printk(KERN_ERR
856 "MCE %#lx: keeping poisoned page in swap cache\n", pfn);
857 ttu |= TTU_IGNORE_HWPOISON;
858 }
859
860 /*
861 * Propagate the dirty bit from PTEs to struct page first, because we
862 * need this to decide if we should kill or just drop the page.
Wu Fengguangdb0480b2009-12-16 12:19:58 +0100863 * XXX: the dirty test could be racy: set_page_dirty() may not always
864 * be called inside page lock (it's recommended but not enforced).
Andi Kleen6a460792009-09-16 11:50:15 +0200865 */
866 mapping = page_mapping(p);
867 if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) {
868 if (page_mkclean(p)) {
869 SetPageDirty(p);
870 } else {
871 kill = 0;
872 ttu |= TTU_IGNORE_HWPOISON;
873 printk(KERN_INFO
874 "MCE %#lx: corrupted page was clean: dropped without side effects\n",
875 pfn);
876 }
877 }
878
879 /*
880 * First collect all the processes that have the page
881 * mapped in dirty form. This has to be done before try_to_unmap,
882 * because ttu takes the rmap data structures down.
883 *
884 * Error handling: We ignore errors here because
885 * there's nothing that can be done.
886 */
887 if (kill)
888 collect_procs(p, &tokill);
889
890 /*
891 * try_to_unmap can fail temporarily due to races.
892 * Try a few times (RED-PEN better strategy?)
893 */
894 for (i = 0; i < N_UNMAP_TRIES; i++) {
895 ret = try_to_unmap(p, ttu);
896 if (ret == SWAP_SUCCESS)
897 break;
898 pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn, ret);
899 }
900
901 if (ret != SWAP_SUCCESS)
902 printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
903 pfn, page_mapcount(p));
904
905 /*
906 * Now that the dirty bit has been propagated to the
907 * struct page and all unmaps done we can decide if
908 * killing is needed or not. Only kill when the page
909 * was dirty, otherwise the tokill list is merely
910 * freed. When there was a problem unmapping earlier
911 * use a more force-full uncatchable kill to prevent
912 * any accesses to the poisoned memory.
913 */
914 kill_procs_ao(&tokill, !!PageDirty(p), trapno,
915 ret != SWAP_SUCCESS, pfn);
Wu Fengguang1668bfd2009-12-16 12:19:58 +0100916
917 return ret;
Andi Kleen6a460792009-09-16 11:50:15 +0200918}
919
Andi Kleen82ba0112009-12-16 12:19:57 +0100920int __memory_failure(unsigned long pfn, int trapno, int flags)
Andi Kleen6a460792009-09-16 11:50:15 +0200921{
922 struct page_state *ps;
923 struct page *p;
924 int res;
925
926 if (!sysctl_memory_failure_recovery)
927 panic("Memory failure from trap %d on page %lx", trapno, pfn);
928
929 if (!pfn_valid(pfn)) {
Wu Fengguanga7560fc2009-12-16 12:19:57 +0100930 printk(KERN_ERR
931 "MCE %#lx: memory outside kernel control\n",
932 pfn);
933 return -ENXIO;
Andi Kleen6a460792009-09-16 11:50:15 +0200934 }
935
936 p = pfn_to_page(pfn);
937 if (TestSetPageHWPoison(p)) {
Wu Fengguangd95ea512009-12-16 12:19:58 +0100938 printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
Andi Kleen6a460792009-09-16 11:50:15 +0200939 return 0;
940 }
941
942 atomic_long_add(1, &mce_bad_pages);
943
944 /*
945 * We need/can do nothing about count=0 pages.
946 * 1) it's a free page, and therefore in safe hand:
947 * prep_new_page() will be the gate keeper.
948 * 2) it's part of a non-compound high order page.
949 * Implies some kernel user: cannot stop them from
950 * R/W the page; let's pray that the page has been
951 * used and will be freed some time later.
952 * In fact it's dangerous to directly bump up page count from 0,
953 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
954 */
Andi Kleen82ba0112009-12-16 12:19:57 +0100955 if (!(flags & MF_COUNT_INCREASED) &&
956 !get_page_unless_zero(compound_head(p))) {
Wu Fengguang8d22ba12009-12-16 12:19:58 +0100957 if (is_free_buddy_page(p)) {
958 action_result(pfn, "free buddy", DELAYED);
959 return 0;
960 } else {
961 action_result(pfn, "high order kernel", IGNORED);
962 return -EBUSY;
963 }
Andi Kleen6a460792009-09-16 11:50:15 +0200964 }
965
966 /*
Wu Fengguange43c3af2009-09-29 13:16:20 +0800967 * We ignore non-LRU pages for good reasons.
968 * - PG_locked is only well defined for LRU pages and a few others
969 * - to avoid races with __set_page_locked()
970 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
971 * The check (unnecessarily) ignores LRU pages being isolated and
972 * walked by the page reclaim code, however that's not a big loss.
973 */
974 if (!PageLRU(p))
Andi Kleenfacb6012009-12-16 12:20:00 +0100975 shake_page(p, 0);
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +0100976 if (!PageLRU(p)) {
Andi Kleen0474a602009-12-16 12:20:00 +0100977 /*
978 * shake_page could have turned it free.
979 */
980 if (is_free_buddy_page(p)) {
981 action_result(pfn, "free buddy, 2nd try", DELAYED);
982 return 0;
983 }
Wu Fengguange43c3af2009-09-29 13:16:20 +0800984 action_result(pfn, "non LRU", IGNORED);
985 put_page(p);
986 return -EBUSY;
987 }
Wu Fengguange43c3af2009-09-29 13:16:20 +0800988
989 /*
Andi Kleen6a460792009-09-16 11:50:15 +0200990 * Lock the page and wait for writeback to finish.
991 * It's very difficult to mess with pages currently under IO
992 * and in many cases impossible, so we just avoid it here.
993 */
994 lock_page_nosync(p);
Wu Fengguang847ce402009-12-16 12:19:58 +0100995
996 /*
997 * unpoison always clear PG_hwpoison inside page lock
998 */
999 if (!PageHWPoison(p)) {
Wu Fengguangd95ea512009-12-16 12:19:58 +01001000 printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
Wu Fengguang847ce402009-12-16 12:19:58 +01001001 res = 0;
1002 goto out;
1003 }
Wu Fengguang7c116f22009-12-16 12:19:59 +01001004 if (hwpoison_filter(p)) {
1005 if (TestClearPageHWPoison(p))
1006 atomic_long_dec(&mce_bad_pages);
1007 unlock_page(p);
1008 put_page(p);
1009 return 0;
1010 }
Wu Fengguang847ce402009-12-16 12:19:58 +01001011
Andi Kleen6a460792009-09-16 11:50:15 +02001012 wait_on_page_writeback(p);
1013
1014 /*
1015 * Now take care of user space mappings.
Wu Fengguang1668bfd2009-12-16 12:19:58 +01001016 * Abort on fail: __remove_from_page_cache() assumes unmapped page.
Andi Kleen6a460792009-09-16 11:50:15 +02001017 */
Wu Fengguang1668bfd2009-12-16 12:19:58 +01001018 if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) {
1019 printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
1020 res = -EBUSY;
1021 goto out;
1022 }
Andi Kleen6a460792009-09-16 11:50:15 +02001023
1024 /*
1025 * Torn down by someone else?
1026 */
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +01001027 if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
Andi Kleen6a460792009-09-16 11:50:15 +02001028 action_result(pfn, "already truncated LRU", IGNORED);
Wu Fengguangd95ea512009-12-16 12:19:58 +01001029 res = -EBUSY;
Andi Kleen6a460792009-09-16 11:50:15 +02001030 goto out;
1031 }
1032
1033 res = -EBUSY;
1034 for (ps = error_states;; ps++) {
Wu Fengguangdc2a1cb2009-12-16 12:19:58 +01001035 if ((p->flags & ps->mask) == ps->res) {
Wu Fengguangbd1ce5f2009-12-16 12:19:57 +01001036 res = page_action(ps, p, pfn);
Andi Kleen6a460792009-09-16 11:50:15 +02001037 break;
1038 }
1039 }
1040out:
1041 unlock_page(p);
1042 return res;
1043}
1044EXPORT_SYMBOL_GPL(__memory_failure);
1045
1046/**
1047 * memory_failure - Handle memory failure of a page.
1048 * @pfn: Page Number of the corrupted page
1049 * @trapno: Trap number reported in the signal to user space.
1050 *
1051 * This function is called by the low level machine check code
1052 * of an architecture when it detects hardware memory corruption
1053 * of a page. It tries its best to recover, which includes
1054 * dropping pages, killing processes etc.
1055 *
1056 * The function is primarily of use for corruptions that
1057 * happen outside the current execution context (e.g. when
1058 * detected by a background scrubber)
1059 *
1060 * Must run in process context (e.g. a work queue) with interrupts
1061 * enabled and no spinlocks hold.
1062 */
1063void memory_failure(unsigned long pfn, int trapno)
1064{
1065 __memory_failure(pfn, trapno, 0);
1066}
Wu Fengguang847ce402009-12-16 12:19:58 +01001067
1068/**
1069 * unpoison_memory - Unpoison a previously poisoned page
1070 * @pfn: Page number of the to be unpoisoned page
1071 *
1072 * Software-unpoison a page that has been poisoned by
1073 * memory_failure() earlier.
1074 *
1075 * This is only done on the software-level, so it only works
1076 * for linux injected failures, not real hardware failures
1077 *
1078 * Returns 0 for success, otherwise -errno.
1079 */
1080int unpoison_memory(unsigned long pfn)
1081{
1082 struct page *page;
1083 struct page *p;
1084 int freeit = 0;
1085
1086 if (!pfn_valid(pfn))
1087 return -ENXIO;
1088
1089 p = pfn_to_page(pfn);
1090 page = compound_head(p);
1091
1092 if (!PageHWPoison(p)) {
1093 pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn);
1094 return 0;
1095 }
1096
1097 if (!get_page_unless_zero(page)) {
1098 if (TestClearPageHWPoison(p))
1099 atomic_long_dec(&mce_bad_pages);
1100 pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn);
1101 return 0;
1102 }
1103
1104 lock_page_nosync(page);
1105 /*
1106 * This test is racy because PG_hwpoison is set outside of page lock.
1107 * That's acceptable because that won't trigger kernel panic. Instead,
1108 * the PG_hwpoison page will be caught and isolated on the entrance to
1109 * the free buddy page pool.
1110 */
1111 if (TestClearPageHWPoison(p)) {
1112 pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn);
1113 atomic_long_dec(&mce_bad_pages);
1114 freeit = 1;
1115 }
1116 unlock_page(page);
1117
1118 put_page(page);
1119 if (freeit)
1120 put_page(page);
1121
1122 return 0;
1123}
1124EXPORT_SYMBOL(unpoison_memory);
Andi Kleenfacb6012009-12-16 12:20:00 +01001125
1126static struct page *new_page(struct page *p, unsigned long private, int **x)
1127{
Andi Kleen12686d12009-12-16 12:20:01 +01001128 int nid = page_to_nid(p);
1129 return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
Andi Kleenfacb6012009-12-16 12:20:00 +01001130}
1131
1132/*
1133 * Safely get reference count of an arbitrary page.
1134 * Returns 0 for a free page, -EIO for a zero refcount page
1135 * that is not free, and 1 for any other page type.
1136 * For 1 the page is returned with increased page count, otherwise not.
1137 */
1138static int get_any_page(struct page *p, unsigned long pfn, int flags)
1139{
1140 int ret;
1141
1142 if (flags & MF_COUNT_INCREASED)
1143 return 1;
1144
1145 /*
1146 * The lock_system_sleep prevents a race with memory hotplug,
1147 * because the isolation assumes there's only a single user.
1148 * This is a big hammer, a better would be nicer.
1149 */
1150 lock_system_sleep();
1151
1152 /*
1153 * Isolate the page, so that it doesn't get reallocated if it
1154 * was free.
1155 */
1156 set_migratetype_isolate(p);
1157 if (!get_page_unless_zero(compound_head(p))) {
1158 if (is_free_buddy_page(p)) {
1159 pr_debug("get_any_page: %#lx free buddy page\n", pfn);
1160 /* Set hwpoison bit while page is still isolated */
1161 SetPageHWPoison(p);
1162 ret = 0;
1163 } else {
1164 pr_debug("get_any_page: %#lx: unknown zero refcount page type %lx\n",
1165 pfn, p->flags);
1166 ret = -EIO;
1167 }
1168 } else {
1169 /* Not a free page */
1170 ret = 1;
1171 }
1172 unset_migratetype_isolate(p);
1173 unlock_system_sleep();
1174 return ret;
1175}
1176
1177/**
1178 * soft_offline_page - Soft offline a page.
1179 * @page: page to offline
1180 * @flags: flags. Same as memory_failure().
1181 *
1182 * Returns 0 on success, otherwise negated errno.
1183 *
1184 * Soft offline a page, by migration or invalidation,
1185 * without killing anything. This is for the case when
1186 * a page is not corrupted yet (so it's still valid to access),
1187 * but has had a number of corrected errors and is better taken
1188 * out.
1189 *
1190 * The actual policy on when to do that is maintained by
1191 * user space.
1192 *
1193 * This should never impact any application or cause data loss,
1194 * however it might take some time.
1195 *
1196 * This is not a 100% solution for all memory, but tries to be
1197 * ``good enough'' for the majority of memory.
1198 */
1199int soft_offline_page(struct page *page, int flags)
1200{
1201 int ret;
1202 unsigned long pfn = page_to_pfn(page);
1203
1204 ret = get_any_page(page, pfn, flags);
1205 if (ret < 0)
1206 return ret;
1207 if (ret == 0)
1208 goto done;
1209
1210 /*
1211 * Page cache page we can handle?
1212 */
1213 if (!PageLRU(page)) {
1214 /*
1215 * Try to free it.
1216 */
1217 put_page(page);
1218 shake_page(page, 1);
1219
1220 /*
1221 * Did it turn free?
1222 */
1223 ret = get_any_page(page, pfn, 0);
1224 if (ret < 0)
1225 return ret;
1226 if (ret == 0)
1227 goto done;
1228 }
1229 if (!PageLRU(page)) {
1230 pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n",
1231 pfn, page->flags);
1232 return -EIO;
1233 }
1234
1235 lock_page(page);
1236 wait_on_page_writeback(page);
1237
1238 /*
1239 * Synchronized using the page lock with memory_failure()
1240 */
1241 if (PageHWPoison(page)) {
1242 unlock_page(page);
1243 put_page(page);
1244 pr_debug("soft offline: %#lx page already poisoned\n", pfn);
1245 return -EBUSY;
1246 }
1247
1248 /*
1249 * Try to invalidate first. This should work for
1250 * non dirty unmapped page cache pages.
1251 */
1252 ret = invalidate_inode_page(page);
1253 unlock_page(page);
1254
1255 /*
1256 * Drop count because page migration doesn't like raised
1257 * counts. The page could get re-allocated, but if it becomes
1258 * LRU the isolation will just fail.
1259 * RED-PEN would be better to keep it isolated here, but we
1260 * would need to fix isolation locking first.
1261 */
1262 put_page(page);
1263 if (ret == 1) {
1264 ret = 0;
1265 pr_debug("soft_offline: %#lx: invalidated\n", pfn);
1266 goto done;
1267 }
1268
1269 /*
1270 * Simple invalidation didn't work.
1271 * Try to migrate to a new page instead. migrate.c
1272 * handles a large number of cases for us.
1273 */
1274 ret = isolate_lru_page(page);
1275 if (!ret) {
1276 LIST_HEAD(pagelist);
1277
1278 list_add(&page->lru, &pagelist);
1279 ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
1280 if (ret) {
1281 pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
1282 pfn, ret, page->flags);
1283 if (ret > 0)
1284 ret = -EIO;
1285 }
1286 } else {
1287 pr_debug("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
1288 pfn, ret, page_count(page), page->flags);
1289 }
1290 if (ret)
1291 return ret;
1292
1293done:
1294 atomic_long_add(1, &mce_bad_pages);
1295 SetPageHWPoison(page);
1296 /* keep elevated page count for bad page */
1297 return ret;
1298}