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6a46079c AK |
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 | |
1c80b990 | 10 | * hardware as being corrupted usually due to a multi-bit ECC memory or cache |
6a46079c | 11 | * failure. |
1c80b990 AK |
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. | |
6a46079c AK |
15 | * |
16 | * Handles page cache pages in various states. The tricky part | |
1c80b990 AK |
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. | |
6a46079c AK |
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 | */ | |
6a46079c AK |
38 | #include <linux/kernel.h> |
39 | #include <linux/mm.h> | |
40 | #include <linux/page-flags.h> | |
478c5ffc | 41 | #include <linux/kernel-page-flags.h> |
6a46079c | 42 | #include <linux/sched.h> |
01e00f88 | 43 | #include <linux/ksm.h> |
6a46079c AK |
44 | #include <linux/rmap.h> |
45 | #include <linux/pagemap.h> | |
46 | #include <linux/swap.h> | |
47 | #include <linux/backing-dev.h> | |
facb6011 AK |
48 | #include <linux/migrate.h> |
49 | #include <linux/page-isolation.h> | |
50 | #include <linux/suspend.h> | |
5a0e3ad6 | 51 | #include <linux/slab.h> |
bf998156 | 52 | #include <linux/swapops.h> |
7af446a8 | 53 | #include <linux/hugetlb.h> |
6a46079c AK |
54 | #include "internal.h" |
55 | ||
56 | int sysctl_memory_failure_early_kill __read_mostly = 0; | |
57 | ||
58 | int sysctl_memory_failure_recovery __read_mostly = 1; | |
59 | ||
60 | atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0); | |
61 | ||
27df5068 AK |
62 | #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE) |
63 | ||
1bfe5feb | 64 | u32 hwpoison_filter_enable = 0; |
7c116f2b WF |
65 | u32 hwpoison_filter_dev_major = ~0U; |
66 | u32 hwpoison_filter_dev_minor = ~0U; | |
478c5ffc WF |
67 | u64 hwpoison_filter_flags_mask; |
68 | u64 hwpoison_filter_flags_value; | |
1bfe5feb | 69 | EXPORT_SYMBOL_GPL(hwpoison_filter_enable); |
7c116f2b WF |
70 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major); |
71 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor); | |
478c5ffc WF |
72 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask); |
73 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value); | |
7c116f2b WF |
74 | |
75 | static int hwpoison_filter_dev(struct page *p) | |
76 | { | |
77 | struct address_space *mapping; | |
78 | dev_t dev; | |
79 | ||
80 | if (hwpoison_filter_dev_major == ~0U && | |
81 | hwpoison_filter_dev_minor == ~0U) | |
82 | return 0; | |
83 | ||
84 | /* | |
1c80b990 | 85 | * page_mapping() does not accept slab pages. |
7c116f2b WF |
86 | */ |
87 | if (PageSlab(p)) | |
88 | return -EINVAL; | |
89 | ||
90 | mapping = page_mapping(p); | |
91 | if (mapping == NULL || mapping->host == NULL) | |
92 | return -EINVAL; | |
93 | ||
94 | dev = mapping->host->i_sb->s_dev; | |
95 | if (hwpoison_filter_dev_major != ~0U && | |
96 | hwpoison_filter_dev_major != MAJOR(dev)) | |
97 | return -EINVAL; | |
98 | if (hwpoison_filter_dev_minor != ~0U && | |
99 | hwpoison_filter_dev_minor != MINOR(dev)) | |
100 | return -EINVAL; | |
101 | ||
102 | return 0; | |
103 | } | |
104 | ||
478c5ffc WF |
105 | static int hwpoison_filter_flags(struct page *p) |
106 | { | |
107 | if (!hwpoison_filter_flags_mask) | |
108 | return 0; | |
109 | ||
110 | if ((stable_page_flags(p) & hwpoison_filter_flags_mask) == | |
111 | hwpoison_filter_flags_value) | |
112 | return 0; | |
113 | else | |
114 | return -EINVAL; | |
115 | } | |
116 | ||
4fd466eb AK |
117 | /* |
118 | * This allows stress tests to limit test scope to a collection of tasks | |
119 | * by putting them under some memcg. This prevents killing unrelated/important | |
120 | * processes such as /sbin/init. Note that the target task may share clean | |
121 | * pages with init (eg. libc text), which is harmless. If the target task | |
122 | * share _dirty_ pages with another task B, the test scheme must make sure B | |
123 | * is also included in the memcg. At last, due to race conditions this filter | |
124 | * can only guarantee that the page either belongs to the memcg tasks, or is | |
125 | * a freed page. | |
126 | */ | |
127 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP | |
128 | u64 hwpoison_filter_memcg; | |
129 | EXPORT_SYMBOL_GPL(hwpoison_filter_memcg); | |
130 | static int hwpoison_filter_task(struct page *p) | |
131 | { | |
132 | struct mem_cgroup *mem; | |
133 | struct cgroup_subsys_state *css; | |
134 | unsigned long ino; | |
135 | ||
136 | if (!hwpoison_filter_memcg) | |
137 | return 0; | |
138 | ||
139 | mem = try_get_mem_cgroup_from_page(p); | |
140 | if (!mem) | |
141 | return -EINVAL; | |
142 | ||
143 | css = mem_cgroup_css(mem); | |
144 | /* root_mem_cgroup has NULL dentries */ | |
145 | if (!css->cgroup->dentry) | |
146 | return -EINVAL; | |
147 | ||
148 | ino = css->cgroup->dentry->d_inode->i_ino; | |
149 | css_put(css); | |
150 | ||
151 | if (ino != hwpoison_filter_memcg) | |
152 | return -EINVAL; | |
153 | ||
154 | return 0; | |
155 | } | |
156 | #else | |
157 | static int hwpoison_filter_task(struct page *p) { return 0; } | |
158 | #endif | |
159 | ||
7c116f2b WF |
160 | int hwpoison_filter(struct page *p) |
161 | { | |
1bfe5feb HL |
162 | if (!hwpoison_filter_enable) |
163 | return 0; | |
164 | ||
7c116f2b WF |
165 | if (hwpoison_filter_dev(p)) |
166 | return -EINVAL; | |
167 | ||
478c5ffc WF |
168 | if (hwpoison_filter_flags(p)) |
169 | return -EINVAL; | |
170 | ||
4fd466eb AK |
171 | if (hwpoison_filter_task(p)) |
172 | return -EINVAL; | |
173 | ||
7c116f2b WF |
174 | return 0; |
175 | } | |
27df5068 AK |
176 | #else |
177 | int hwpoison_filter(struct page *p) | |
178 | { | |
179 | return 0; | |
180 | } | |
181 | #endif | |
182 | ||
7c116f2b WF |
183 | EXPORT_SYMBOL_GPL(hwpoison_filter); |
184 | ||
6a46079c AK |
185 | /* |
186 | * Send all the processes who have the page mapped an ``action optional'' | |
187 | * signal. | |
188 | */ | |
189 | static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno, | |
0d9ee6a2 | 190 | unsigned long pfn, struct page *page) |
6a46079c AK |
191 | { |
192 | struct siginfo si; | |
193 | int ret; | |
194 | ||
195 | printk(KERN_ERR | |
196 | "MCE %#lx: Killing %s:%d early due to hardware memory corruption\n", | |
197 | pfn, t->comm, t->pid); | |
198 | si.si_signo = SIGBUS; | |
199 | si.si_errno = 0; | |
200 | si.si_code = BUS_MCEERR_AO; | |
201 | si.si_addr = (void *)addr; | |
202 | #ifdef __ARCH_SI_TRAPNO | |
203 | si.si_trapno = trapno; | |
204 | #endif | |
0d9ee6a2 | 205 | si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT; |
6a46079c AK |
206 | /* |
207 | * Don't use force here, it's convenient if the signal | |
208 | * can be temporarily blocked. | |
209 | * This could cause a loop when the user sets SIGBUS | |
210 | * to SIG_IGN, but hopefully noone will do that? | |
211 | */ | |
212 | ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */ | |
213 | if (ret < 0) | |
214 | printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n", | |
215 | t->comm, t->pid, ret); | |
216 | return ret; | |
217 | } | |
218 | ||
588f9ce6 AK |
219 | /* |
220 | * When a unknown page type is encountered drain as many buffers as possible | |
221 | * in the hope to turn the page into a LRU or free page, which we can handle. | |
222 | */ | |
facb6011 | 223 | void shake_page(struct page *p, int access) |
588f9ce6 AK |
224 | { |
225 | if (!PageSlab(p)) { | |
226 | lru_add_drain_all(); | |
227 | if (PageLRU(p)) | |
228 | return; | |
229 | drain_all_pages(); | |
230 | if (PageLRU(p) || is_free_buddy_page(p)) | |
231 | return; | |
232 | } | |
facb6011 | 233 | |
588f9ce6 | 234 | /* |
facb6011 AK |
235 | * Only all shrink_slab here (which would also |
236 | * shrink other caches) if access is not potentially fatal. | |
588f9ce6 | 237 | */ |
facb6011 AK |
238 | if (access) { |
239 | int nr; | |
240 | do { | |
241 | nr = shrink_slab(1000, GFP_KERNEL, 1000); | |
47f43e7e | 242 | if (page_count(p) == 1) |
facb6011 AK |
243 | break; |
244 | } while (nr > 10); | |
245 | } | |
588f9ce6 AK |
246 | } |
247 | EXPORT_SYMBOL_GPL(shake_page); | |
248 | ||
6a46079c AK |
249 | /* |
250 | * Kill all processes that have a poisoned page mapped and then isolate | |
251 | * the page. | |
252 | * | |
253 | * General strategy: | |
254 | * Find all processes having the page mapped and kill them. | |
255 | * But we keep a page reference around so that the page is not | |
256 | * actually freed yet. | |
257 | * Then stash the page away | |
258 | * | |
259 | * There's no convenient way to get back to mapped processes | |
260 | * from the VMAs. So do a brute-force search over all | |
261 | * running processes. | |
262 | * | |
263 | * Remember that machine checks are not common (or rather | |
264 | * if they are common you have other problems), so this shouldn't | |
265 | * be a performance issue. | |
266 | * | |
267 | * Also there are some races possible while we get from the | |
268 | * error detection to actually handle it. | |
269 | */ | |
270 | ||
271 | struct to_kill { | |
272 | struct list_head nd; | |
273 | struct task_struct *tsk; | |
274 | unsigned long addr; | |
9033ae16 | 275 | char addr_valid; |
6a46079c AK |
276 | }; |
277 | ||
278 | /* | |
279 | * Failure handling: if we can't find or can't kill a process there's | |
280 | * not much we can do. We just print a message and ignore otherwise. | |
281 | */ | |
282 | ||
283 | /* | |
284 | * Schedule a process for later kill. | |
285 | * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM. | |
286 | * TBD would GFP_NOIO be enough? | |
287 | */ | |
288 | static void add_to_kill(struct task_struct *tsk, struct page *p, | |
289 | struct vm_area_struct *vma, | |
290 | struct list_head *to_kill, | |
291 | struct to_kill **tkc) | |
292 | { | |
293 | struct to_kill *tk; | |
294 | ||
295 | if (*tkc) { | |
296 | tk = *tkc; | |
297 | *tkc = NULL; | |
298 | } else { | |
299 | tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC); | |
300 | if (!tk) { | |
301 | printk(KERN_ERR | |
302 | "MCE: Out of memory while machine check handling\n"); | |
303 | return; | |
304 | } | |
305 | } | |
306 | tk->addr = page_address_in_vma(p, vma); | |
307 | tk->addr_valid = 1; | |
308 | ||
309 | /* | |
310 | * In theory we don't have to kill when the page was | |
311 | * munmaped. But it could be also a mremap. Since that's | |
312 | * likely very rare kill anyways just out of paranoia, but use | |
313 | * a SIGKILL because the error is not contained anymore. | |
314 | */ | |
315 | if (tk->addr == -EFAULT) { | |
fb46e735 | 316 | pr_info("MCE: Unable to find user space address %lx in %s\n", |
6a46079c AK |
317 | page_to_pfn(p), tsk->comm); |
318 | tk->addr_valid = 0; | |
319 | } | |
320 | get_task_struct(tsk); | |
321 | tk->tsk = tsk; | |
322 | list_add_tail(&tk->nd, to_kill); | |
323 | } | |
324 | ||
325 | /* | |
326 | * Kill the processes that have been collected earlier. | |
327 | * | |
328 | * Only do anything when DOIT is set, otherwise just free the list | |
329 | * (this is used for clean pages which do not need killing) | |
330 | * Also when FAIL is set do a force kill because something went | |
331 | * wrong earlier. | |
332 | */ | |
333 | static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno, | |
0d9ee6a2 | 334 | int fail, struct page *page, unsigned long pfn) |
6a46079c AK |
335 | { |
336 | struct to_kill *tk, *next; | |
337 | ||
338 | list_for_each_entry_safe (tk, next, to_kill, nd) { | |
339 | if (doit) { | |
340 | /* | |
af901ca1 | 341 | * In case something went wrong with munmapping |
6a46079c AK |
342 | * make sure the process doesn't catch the |
343 | * signal and then access the memory. Just kill it. | |
6a46079c AK |
344 | */ |
345 | if (fail || tk->addr_valid == 0) { | |
346 | printk(KERN_ERR | |
347 | "MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", | |
348 | pfn, tk->tsk->comm, tk->tsk->pid); | |
349 | force_sig(SIGKILL, tk->tsk); | |
350 | } | |
351 | ||
352 | /* | |
353 | * In theory the process could have mapped | |
354 | * something else on the address in-between. We could | |
355 | * check for that, but we need to tell the | |
356 | * process anyways. | |
357 | */ | |
358 | else if (kill_proc_ao(tk->tsk, tk->addr, trapno, | |
0d9ee6a2 | 359 | pfn, page) < 0) |
6a46079c AK |
360 | printk(KERN_ERR |
361 | "MCE %#lx: Cannot send advisory machine check signal to %s:%d\n", | |
362 | pfn, tk->tsk->comm, tk->tsk->pid); | |
363 | } | |
364 | put_task_struct(tk->tsk); | |
365 | kfree(tk); | |
366 | } | |
367 | } | |
368 | ||
369 | static int task_early_kill(struct task_struct *tsk) | |
370 | { | |
371 | if (!tsk->mm) | |
372 | return 0; | |
373 | if (tsk->flags & PF_MCE_PROCESS) | |
374 | return !!(tsk->flags & PF_MCE_EARLY); | |
375 | return sysctl_memory_failure_early_kill; | |
376 | } | |
377 | ||
378 | /* | |
379 | * Collect processes when the error hit an anonymous page. | |
380 | */ | |
381 | static void collect_procs_anon(struct page *page, struct list_head *to_kill, | |
382 | struct to_kill **tkc) | |
383 | { | |
384 | struct vm_area_struct *vma; | |
385 | struct task_struct *tsk; | |
386 | struct anon_vma *av; | |
387 | ||
388 | read_lock(&tasklist_lock); | |
389 | av = page_lock_anon_vma(page); | |
390 | if (av == NULL) /* Not actually mapped anymore */ | |
391 | goto out; | |
392 | for_each_process (tsk) { | |
5beb4930 RR |
393 | struct anon_vma_chain *vmac; |
394 | ||
6a46079c AK |
395 | if (!task_early_kill(tsk)) |
396 | continue; | |
5beb4930 RR |
397 | list_for_each_entry(vmac, &av->head, same_anon_vma) { |
398 | vma = vmac->vma; | |
6a46079c AK |
399 | if (!page_mapped_in_vma(page, vma)) |
400 | continue; | |
401 | if (vma->vm_mm == tsk->mm) | |
402 | add_to_kill(tsk, page, vma, to_kill, tkc); | |
403 | } | |
404 | } | |
405 | page_unlock_anon_vma(av); | |
406 | out: | |
407 | read_unlock(&tasklist_lock); | |
408 | } | |
409 | ||
410 | /* | |
411 | * Collect processes when the error hit a file mapped page. | |
412 | */ | |
413 | static void collect_procs_file(struct page *page, struct list_head *to_kill, | |
414 | struct to_kill **tkc) | |
415 | { | |
416 | struct vm_area_struct *vma; | |
417 | struct task_struct *tsk; | |
418 | struct prio_tree_iter iter; | |
419 | struct address_space *mapping = page->mapping; | |
420 | ||
421 | /* | |
422 | * A note on the locking order between the two locks. | |
423 | * We don't rely on this particular order. | |
424 | * If you have some other code that needs a different order | |
425 | * feel free to switch them around. Or add a reverse link | |
426 | * from mm_struct to task_struct, then this could be all | |
427 | * done without taking tasklist_lock and looping over all tasks. | |
428 | */ | |
429 | ||
430 | read_lock(&tasklist_lock); | |
431 | spin_lock(&mapping->i_mmap_lock); | |
432 | for_each_process(tsk) { | |
433 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
434 | ||
435 | if (!task_early_kill(tsk)) | |
436 | continue; | |
437 | ||
438 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, | |
439 | pgoff) { | |
440 | /* | |
441 | * Send early kill signal to tasks where a vma covers | |
442 | * the page but the corrupted page is not necessarily | |
443 | * mapped it in its pte. | |
444 | * Assume applications who requested early kill want | |
445 | * to be informed of all such data corruptions. | |
446 | */ | |
447 | if (vma->vm_mm == tsk->mm) | |
448 | add_to_kill(tsk, page, vma, to_kill, tkc); | |
449 | } | |
450 | } | |
451 | spin_unlock(&mapping->i_mmap_lock); | |
452 | read_unlock(&tasklist_lock); | |
453 | } | |
454 | ||
455 | /* | |
456 | * Collect the processes who have the corrupted page mapped to kill. | |
457 | * This is done in two steps for locking reasons. | |
458 | * First preallocate one tokill structure outside the spin locks, | |
459 | * so that we can kill at least one process reasonably reliable. | |
460 | */ | |
461 | static void collect_procs(struct page *page, struct list_head *tokill) | |
462 | { | |
463 | struct to_kill *tk; | |
464 | ||
465 | if (!page->mapping) | |
466 | return; | |
467 | ||
468 | tk = kmalloc(sizeof(struct to_kill), GFP_NOIO); | |
469 | if (!tk) | |
470 | return; | |
471 | if (PageAnon(page)) | |
472 | collect_procs_anon(page, tokill, &tk); | |
473 | else | |
474 | collect_procs_file(page, tokill, &tk); | |
475 | kfree(tk); | |
476 | } | |
477 | ||
478 | /* | |
479 | * Error handlers for various types of pages. | |
480 | */ | |
481 | ||
482 | enum outcome { | |
d95ea51e WF |
483 | IGNORED, /* Error: cannot be handled */ |
484 | FAILED, /* Error: handling failed */ | |
6a46079c | 485 | DELAYED, /* Will be handled later */ |
6a46079c AK |
486 | RECOVERED, /* Successfully recovered */ |
487 | }; | |
488 | ||
489 | static const char *action_name[] = { | |
d95ea51e | 490 | [IGNORED] = "Ignored", |
6a46079c AK |
491 | [FAILED] = "Failed", |
492 | [DELAYED] = "Delayed", | |
6a46079c AK |
493 | [RECOVERED] = "Recovered", |
494 | }; | |
495 | ||
dc2a1cbf WF |
496 | /* |
497 | * XXX: It is possible that a page is isolated from LRU cache, | |
498 | * and then kept in swap cache or failed to remove from page cache. | |
499 | * The page count will stop it from being freed by unpoison. | |
500 | * Stress tests should be aware of this memory leak problem. | |
501 | */ | |
502 | static int delete_from_lru_cache(struct page *p) | |
503 | { | |
504 | if (!isolate_lru_page(p)) { | |
505 | /* | |
506 | * Clear sensible page flags, so that the buddy system won't | |
507 | * complain when the page is unpoison-and-freed. | |
508 | */ | |
509 | ClearPageActive(p); | |
510 | ClearPageUnevictable(p); | |
511 | /* | |
512 | * drop the page count elevated by isolate_lru_page() | |
513 | */ | |
514 | page_cache_release(p); | |
515 | return 0; | |
516 | } | |
517 | return -EIO; | |
518 | } | |
519 | ||
6a46079c AK |
520 | /* |
521 | * Error hit kernel page. | |
522 | * Do nothing, try to be lucky and not touch this instead. For a few cases we | |
523 | * could be more sophisticated. | |
524 | */ | |
525 | static int me_kernel(struct page *p, unsigned long pfn) | |
6a46079c AK |
526 | { |
527 | return IGNORED; | |
528 | } | |
529 | ||
530 | /* | |
531 | * Page in unknown state. Do nothing. | |
532 | */ | |
533 | static int me_unknown(struct page *p, unsigned long pfn) | |
534 | { | |
535 | printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn); | |
536 | return FAILED; | |
537 | } | |
538 | ||
6a46079c AK |
539 | /* |
540 | * Clean (or cleaned) page cache page. | |
541 | */ | |
542 | static int me_pagecache_clean(struct page *p, unsigned long pfn) | |
543 | { | |
544 | int err; | |
545 | int ret = FAILED; | |
546 | struct address_space *mapping; | |
547 | ||
dc2a1cbf WF |
548 | delete_from_lru_cache(p); |
549 | ||
6a46079c AK |
550 | /* |
551 | * For anonymous pages we're done the only reference left | |
552 | * should be the one m_f() holds. | |
553 | */ | |
554 | if (PageAnon(p)) | |
555 | return RECOVERED; | |
556 | ||
557 | /* | |
558 | * Now truncate the page in the page cache. This is really | |
559 | * more like a "temporary hole punch" | |
560 | * Don't do this for block devices when someone else | |
561 | * has a reference, because it could be file system metadata | |
562 | * and that's not safe to truncate. | |
563 | */ | |
564 | mapping = page_mapping(p); | |
565 | if (!mapping) { | |
566 | /* | |
567 | * Page has been teared down in the meanwhile | |
568 | */ | |
569 | return FAILED; | |
570 | } | |
571 | ||
572 | /* | |
573 | * Truncation is a bit tricky. Enable it per file system for now. | |
574 | * | |
575 | * Open: to take i_mutex or not for this? Right now we don't. | |
576 | */ | |
577 | if (mapping->a_ops->error_remove_page) { | |
578 | err = mapping->a_ops->error_remove_page(mapping, p); | |
579 | if (err != 0) { | |
580 | printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n", | |
581 | pfn, err); | |
582 | } else if (page_has_private(p) && | |
583 | !try_to_release_page(p, GFP_NOIO)) { | |
fb46e735 | 584 | pr_info("MCE %#lx: failed to release buffers\n", pfn); |
6a46079c AK |
585 | } else { |
586 | ret = RECOVERED; | |
587 | } | |
588 | } else { | |
589 | /* | |
590 | * If the file system doesn't support it just invalidate | |
591 | * This fails on dirty or anything with private pages | |
592 | */ | |
593 | if (invalidate_inode_page(p)) | |
594 | ret = RECOVERED; | |
595 | else | |
596 | printk(KERN_INFO "MCE %#lx: Failed to invalidate\n", | |
597 | pfn); | |
598 | } | |
599 | return ret; | |
600 | } | |
601 | ||
602 | /* | |
603 | * Dirty cache page page | |
604 | * Issues: when the error hit a hole page the error is not properly | |
605 | * propagated. | |
606 | */ | |
607 | static int me_pagecache_dirty(struct page *p, unsigned long pfn) | |
608 | { | |
609 | struct address_space *mapping = page_mapping(p); | |
610 | ||
611 | SetPageError(p); | |
612 | /* TBD: print more information about the file. */ | |
613 | if (mapping) { | |
614 | /* | |
615 | * IO error will be reported by write(), fsync(), etc. | |
616 | * who check the mapping. | |
617 | * This way the application knows that something went | |
618 | * wrong with its dirty file data. | |
619 | * | |
620 | * There's one open issue: | |
621 | * | |
622 | * The EIO will be only reported on the next IO | |
623 | * operation and then cleared through the IO map. | |
624 | * Normally Linux has two mechanisms to pass IO error | |
625 | * first through the AS_EIO flag in the address space | |
626 | * and then through the PageError flag in the page. | |
627 | * Since we drop pages on memory failure handling the | |
628 | * only mechanism open to use is through AS_AIO. | |
629 | * | |
630 | * This has the disadvantage that it gets cleared on | |
631 | * the first operation that returns an error, while | |
632 | * the PageError bit is more sticky and only cleared | |
633 | * when the page is reread or dropped. If an | |
634 | * application assumes it will always get error on | |
635 | * fsync, but does other operations on the fd before | |
636 | * and the page is dropped inbetween then the error | |
637 | * will not be properly reported. | |
638 | * | |
639 | * This can already happen even without hwpoisoned | |
640 | * pages: first on metadata IO errors (which only | |
641 | * report through AS_EIO) or when the page is dropped | |
642 | * at the wrong time. | |
643 | * | |
644 | * So right now we assume that the application DTRT on | |
645 | * the first EIO, but we're not worse than other parts | |
646 | * of the kernel. | |
647 | */ | |
648 | mapping_set_error(mapping, EIO); | |
649 | } | |
650 | ||
651 | return me_pagecache_clean(p, pfn); | |
652 | } | |
653 | ||
654 | /* | |
655 | * Clean and dirty swap cache. | |
656 | * | |
657 | * Dirty swap cache page is tricky to handle. The page could live both in page | |
658 | * cache and swap cache(ie. page is freshly swapped in). So it could be | |
659 | * referenced concurrently by 2 types of PTEs: | |
660 | * normal PTEs and swap PTEs. We try to handle them consistently by calling | |
661 | * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs, | |
662 | * and then | |
663 | * - clear dirty bit to prevent IO | |
664 | * - remove from LRU | |
665 | * - but keep in the swap cache, so that when we return to it on | |
666 | * a later page fault, we know the application is accessing | |
667 | * corrupted data and shall be killed (we installed simple | |
668 | * interception code in do_swap_page to catch it). | |
669 | * | |
670 | * Clean swap cache pages can be directly isolated. A later page fault will | |
671 | * bring in the known good data from disk. | |
672 | */ | |
673 | static int me_swapcache_dirty(struct page *p, unsigned long pfn) | |
674 | { | |
6a46079c AK |
675 | ClearPageDirty(p); |
676 | /* Trigger EIO in shmem: */ | |
677 | ClearPageUptodate(p); | |
678 | ||
dc2a1cbf WF |
679 | if (!delete_from_lru_cache(p)) |
680 | return DELAYED; | |
681 | else | |
682 | return FAILED; | |
6a46079c AK |
683 | } |
684 | ||
685 | static int me_swapcache_clean(struct page *p, unsigned long pfn) | |
686 | { | |
6a46079c | 687 | delete_from_swap_cache(p); |
e43c3afb | 688 | |
dc2a1cbf WF |
689 | if (!delete_from_lru_cache(p)) |
690 | return RECOVERED; | |
691 | else | |
692 | return FAILED; | |
6a46079c AK |
693 | } |
694 | ||
695 | /* | |
696 | * Huge pages. Needs work. | |
697 | * Issues: | |
93f70f90 NH |
698 | * - Error on hugepage is contained in hugepage unit (not in raw page unit.) |
699 | * To narrow down kill region to one page, we need to break up pmd. | |
6a46079c AK |
700 | */ |
701 | static int me_huge_page(struct page *p, unsigned long pfn) | |
702 | { | |
6de2b1aa | 703 | int res = 0; |
93f70f90 NH |
704 | struct page *hpage = compound_head(p); |
705 | /* | |
706 | * We can safely recover from error on free or reserved (i.e. | |
707 | * not in-use) hugepage by dequeuing it from freelist. | |
708 | * To check whether a hugepage is in-use or not, we can't use | |
709 | * page->lru because it can be used in other hugepage operations, | |
710 | * such as __unmap_hugepage_range() and gather_surplus_pages(). | |
711 | * So instead we use page_mapping() and PageAnon(). | |
712 | * We assume that this function is called with page lock held, | |
713 | * so there is no race between isolation and mapping/unmapping. | |
714 | */ | |
715 | if (!(page_mapping(hpage) || PageAnon(hpage))) { | |
6de2b1aa NH |
716 | res = dequeue_hwpoisoned_huge_page(hpage); |
717 | if (!res) | |
718 | return RECOVERED; | |
93f70f90 NH |
719 | } |
720 | return DELAYED; | |
6a46079c AK |
721 | } |
722 | ||
723 | /* | |
724 | * Various page states we can handle. | |
725 | * | |
726 | * A page state is defined by its current page->flags bits. | |
727 | * The table matches them in order and calls the right handler. | |
728 | * | |
729 | * This is quite tricky because we can access page at any time | |
730 | * in its live cycle, so all accesses have to be extremly careful. | |
731 | * | |
732 | * This is not complete. More states could be added. | |
733 | * For any missing state don't attempt recovery. | |
734 | */ | |
735 | ||
736 | #define dirty (1UL << PG_dirty) | |
737 | #define sc (1UL << PG_swapcache) | |
738 | #define unevict (1UL << PG_unevictable) | |
739 | #define mlock (1UL << PG_mlocked) | |
740 | #define writeback (1UL << PG_writeback) | |
741 | #define lru (1UL << PG_lru) | |
742 | #define swapbacked (1UL << PG_swapbacked) | |
743 | #define head (1UL << PG_head) | |
744 | #define tail (1UL << PG_tail) | |
745 | #define compound (1UL << PG_compound) | |
746 | #define slab (1UL << PG_slab) | |
6a46079c AK |
747 | #define reserved (1UL << PG_reserved) |
748 | ||
749 | static struct page_state { | |
750 | unsigned long mask; | |
751 | unsigned long res; | |
752 | char *msg; | |
753 | int (*action)(struct page *p, unsigned long pfn); | |
754 | } error_states[] = { | |
d95ea51e | 755 | { reserved, reserved, "reserved kernel", me_kernel }, |
95d01fc6 WF |
756 | /* |
757 | * free pages are specially detected outside this table: | |
758 | * PG_buddy pages only make a small fraction of all free pages. | |
759 | */ | |
6a46079c AK |
760 | |
761 | /* | |
762 | * Could in theory check if slab page is free or if we can drop | |
763 | * currently unused objects without touching them. But just | |
764 | * treat it as standard kernel for now. | |
765 | */ | |
766 | { slab, slab, "kernel slab", me_kernel }, | |
767 | ||
768 | #ifdef CONFIG_PAGEFLAGS_EXTENDED | |
769 | { head, head, "huge", me_huge_page }, | |
770 | { tail, tail, "huge", me_huge_page }, | |
771 | #else | |
772 | { compound, compound, "huge", me_huge_page }, | |
773 | #endif | |
774 | ||
775 | { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty }, | |
776 | { sc|dirty, sc, "swapcache", me_swapcache_clean }, | |
777 | ||
778 | { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty}, | |
779 | { unevict, unevict, "unevictable LRU", me_pagecache_clean}, | |
780 | ||
6a46079c AK |
781 | { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty }, |
782 | { mlock, mlock, "mlocked LRU", me_pagecache_clean }, | |
6a46079c AK |
783 | |
784 | { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty }, | |
785 | { lru|dirty, lru, "clean LRU", me_pagecache_clean }, | |
6a46079c AK |
786 | |
787 | /* | |
788 | * Catchall entry: must be at end. | |
789 | */ | |
790 | { 0, 0, "unknown page state", me_unknown }, | |
791 | }; | |
792 | ||
2326c467 AK |
793 | #undef dirty |
794 | #undef sc | |
795 | #undef unevict | |
796 | #undef mlock | |
797 | #undef writeback | |
798 | #undef lru | |
799 | #undef swapbacked | |
800 | #undef head | |
801 | #undef tail | |
802 | #undef compound | |
803 | #undef slab | |
804 | #undef reserved | |
805 | ||
6a46079c AK |
806 | static void action_result(unsigned long pfn, char *msg, int result) |
807 | { | |
a7560fc8 | 808 | struct page *page = pfn_to_page(pfn); |
6a46079c AK |
809 | |
810 | printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n", | |
811 | pfn, | |
a7560fc8 | 812 | PageDirty(page) ? "dirty " : "", |
6a46079c AK |
813 | msg, action_name[result]); |
814 | } | |
815 | ||
816 | static int page_action(struct page_state *ps, struct page *p, | |
bd1ce5f9 | 817 | unsigned long pfn) |
6a46079c AK |
818 | { |
819 | int result; | |
7456b040 | 820 | int count; |
6a46079c AK |
821 | |
822 | result = ps->action(p, pfn); | |
823 | action_result(pfn, ps->msg, result); | |
7456b040 | 824 | |
bd1ce5f9 | 825 | count = page_count(p) - 1; |
138ce286 WF |
826 | if (ps->action == me_swapcache_dirty && result == DELAYED) |
827 | count--; | |
828 | if (count != 0) { | |
6a46079c AK |
829 | printk(KERN_ERR |
830 | "MCE %#lx: %s page still referenced by %d users\n", | |
7456b040 | 831 | pfn, ps->msg, count); |
138ce286 WF |
832 | result = FAILED; |
833 | } | |
6a46079c AK |
834 | |
835 | /* Could do more checks here if page looks ok */ | |
836 | /* | |
837 | * Could adjust zone counters here to correct for the missing page. | |
838 | */ | |
839 | ||
138ce286 | 840 | return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY; |
6a46079c AK |
841 | } |
842 | ||
6a46079c AK |
843 | /* |
844 | * Do all that is necessary to remove user space mappings. Unmap | |
845 | * the pages and send SIGBUS to the processes if the data was dirty. | |
846 | */ | |
1668bfd5 | 847 | static int hwpoison_user_mappings(struct page *p, unsigned long pfn, |
6a46079c AK |
848 | int trapno) |
849 | { | |
850 | enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; | |
851 | struct address_space *mapping; | |
852 | LIST_HEAD(tokill); | |
853 | int ret; | |
6a46079c | 854 | int kill = 1; |
7af446a8 | 855 | struct page *hpage = compound_head(p); |
6a46079c | 856 | |
1668bfd5 WF |
857 | if (PageReserved(p) || PageSlab(p)) |
858 | return SWAP_SUCCESS; | |
6a46079c | 859 | |
6a46079c AK |
860 | /* |
861 | * This check implies we don't kill processes if their pages | |
862 | * are in the swap cache early. Those are always late kills. | |
863 | */ | |
7af446a8 | 864 | if (!page_mapped(hpage)) |
1668bfd5 WF |
865 | return SWAP_SUCCESS; |
866 | ||
7af446a8 | 867 | if (PageKsm(p)) |
1668bfd5 | 868 | return SWAP_FAIL; |
6a46079c AK |
869 | |
870 | if (PageSwapCache(p)) { | |
871 | printk(KERN_ERR | |
872 | "MCE %#lx: keeping poisoned page in swap cache\n", pfn); | |
873 | ttu |= TTU_IGNORE_HWPOISON; | |
874 | } | |
875 | ||
876 | /* | |
877 | * Propagate the dirty bit from PTEs to struct page first, because we | |
878 | * need this to decide if we should kill or just drop the page. | |
db0480b3 WF |
879 | * XXX: the dirty test could be racy: set_page_dirty() may not always |
880 | * be called inside page lock (it's recommended but not enforced). | |
6a46079c | 881 | */ |
7af446a8 NH |
882 | mapping = page_mapping(hpage); |
883 | if (!PageDirty(hpage) && mapping && | |
884 | mapping_cap_writeback_dirty(mapping)) { | |
885 | if (page_mkclean(hpage)) { | |
886 | SetPageDirty(hpage); | |
6a46079c AK |
887 | } else { |
888 | kill = 0; | |
889 | ttu |= TTU_IGNORE_HWPOISON; | |
890 | printk(KERN_INFO | |
891 | "MCE %#lx: corrupted page was clean: dropped without side effects\n", | |
892 | pfn); | |
893 | } | |
894 | } | |
895 | ||
896 | /* | |
897 | * First collect all the processes that have the page | |
898 | * mapped in dirty form. This has to be done before try_to_unmap, | |
899 | * because ttu takes the rmap data structures down. | |
900 | * | |
901 | * Error handling: We ignore errors here because | |
902 | * there's nothing that can be done. | |
903 | */ | |
904 | if (kill) | |
7af446a8 | 905 | collect_procs(hpage, &tokill); |
6a46079c | 906 | |
a08c80eb | 907 | ret = try_to_unmap(hpage, ttu); |
6a46079c AK |
908 | if (ret != SWAP_SUCCESS) |
909 | printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n", | |
7af446a8 | 910 | pfn, page_mapcount(hpage)); |
6a46079c AK |
911 | |
912 | /* | |
913 | * Now that the dirty bit has been propagated to the | |
914 | * struct page and all unmaps done we can decide if | |
915 | * killing is needed or not. Only kill when the page | |
916 | * was dirty, otherwise the tokill list is merely | |
917 | * freed. When there was a problem unmapping earlier | |
918 | * use a more force-full uncatchable kill to prevent | |
919 | * any accesses to the poisoned memory. | |
920 | */ | |
7af446a8 | 921 | kill_procs_ao(&tokill, !!PageDirty(hpage), trapno, |
0d9ee6a2 | 922 | ret != SWAP_SUCCESS, p, pfn); |
1668bfd5 WF |
923 | |
924 | return ret; | |
6a46079c AK |
925 | } |
926 | ||
7013febc NH |
927 | static void set_page_hwpoison_huge_page(struct page *hpage) |
928 | { | |
929 | int i; | |
930 | int nr_pages = 1 << compound_order(hpage); | |
931 | for (i = 0; i < nr_pages; i++) | |
932 | SetPageHWPoison(hpage + i); | |
933 | } | |
934 | ||
935 | static void clear_page_hwpoison_huge_page(struct page *hpage) | |
936 | { | |
937 | int i; | |
938 | int nr_pages = 1 << compound_order(hpage); | |
939 | for (i = 0; i < nr_pages; i++) | |
940 | ClearPageHWPoison(hpage + i); | |
941 | } | |
942 | ||
82ba011b | 943 | int __memory_failure(unsigned long pfn, int trapno, int flags) |
6a46079c AK |
944 | { |
945 | struct page_state *ps; | |
946 | struct page *p; | |
7af446a8 | 947 | struct page *hpage; |
6a46079c | 948 | int res; |
c9fbdd5f | 949 | unsigned int nr_pages; |
6a46079c AK |
950 | |
951 | if (!sysctl_memory_failure_recovery) | |
952 | panic("Memory failure from trap %d on page %lx", trapno, pfn); | |
953 | ||
954 | if (!pfn_valid(pfn)) { | |
a7560fc8 WF |
955 | printk(KERN_ERR |
956 | "MCE %#lx: memory outside kernel control\n", | |
957 | pfn); | |
958 | return -ENXIO; | |
6a46079c AK |
959 | } |
960 | ||
961 | p = pfn_to_page(pfn); | |
7af446a8 | 962 | hpage = compound_head(p); |
6a46079c | 963 | if (TestSetPageHWPoison(p)) { |
d95ea51e | 964 | printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn); |
6a46079c AK |
965 | return 0; |
966 | } | |
967 | ||
c9fbdd5f NH |
968 | nr_pages = 1 << compound_order(hpage); |
969 | atomic_long_add(nr_pages, &mce_bad_pages); | |
6a46079c AK |
970 | |
971 | /* | |
972 | * We need/can do nothing about count=0 pages. | |
973 | * 1) it's a free page, and therefore in safe hand: | |
974 | * prep_new_page() will be the gate keeper. | |
8c6c2ecb NH |
975 | * 2) it's a free hugepage, which is also safe: |
976 | * an affected hugepage will be dequeued from hugepage freelist, | |
977 | * so there's no concern about reusing it ever after. | |
978 | * 3) it's part of a non-compound high order page. | |
6a46079c AK |
979 | * Implies some kernel user: cannot stop them from |
980 | * R/W the page; let's pray that the page has been | |
981 | * used and will be freed some time later. | |
982 | * In fact it's dangerous to directly bump up page count from 0, | |
983 | * that may make page_freeze_refs()/page_unfreeze_refs() mismatch. | |
984 | */ | |
82ba011b | 985 | if (!(flags & MF_COUNT_INCREASED) && |
7af446a8 | 986 | !get_page_unless_zero(hpage)) { |
8d22ba1b WF |
987 | if (is_free_buddy_page(p)) { |
988 | action_result(pfn, "free buddy", DELAYED); | |
989 | return 0; | |
8c6c2ecb NH |
990 | } else if (PageHuge(hpage)) { |
991 | /* | |
992 | * Check "just unpoisoned", "filter hit", and | |
993 | * "race with other subpage." | |
994 | */ | |
995 | lock_page_nosync(hpage); | |
996 | if (!PageHWPoison(hpage) | |
997 | || (hwpoison_filter(p) && TestClearPageHWPoison(p)) | |
998 | || (p != hpage && TestSetPageHWPoison(hpage))) { | |
999 | atomic_long_sub(nr_pages, &mce_bad_pages); | |
1000 | return 0; | |
1001 | } | |
1002 | set_page_hwpoison_huge_page(hpage); | |
1003 | res = dequeue_hwpoisoned_huge_page(hpage); | |
1004 | action_result(pfn, "free huge", | |
1005 | res ? IGNORED : DELAYED); | |
1006 | unlock_page(hpage); | |
1007 | return res; | |
8d22ba1b WF |
1008 | } else { |
1009 | action_result(pfn, "high order kernel", IGNORED); | |
1010 | return -EBUSY; | |
1011 | } | |
6a46079c AK |
1012 | } |
1013 | ||
e43c3afb WF |
1014 | /* |
1015 | * We ignore non-LRU pages for good reasons. | |
1016 | * - PG_locked is only well defined for LRU pages and a few others | |
1017 | * - to avoid races with __set_page_locked() | |
1018 | * - to avoid races with __SetPageSlab*() (and more non-atomic ops) | |
1019 | * The check (unnecessarily) ignores LRU pages being isolated and | |
1020 | * walked by the page reclaim code, however that's not a big loss. | |
1021 | */ | |
7af446a8 | 1022 | if (!PageLRU(p) && !PageHuge(p)) |
facb6011 | 1023 | shake_page(p, 0); |
7af446a8 | 1024 | if (!PageLRU(p) && !PageHuge(p)) { |
0474a60e AK |
1025 | /* |
1026 | * shake_page could have turned it free. | |
1027 | */ | |
1028 | if (is_free_buddy_page(p)) { | |
1029 | action_result(pfn, "free buddy, 2nd try", DELAYED); | |
1030 | return 0; | |
1031 | } | |
e43c3afb WF |
1032 | action_result(pfn, "non LRU", IGNORED); |
1033 | put_page(p); | |
1034 | return -EBUSY; | |
1035 | } | |
e43c3afb | 1036 | |
6a46079c AK |
1037 | /* |
1038 | * Lock the page and wait for writeback to finish. | |
1039 | * It's very difficult to mess with pages currently under IO | |
1040 | * and in many cases impossible, so we just avoid it here. | |
1041 | */ | |
7af446a8 | 1042 | lock_page_nosync(hpage); |
847ce401 WF |
1043 | |
1044 | /* | |
1045 | * unpoison always clear PG_hwpoison inside page lock | |
1046 | */ | |
1047 | if (!PageHWPoison(p)) { | |
d95ea51e | 1048 | printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn); |
847ce401 WF |
1049 | res = 0; |
1050 | goto out; | |
1051 | } | |
7c116f2b WF |
1052 | if (hwpoison_filter(p)) { |
1053 | if (TestClearPageHWPoison(p)) | |
c9fbdd5f | 1054 | atomic_long_sub(nr_pages, &mce_bad_pages); |
7af446a8 NH |
1055 | unlock_page(hpage); |
1056 | put_page(hpage); | |
7c116f2b WF |
1057 | return 0; |
1058 | } | |
847ce401 | 1059 | |
7013febc NH |
1060 | /* |
1061 | * For error on the tail page, we should set PG_hwpoison | |
1062 | * on the head page to show that the hugepage is hwpoisoned | |
1063 | */ | |
1064 | if (PageTail(p) && TestSetPageHWPoison(hpage)) { | |
1065 | action_result(pfn, "hugepage already hardware poisoned", | |
1066 | IGNORED); | |
1067 | unlock_page(hpage); | |
1068 | put_page(hpage); | |
1069 | return 0; | |
1070 | } | |
1071 | /* | |
1072 | * Set PG_hwpoison on all pages in an error hugepage, | |
1073 | * because containment is done in hugepage unit for now. | |
1074 | * Since we have done TestSetPageHWPoison() for the head page with | |
1075 | * page lock held, we can safely set PG_hwpoison bits on tail pages. | |
1076 | */ | |
1077 | if (PageHuge(p)) | |
1078 | set_page_hwpoison_huge_page(hpage); | |
1079 | ||
6a46079c AK |
1080 | wait_on_page_writeback(p); |
1081 | ||
1082 | /* | |
1083 | * Now take care of user space mappings. | |
1668bfd5 | 1084 | * Abort on fail: __remove_from_page_cache() assumes unmapped page. |
6a46079c | 1085 | */ |
1668bfd5 WF |
1086 | if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) { |
1087 | printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn); | |
1088 | res = -EBUSY; | |
1089 | goto out; | |
1090 | } | |
6a46079c AK |
1091 | |
1092 | /* | |
1093 | * Torn down by someone else? | |
1094 | */ | |
dc2a1cbf | 1095 | if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) { |
6a46079c | 1096 | action_result(pfn, "already truncated LRU", IGNORED); |
d95ea51e | 1097 | res = -EBUSY; |
6a46079c AK |
1098 | goto out; |
1099 | } | |
1100 | ||
1101 | res = -EBUSY; | |
1102 | for (ps = error_states;; ps++) { | |
dc2a1cbf | 1103 | if ((p->flags & ps->mask) == ps->res) { |
bd1ce5f9 | 1104 | res = page_action(ps, p, pfn); |
6a46079c AK |
1105 | break; |
1106 | } | |
1107 | } | |
1108 | out: | |
7af446a8 | 1109 | unlock_page(hpage); |
6a46079c AK |
1110 | return res; |
1111 | } | |
1112 | EXPORT_SYMBOL_GPL(__memory_failure); | |
1113 | ||
1114 | /** | |
1115 | * memory_failure - Handle memory failure of a page. | |
1116 | * @pfn: Page Number of the corrupted page | |
1117 | * @trapno: Trap number reported in the signal to user space. | |
1118 | * | |
1119 | * This function is called by the low level machine check code | |
1120 | * of an architecture when it detects hardware memory corruption | |
1121 | * of a page. It tries its best to recover, which includes | |
1122 | * dropping pages, killing processes etc. | |
1123 | * | |
1124 | * The function is primarily of use for corruptions that | |
1125 | * happen outside the current execution context (e.g. when | |
1126 | * detected by a background scrubber) | |
1127 | * | |
1128 | * Must run in process context (e.g. a work queue) with interrupts | |
1129 | * enabled and no spinlocks hold. | |
1130 | */ | |
1131 | void memory_failure(unsigned long pfn, int trapno) | |
1132 | { | |
1133 | __memory_failure(pfn, trapno, 0); | |
1134 | } | |
847ce401 WF |
1135 | |
1136 | /** | |
1137 | * unpoison_memory - Unpoison a previously poisoned page | |
1138 | * @pfn: Page number of the to be unpoisoned page | |
1139 | * | |
1140 | * Software-unpoison a page that has been poisoned by | |
1141 | * memory_failure() earlier. | |
1142 | * | |
1143 | * This is only done on the software-level, so it only works | |
1144 | * for linux injected failures, not real hardware failures | |
1145 | * | |
1146 | * Returns 0 for success, otherwise -errno. | |
1147 | */ | |
1148 | int unpoison_memory(unsigned long pfn) | |
1149 | { | |
1150 | struct page *page; | |
1151 | struct page *p; | |
1152 | int freeit = 0; | |
c9fbdd5f | 1153 | unsigned int nr_pages; |
847ce401 WF |
1154 | |
1155 | if (!pfn_valid(pfn)) | |
1156 | return -ENXIO; | |
1157 | ||
1158 | p = pfn_to_page(pfn); | |
1159 | page = compound_head(p); | |
1160 | ||
1161 | if (!PageHWPoison(p)) { | |
fb46e735 | 1162 | pr_info("MCE: Page was already unpoisoned %#lx\n", pfn); |
847ce401 WF |
1163 | return 0; |
1164 | } | |
1165 | ||
c9fbdd5f NH |
1166 | nr_pages = 1 << compound_order(page); |
1167 | ||
847ce401 | 1168 | if (!get_page_unless_zero(page)) { |
8c6c2ecb NH |
1169 | /* |
1170 | * Since HWPoisoned hugepage should have non-zero refcount, | |
1171 | * race between memory failure and unpoison seems to happen. | |
1172 | * In such case unpoison fails and memory failure runs | |
1173 | * to the end. | |
1174 | */ | |
1175 | if (PageHuge(page)) { | |
1176 | pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); | |
1177 | return 0; | |
1178 | } | |
847ce401 | 1179 | if (TestClearPageHWPoison(p)) |
c9fbdd5f | 1180 | atomic_long_sub(nr_pages, &mce_bad_pages); |
fb46e735 | 1181 | pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn); |
847ce401 WF |
1182 | return 0; |
1183 | } | |
1184 | ||
1185 | lock_page_nosync(page); | |
1186 | /* | |
1187 | * This test is racy because PG_hwpoison is set outside of page lock. | |
1188 | * That's acceptable because that won't trigger kernel panic. Instead, | |
1189 | * the PG_hwpoison page will be caught and isolated on the entrance to | |
1190 | * the free buddy page pool. | |
1191 | */ | |
c9fbdd5f | 1192 | if (TestClearPageHWPoison(page)) { |
fb46e735 | 1193 | pr_info("MCE: Software-unpoisoned page %#lx\n", pfn); |
c9fbdd5f | 1194 | atomic_long_sub(nr_pages, &mce_bad_pages); |
847ce401 | 1195 | freeit = 1; |
6a90181c NH |
1196 | if (PageHuge(page)) |
1197 | clear_page_hwpoison_huge_page(page); | |
847ce401 WF |
1198 | } |
1199 | unlock_page(page); | |
1200 | ||
1201 | put_page(page); | |
1202 | if (freeit) | |
1203 | put_page(page); | |
1204 | ||
1205 | return 0; | |
1206 | } | |
1207 | EXPORT_SYMBOL(unpoison_memory); | |
facb6011 AK |
1208 | |
1209 | static struct page *new_page(struct page *p, unsigned long private, int **x) | |
1210 | { | |
12686d15 | 1211 | int nid = page_to_nid(p); |
d950b958 NH |
1212 | if (PageHuge(p)) |
1213 | return alloc_huge_page_node(page_hstate(compound_head(p)), | |
1214 | nid); | |
1215 | else | |
1216 | return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0); | |
facb6011 AK |
1217 | } |
1218 | ||
1219 | /* | |
1220 | * Safely get reference count of an arbitrary page. | |
1221 | * Returns 0 for a free page, -EIO for a zero refcount page | |
1222 | * that is not free, and 1 for any other page type. | |
1223 | * For 1 the page is returned with increased page count, otherwise not. | |
1224 | */ | |
1225 | static int get_any_page(struct page *p, unsigned long pfn, int flags) | |
1226 | { | |
1227 | int ret; | |
1228 | ||
1229 | if (flags & MF_COUNT_INCREASED) | |
1230 | return 1; | |
1231 | ||
1232 | /* | |
1233 | * The lock_system_sleep prevents a race with memory hotplug, | |
1234 | * because the isolation assumes there's only a single user. | |
1235 | * This is a big hammer, a better would be nicer. | |
1236 | */ | |
1237 | lock_system_sleep(); | |
1238 | ||
1239 | /* | |
1240 | * Isolate the page, so that it doesn't get reallocated if it | |
1241 | * was free. | |
1242 | */ | |
1243 | set_migratetype_isolate(p); | |
d950b958 NH |
1244 | /* |
1245 | * When the target page is a free hugepage, just remove it | |
1246 | * from free hugepage list. | |
1247 | */ | |
facb6011 | 1248 | if (!get_page_unless_zero(compound_head(p))) { |
d950b958 | 1249 | if (PageHuge(p)) { |
46e387bb | 1250 | pr_info("get_any_page: %#lx free huge page\n", pfn); |
d950b958 NH |
1251 | ret = dequeue_hwpoisoned_huge_page(compound_head(p)); |
1252 | } else if (is_free_buddy_page(p)) { | |
fb46e735 | 1253 | pr_info("get_any_page: %#lx free buddy page\n", pfn); |
facb6011 AK |
1254 | /* Set hwpoison bit while page is still isolated */ |
1255 | SetPageHWPoison(p); | |
1256 | ret = 0; | |
1257 | } else { | |
fb46e735 | 1258 | pr_info("get_any_page: %#lx: unknown zero refcount page type %lx\n", |
facb6011 AK |
1259 | pfn, p->flags); |
1260 | ret = -EIO; | |
1261 | } | |
1262 | } else { | |
1263 | /* Not a free page */ | |
1264 | ret = 1; | |
1265 | } | |
1266 | unset_migratetype_isolate(p); | |
1267 | unlock_system_sleep(); | |
1268 | return ret; | |
1269 | } | |
1270 | ||
d950b958 NH |
1271 | static int soft_offline_huge_page(struct page *page, int flags) |
1272 | { | |
1273 | int ret; | |
1274 | unsigned long pfn = page_to_pfn(page); | |
1275 | struct page *hpage = compound_head(page); | |
1276 | LIST_HEAD(pagelist); | |
1277 | ||
1278 | ret = get_any_page(page, pfn, flags); | |
1279 | if (ret < 0) | |
1280 | return ret; | |
1281 | if (ret == 0) | |
1282 | goto done; | |
1283 | ||
1284 | if (PageHWPoison(hpage)) { | |
1285 | put_page(hpage); | |
1286 | pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn); | |
1287 | return -EBUSY; | |
1288 | } | |
1289 | ||
1290 | /* Keep page count to indicate a given hugepage is isolated. */ | |
1291 | ||
1292 | list_add(&hpage->lru, &pagelist); | |
1293 | ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0); | |
1294 | if (ret) { | |
cf608ac1 | 1295 | putback_lru_pages(&pagelist); |
d950b958 NH |
1296 | pr_debug("soft offline: %#lx: migration failed %d, type %lx\n", |
1297 | pfn, ret, page->flags); | |
1298 | if (ret > 0) | |
1299 | ret = -EIO; | |
1300 | return ret; | |
1301 | } | |
1302 | done: | |
1303 | if (!PageHWPoison(hpage)) | |
1304 | atomic_long_add(1 << compound_order(hpage), &mce_bad_pages); | |
1305 | set_page_hwpoison_huge_page(hpage); | |
1306 | dequeue_hwpoisoned_huge_page(hpage); | |
1307 | /* keep elevated page count for bad page */ | |
1308 | return ret; | |
1309 | } | |
1310 | ||
facb6011 AK |
1311 | /** |
1312 | * soft_offline_page - Soft offline a page. | |
1313 | * @page: page to offline | |
1314 | * @flags: flags. Same as memory_failure(). | |
1315 | * | |
1316 | * Returns 0 on success, otherwise negated errno. | |
1317 | * | |
1318 | * Soft offline a page, by migration or invalidation, | |
1319 | * without killing anything. This is for the case when | |
1320 | * a page is not corrupted yet (so it's still valid to access), | |
1321 | * but has had a number of corrected errors and is better taken | |
1322 | * out. | |
1323 | * | |
1324 | * The actual policy on when to do that is maintained by | |
1325 | * user space. | |
1326 | * | |
1327 | * This should never impact any application or cause data loss, | |
1328 | * however it might take some time. | |
1329 | * | |
1330 | * This is not a 100% solution for all memory, but tries to be | |
1331 | * ``good enough'' for the majority of memory. | |
1332 | */ | |
1333 | int soft_offline_page(struct page *page, int flags) | |
1334 | { | |
1335 | int ret; | |
1336 | unsigned long pfn = page_to_pfn(page); | |
1337 | ||
d950b958 NH |
1338 | if (PageHuge(page)) |
1339 | return soft_offline_huge_page(page, flags); | |
1340 | ||
facb6011 AK |
1341 | ret = get_any_page(page, pfn, flags); |
1342 | if (ret < 0) | |
1343 | return ret; | |
1344 | if (ret == 0) | |
1345 | goto done; | |
1346 | ||
1347 | /* | |
1348 | * Page cache page we can handle? | |
1349 | */ | |
1350 | if (!PageLRU(page)) { | |
1351 | /* | |
1352 | * Try to free it. | |
1353 | */ | |
1354 | put_page(page); | |
1355 | shake_page(page, 1); | |
1356 | ||
1357 | /* | |
1358 | * Did it turn free? | |
1359 | */ | |
1360 | ret = get_any_page(page, pfn, 0); | |
1361 | if (ret < 0) | |
1362 | return ret; | |
1363 | if (ret == 0) | |
1364 | goto done; | |
1365 | } | |
1366 | if (!PageLRU(page)) { | |
fb46e735 | 1367 | pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", |
facb6011 AK |
1368 | pfn, page->flags); |
1369 | return -EIO; | |
1370 | } | |
1371 | ||
1372 | lock_page(page); | |
1373 | wait_on_page_writeback(page); | |
1374 | ||
1375 | /* | |
1376 | * Synchronized using the page lock with memory_failure() | |
1377 | */ | |
1378 | if (PageHWPoison(page)) { | |
1379 | unlock_page(page); | |
1380 | put_page(page); | |
fb46e735 | 1381 | pr_info("soft offline: %#lx page already poisoned\n", pfn); |
facb6011 AK |
1382 | return -EBUSY; |
1383 | } | |
1384 | ||
1385 | /* | |
1386 | * Try to invalidate first. This should work for | |
1387 | * non dirty unmapped page cache pages. | |
1388 | */ | |
1389 | ret = invalidate_inode_page(page); | |
1390 | unlock_page(page); | |
1391 | ||
1392 | /* | |
1393 | * Drop count because page migration doesn't like raised | |
1394 | * counts. The page could get re-allocated, but if it becomes | |
1395 | * LRU the isolation will just fail. | |
1396 | * RED-PEN would be better to keep it isolated here, but we | |
1397 | * would need to fix isolation locking first. | |
1398 | */ | |
1399 | put_page(page); | |
1400 | if (ret == 1) { | |
1401 | ret = 0; | |
fb46e735 | 1402 | pr_info("soft_offline: %#lx: invalidated\n", pfn); |
facb6011 AK |
1403 | goto done; |
1404 | } | |
1405 | ||
1406 | /* | |
1407 | * Simple invalidation didn't work. | |
1408 | * Try to migrate to a new page instead. migrate.c | |
1409 | * handles a large number of cases for us. | |
1410 | */ | |
1411 | ret = isolate_lru_page(page); | |
1412 | if (!ret) { | |
1413 | LIST_HEAD(pagelist); | |
1414 | ||
1415 | list_add(&page->lru, &pagelist); | |
1416 | ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0); | |
1417 | if (ret) { | |
fb46e735 | 1418 | pr_info("soft offline: %#lx: migration failed %d, type %lx\n", |
facb6011 AK |
1419 | pfn, ret, page->flags); |
1420 | if (ret > 0) | |
1421 | ret = -EIO; | |
1422 | } | |
1423 | } else { | |
fb46e735 | 1424 | pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", |
facb6011 AK |
1425 | pfn, ret, page_count(page), page->flags); |
1426 | } | |
1427 | if (ret) | |
1428 | return ret; | |
1429 | ||
1430 | done: | |
1431 | atomic_long_add(1, &mce_bad_pages); | |
1432 | SetPageHWPoison(page); | |
1433 | /* keep elevated page count for bad page */ | |
1434 | return ret; | |
1435 | } | |
bf998156 | 1436 | |
bbeb3406 HY |
1437 | /* |
1438 | * The caller must hold current->mm->mmap_sem in read mode. | |
1439 | */ | |
bf998156 HY |
1440 | int is_hwpoison_address(unsigned long addr) |
1441 | { | |
1442 | pgd_t *pgdp; | |
1443 | pud_t pud, *pudp; | |
1444 | pmd_t pmd, *pmdp; | |
1445 | pte_t pte, *ptep; | |
1446 | swp_entry_t entry; | |
1447 | ||
1448 | pgdp = pgd_offset(current->mm, addr); | |
1449 | if (!pgd_present(*pgdp)) | |
1450 | return 0; | |
1451 | pudp = pud_offset(pgdp, addr); | |
1452 | pud = *pudp; | |
1453 | if (!pud_present(pud) || pud_large(pud)) | |
1454 | return 0; | |
1455 | pmdp = pmd_offset(pudp, addr); | |
1456 | pmd = *pmdp; | |
1457 | if (!pmd_present(pmd) || pmd_large(pmd)) | |
1458 | return 0; | |
1459 | ptep = pte_offset_map(pmdp, addr); | |
1460 | pte = *ptep; | |
1461 | pte_unmap(ptep); | |
1462 | if (!is_swap_pte(pte)) | |
1463 | return 0; | |
1464 | entry = pte_to_swp_entry(pte); | |
1465 | return is_hwpoison_entry(entry); | |
1466 | } | |
1467 | EXPORT_SYMBOL_GPL(is_hwpoison_address); |