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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 | 44 | #include <linux/rmap.h> |
b9e15baf | 45 | #include <linux/export.h> |
6a46079c AK |
46 | #include <linux/pagemap.h> |
47 | #include <linux/swap.h> | |
48 | #include <linux/backing-dev.h> | |
facb6011 AK |
49 | #include <linux/migrate.h> |
50 | #include <linux/page-isolation.h> | |
51 | #include <linux/suspend.h> | |
5a0e3ad6 | 52 | #include <linux/slab.h> |
bf998156 | 53 | #include <linux/swapops.h> |
7af446a8 | 54 | #include <linux/hugetlb.h> |
20d6c96b | 55 | #include <linux/memory_hotplug.h> |
5db8a73a | 56 | #include <linux/mm_inline.h> |
ea8f5fb8 | 57 | #include <linux/kfifo.h> |
6a46079c AK |
58 | #include "internal.h" |
59 | ||
60 | int sysctl_memory_failure_early_kill __read_mostly = 0; | |
61 | ||
62 | int sysctl_memory_failure_recovery __read_mostly = 1; | |
63 | ||
64 | atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0); | |
65 | ||
27df5068 AK |
66 | #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE) |
67 | ||
1bfe5feb | 68 | u32 hwpoison_filter_enable = 0; |
7c116f2b WF |
69 | u32 hwpoison_filter_dev_major = ~0U; |
70 | u32 hwpoison_filter_dev_minor = ~0U; | |
478c5ffc WF |
71 | u64 hwpoison_filter_flags_mask; |
72 | u64 hwpoison_filter_flags_value; | |
1bfe5feb | 73 | EXPORT_SYMBOL_GPL(hwpoison_filter_enable); |
7c116f2b WF |
74 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major); |
75 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor); | |
478c5ffc WF |
76 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask); |
77 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value); | |
7c116f2b WF |
78 | |
79 | static int hwpoison_filter_dev(struct page *p) | |
80 | { | |
81 | struct address_space *mapping; | |
82 | dev_t dev; | |
83 | ||
84 | if (hwpoison_filter_dev_major == ~0U && | |
85 | hwpoison_filter_dev_minor == ~0U) | |
86 | return 0; | |
87 | ||
88 | /* | |
1c80b990 | 89 | * page_mapping() does not accept slab pages. |
7c116f2b WF |
90 | */ |
91 | if (PageSlab(p)) | |
92 | return -EINVAL; | |
93 | ||
94 | mapping = page_mapping(p); | |
95 | if (mapping == NULL || mapping->host == NULL) | |
96 | return -EINVAL; | |
97 | ||
98 | dev = mapping->host->i_sb->s_dev; | |
99 | if (hwpoison_filter_dev_major != ~0U && | |
100 | hwpoison_filter_dev_major != MAJOR(dev)) | |
101 | return -EINVAL; | |
102 | if (hwpoison_filter_dev_minor != ~0U && | |
103 | hwpoison_filter_dev_minor != MINOR(dev)) | |
104 | return -EINVAL; | |
105 | ||
106 | return 0; | |
107 | } | |
108 | ||
478c5ffc WF |
109 | static int hwpoison_filter_flags(struct page *p) |
110 | { | |
111 | if (!hwpoison_filter_flags_mask) | |
112 | return 0; | |
113 | ||
114 | if ((stable_page_flags(p) & hwpoison_filter_flags_mask) == | |
115 | hwpoison_filter_flags_value) | |
116 | return 0; | |
117 | else | |
118 | return -EINVAL; | |
119 | } | |
120 | ||
4fd466eb AK |
121 | /* |
122 | * This allows stress tests to limit test scope to a collection of tasks | |
123 | * by putting them under some memcg. This prevents killing unrelated/important | |
124 | * processes such as /sbin/init. Note that the target task may share clean | |
125 | * pages with init (eg. libc text), which is harmless. If the target task | |
126 | * share _dirty_ pages with another task B, the test scheme must make sure B | |
127 | * is also included in the memcg. At last, due to race conditions this filter | |
128 | * can only guarantee that the page either belongs to the memcg tasks, or is | |
129 | * a freed page. | |
130 | */ | |
131 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP | |
132 | u64 hwpoison_filter_memcg; | |
133 | EXPORT_SYMBOL_GPL(hwpoison_filter_memcg); | |
134 | static int hwpoison_filter_task(struct page *p) | |
135 | { | |
136 | struct mem_cgroup *mem; | |
137 | struct cgroup_subsys_state *css; | |
138 | unsigned long ino; | |
139 | ||
140 | if (!hwpoison_filter_memcg) | |
141 | return 0; | |
142 | ||
143 | mem = try_get_mem_cgroup_from_page(p); | |
144 | if (!mem) | |
145 | return -EINVAL; | |
146 | ||
147 | css = mem_cgroup_css(mem); | |
148 | /* root_mem_cgroup has NULL dentries */ | |
149 | if (!css->cgroup->dentry) | |
150 | return -EINVAL; | |
151 | ||
152 | ino = css->cgroup->dentry->d_inode->i_ino; | |
153 | css_put(css); | |
154 | ||
155 | if (ino != hwpoison_filter_memcg) | |
156 | return -EINVAL; | |
157 | ||
158 | return 0; | |
159 | } | |
160 | #else | |
161 | static int hwpoison_filter_task(struct page *p) { return 0; } | |
162 | #endif | |
163 | ||
7c116f2b WF |
164 | int hwpoison_filter(struct page *p) |
165 | { | |
1bfe5feb HL |
166 | if (!hwpoison_filter_enable) |
167 | return 0; | |
168 | ||
7c116f2b WF |
169 | if (hwpoison_filter_dev(p)) |
170 | return -EINVAL; | |
171 | ||
478c5ffc WF |
172 | if (hwpoison_filter_flags(p)) |
173 | return -EINVAL; | |
174 | ||
4fd466eb AK |
175 | if (hwpoison_filter_task(p)) |
176 | return -EINVAL; | |
177 | ||
7c116f2b WF |
178 | return 0; |
179 | } | |
27df5068 AK |
180 | #else |
181 | int hwpoison_filter(struct page *p) | |
182 | { | |
183 | return 0; | |
184 | } | |
185 | #endif | |
186 | ||
7c116f2b WF |
187 | EXPORT_SYMBOL_GPL(hwpoison_filter); |
188 | ||
6a46079c AK |
189 | /* |
190 | * Send all the processes who have the page mapped an ``action optional'' | |
191 | * signal. | |
192 | */ | |
193 | static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno, | |
0d9ee6a2 | 194 | unsigned long pfn, struct page *page) |
6a46079c AK |
195 | { |
196 | struct siginfo si; | |
197 | int ret; | |
198 | ||
199 | printk(KERN_ERR | |
200 | "MCE %#lx: Killing %s:%d early due to hardware memory corruption\n", | |
201 | pfn, t->comm, t->pid); | |
202 | si.si_signo = SIGBUS; | |
203 | si.si_errno = 0; | |
204 | si.si_code = BUS_MCEERR_AO; | |
205 | si.si_addr = (void *)addr; | |
206 | #ifdef __ARCH_SI_TRAPNO | |
207 | si.si_trapno = trapno; | |
208 | #endif | |
37c2ac78 | 209 | si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT; |
6a46079c AK |
210 | /* |
211 | * Don't use force here, it's convenient if the signal | |
212 | * can be temporarily blocked. | |
213 | * This could cause a loop when the user sets SIGBUS | |
25985edc | 214 | * to SIG_IGN, but hopefully no one will do that? |
6a46079c AK |
215 | */ |
216 | ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */ | |
217 | if (ret < 0) | |
218 | printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n", | |
219 | t->comm, t->pid, ret); | |
220 | return ret; | |
221 | } | |
222 | ||
588f9ce6 AK |
223 | /* |
224 | * When a unknown page type is encountered drain as many buffers as possible | |
225 | * in the hope to turn the page into a LRU or free page, which we can handle. | |
226 | */ | |
facb6011 | 227 | void shake_page(struct page *p, int access) |
588f9ce6 AK |
228 | { |
229 | if (!PageSlab(p)) { | |
230 | lru_add_drain_all(); | |
231 | if (PageLRU(p)) | |
232 | return; | |
233 | drain_all_pages(); | |
234 | if (PageLRU(p) || is_free_buddy_page(p)) | |
235 | return; | |
236 | } | |
facb6011 | 237 | |
588f9ce6 | 238 | /* |
af241a08 JD |
239 | * Only call shrink_slab here (which would also shrink other caches) if |
240 | * access is not potentially fatal. | |
588f9ce6 | 241 | */ |
facb6011 AK |
242 | if (access) { |
243 | int nr; | |
244 | do { | |
a09ed5e0 YH |
245 | struct shrink_control shrink = { |
246 | .gfp_mask = GFP_KERNEL, | |
a09ed5e0 YH |
247 | }; |
248 | ||
1495f230 | 249 | nr = shrink_slab(&shrink, 1000, 1000); |
47f43e7e | 250 | if (page_count(p) == 1) |
facb6011 AK |
251 | break; |
252 | } while (nr > 10); | |
253 | } | |
588f9ce6 AK |
254 | } |
255 | EXPORT_SYMBOL_GPL(shake_page); | |
256 | ||
6a46079c AK |
257 | /* |
258 | * Kill all processes that have a poisoned page mapped and then isolate | |
259 | * the page. | |
260 | * | |
261 | * General strategy: | |
262 | * Find all processes having the page mapped and kill them. | |
263 | * But we keep a page reference around so that the page is not | |
264 | * actually freed yet. | |
265 | * Then stash the page away | |
266 | * | |
267 | * There's no convenient way to get back to mapped processes | |
268 | * from the VMAs. So do a brute-force search over all | |
269 | * running processes. | |
270 | * | |
271 | * Remember that machine checks are not common (or rather | |
272 | * if they are common you have other problems), so this shouldn't | |
273 | * be a performance issue. | |
274 | * | |
275 | * Also there are some races possible while we get from the | |
276 | * error detection to actually handle it. | |
277 | */ | |
278 | ||
279 | struct to_kill { | |
280 | struct list_head nd; | |
281 | struct task_struct *tsk; | |
282 | unsigned long addr; | |
9033ae16 | 283 | char addr_valid; |
6a46079c AK |
284 | }; |
285 | ||
286 | /* | |
287 | * Failure handling: if we can't find or can't kill a process there's | |
288 | * not much we can do. We just print a message and ignore otherwise. | |
289 | */ | |
290 | ||
291 | /* | |
292 | * Schedule a process for later kill. | |
293 | * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM. | |
294 | * TBD would GFP_NOIO be enough? | |
295 | */ | |
296 | static void add_to_kill(struct task_struct *tsk, struct page *p, | |
297 | struct vm_area_struct *vma, | |
298 | struct list_head *to_kill, | |
299 | struct to_kill **tkc) | |
300 | { | |
301 | struct to_kill *tk; | |
302 | ||
303 | if (*tkc) { | |
304 | tk = *tkc; | |
305 | *tkc = NULL; | |
306 | } else { | |
307 | tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC); | |
308 | if (!tk) { | |
309 | printk(KERN_ERR | |
310 | "MCE: Out of memory while machine check handling\n"); | |
311 | return; | |
312 | } | |
313 | } | |
314 | tk->addr = page_address_in_vma(p, vma); | |
315 | tk->addr_valid = 1; | |
316 | ||
317 | /* | |
318 | * In theory we don't have to kill when the page was | |
319 | * munmaped. But it could be also a mremap. Since that's | |
320 | * likely very rare kill anyways just out of paranoia, but use | |
321 | * a SIGKILL because the error is not contained anymore. | |
322 | */ | |
323 | if (tk->addr == -EFAULT) { | |
fb46e735 | 324 | pr_info("MCE: Unable to find user space address %lx in %s\n", |
6a46079c AK |
325 | page_to_pfn(p), tsk->comm); |
326 | tk->addr_valid = 0; | |
327 | } | |
328 | get_task_struct(tsk); | |
329 | tk->tsk = tsk; | |
330 | list_add_tail(&tk->nd, to_kill); | |
331 | } | |
332 | ||
333 | /* | |
334 | * Kill the processes that have been collected earlier. | |
335 | * | |
336 | * Only do anything when DOIT is set, otherwise just free the list | |
337 | * (this is used for clean pages which do not need killing) | |
338 | * Also when FAIL is set do a force kill because something went | |
339 | * wrong earlier. | |
340 | */ | |
341 | static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno, | |
0d9ee6a2 | 342 | int fail, struct page *page, unsigned long pfn) |
6a46079c AK |
343 | { |
344 | struct to_kill *tk, *next; | |
345 | ||
346 | list_for_each_entry_safe (tk, next, to_kill, nd) { | |
347 | if (doit) { | |
348 | /* | |
af901ca1 | 349 | * In case something went wrong with munmapping |
6a46079c AK |
350 | * make sure the process doesn't catch the |
351 | * signal and then access the memory. Just kill it. | |
6a46079c AK |
352 | */ |
353 | if (fail || tk->addr_valid == 0) { | |
354 | printk(KERN_ERR | |
355 | "MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", | |
356 | pfn, tk->tsk->comm, tk->tsk->pid); | |
357 | force_sig(SIGKILL, tk->tsk); | |
358 | } | |
359 | ||
360 | /* | |
361 | * In theory the process could have mapped | |
362 | * something else on the address in-between. We could | |
363 | * check for that, but we need to tell the | |
364 | * process anyways. | |
365 | */ | |
366 | else if (kill_proc_ao(tk->tsk, tk->addr, trapno, | |
0d9ee6a2 | 367 | pfn, page) < 0) |
6a46079c AK |
368 | printk(KERN_ERR |
369 | "MCE %#lx: Cannot send advisory machine check signal to %s:%d\n", | |
370 | pfn, tk->tsk->comm, tk->tsk->pid); | |
371 | } | |
372 | put_task_struct(tk->tsk); | |
373 | kfree(tk); | |
374 | } | |
375 | } | |
376 | ||
377 | static int task_early_kill(struct task_struct *tsk) | |
378 | { | |
379 | if (!tsk->mm) | |
380 | return 0; | |
381 | if (tsk->flags & PF_MCE_PROCESS) | |
382 | return !!(tsk->flags & PF_MCE_EARLY); | |
383 | return sysctl_memory_failure_early_kill; | |
384 | } | |
385 | ||
386 | /* | |
387 | * Collect processes when the error hit an anonymous page. | |
388 | */ | |
389 | static void collect_procs_anon(struct page *page, struct list_head *to_kill, | |
390 | struct to_kill **tkc) | |
391 | { | |
392 | struct vm_area_struct *vma; | |
393 | struct task_struct *tsk; | |
394 | struct anon_vma *av; | |
395 | ||
6a46079c AK |
396 | av = page_lock_anon_vma(page); |
397 | if (av == NULL) /* Not actually mapped anymore */ | |
9b679320 PZ |
398 | return; |
399 | ||
400 | read_lock(&tasklist_lock); | |
6a46079c | 401 | for_each_process (tsk) { |
5beb4930 RR |
402 | struct anon_vma_chain *vmac; |
403 | ||
6a46079c AK |
404 | if (!task_early_kill(tsk)) |
405 | continue; | |
5beb4930 RR |
406 | list_for_each_entry(vmac, &av->head, same_anon_vma) { |
407 | vma = vmac->vma; | |
6a46079c AK |
408 | if (!page_mapped_in_vma(page, vma)) |
409 | continue; | |
410 | if (vma->vm_mm == tsk->mm) | |
411 | add_to_kill(tsk, page, vma, to_kill, tkc); | |
412 | } | |
413 | } | |
6a46079c | 414 | read_unlock(&tasklist_lock); |
9b679320 | 415 | page_unlock_anon_vma(av); |
6a46079c AK |
416 | } |
417 | ||
418 | /* | |
419 | * Collect processes when the error hit a file mapped page. | |
420 | */ | |
421 | static void collect_procs_file(struct page *page, struct list_head *to_kill, | |
422 | struct to_kill **tkc) | |
423 | { | |
424 | struct vm_area_struct *vma; | |
425 | struct task_struct *tsk; | |
426 | struct prio_tree_iter iter; | |
427 | struct address_space *mapping = page->mapping; | |
428 | ||
3d48ae45 | 429 | mutex_lock(&mapping->i_mmap_mutex); |
9b679320 | 430 | read_lock(&tasklist_lock); |
6a46079c AK |
431 | for_each_process(tsk) { |
432 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
433 | ||
434 | if (!task_early_kill(tsk)) | |
435 | continue; | |
436 | ||
437 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, | |
438 | pgoff) { | |
439 | /* | |
440 | * Send early kill signal to tasks where a vma covers | |
441 | * the page but the corrupted page is not necessarily | |
442 | * mapped it in its pte. | |
443 | * Assume applications who requested early kill want | |
444 | * to be informed of all such data corruptions. | |
445 | */ | |
446 | if (vma->vm_mm == tsk->mm) | |
447 | add_to_kill(tsk, page, vma, to_kill, tkc); | |
448 | } | |
449 | } | |
6a46079c | 450 | read_unlock(&tasklist_lock); |
9b679320 | 451 | mutex_unlock(&mapping->i_mmap_mutex); |
6a46079c AK |
452 | } |
453 | ||
454 | /* | |
455 | * Collect the processes who have the corrupted page mapped to kill. | |
456 | * This is done in two steps for locking reasons. | |
457 | * First preallocate one tokill structure outside the spin locks, | |
458 | * so that we can kill at least one process reasonably reliable. | |
459 | */ | |
460 | static void collect_procs(struct page *page, struct list_head *tokill) | |
461 | { | |
462 | struct to_kill *tk; | |
463 | ||
464 | if (!page->mapping) | |
465 | return; | |
466 | ||
467 | tk = kmalloc(sizeof(struct to_kill), GFP_NOIO); | |
468 | if (!tk) | |
469 | return; | |
470 | if (PageAnon(page)) | |
471 | collect_procs_anon(page, tokill, &tk); | |
472 | else | |
473 | collect_procs_file(page, tokill, &tk); | |
474 | kfree(tk); | |
475 | } | |
476 | ||
477 | /* | |
478 | * Error handlers for various types of pages. | |
479 | */ | |
480 | ||
481 | enum outcome { | |
d95ea51e WF |
482 | IGNORED, /* Error: cannot be handled */ |
483 | FAILED, /* Error: handling failed */ | |
6a46079c | 484 | DELAYED, /* Will be handled later */ |
6a46079c AK |
485 | RECOVERED, /* Successfully recovered */ |
486 | }; | |
487 | ||
488 | static const char *action_name[] = { | |
d95ea51e | 489 | [IGNORED] = "Ignored", |
6a46079c AK |
490 | [FAILED] = "Failed", |
491 | [DELAYED] = "Delayed", | |
6a46079c AK |
492 | [RECOVERED] = "Recovered", |
493 | }; | |
494 | ||
dc2a1cbf WF |
495 | /* |
496 | * XXX: It is possible that a page is isolated from LRU cache, | |
497 | * and then kept in swap cache or failed to remove from page cache. | |
498 | * The page count will stop it from being freed by unpoison. | |
499 | * Stress tests should be aware of this memory leak problem. | |
500 | */ | |
501 | static int delete_from_lru_cache(struct page *p) | |
502 | { | |
503 | if (!isolate_lru_page(p)) { | |
504 | /* | |
505 | * Clear sensible page flags, so that the buddy system won't | |
506 | * complain when the page is unpoison-and-freed. | |
507 | */ | |
508 | ClearPageActive(p); | |
509 | ClearPageUnevictable(p); | |
510 | /* | |
511 | * drop the page count elevated by isolate_lru_page() | |
512 | */ | |
513 | page_cache_release(p); | |
514 | return 0; | |
515 | } | |
516 | return -EIO; | |
517 | } | |
518 | ||
6a46079c AK |
519 | /* |
520 | * Error hit kernel page. | |
521 | * Do nothing, try to be lucky and not touch this instead. For a few cases we | |
522 | * could be more sophisticated. | |
523 | */ | |
524 | static int me_kernel(struct page *p, unsigned long pfn) | |
6a46079c AK |
525 | { |
526 | return IGNORED; | |
527 | } | |
528 | ||
529 | /* | |
530 | * Page in unknown state. Do nothing. | |
531 | */ | |
532 | static int me_unknown(struct page *p, unsigned long pfn) | |
533 | { | |
534 | printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn); | |
535 | return FAILED; | |
536 | } | |
537 | ||
6a46079c AK |
538 | /* |
539 | * Clean (or cleaned) page cache page. | |
540 | */ | |
541 | static int me_pagecache_clean(struct page *p, unsigned long pfn) | |
542 | { | |
543 | int err; | |
544 | int ret = FAILED; | |
545 | struct address_space *mapping; | |
546 | ||
dc2a1cbf WF |
547 | delete_from_lru_cache(p); |
548 | ||
6a46079c AK |
549 | /* |
550 | * For anonymous pages we're done the only reference left | |
551 | * should be the one m_f() holds. | |
552 | */ | |
553 | if (PageAnon(p)) | |
554 | return RECOVERED; | |
555 | ||
556 | /* | |
557 | * Now truncate the page in the page cache. This is really | |
558 | * more like a "temporary hole punch" | |
559 | * Don't do this for block devices when someone else | |
560 | * has a reference, because it could be file system metadata | |
561 | * and that's not safe to truncate. | |
562 | */ | |
563 | mapping = page_mapping(p); | |
564 | if (!mapping) { | |
565 | /* | |
566 | * Page has been teared down in the meanwhile | |
567 | */ | |
568 | return FAILED; | |
569 | } | |
570 | ||
571 | /* | |
572 | * Truncation is a bit tricky. Enable it per file system for now. | |
573 | * | |
574 | * Open: to take i_mutex or not for this? Right now we don't. | |
575 | */ | |
576 | if (mapping->a_ops->error_remove_page) { | |
577 | err = mapping->a_ops->error_remove_page(mapping, p); | |
578 | if (err != 0) { | |
579 | printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n", | |
580 | pfn, err); | |
581 | } else if (page_has_private(p) && | |
582 | !try_to_release_page(p, GFP_NOIO)) { | |
fb46e735 | 583 | pr_info("MCE %#lx: failed to release buffers\n", pfn); |
6a46079c AK |
584 | } else { |
585 | ret = RECOVERED; | |
586 | } | |
587 | } else { | |
588 | /* | |
589 | * If the file system doesn't support it just invalidate | |
590 | * This fails on dirty or anything with private pages | |
591 | */ | |
592 | if (invalidate_inode_page(p)) | |
593 | ret = RECOVERED; | |
594 | else | |
595 | printk(KERN_INFO "MCE %#lx: Failed to invalidate\n", | |
596 | pfn); | |
597 | } | |
598 | return ret; | |
599 | } | |
600 | ||
601 | /* | |
602 | * Dirty cache page page | |
603 | * Issues: when the error hit a hole page the error is not properly | |
604 | * propagated. | |
605 | */ | |
606 | static int me_pagecache_dirty(struct page *p, unsigned long pfn) | |
607 | { | |
608 | struct address_space *mapping = page_mapping(p); | |
609 | ||
610 | SetPageError(p); | |
611 | /* TBD: print more information about the file. */ | |
612 | if (mapping) { | |
613 | /* | |
614 | * IO error will be reported by write(), fsync(), etc. | |
615 | * who check the mapping. | |
616 | * This way the application knows that something went | |
617 | * wrong with its dirty file data. | |
618 | * | |
619 | * There's one open issue: | |
620 | * | |
621 | * The EIO will be only reported on the next IO | |
622 | * operation and then cleared through the IO map. | |
623 | * Normally Linux has two mechanisms to pass IO error | |
624 | * first through the AS_EIO flag in the address space | |
625 | * and then through the PageError flag in the page. | |
626 | * Since we drop pages on memory failure handling the | |
627 | * only mechanism open to use is through AS_AIO. | |
628 | * | |
629 | * This has the disadvantage that it gets cleared on | |
630 | * the first operation that returns an error, while | |
631 | * the PageError bit is more sticky and only cleared | |
632 | * when the page is reread or dropped. If an | |
633 | * application assumes it will always get error on | |
634 | * fsync, but does other operations on the fd before | |
25985edc | 635 | * and the page is dropped between then the error |
6a46079c AK |
636 | * will not be properly reported. |
637 | * | |
638 | * This can already happen even without hwpoisoned | |
639 | * pages: first on metadata IO errors (which only | |
640 | * report through AS_EIO) or when the page is dropped | |
641 | * at the wrong time. | |
642 | * | |
643 | * So right now we assume that the application DTRT on | |
644 | * the first EIO, but we're not worse than other parts | |
645 | * of the kernel. | |
646 | */ | |
647 | mapping_set_error(mapping, EIO); | |
648 | } | |
649 | ||
650 | return me_pagecache_clean(p, pfn); | |
651 | } | |
652 | ||
653 | /* | |
654 | * Clean and dirty swap cache. | |
655 | * | |
656 | * Dirty swap cache page is tricky to handle. The page could live both in page | |
657 | * cache and swap cache(ie. page is freshly swapped in). So it could be | |
658 | * referenced concurrently by 2 types of PTEs: | |
659 | * normal PTEs and swap PTEs. We try to handle them consistently by calling | |
660 | * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs, | |
661 | * and then | |
662 | * - clear dirty bit to prevent IO | |
663 | * - remove from LRU | |
664 | * - but keep in the swap cache, so that when we return to it on | |
665 | * a later page fault, we know the application is accessing | |
666 | * corrupted data and shall be killed (we installed simple | |
667 | * interception code in do_swap_page to catch it). | |
668 | * | |
669 | * Clean swap cache pages can be directly isolated. A later page fault will | |
670 | * bring in the known good data from disk. | |
671 | */ | |
672 | static int me_swapcache_dirty(struct page *p, unsigned long pfn) | |
673 | { | |
6a46079c AK |
674 | ClearPageDirty(p); |
675 | /* Trigger EIO in shmem: */ | |
676 | ClearPageUptodate(p); | |
677 | ||
dc2a1cbf WF |
678 | if (!delete_from_lru_cache(p)) |
679 | return DELAYED; | |
680 | else | |
681 | return FAILED; | |
6a46079c AK |
682 | } |
683 | ||
684 | static int me_swapcache_clean(struct page *p, unsigned long pfn) | |
685 | { | |
6a46079c | 686 | delete_from_swap_cache(p); |
e43c3afb | 687 | |
dc2a1cbf WF |
688 | if (!delete_from_lru_cache(p)) |
689 | return RECOVERED; | |
690 | else | |
691 | return FAILED; | |
6a46079c AK |
692 | } |
693 | ||
694 | /* | |
695 | * Huge pages. Needs work. | |
696 | * Issues: | |
93f70f90 NH |
697 | * - Error on hugepage is contained in hugepage unit (not in raw page unit.) |
698 | * To narrow down kill region to one page, we need to break up pmd. | |
6a46079c AK |
699 | */ |
700 | static int me_huge_page(struct page *p, unsigned long pfn) | |
701 | { | |
6de2b1aa | 702 | int res = 0; |
93f70f90 NH |
703 | struct page *hpage = compound_head(p); |
704 | /* | |
705 | * We can safely recover from error on free or reserved (i.e. | |
706 | * not in-use) hugepage by dequeuing it from freelist. | |
707 | * To check whether a hugepage is in-use or not, we can't use | |
708 | * page->lru because it can be used in other hugepage operations, | |
709 | * such as __unmap_hugepage_range() and gather_surplus_pages(). | |
710 | * So instead we use page_mapping() and PageAnon(). | |
711 | * We assume that this function is called with page lock held, | |
712 | * so there is no race between isolation and mapping/unmapping. | |
713 | */ | |
714 | if (!(page_mapping(hpage) || PageAnon(hpage))) { | |
6de2b1aa NH |
715 | res = dequeue_hwpoisoned_huge_page(hpage); |
716 | if (!res) | |
717 | return RECOVERED; | |
93f70f90 NH |
718 | } |
719 | return DELAYED; | |
6a46079c AK |
720 | } |
721 | ||
722 | /* | |
723 | * Various page states we can handle. | |
724 | * | |
725 | * A page state is defined by its current page->flags bits. | |
726 | * The table matches them in order and calls the right handler. | |
727 | * | |
728 | * This is quite tricky because we can access page at any time | |
25985edc | 729 | * in its live cycle, so all accesses have to be extremely careful. |
6a46079c AK |
730 | * |
731 | * This is not complete. More states could be added. | |
732 | * For any missing state don't attempt recovery. | |
733 | */ | |
734 | ||
735 | #define dirty (1UL << PG_dirty) | |
736 | #define sc (1UL << PG_swapcache) | |
737 | #define unevict (1UL << PG_unevictable) | |
738 | #define mlock (1UL << PG_mlocked) | |
739 | #define writeback (1UL << PG_writeback) | |
740 | #define lru (1UL << PG_lru) | |
741 | #define swapbacked (1UL << PG_swapbacked) | |
742 | #define head (1UL << PG_head) | |
743 | #define tail (1UL << PG_tail) | |
744 | #define compound (1UL << PG_compound) | |
745 | #define slab (1UL << PG_slab) | |
6a46079c AK |
746 | #define reserved (1UL << PG_reserved) |
747 | ||
748 | static struct page_state { | |
749 | unsigned long mask; | |
750 | unsigned long res; | |
751 | char *msg; | |
752 | int (*action)(struct page *p, unsigned long pfn); | |
753 | } error_states[] = { | |
d95ea51e | 754 | { reserved, reserved, "reserved kernel", me_kernel }, |
95d01fc6 WF |
755 | /* |
756 | * free pages are specially detected outside this table: | |
757 | * PG_buddy pages only make a small fraction of all free pages. | |
758 | */ | |
6a46079c AK |
759 | |
760 | /* | |
761 | * Could in theory check if slab page is free or if we can drop | |
762 | * currently unused objects without touching them. But just | |
763 | * treat it as standard kernel for now. | |
764 | */ | |
765 | { slab, slab, "kernel slab", me_kernel }, | |
766 | ||
767 | #ifdef CONFIG_PAGEFLAGS_EXTENDED | |
768 | { head, head, "huge", me_huge_page }, | |
769 | { tail, tail, "huge", me_huge_page }, | |
770 | #else | |
771 | { compound, compound, "huge", me_huge_page }, | |
772 | #endif | |
773 | ||
774 | { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty }, | |
775 | { sc|dirty, sc, "swapcache", me_swapcache_clean }, | |
776 | ||
777 | { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty}, | |
778 | { unevict, unevict, "unevictable LRU", me_pagecache_clean}, | |
779 | ||
6a46079c AK |
780 | { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty }, |
781 | { mlock, mlock, "mlocked LRU", me_pagecache_clean }, | |
6a46079c AK |
782 | |
783 | { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty }, | |
784 | { lru|dirty, lru, "clean LRU", me_pagecache_clean }, | |
6a46079c AK |
785 | |
786 | /* | |
787 | * Catchall entry: must be at end. | |
788 | */ | |
789 | { 0, 0, "unknown page state", me_unknown }, | |
790 | }; | |
791 | ||
2326c467 AK |
792 | #undef dirty |
793 | #undef sc | |
794 | #undef unevict | |
795 | #undef mlock | |
796 | #undef writeback | |
797 | #undef lru | |
798 | #undef swapbacked | |
799 | #undef head | |
800 | #undef tail | |
801 | #undef compound | |
802 | #undef slab | |
803 | #undef reserved | |
804 | ||
6a46079c AK |
805 | static void action_result(unsigned long pfn, char *msg, int result) |
806 | { | |
a7560fc8 | 807 | struct page *page = pfn_to_page(pfn); |
6a46079c AK |
808 | |
809 | printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n", | |
810 | pfn, | |
a7560fc8 | 811 | PageDirty(page) ? "dirty " : "", |
6a46079c AK |
812 | msg, action_name[result]); |
813 | } | |
814 | ||
815 | static int page_action(struct page_state *ps, struct page *p, | |
bd1ce5f9 | 816 | unsigned long pfn) |
6a46079c AK |
817 | { |
818 | int result; | |
7456b040 | 819 | int count; |
6a46079c AK |
820 | |
821 | result = ps->action(p, pfn); | |
822 | action_result(pfn, ps->msg, result); | |
7456b040 | 823 | |
bd1ce5f9 | 824 | count = page_count(p) - 1; |
138ce286 WF |
825 | if (ps->action == me_swapcache_dirty && result == DELAYED) |
826 | count--; | |
827 | if (count != 0) { | |
6a46079c AK |
828 | printk(KERN_ERR |
829 | "MCE %#lx: %s page still referenced by %d users\n", | |
7456b040 | 830 | pfn, ps->msg, count); |
138ce286 WF |
831 | result = FAILED; |
832 | } | |
6a46079c AK |
833 | |
834 | /* Could do more checks here if page looks ok */ | |
835 | /* | |
836 | * Could adjust zone counters here to correct for the missing page. | |
837 | */ | |
838 | ||
138ce286 | 839 | return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY; |
6a46079c AK |
840 | } |
841 | ||
6a46079c AK |
842 | /* |
843 | * Do all that is necessary to remove user space mappings. Unmap | |
844 | * the pages and send SIGBUS to the processes if the data was dirty. | |
845 | */ | |
1668bfd5 | 846 | static int hwpoison_user_mappings(struct page *p, unsigned long pfn, |
6a46079c AK |
847 | int trapno) |
848 | { | |
849 | enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; | |
850 | struct address_space *mapping; | |
851 | LIST_HEAD(tokill); | |
852 | int ret; | |
6a46079c | 853 | int kill = 1; |
7af446a8 | 854 | struct page *hpage = compound_head(p); |
a6d30ddd | 855 | struct page *ppage; |
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 | ||
a6d30ddd JD |
896 | /* |
897 | * ppage: poisoned page | |
898 | * if p is regular page(4k page) | |
899 | * ppage == real poisoned page; | |
900 | * else p is hugetlb or THP, ppage == head page. | |
901 | */ | |
902 | ppage = hpage; | |
903 | ||
efeda7a4 JD |
904 | if (PageTransHuge(hpage)) { |
905 | /* | |
906 | * Verify that this isn't a hugetlbfs head page, the check for | |
907 | * PageAnon is just for avoid tripping a split_huge_page | |
908 | * internal debug check, as split_huge_page refuses to deal with | |
909 | * anything that isn't an anon page. PageAnon can't go away fro | |
910 | * under us because we hold a refcount on the hpage, without a | |
911 | * refcount on the hpage. split_huge_page can't be safely called | |
912 | * in the first place, having a refcount on the tail isn't | |
913 | * enough * to be safe. | |
914 | */ | |
915 | if (!PageHuge(hpage) && PageAnon(hpage)) { | |
916 | if (unlikely(split_huge_page(hpage))) { | |
917 | /* | |
918 | * FIXME: if splitting THP is failed, it is | |
919 | * better to stop the following operation rather | |
920 | * than causing panic by unmapping. System might | |
921 | * survive if the page is freed later. | |
922 | */ | |
923 | printk(KERN_INFO | |
924 | "MCE %#lx: failed to split THP\n", pfn); | |
925 | ||
926 | BUG_ON(!PageHWPoison(p)); | |
927 | return SWAP_FAIL; | |
928 | } | |
a6d30ddd JD |
929 | /* THP is split, so ppage should be the real poisoned page. */ |
930 | ppage = p; | |
efeda7a4 JD |
931 | } |
932 | } | |
933 | ||
6a46079c AK |
934 | /* |
935 | * First collect all the processes that have the page | |
936 | * mapped in dirty form. This has to be done before try_to_unmap, | |
937 | * because ttu takes the rmap data structures down. | |
938 | * | |
939 | * Error handling: We ignore errors here because | |
940 | * there's nothing that can be done. | |
941 | */ | |
942 | if (kill) | |
a6d30ddd | 943 | collect_procs(ppage, &tokill); |
6a46079c | 944 | |
a6d30ddd | 945 | if (hpage != ppage) |
7eaceacc | 946 | lock_page(ppage); |
a6d30ddd JD |
947 | |
948 | ret = try_to_unmap(ppage, ttu); | |
6a46079c AK |
949 | if (ret != SWAP_SUCCESS) |
950 | printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n", | |
a6d30ddd JD |
951 | pfn, page_mapcount(ppage)); |
952 | ||
953 | if (hpage != ppage) | |
954 | unlock_page(ppage); | |
6a46079c AK |
955 | |
956 | /* | |
957 | * Now that the dirty bit has been propagated to the | |
958 | * struct page and all unmaps done we can decide if | |
959 | * killing is needed or not. Only kill when the page | |
960 | * was dirty, otherwise the tokill list is merely | |
961 | * freed. When there was a problem unmapping earlier | |
962 | * use a more force-full uncatchable kill to prevent | |
963 | * any accesses to the poisoned memory. | |
964 | */ | |
a6d30ddd | 965 | kill_procs_ao(&tokill, !!PageDirty(ppage), trapno, |
0d9ee6a2 | 966 | ret != SWAP_SUCCESS, p, pfn); |
1668bfd5 WF |
967 | |
968 | return ret; | |
6a46079c AK |
969 | } |
970 | ||
7013febc NH |
971 | static void set_page_hwpoison_huge_page(struct page *hpage) |
972 | { | |
973 | int i; | |
37c2ac78 | 974 | int nr_pages = 1 << compound_trans_order(hpage); |
7013febc NH |
975 | for (i = 0; i < nr_pages; i++) |
976 | SetPageHWPoison(hpage + i); | |
977 | } | |
978 | ||
979 | static void clear_page_hwpoison_huge_page(struct page *hpage) | |
980 | { | |
981 | int i; | |
37c2ac78 | 982 | int nr_pages = 1 << compound_trans_order(hpage); |
7013febc NH |
983 | for (i = 0; i < nr_pages; i++) |
984 | ClearPageHWPoison(hpage + i); | |
985 | } | |
986 | ||
82ba011b | 987 | int __memory_failure(unsigned long pfn, int trapno, int flags) |
6a46079c AK |
988 | { |
989 | struct page_state *ps; | |
990 | struct page *p; | |
7af446a8 | 991 | struct page *hpage; |
6a46079c | 992 | int res; |
c9fbdd5f | 993 | unsigned int nr_pages; |
6a46079c AK |
994 | |
995 | if (!sysctl_memory_failure_recovery) | |
996 | panic("Memory failure from trap %d on page %lx", trapno, pfn); | |
997 | ||
998 | if (!pfn_valid(pfn)) { | |
a7560fc8 WF |
999 | printk(KERN_ERR |
1000 | "MCE %#lx: memory outside kernel control\n", | |
1001 | pfn); | |
1002 | return -ENXIO; | |
6a46079c AK |
1003 | } |
1004 | ||
1005 | p = pfn_to_page(pfn); | |
7af446a8 | 1006 | hpage = compound_head(p); |
6a46079c | 1007 | if (TestSetPageHWPoison(p)) { |
d95ea51e | 1008 | printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn); |
6a46079c AK |
1009 | return 0; |
1010 | } | |
1011 | ||
37c2ac78 | 1012 | nr_pages = 1 << compound_trans_order(hpage); |
c9fbdd5f | 1013 | atomic_long_add(nr_pages, &mce_bad_pages); |
6a46079c AK |
1014 | |
1015 | /* | |
1016 | * We need/can do nothing about count=0 pages. | |
1017 | * 1) it's a free page, and therefore in safe hand: | |
1018 | * prep_new_page() will be the gate keeper. | |
8c6c2ecb NH |
1019 | * 2) it's a free hugepage, which is also safe: |
1020 | * an affected hugepage will be dequeued from hugepage freelist, | |
1021 | * so there's no concern about reusing it ever after. | |
1022 | * 3) it's part of a non-compound high order page. | |
6a46079c AK |
1023 | * Implies some kernel user: cannot stop them from |
1024 | * R/W the page; let's pray that the page has been | |
1025 | * used and will be freed some time later. | |
1026 | * In fact it's dangerous to directly bump up page count from 0, | |
1027 | * that may make page_freeze_refs()/page_unfreeze_refs() mismatch. | |
1028 | */ | |
82ba011b | 1029 | if (!(flags & MF_COUNT_INCREASED) && |
7af446a8 | 1030 | !get_page_unless_zero(hpage)) { |
8d22ba1b WF |
1031 | if (is_free_buddy_page(p)) { |
1032 | action_result(pfn, "free buddy", DELAYED); | |
1033 | return 0; | |
8c6c2ecb NH |
1034 | } else if (PageHuge(hpage)) { |
1035 | /* | |
1036 | * Check "just unpoisoned", "filter hit", and | |
1037 | * "race with other subpage." | |
1038 | */ | |
7eaceacc | 1039 | lock_page(hpage); |
8c6c2ecb NH |
1040 | if (!PageHWPoison(hpage) |
1041 | || (hwpoison_filter(p) && TestClearPageHWPoison(p)) | |
1042 | || (p != hpage && TestSetPageHWPoison(hpage))) { | |
1043 | atomic_long_sub(nr_pages, &mce_bad_pages); | |
1044 | return 0; | |
1045 | } | |
1046 | set_page_hwpoison_huge_page(hpage); | |
1047 | res = dequeue_hwpoisoned_huge_page(hpage); | |
1048 | action_result(pfn, "free huge", | |
1049 | res ? IGNORED : DELAYED); | |
1050 | unlock_page(hpage); | |
1051 | return res; | |
8d22ba1b WF |
1052 | } else { |
1053 | action_result(pfn, "high order kernel", IGNORED); | |
1054 | return -EBUSY; | |
1055 | } | |
6a46079c AK |
1056 | } |
1057 | ||
e43c3afb WF |
1058 | /* |
1059 | * We ignore non-LRU pages for good reasons. | |
1060 | * - PG_locked is only well defined for LRU pages and a few others | |
1061 | * - to avoid races with __set_page_locked() | |
1062 | * - to avoid races with __SetPageSlab*() (and more non-atomic ops) | |
1063 | * The check (unnecessarily) ignores LRU pages being isolated and | |
1064 | * walked by the page reclaim code, however that's not a big loss. | |
1065 | */ | |
af241a08 JD |
1066 | if (!PageHuge(p) && !PageTransCompound(p)) { |
1067 | if (!PageLRU(p)) | |
1068 | shake_page(p, 0); | |
1069 | if (!PageLRU(p)) { | |
1070 | /* | |
1071 | * shake_page could have turned it free. | |
1072 | */ | |
1073 | if (is_free_buddy_page(p)) { | |
1074 | action_result(pfn, "free buddy, 2nd try", | |
1075 | DELAYED); | |
1076 | return 0; | |
1077 | } | |
1078 | action_result(pfn, "non LRU", IGNORED); | |
1079 | put_page(p); | |
1080 | return -EBUSY; | |
0474a60e | 1081 | } |
e43c3afb | 1082 | } |
e43c3afb | 1083 | |
6a46079c AK |
1084 | /* |
1085 | * Lock the page and wait for writeback to finish. | |
1086 | * It's very difficult to mess with pages currently under IO | |
1087 | * and in many cases impossible, so we just avoid it here. | |
1088 | */ | |
7eaceacc | 1089 | lock_page(hpage); |
847ce401 WF |
1090 | |
1091 | /* | |
1092 | * unpoison always clear PG_hwpoison inside page lock | |
1093 | */ | |
1094 | if (!PageHWPoison(p)) { | |
d95ea51e | 1095 | printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn); |
847ce401 WF |
1096 | res = 0; |
1097 | goto out; | |
1098 | } | |
7c116f2b WF |
1099 | if (hwpoison_filter(p)) { |
1100 | if (TestClearPageHWPoison(p)) | |
c9fbdd5f | 1101 | atomic_long_sub(nr_pages, &mce_bad_pages); |
7af446a8 NH |
1102 | unlock_page(hpage); |
1103 | put_page(hpage); | |
7c116f2b WF |
1104 | return 0; |
1105 | } | |
847ce401 | 1106 | |
7013febc NH |
1107 | /* |
1108 | * For error on the tail page, we should set PG_hwpoison | |
1109 | * on the head page to show that the hugepage is hwpoisoned | |
1110 | */ | |
a6d30ddd | 1111 | if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) { |
7013febc NH |
1112 | action_result(pfn, "hugepage already hardware poisoned", |
1113 | IGNORED); | |
1114 | unlock_page(hpage); | |
1115 | put_page(hpage); | |
1116 | return 0; | |
1117 | } | |
1118 | /* | |
1119 | * Set PG_hwpoison on all pages in an error hugepage, | |
1120 | * because containment is done in hugepage unit for now. | |
1121 | * Since we have done TestSetPageHWPoison() for the head page with | |
1122 | * page lock held, we can safely set PG_hwpoison bits on tail pages. | |
1123 | */ | |
1124 | if (PageHuge(p)) | |
1125 | set_page_hwpoison_huge_page(hpage); | |
1126 | ||
6a46079c AK |
1127 | wait_on_page_writeback(p); |
1128 | ||
1129 | /* | |
1130 | * Now take care of user space mappings. | |
e64a782f | 1131 | * Abort on fail: __delete_from_page_cache() assumes unmapped page. |
6a46079c | 1132 | */ |
1668bfd5 WF |
1133 | if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) { |
1134 | printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn); | |
1135 | res = -EBUSY; | |
1136 | goto out; | |
1137 | } | |
6a46079c AK |
1138 | |
1139 | /* | |
1140 | * Torn down by someone else? | |
1141 | */ | |
dc2a1cbf | 1142 | if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) { |
6a46079c | 1143 | action_result(pfn, "already truncated LRU", IGNORED); |
d95ea51e | 1144 | res = -EBUSY; |
6a46079c AK |
1145 | goto out; |
1146 | } | |
1147 | ||
1148 | res = -EBUSY; | |
1149 | for (ps = error_states;; ps++) { | |
dc2a1cbf | 1150 | if ((p->flags & ps->mask) == ps->res) { |
bd1ce5f9 | 1151 | res = page_action(ps, p, pfn); |
6a46079c AK |
1152 | break; |
1153 | } | |
1154 | } | |
1155 | out: | |
7af446a8 | 1156 | unlock_page(hpage); |
6a46079c AK |
1157 | return res; |
1158 | } | |
1159 | EXPORT_SYMBOL_GPL(__memory_failure); | |
1160 | ||
1161 | /** | |
1162 | * memory_failure - Handle memory failure of a page. | |
1163 | * @pfn: Page Number of the corrupted page | |
1164 | * @trapno: Trap number reported in the signal to user space. | |
1165 | * | |
1166 | * This function is called by the low level machine check code | |
1167 | * of an architecture when it detects hardware memory corruption | |
1168 | * of a page. It tries its best to recover, which includes | |
1169 | * dropping pages, killing processes etc. | |
1170 | * | |
1171 | * The function is primarily of use for corruptions that | |
1172 | * happen outside the current execution context (e.g. when | |
1173 | * detected by a background scrubber) | |
1174 | * | |
1175 | * Must run in process context (e.g. a work queue) with interrupts | |
1176 | * enabled and no spinlocks hold. | |
1177 | */ | |
1178 | void memory_failure(unsigned long pfn, int trapno) | |
1179 | { | |
1180 | __memory_failure(pfn, trapno, 0); | |
1181 | } | |
847ce401 | 1182 | |
ea8f5fb8 HY |
1183 | #define MEMORY_FAILURE_FIFO_ORDER 4 |
1184 | #define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER) | |
1185 | ||
1186 | struct memory_failure_entry { | |
1187 | unsigned long pfn; | |
1188 | int trapno; | |
1189 | int flags; | |
1190 | }; | |
1191 | ||
1192 | struct memory_failure_cpu { | |
1193 | DECLARE_KFIFO(fifo, struct memory_failure_entry, | |
1194 | MEMORY_FAILURE_FIFO_SIZE); | |
1195 | spinlock_t lock; | |
1196 | struct work_struct work; | |
1197 | }; | |
1198 | ||
1199 | static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu); | |
1200 | ||
1201 | /** | |
1202 | * memory_failure_queue - Schedule handling memory failure of a page. | |
1203 | * @pfn: Page Number of the corrupted page | |
1204 | * @trapno: Trap number reported in the signal to user space. | |
1205 | * @flags: Flags for memory failure handling | |
1206 | * | |
1207 | * This function is called by the low level hardware error handler | |
1208 | * when it detects hardware memory corruption of a page. It schedules | |
1209 | * the recovering of error page, including dropping pages, killing | |
1210 | * processes etc. | |
1211 | * | |
1212 | * The function is primarily of use for corruptions that | |
1213 | * happen outside the current execution context (e.g. when | |
1214 | * detected by a background scrubber) | |
1215 | * | |
1216 | * Can run in IRQ context. | |
1217 | */ | |
1218 | void memory_failure_queue(unsigned long pfn, int trapno, int flags) | |
1219 | { | |
1220 | struct memory_failure_cpu *mf_cpu; | |
1221 | unsigned long proc_flags; | |
1222 | struct memory_failure_entry entry = { | |
1223 | .pfn = pfn, | |
1224 | .trapno = trapno, | |
1225 | .flags = flags, | |
1226 | }; | |
1227 | ||
1228 | mf_cpu = &get_cpu_var(memory_failure_cpu); | |
1229 | spin_lock_irqsave(&mf_cpu->lock, proc_flags); | |
1230 | if (kfifo_put(&mf_cpu->fifo, &entry)) | |
1231 | schedule_work_on(smp_processor_id(), &mf_cpu->work); | |
1232 | else | |
1233 | pr_err("Memory failure: buffer overflow when queuing memory failure at 0x%#lx\n", | |
1234 | pfn); | |
1235 | spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); | |
1236 | put_cpu_var(memory_failure_cpu); | |
1237 | } | |
1238 | EXPORT_SYMBOL_GPL(memory_failure_queue); | |
1239 | ||
1240 | static void memory_failure_work_func(struct work_struct *work) | |
1241 | { | |
1242 | struct memory_failure_cpu *mf_cpu; | |
1243 | struct memory_failure_entry entry = { 0, }; | |
1244 | unsigned long proc_flags; | |
1245 | int gotten; | |
1246 | ||
1247 | mf_cpu = &__get_cpu_var(memory_failure_cpu); | |
1248 | for (;;) { | |
1249 | spin_lock_irqsave(&mf_cpu->lock, proc_flags); | |
1250 | gotten = kfifo_get(&mf_cpu->fifo, &entry); | |
1251 | spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); | |
1252 | if (!gotten) | |
1253 | break; | |
1254 | __memory_failure(entry.pfn, entry.trapno, entry.flags); | |
1255 | } | |
1256 | } | |
1257 | ||
1258 | static int __init memory_failure_init(void) | |
1259 | { | |
1260 | struct memory_failure_cpu *mf_cpu; | |
1261 | int cpu; | |
1262 | ||
1263 | for_each_possible_cpu(cpu) { | |
1264 | mf_cpu = &per_cpu(memory_failure_cpu, cpu); | |
1265 | spin_lock_init(&mf_cpu->lock); | |
1266 | INIT_KFIFO(mf_cpu->fifo); | |
1267 | INIT_WORK(&mf_cpu->work, memory_failure_work_func); | |
1268 | } | |
1269 | ||
1270 | return 0; | |
1271 | } | |
1272 | core_initcall(memory_failure_init); | |
1273 | ||
847ce401 WF |
1274 | /** |
1275 | * unpoison_memory - Unpoison a previously poisoned page | |
1276 | * @pfn: Page number of the to be unpoisoned page | |
1277 | * | |
1278 | * Software-unpoison a page that has been poisoned by | |
1279 | * memory_failure() earlier. | |
1280 | * | |
1281 | * This is only done on the software-level, so it only works | |
1282 | * for linux injected failures, not real hardware failures | |
1283 | * | |
1284 | * Returns 0 for success, otherwise -errno. | |
1285 | */ | |
1286 | int unpoison_memory(unsigned long pfn) | |
1287 | { | |
1288 | struct page *page; | |
1289 | struct page *p; | |
1290 | int freeit = 0; | |
c9fbdd5f | 1291 | unsigned int nr_pages; |
847ce401 WF |
1292 | |
1293 | if (!pfn_valid(pfn)) | |
1294 | return -ENXIO; | |
1295 | ||
1296 | p = pfn_to_page(pfn); | |
1297 | page = compound_head(p); | |
1298 | ||
1299 | if (!PageHWPoison(p)) { | |
fb46e735 | 1300 | pr_info("MCE: Page was already unpoisoned %#lx\n", pfn); |
847ce401 WF |
1301 | return 0; |
1302 | } | |
1303 | ||
37c2ac78 | 1304 | nr_pages = 1 << compound_trans_order(page); |
c9fbdd5f | 1305 | |
847ce401 | 1306 | if (!get_page_unless_zero(page)) { |
8c6c2ecb NH |
1307 | /* |
1308 | * Since HWPoisoned hugepage should have non-zero refcount, | |
1309 | * race between memory failure and unpoison seems to happen. | |
1310 | * In such case unpoison fails and memory failure runs | |
1311 | * to the end. | |
1312 | */ | |
1313 | if (PageHuge(page)) { | |
dd73e85f | 1314 | pr_info("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); |
8c6c2ecb NH |
1315 | return 0; |
1316 | } | |
847ce401 | 1317 | if (TestClearPageHWPoison(p)) |
c9fbdd5f | 1318 | atomic_long_sub(nr_pages, &mce_bad_pages); |
fb46e735 | 1319 | pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn); |
847ce401 WF |
1320 | return 0; |
1321 | } | |
1322 | ||
7eaceacc | 1323 | lock_page(page); |
847ce401 WF |
1324 | /* |
1325 | * This test is racy because PG_hwpoison is set outside of page lock. | |
1326 | * That's acceptable because that won't trigger kernel panic. Instead, | |
1327 | * the PG_hwpoison page will be caught and isolated on the entrance to | |
1328 | * the free buddy page pool. | |
1329 | */ | |
c9fbdd5f | 1330 | if (TestClearPageHWPoison(page)) { |
fb46e735 | 1331 | pr_info("MCE: Software-unpoisoned page %#lx\n", pfn); |
c9fbdd5f | 1332 | atomic_long_sub(nr_pages, &mce_bad_pages); |
847ce401 | 1333 | freeit = 1; |
6a90181c NH |
1334 | if (PageHuge(page)) |
1335 | clear_page_hwpoison_huge_page(page); | |
847ce401 WF |
1336 | } |
1337 | unlock_page(page); | |
1338 | ||
1339 | put_page(page); | |
1340 | if (freeit) | |
1341 | put_page(page); | |
1342 | ||
1343 | return 0; | |
1344 | } | |
1345 | EXPORT_SYMBOL(unpoison_memory); | |
facb6011 AK |
1346 | |
1347 | static struct page *new_page(struct page *p, unsigned long private, int **x) | |
1348 | { | |
12686d15 | 1349 | int nid = page_to_nid(p); |
d950b958 NH |
1350 | if (PageHuge(p)) |
1351 | return alloc_huge_page_node(page_hstate(compound_head(p)), | |
1352 | nid); | |
1353 | else | |
1354 | return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0); | |
facb6011 AK |
1355 | } |
1356 | ||
1357 | /* | |
1358 | * Safely get reference count of an arbitrary page. | |
1359 | * Returns 0 for a free page, -EIO for a zero refcount page | |
1360 | * that is not free, and 1 for any other page type. | |
1361 | * For 1 the page is returned with increased page count, otherwise not. | |
1362 | */ | |
1363 | static int get_any_page(struct page *p, unsigned long pfn, int flags) | |
1364 | { | |
1365 | int ret; | |
1366 | ||
1367 | if (flags & MF_COUNT_INCREASED) | |
1368 | return 1; | |
1369 | ||
1370 | /* | |
20d6c96b | 1371 | * The lock_memory_hotplug prevents a race with memory hotplug. |
facb6011 AK |
1372 | * This is a big hammer, a better would be nicer. |
1373 | */ | |
20d6c96b | 1374 | lock_memory_hotplug(); |
facb6011 AK |
1375 | |
1376 | /* | |
1377 | * Isolate the page, so that it doesn't get reallocated if it | |
1378 | * was free. | |
1379 | */ | |
1380 | set_migratetype_isolate(p); | |
d950b958 NH |
1381 | /* |
1382 | * When the target page is a free hugepage, just remove it | |
1383 | * from free hugepage list. | |
1384 | */ | |
facb6011 | 1385 | if (!get_page_unless_zero(compound_head(p))) { |
d950b958 | 1386 | if (PageHuge(p)) { |
46e387bb | 1387 | pr_info("get_any_page: %#lx free huge page\n", pfn); |
d950b958 NH |
1388 | ret = dequeue_hwpoisoned_huge_page(compound_head(p)); |
1389 | } else if (is_free_buddy_page(p)) { | |
fb46e735 | 1390 | pr_info("get_any_page: %#lx free buddy page\n", pfn); |
facb6011 AK |
1391 | /* Set hwpoison bit while page is still isolated */ |
1392 | SetPageHWPoison(p); | |
1393 | ret = 0; | |
1394 | } else { | |
fb46e735 | 1395 | pr_info("get_any_page: %#lx: unknown zero refcount page type %lx\n", |
facb6011 AK |
1396 | pfn, p->flags); |
1397 | ret = -EIO; | |
1398 | } | |
1399 | } else { | |
1400 | /* Not a free page */ | |
1401 | ret = 1; | |
1402 | } | |
1403 | unset_migratetype_isolate(p); | |
20d6c96b | 1404 | unlock_memory_hotplug(); |
facb6011 AK |
1405 | return ret; |
1406 | } | |
1407 | ||
d950b958 NH |
1408 | static int soft_offline_huge_page(struct page *page, int flags) |
1409 | { | |
1410 | int ret; | |
1411 | unsigned long pfn = page_to_pfn(page); | |
1412 | struct page *hpage = compound_head(page); | |
1413 | LIST_HEAD(pagelist); | |
1414 | ||
1415 | ret = get_any_page(page, pfn, flags); | |
1416 | if (ret < 0) | |
1417 | return ret; | |
1418 | if (ret == 0) | |
1419 | goto done; | |
1420 | ||
1421 | if (PageHWPoison(hpage)) { | |
1422 | put_page(hpage); | |
dd73e85f | 1423 | pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); |
d950b958 NH |
1424 | return -EBUSY; |
1425 | } | |
1426 | ||
1427 | /* Keep page count to indicate a given hugepage is isolated. */ | |
1428 | ||
1429 | list_add(&hpage->lru, &pagelist); | |
77f1fe6b MG |
1430 | ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0, |
1431 | true); | |
d950b958 | 1432 | if (ret) { |
48db54ee MK |
1433 | struct page *page1, *page2; |
1434 | list_for_each_entry_safe(page1, page2, &pagelist, lru) | |
1435 | put_page(page1); | |
1436 | ||
dd73e85f DN |
1437 | pr_info("soft offline: %#lx: migration failed %d, type %lx\n", |
1438 | pfn, ret, page->flags); | |
d950b958 NH |
1439 | if (ret > 0) |
1440 | ret = -EIO; | |
1441 | return ret; | |
1442 | } | |
1443 | done: | |
1444 | if (!PageHWPoison(hpage)) | |
37c2ac78 | 1445 | atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages); |
d950b958 NH |
1446 | set_page_hwpoison_huge_page(hpage); |
1447 | dequeue_hwpoisoned_huge_page(hpage); | |
1448 | /* keep elevated page count for bad page */ | |
1449 | return ret; | |
1450 | } | |
1451 | ||
facb6011 AK |
1452 | /** |
1453 | * soft_offline_page - Soft offline a page. | |
1454 | * @page: page to offline | |
1455 | * @flags: flags. Same as memory_failure(). | |
1456 | * | |
1457 | * Returns 0 on success, otherwise negated errno. | |
1458 | * | |
1459 | * Soft offline a page, by migration or invalidation, | |
1460 | * without killing anything. This is for the case when | |
1461 | * a page is not corrupted yet (so it's still valid to access), | |
1462 | * but has had a number of corrected errors and is better taken | |
1463 | * out. | |
1464 | * | |
1465 | * The actual policy on when to do that is maintained by | |
1466 | * user space. | |
1467 | * | |
1468 | * This should never impact any application or cause data loss, | |
1469 | * however it might take some time. | |
1470 | * | |
1471 | * This is not a 100% solution for all memory, but tries to be | |
1472 | * ``good enough'' for the majority of memory. | |
1473 | */ | |
1474 | int soft_offline_page(struct page *page, int flags) | |
1475 | { | |
1476 | int ret; | |
1477 | unsigned long pfn = page_to_pfn(page); | |
1478 | ||
d950b958 NH |
1479 | if (PageHuge(page)) |
1480 | return soft_offline_huge_page(page, flags); | |
1481 | ||
facb6011 AK |
1482 | ret = get_any_page(page, pfn, flags); |
1483 | if (ret < 0) | |
1484 | return ret; | |
1485 | if (ret == 0) | |
1486 | goto done; | |
1487 | ||
1488 | /* | |
1489 | * Page cache page we can handle? | |
1490 | */ | |
1491 | if (!PageLRU(page)) { | |
1492 | /* | |
1493 | * Try to free it. | |
1494 | */ | |
1495 | put_page(page); | |
1496 | shake_page(page, 1); | |
1497 | ||
1498 | /* | |
1499 | * Did it turn free? | |
1500 | */ | |
1501 | ret = get_any_page(page, pfn, 0); | |
1502 | if (ret < 0) | |
1503 | return ret; | |
1504 | if (ret == 0) | |
1505 | goto done; | |
1506 | } | |
1507 | if (!PageLRU(page)) { | |
fb46e735 | 1508 | pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", |
dd73e85f | 1509 | pfn, page->flags); |
facb6011 AK |
1510 | return -EIO; |
1511 | } | |
1512 | ||
1513 | lock_page(page); | |
1514 | wait_on_page_writeback(page); | |
1515 | ||
1516 | /* | |
1517 | * Synchronized using the page lock with memory_failure() | |
1518 | */ | |
1519 | if (PageHWPoison(page)) { | |
1520 | unlock_page(page); | |
1521 | put_page(page); | |
fb46e735 | 1522 | pr_info("soft offline: %#lx page already poisoned\n", pfn); |
facb6011 AK |
1523 | return -EBUSY; |
1524 | } | |
1525 | ||
1526 | /* | |
1527 | * Try to invalidate first. This should work for | |
1528 | * non dirty unmapped page cache pages. | |
1529 | */ | |
1530 | ret = invalidate_inode_page(page); | |
1531 | unlock_page(page); | |
facb6011 | 1532 | /* |
facb6011 AK |
1533 | * RED-PEN would be better to keep it isolated here, but we |
1534 | * would need to fix isolation locking first. | |
1535 | */ | |
facb6011 | 1536 | if (ret == 1) { |
bd486285 | 1537 | put_page(page); |
facb6011 | 1538 | ret = 0; |
fb46e735 | 1539 | pr_info("soft_offline: %#lx: invalidated\n", pfn); |
facb6011 AK |
1540 | goto done; |
1541 | } | |
1542 | ||
1543 | /* | |
1544 | * Simple invalidation didn't work. | |
1545 | * Try to migrate to a new page instead. migrate.c | |
1546 | * handles a large number of cases for us. | |
1547 | */ | |
1548 | ret = isolate_lru_page(page); | |
bd486285 KK |
1549 | /* |
1550 | * Drop page reference which is came from get_any_page() | |
1551 | * successful isolate_lru_page() already took another one. | |
1552 | */ | |
1553 | put_page(page); | |
facb6011 AK |
1554 | if (!ret) { |
1555 | LIST_HEAD(pagelist); | |
5db8a73a MK |
1556 | inc_zone_page_state(page, NR_ISOLATED_ANON + |
1557 | page_is_file_cache(page)); | |
facb6011 | 1558 | list_add(&page->lru, &pagelist); |
77f1fe6b MG |
1559 | ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, |
1560 | 0, true); | |
facb6011 | 1561 | if (ret) { |
57fc4a5e | 1562 | putback_lru_pages(&pagelist); |
fb46e735 | 1563 | pr_info("soft offline: %#lx: migration failed %d, type %lx\n", |
facb6011 AK |
1564 | pfn, ret, page->flags); |
1565 | if (ret > 0) | |
1566 | ret = -EIO; | |
1567 | } | |
1568 | } else { | |
fb46e735 | 1569 | pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", |
dd73e85f | 1570 | pfn, ret, page_count(page), page->flags); |
facb6011 AK |
1571 | } |
1572 | if (ret) | |
1573 | return ret; | |
1574 | ||
1575 | done: | |
1576 | atomic_long_add(1, &mce_bad_pages); | |
1577 | SetPageHWPoison(page); | |
1578 | /* keep elevated page count for bad page */ | |
1579 | return ret; | |
1580 | } |