1 | /* |
2 | * Copyright (C) 2008, 2009 Intel Corporation |
3 | * Authors: Andi Kleen, Fengguang Wu |
4 | * |
5 | * This software may be redistributed and/or modified under the terms of |
6 | * the GNU General Public License ("GPL") version 2 only as published by the |
7 | * Free Software Foundation. |
8 | * |
9 | * High level machine check handler. Handles pages reported by the |
10 | * hardware as being corrupted usually due to a multi-bit ECC memory or cache |
11 | * failure. |
12 | * |
13 | * In addition there is a "soft offline" entry point that allows stop using |
14 | * not-yet-corrupted-by-suspicious pages without killing anything. |
15 | * |
16 | * Handles page cache pages in various states. The tricky part |
17 | * here is that we can access any page asynchronously in respect to |
18 | * other VM users, because memory failures could happen anytime and |
19 | * anywhere. This could violate some of their assumptions. This is why |
20 | * this code has to be extremely careful. Generally it tries to use |
21 | * normal locking rules, as in get the standard locks, even if that means |
22 | * the error handling takes potentially a long time. |
23 | * |
24 | * It can be very tempting to add handling for obscure cases here. |
25 | * In general any code for handling new cases should only be added iff: |
26 | * - You know how to test it. |
27 | * - You have a test that can be added to mce-test |
28 | * https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/ |
29 | * - The case actually shows up as a frequent (top 10) page state in |
30 | * tools/vm/page-types when running a real workload. |
31 | * |
32 | * There are several operations here with exponential complexity because |
33 | * of unsuitable VM data structures. For example the operation to map back |
34 | * from RMAP chains to processes has to walk the complete process list and |
35 | * has non linear complexity with the number. But since memory corruptions |
36 | * are rare we hope to get away with this. This avoids impacting the core |
37 | * VM. |
38 | */ |
39 | #include <linux/kernel.h> |
40 | #include <linux/mm.h> |
41 | #include <linux/page-flags.h> |
42 | #include <linux/kernel-page-flags.h> |
43 | #include <linux/sched/signal.h> |
44 | #include <linux/sched/task.h> |
45 | #include <linux/ksm.h> |
46 | #include <linux/rmap.h> |
47 | #include <linux/export.h> |
48 | #include <linux/pagemap.h> |
49 | #include <linux/swap.h> |
50 | #include <linux/backing-dev.h> |
51 | #include <linux/migrate.h> |
52 | #include <linux/suspend.h> |
53 | #include <linux/slab.h> |
54 | #include <linux/swapops.h> |
55 | #include <linux/hugetlb.h> |
56 | #include <linux/memory_hotplug.h> |
57 | #include <linux/mm_inline.h> |
58 | #include <linux/memremap.h> |
59 | #include <linux/kfifo.h> |
60 | #include <linux/ratelimit.h> |
61 | #include <linux/page-isolation.h> |
62 | #include "internal.h" |
63 | #include "ras/ras_event.h" |
64 | |
65 | int sysctl_memory_failure_early_kill __read_mostly = 0; |
66 | |
67 | int sysctl_memory_failure_recovery __read_mostly = 1; |
68 | |
69 | atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0); |
70 | |
71 | #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE) |
72 | |
73 | u32 hwpoison_filter_enable = 0; |
74 | u32 hwpoison_filter_dev_major = ~0U; |
75 | u32 hwpoison_filter_dev_minor = ~0U; |
76 | u64 hwpoison_filter_flags_mask; |
77 | u64 hwpoison_filter_flags_value; |
78 | EXPORT_SYMBOL_GPL(hwpoison_filter_enable); |
79 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major); |
80 | EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor); |
81 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask); |
82 | EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value); |
83 | |
84 | static int hwpoison_filter_dev(struct page *p) |
85 | { |
86 | struct address_space *mapping; |
87 | dev_t dev; |
88 | |
89 | if (hwpoison_filter_dev_major == ~0U && |
90 | hwpoison_filter_dev_minor == ~0U) |
91 | return 0; |
92 | |
93 | /* |
94 | * page_mapping() does not accept slab pages. |
95 | */ |
96 | if (PageSlab(p)) |
97 | return -EINVAL; |
98 | |
99 | mapping = page_mapping(p); |
100 | if (mapping == NULL || mapping->host == NULL) |
101 | return -EINVAL; |
102 | |
103 | dev = mapping->host->i_sb->s_dev; |
104 | if (hwpoison_filter_dev_major != ~0U && |
105 | hwpoison_filter_dev_major != MAJOR(dev)) |
106 | return -EINVAL; |
107 | if (hwpoison_filter_dev_minor != ~0U && |
108 | hwpoison_filter_dev_minor != MINOR(dev)) |
109 | return -EINVAL; |
110 | |
111 | return 0; |
112 | } |
113 | |
114 | static int hwpoison_filter_flags(struct page *p) |
115 | { |
116 | if (!hwpoison_filter_flags_mask) |
117 | return 0; |
118 | |
119 | if ((stable_page_flags(p) & hwpoison_filter_flags_mask) == |
120 | hwpoison_filter_flags_value) |
121 | return 0; |
122 | else |
123 | return -EINVAL; |
124 | } |
125 | |
126 | /* |
127 | * This allows stress tests to limit test scope to a collection of tasks |
128 | * by putting them under some memcg. This prevents killing unrelated/important |
129 | * processes such as /sbin/init. Note that the target task may share clean |
130 | * pages with init (eg. libc text), which is harmless. If the target task |
131 | * share _dirty_ pages with another task B, the test scheme must make sure B |
132 | * is also included in the memcg. At last, due to race conditions this filter |
133 | * can only guarantee that the page either belongs to the memcg tasks, or is |
134 | * a freed page. |
135 | */ |
136 | #ifdef CONFIG_MEMCG |
137 | u64 hwpoison_filter_memcg; |
138 | EXPORT_SYMBOL_GPL(hwpoison_filter_memcg); |
139 | static int hwpoison_filter_task(struct page *p) |
140 | { |
141 | if (!hwpoison_filter_memcg) |
142 | return 0; |
143 | |
144 | if (page_cgroup_ino(p) != hwpoison_filter_memcg) |
145 | return -EINVAL; |
146 | |
147 | return 0; |
148 | } |
149 | #else |
150 | static int hwpoison_filter_task(struct page *p) { return 0; } |
151 | #endif |
152 | |
153 | int hwpoison_filter(struct page *p) |
154 | { |
155 | if (!hwpoison_filter_enable) |
156 | return 0; |
157 | |
158 | if (hwpoison_filter_dev(p)) |
159 | return -EINVAL; |
160 | |
161 | if (hwpoison_filter_flags(p)) |
162 | return -EINVAL; |
163 | |
164 | if (hwpoison_filter_task(p)) |
165 | return -EINVAL; |
166 | |
167 | return 0; |
168 | } |
169 | #else |
170 | int hwpoison_filter(struct page *p) |
171 | { |
172 | return 0; |
173 | } |
174 | #endif |
175 | |
176 | EXPORT_SYMBOL_GPL(hwpoison_filter); |
177 | |
178 | /* |
179 | * Kill all processes that have a poisoned page mapped and then isolate |
180 | * the page. |
181 | * |
182 | * General strategy: |
183 | * Find all processes having the page mapped and kill them. |
184 | * But we keep a page reference around so that the page is not |
185 | * actually freed yet. |
186 | * Then stash the page away |
187 | * |
188 | * There's no convenient way to get back to mapped processes |
189 | * from the VMAs. So do a brute-force search over all |
190 | * running processes. |
191 | * |
192 | * Remember that machine checks are not common (or rather |
193 | * if they are common you have other problems), so this shouldn't |
194 | * be a performance issue. |
195 | * |
196 | * Also there are some races possible while we get from the |
197 | * error detection to actually handle it. |
198 | */ |
199 | |
200 | struct to_kill { |
201 | struct list_head nd; |
202 | struct task_struct *tsk; |
203 | unsigned long addr; |
204 | short size_shift; |
205 | char addr_valid; |
206 | }; |
207 | |
208 | /* |
209 | * Send all the processes who have the page mapped a signal. |
210 | * ``action optional'' if they are not immediately affected by the error |
211 | * ``action required'' if error happened in current execution context |
212 | */ |
213 | static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags) |
214 | { |
215 | struct task_struct *t = tk->tsk; |
216 | short addr_lsb = tk->size_shift; |
217 | int ret; |
218 | |
219 | pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n" , |
220 | pfn, t->comm, t->pid); |
221 | |
222 | if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) { |
223 | ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr, |
224 | addr_lsb, current); |
225 | } else { |
226 | /* |
227 | * Don't use force here, it's convenient if the signal |
228 | * can be temporarily blocked. |
229 | * This could cause a loop when the user sets SIGBUS |
230 | * to SIG_IGN, but hopefully no one will do that? |
231 | */ |
232 | ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr, |
233 | addr_lsb, t); /* synchronous? */ |
234 | } |
235 | if (ret < 0) |
236 | pr_info("Memory failure: Error sending signal to %s:%d: %d\n" , |
237 | t->comm, t->pid, ret); |
238 | return ret; |
239 | } |
240 | |
241 | /* |
242 | * When a unknown page type is encountered drain as many buffers as possible |
243 | * in the hope to turn the page into a LRU or free page, which we can handle. |
244 | */ |
245 | void shake_page(struct page *p, int access) |
246 | { |
247 | if (PageHuge(p)) |
248 | return; |
249 | |
250 | if (!PageSlab(p)) { |
251 | lru_add_drain_all(); |
252 | if (PageLRU(p)) |
253 | return; |
254 | drain_all_pages(page_zone(p)); |
255 | if (PageLRU(p) || is_free_buddy_page(p)) |
256 | return; |
257 | } |
258 | |
259 | /* |
260 | * Only call shrink_node_slabs here (which would also shrink |
261 | * other caches) if access is not potentially fatal. |
262 | */ |
263 | if (access) |
264 | drop_slab_node(page_to_nid(p)); |
265 | } |
266 | EXPORT_SYMBOL_GPL(shake_page); |
267 | |
268 | static unsigned long dev_pagemap_mapping_shift(struct page *page, |
269 | struct vm_area_struct *vma) |
270 | { |
271 | unsigned long address = vma_address(page, vma); |
272 | pgd_t *pgd; |
273 | p4d_t *p4d; |
274 | pud_t *pud; |
275 | pmd_t *pmd; |
276 | pte_t *pte; |
277 | |
278 | pgd = pgd_offset(vma->vm_mm, address); |
279 | if (!pgd_present(*pgd)) |
280 | return 0; |
281 | p4d = p4d_offset(pgd, address); |
282 | if (!p4d_present(*p4d)) |
283 | return 0; |
284 | pud = pud_offset(p4d, address); |
285 | if (!pud_present(*pud)) |
286 | return 0; |
287 | if (pud_devmap(*pud)) |
288 | return PUD_SHIFT; |
289 | pmd = pmd_offset(pud, address); |
290 | if (!pmd_present(*pmd)) |
291 | return 0; |
292 | if (pmd_devmap(*pmd)) |
293 | return PMD_SHIFT; |
294 | pte = pte_offset_map(pmd, address); |
295 | if (!pte_present(*pte)) |
296 | return 0; |
297 | if (pte_devmap(*pte)) |
298 | return PAGE_SHIFT; |
299 | return 0; |
300 | } |
301 | |
302 | /* |
303 | * Failure handling: if we can't find or can't kill a process there's |
304 | * not much we can do. We just print a message and ignore otherwise. |
305 | */ |
306 | |
307 | /* |
308 | * Schedule a process for later kill. |
309 | * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM. |
310 | * TBD would GFP_NOIO be enough? |
311 | */ |
312 | static void add_to_kill(struct task_struct *tsk, struct page *p, |
313 | struct vm_area_struct *vma, |
314 | struct list_head *to_kill, |
315 | struct to_kill **tkc) |
316 | { |
317 | struct to_kill *tk; |
318 | |
319 | if (*tkc) { |
320 | tk = *tkc; |
321 | *tkc = NULL; |
322 | } else { |
323 | tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC); |
324 | if (!tk) { |
325 | pr_err("Memory failure: Out of memory while machine check handling\n" ); |
326 | return; |
327 | } |
328 | } |
329 | tk->addr = page_address_in_vma(p, vma); |
330 | tk->addr_valid = 1; |
331 | if (is_zone_device_page(p)) |
332 | tk->size_shift = dev_pagemap_mapping_shift(p, vma); |
333 | else |
334 | tk->size_shift = compound_order(compound_head(p)) + PAGE_SHIFT; |
335 | |
336 | /* |
337 | * In theory we don't have to kill when the page was |
338 | * munmaped. But it could be also a mremap. Since that's |
339 | * likely very rare kill anyways just out of paranoia, but use |
340 | * a SIGKILL because the error is not contained anymore. |
341 | */ |
342 | if (tk->addr == -EFAULT || tk->size_shift == 0) { |
343 | pr_info("Memory failure: Unable to find user space address %lx in %s\n" , |
344 | page_to_pfn(p), tsk->comm); |
345 | tk->addr_valid = 0; |
346 | } |
347 | get_task_struct(tsk); |
348 | tk->tsk = tsk; |
349 | list_add_tail(&tk->nd, to_kill); |
350 | } |
351 | |
352 | /* |
353 | * Kill the processes that have been collected earlier. |
354 | * |
355 | * Only do anything when DOIT is set, otherwise just free the list |
356 | * (this is used for clean pages which do not need killing) |
357 | * Also when FAIL is set do a force kill because something went |
358 | * wrong earlier. |
359 | */ |
360 | static void kill_procs(struct list_head *to_kill, int forcekill, bool fail, |
361 | unsigned long pfn, int flags) |
362 | { |
363 | struct to_kill *tk, *next; |
364 | |
365 | list_for_each_entry_safe (tk, next, to_kill, nd) { |
366 | if (forcekill) { |
367 | /* |
368 | * In case something went wrong with munmapping |
369 | * make sure the process doesn't catch the |
370 | * signal and then access the memory. Just kill it. |
371 | */ |
372 | if (fail || tk->addr_valid == 0) { |
373 | pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n" , |
374 | pfn, tk->tsk->comm, tk->tsk->pid); |
375 | do_send_sig_info(SIGKILL, SEND_SIG_PRIV, |
376 | tk->tsk, PIDTYPE_PID); |
377 | } |
378 | |
379 | /* |
380 | * In theory the process could have mapped |
381 | * something else on the address in-between. We could |
382 | * check for that, but we need to tell the |
383 | * process anyways. |
384 | */ |
385 | else if (kill_proc(tk, pfn, flags) < 0) |
386 | pr_err("Memory failure: %#lx: Cannot send advisory machine check signal to %s:%d\n" , |
387 | pfn, tk->tsk->comm, tk->tsk->pid); |
388 | } |
389 | put_task_struct(tk->tsk); |
390 | kfree(tk); |
391 | } |
392 | } |
393 | |
394 | /* |
395 | * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO) |
396 | * on behalf of the thread group. Return task_struct of the (first found) |
397 | * dedicated thread if found, and return NULL otherwise. |
398 | * |
399 | * We already hold read_lock(&tasklist_lock) in the caller, so we don't |
400 | * have to call rcu_read_lock/unlock() in this function. |
401 | */ |
402 | static struct task_struct *find_early_kill_thread(struct task_struct *tsk) |
403 | { |
404 | struct task_struct *t; |
405 | |
406 | for_each_thread(tsk, t) |
407 | if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY)) |
408 | return t; |
409 | return NULL; |
410 | } |
411 | |
412 | /* |
413 | * Determine whether a given process is "early kill" process which expects |
414 | * to be signaled when some page under the process is hwpoisoned. |
415 | * Return task_struct of the dedicated thread (main thread unless explicitly |
416 | * specified) if the process is "early kill," and otherwise returns NULL. |
417 | */ |
418 | static struct task_struct *task_early_kill(struct task_struct *tsk, |
419 | int force_early) |
420 | { |
421 | struct task_struct *t; |
422 | if (!tsk->mm) |
423 | return NULL; |
424 | if (force_early) |
425 | return tsk; |
426 | t = find_early_kill_thread(tsk); |
427 | if (t) |
428 | return t; |
429 | if (sysctl_memory_failure_early_kill) |
430 | return tsk; |
431 | return NULL; |
432 | } |
433 | |
434 | /* |
435 | * Collect processes when the error hit an anonymous page. |
436 | */ |
437 | static void collect_procs_anon(struct page *page, struct list_head *to_kill, |
438 | struct to_kill **tkc, int force_early) |
439 | { |
440 | struct vm_area_struct *vma; |
441 | struct task_struct *tsk; |
442 | struct anon_vma *av; |
443 | pgoff_t pgoff; |
444 | |
445 | av = page_lock_anon_vma_read(page); |
446 | if (av == NULL) /* Not actually mapped anymore */ |
447 | return; |
448 | |
449 | pgoff = page_to_pgoff(page); |
450 | read_lock(&tasklist_lock); |
451 | for_each_process (tsk) { |
452 | struct anon_vma_chain *vmac; |
453 | struct task_struct *t = task_early_kill(tsk, force_early); |
454 | |
455 | if (!t) |
456 | continue; |
457 | anon_vma_interval_tree_foreach(vmac, &av->rb_root, |
458 | pgoff, pgoff) { |
459 | vma = vmac->vma; |
460 | if (!page_mapped_in_vma(page, vma)) |
461 | continue; |
462 | if (vma->vm_mm == t->mm) |
463 | add_to_kill(t, page, vma, to_kill, tkc); |
464 | } |
465 | } |
466 | read_unlock(&tasklist_lock); |
467 | page_unlock_anon_vma_read(av); |
468 | } |
469 | |
470 | /* |
471 | * Collect processes when the error hit a file mapped page. |
472 | */ |
473 | static void collect_procs_file(struct page *page, struct list_head *to_kill, |
474 | struct to_kill **tkc, int force_early) |
475 | { |
476 | struct vm_area_struct *vma; |
477 | struct task_struct *tsk; |
478 | struct address_space *mapping = page->mapping; |
479 | |
480 | i_mmap_lock_read(mapping); |
481 | read_lock(&tasklist_lock); |
482 | for_each_process(tsk) { |
483 | pgoff_t pgoff = page_to_pgoff(page); |
484 | struct task_struct *t = task_early_kill(tsk, force_early); |
485 | |
486 | if (!t) |
487 | continue; |
488 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, |
489 | pgoff) { |
490 | /* |
491 | * Send early kill signal to tasks where a vma covers |
492 | * the page but the corrupted page is not necessarily |
493 | * mapped it in its pte. |
494 | * Assume applications who requested early kill want |
495 | * to be informed of all such data corruptions. |
496 | */ |
497 | if (vma->vm_mm == t->mm) |
498 | add_to_kill(t, page, vma, to_kill, tkc); |
499 | } |
500 | } |
501 | read_unlock(&tasklist_lock); |
502 | i_mmap_unlock_read(mapping); |
503 | } |
504 | |
505 | /* |
506 | * Collect the processes who have the corrupted page mapped to kill. |
507 | * This is done in two steps for locking reasons. |
508 | * First preallocate one tokill structure outside the spin locks, |
509 | * so that we can kill at least one process reasonably reliable. |
510 | */ |
511 | static void collect_procs(struct page *page, struct list_head *tokill, |
512 | int force_early) |
513 | { |
514 | struct to_kill *tk; |
515 | |
516 | if (!page->mapping) |
517 | return; |
518 | |
519 | tk = kmalloc(sizeof(struct to_kill), GFP_NOIO); |
520 | if (!tk) |
521 | return; |
522 | if (PageAnon(page)) |
523 | collect_procs_anon(page, tokill, &tk, force_early); |
524 | else |
525 | collect_procs_file(page, tokill, &tk, force_early); |
526 | kfree(tk); |
527 | } |
528 | |
529 | static const char *action_name[] = { |
530 | [MF_IGNORED] = "Ignored" , |
531 | [MF_FAILED] = "Failed" , |
532 | [MF_DELAYED] = "Delayed" , |
533 | [MF_RECOVERED] = "Recovered" , |
534 | }; |
535 | |
536 | static const char * const action_page_types[] = { |
537 | [MF_MSG_KERNEL] = "reserved kernel page" , |
538 | [MF_MSG_KERNEL_HIGH_ORDER] = "high-order kernel page" , |
539 | [MF_MSG_SLAB] = "kernel slab page" , |
540 | [MF_MSG_DIFFERENT_COMPOUND] = "different compound page after locking" , |
541 | [MF_MSG_POISONED_HUGE] = "huge page already hardware poisoned" , |
542 | [MF_MSG_HUGE] = "huge page" , |
543 | [MF_MSG_FREE_HUGE] = "free huge page" , |
544 | [MF_MSG_NON_PMD_HUGE] = "non-pmd-sized huge page" , |
545 | [MF_MSG_UNMAP_FAILED] = "unmapping failed page" , |
546 | [MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page" , |
547 | [MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page" , |
548 | [MF_MSG_DIRTY_MLOCKED_LRU] = "dirty mlocked LRU page" , |
549 | [MF_MSG_CLEAN_MLOCKED_LRU] = "clean mlocked LRU page" , |
550 | [MF_MSG_DIRTY_UNEVICTABLE_LRU] = "dirty unevictable LRU page" , |
551 | [MF_MSG_CLEAN_UNEVICTABLE_LRU] = "clean unevictable LRU page" , |
552 | [MF_MSG_DIRTY_LRU] = "dirty LRU page" , |
553 | [MF_MSG_CLEAN_LRU] = "clean LRU page" , |
554 | [MF_MSG_TRUNCATED_LRU] = "already truncated LRU page" , |
555 | [MF_MSG_BUDDY] = "free buddy page" , |
556 | [MF_MSG_BUDDY_2ND] = "free buddy page (2nd try)" , |
557 | [MF_MSG_DAX] = "dax page" , |
558 | [MF_MSG_UNKNOWN] = "unknown page" , |
559 | }; |
560 | |
561 | /* |
562 | * XXX: It is possible that a page is isolated from LRU cache, |
563 | * and then kept in swap cache or failed to remove from page cache. |
564 | * The page count will stop it from being freed by unpoison. |
565 | * Stress tests should be aware of this memory leak problem. |
566 | */ |
567 | static int delete_from_lru_cache(struct page *p) |
568 | { |
569 | if (!isolate_lru_page(p)) { |
570 | /* |
571 | * Clear sensible page flags, so that the buddy system won't |
572 | * complain when the page is unpoison-and-freed. |
573 | */ |
574 | ClearPageActive(p); |
575 | ClearPageUnevictable(p); |
576 | |
577 | /* |
578 | * Poisoned page might never drop its ref count to 0 so we have |
579 | * to uncharge it manually from its memcg. |
580 | */ |
581 | mem_cgroup_uncharge(p); |
582 | |
583 | /* |
584 | * drop the page count elevated by isolate_lru_page() |
585 | */ |
586 | put_page(p); |
587 | return 0; |
588 | } |
589 | return -EIO; |
590 | } |
591 | |
592 | static int truncate_error_page(struct page *p, unsigned long pfn, |
593 | struct address_space *mapping) |
594 | { |
595 | int ret = MF_FAILED; |
596 | |
597 | if (mapping->a_ops->error_remove_page) { |
598 | int err = mapping->a_ops->error_remove_page(mapping, p); |
599 | |
600 | if (err != 0) { |
601 | pr_info("Memory failure: %#lx: Failed to punch page: %d\n" , |
602 | pfn, err); |
603 | } else if (page_has_private(p) && |
604 | !try_to_release_page(p, GFP_NOIO)) { |
605 | pr_info("Memory failure: %#lx: failed to release buffers\n" , |
606 | pfn); |
607 | } else { |
608 | ret = MF_RECOVERED; |
609 | } |
610 | } else { |
611 | /* |
612 | * If the file system doesn't support it just invalidate |
613 | * This fails on dirty or anything with private pages |
614 | */ |
615 | if (invalidate_inode_page(p)) |
616 | ret = MF_RECOVERED; |
617 | else |
618 | pr_info("Memory failure: %#lx: Failed to invalidate\n" , |
619 | pfn); |
620 | } |
621 | |
622 | return ret; |
623 | } |
624 | |
625 | /* |
626 | * Error hit kernel page. |
627 | * Do nothing, try to be lucky and not touch this instead. For a few cases we |
628 | * could be more sophisticated. |
629 | */ |
630 | static int me_kernel(struct page *p, unsigned long pfn) |
631 | { |
632 | return MF_IGNORED; |
633 | } |
634 | |
635 | /* |
636 | * Page in unknown state. Do nothing. |
637 | */ |
638 | static int me_unknown(struct page *p, unsigned long pfn) |
639 | { |
640 | pr_err("Memory failure: %#lx: Unknown page state\n" , pfn); |
641 | return MF_FAILED; |
642 | } |
643 | |
644 | /* |
645 | * Clean (or cleaned) page cache page. |
646 | */ |
647 | static int me_pagecache_clean(struct page *p, unsigned long pfn) |
648 | { |
649 | struct address_space *mapping; |
650 | |
651 | delete_from_lru_cache(p); |
652 | |
653 | /* |
654 | * For anonymous pages we're done the only reference left |
655 | * should be the one m_f() holds. |
656 | */ |
657 | if (PageAnon(p)) |
658 | return MF_RECOVERED; |
659 | |
660 | /* |
661 | * Now truncate the page in the page cache. This is really |
662 | * more like a "temporary hole punch" |
663 | * Don't do this for block devices when someone else |
664 | * has a reference, because it could be file system metadata |
665 | * and that's not safe to truncate. |
666 | */ |
667 | mapping = page_mapping(p); |
668 | if (!mapping) { |
669 | /* |
670 | * Page has been teared down in the meanwhile |
671 | */ |
672 | return MF_FAILED; |
673 | } |
674 | |
675 | /* |
676 | * Truncation is a bit tricky. Enable it per file system for now. |
677 | * |
678 | * Open: to take i_mutex or not for this? Right now we don't. |
679 | */ |
680 | return truncate_error_page(p, pfn, mapping); |
681 | } |
682 | |
683 | /* |
684 | * Dirty pagecache page |
685 | * Issues: when the error hit a hole page the error is not properly |
686 | * propagated. |
687 | */ |
688 | static int me_pagecache_dirty(struct page *p, unsigned long pfn) |
689 | { |
690 | struct address_space *mapping = page_mapping(p); |
691 | |
692 | SetPageError(p); |
693 | /* TBD: print more information about the file. */ |
694 | if (mapping) { |
695 | /* |
696 | * IO error will be reported by write(), fsync(), etc. |
697 | * who check the mapping. |
698 | * This way the application knows that something went |
699 | * wrong with its dirty file data. |
700 | * |
701 | * There's one open issue: |
702 | * |
703 | * The EIO will be only reported on the next IO |
704 | * operation and then cleared through the IO map. |
705 | * Normally Linux has two mechanisms to pass IO error |
706 | * first through the AS_EIO flag in the address space |
707 | * and then through the PageError flag in the page. |
708 | * Since we drop pages on memory failure handling the |
709 | * only mechanism open to use is through AS_AIO. |
710 | * |
711 | * This has the disadvantage that it gets cleared on |
712 | * the first operation that returns an error, while |
713 | * the PageError bit is more sticky and only cleared |
714 | * when the page is reread or dropped. If an |
715 | * application assumes it will always get error on |
716 | * fsync, but does other operations on the fd before |
717 | * and the page is dropped between then the error |
718 | * will not be properly reported. |
719 | * |
720 | * This can already happen even without hwpoisoned |
721 | * pages: first on metadata IO errors (which only |
722 | * report through AS_EIO) or when the page is dropped |
723 | * at the wrong time. |
724 | * |
725 | * So right now we assume that the application DTRT on |
726 | * the first EIO, but we're not worse than other parts |
727 | * of the kernel. |
728 | */ |
729 | mapping_set_error(mapping, -EIO); |
730 | } |
731 | |
732 | return me_pagecache_clean(p, pfn); |
733 | } |
734 | |
735 | /* |
736 | * Clean and dirty swap cache. |
737 | * |
738 | * Dirty swap cache page is tricky to handle. The page could live both in page |
739 | * cache and swap cache(ie. page is freshly swapped in). So it could be |
740 | * referenced concurrently by 2 types of PTEs: |
741 | * normal PTEs and swap PTEs. We try to handle them consistently by calling |
742 | * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs, |
743 | * and then |
744 | * - clear dirty bit to prevent IO |
745 | * - remove from LRU |
746 | * - but keep in the swap cache, so that when we return to it on |
747 | * a later page fault, we know the application is accessing |
748 | * corrupted data and shall be killed (we installed simple |
749 | * interception code in do_swap_page to catch it). |
750 | * |
751 | * Clean swap cache pages can be directly isolated. A later page fault will |
752 | * bring in the known good data from disk. |
753 | */ |
754 | static int me_swapcache_dirty(struct page *p, unsigned long pfn) |
755 | { |
756 | ClearPageDirty(p); |
757 | /* Trigger EIO in shmem: */ |
758 | ClearPageUptodate(p); |
759 | |
760 | if (!delete_from_lru_cache(p)) |
761 | return MF_DELAYED; |
762 | else |
763 | return MF_FAILED; |
764 | } |
765 | |
766 | static int me_swapcache_clean(struct page *p, unsigned long pfn) |
767 | { |
768 | delete_from_swap_cache(p); |
769 | |
770 | if (!delete_from_lru_cache(p)) |
771 | return MF_RECOVERED; |
772 | else |
773 | return MF_FAILED; |
774 | } |
775 | |
776 | /* |
777 | * Huge pages. Needs work. |
778 | * Issues: |
779 | * - Error on hugepage is contained in hugepage unit (not in raw page unit.) |
780 | * To narrow down kill region to one page, we need to break up pmd. |
781 | */ |
782 | static int me_huge_page(struct page *p, unsigned long pfn) |
783 | { |
784 | int res = 0; |
785 | struct page *hpage = compound_head(p); |
786 | struct address_space *mapping; |
787 | |
788 | if (!PageHuge(hpage)) |
789 | return MF_DELAYED; |
790 | |
791 | mapping = page_mapping(hpage); |
792 | if (mapping) { |
793 | res = truncate_error_page(hpage, pfn, mapping); |
794 | } else { |
795 | unlock_page(hpage); |
796 | /* |
797 | * migration entry prevents later access on error anonymous |
798 | * hugepage, so we can free and dissolve it into buddy to |
799 | * save healthy subpages. |
800 | */ |
801 | if (PageAnon(hpage)) |
802 | put_page(hpage); |
803 | dissolve_free_huge_page(p); |
804 | res = MF_RECOVERED; |
805 | lock_page(hpage); |
806 | } |
807 | |
808 | return res; |
809 | } |
810 | |
811 | /* |
812 | * Various page states we can handle. |
813 | * |
814 | * A page state is defined by its current page->flags bits. |
815 | * The table matches them in order and calls the right handler. |
816 | * |
817 | * This is quite tricky because we can access page at any time |
818 | * in its live cycle, so all accesses have to be extremely careful. |
819 | * |
820 | * This is not complete. More states could be added. |
821 | * For any missing state don't attempt recovery. |
822 | */ |
823 | |
824 | #define dirty (1UL << PG_dirty) |
825 | #define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked)) |
826 | #define unevict (1UL << PG_unevictable) |
827 | #define mlock (1UL << PG_mlocked) |
828 | #define writeback (1UL << PG_writeback) |
829 | #define lru (1UL << PG_lru) |
830 | #define head (1UL << PG_head) |
831 | #define slab (1UL << PG_slab) |
832 | #define reserved (1UL << PG_reserved) |
833 | |
834 | static struct page_state { |
835 | unsigned long mask; |
836 | unsigned long res; |
837 | enum mf_action_page_type type; |
838 | int (*action)(struct page *p, unsigned long pfn); |
839 | } error_states[] = { |
840 | { reserved, reserved, MF_MSG_KERNEL, me_kernel }, |
841 | /* |
842 | * free pages are specially detected outside this table: |
843 | * PG_buddy pages only make a small fraction of all free pages. |
844 | */ |
845 | |
846 | /* |
847 | * Could in theory check if slab page is free or if we can drop |
848 | * currently unused objects without touching them. But just |
849 | * treat it as standard kernel for now. |
850 | */ |
851 | { slab, slab, MF_MSG_SLAB, me_kernel }, |
852 | |
853 | { head, head, MF_MSG_HUGE, me_huge_page }, |
854 | |
855 | { sc|dirty, sc|dirty, MF_MSG_DIRTY_SWAPCACHE, me_swapcache_dirty }, |
856 | { sc|dirty, sc, MF_MSG_CLEAN_SWAPCACHE, me_swapcache_clean }, |
857 | |
858 | { mlock|dirty, mlock|dirty, MF_MSG_DIRTY_MLOCKED_LRU, me_pagecache_dirty }, |
859 | { mlock|dirty, mlock, MF_MSG_CLEAN_MLOCKED_LRU, me_pagecache_clean }, |
860 | |
861 | { unevict|dirty, unevict|dirty, MF_MSG_DIRTY_UNEVICTABLE_LRU, me_pagecache_dirty }, |
862 | { unevict|dirty, unevict, MF_MSG_CLEAN_UNEVICTABLE_LRU, me_pagecache_clean }, |
863 | |
864 | { lru|dirty, lru|dirty, MF_MSG_DIRTY_LRU, me_pagecache_dirty }, |
865 | { lru|dirty, lru, MF_MSG_CLEAN_LRU, me_pagecache_clean }, |
866 | |
867 | /* |
868 | * Catchall entry: must be at end. |
869 | */ |
870 | { 0, 0, MF_MSG_UNKNOWN, me_unknown }, |
871 | }; |
872 | |
873 | #undef dirty |
874 | #undef sc |
875 | #undef unevict |
876 | #undef mlock |
877 | #undef writeback |
878 | #undef lru |
879 | #undef head |
880 | #undef slab |
881 | #undef reserved |
882 | |
883 | /* |
884 | * "Dirty/Clean" indication is not 100% accurate due to the possibility of |
885 | * setting PG_dirty outside page lock. See also comment above set_page_dirty(). |
886 | */ |
887 | static void action_result(unsigned long pfn, enum mf_action_page_type type, |
888 | enum mf_result result) |
889 | { |
890 | trace_memory_failure_event(pfn, type, result); |
891 | |
892 | pr_err("Memory failure: %#lx: recovery action for %s: %s\n" , |
893 | pfn, action_page_types[type], action_name[result]); |
894 | } |
895 | |
896 | static int page_action(struct page_state *ps, struct page *p, |
897 | unsigned long pfn) |
898 | { |
899 | int result; |
900 | int count; |
901 | |
902 | result = ps->action(p, pfn); |
903 | |
904 | count = page_count(p) - 1; |
905 | if (ps->action == me_swapcache_dirty && result == MF_DELAYED) |
906 | count--; |
907 | if (count > 0) { |
908 | pr_err("Memory failure: %#lx: %s still referenced by %d users\n" , |
909 | pfn, action_page_types[ps->type], count); |
910 | result = MF_FAILED; |
911 | } |
912 | action_result(pfn, ps->type, result); |
913 | |
914 | /* Could do more checks here if page looks ok */ |
915 | /* |
916 | * Could adjust zone counters here to correct for the missing page. |
917 | */ |
918 | |
919 | return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY; |
920 | } |
921 | |
922 | /** |
923 | * get_hwpoison_page() - Get refcount for memory error handling: |
924 | * @page: raw error page (hit by memory error) |
925 | * |
926 | * Return: return 0 if failed to grab the refcount, otherwise true (some |
927 | * non-zero value.) |
928 | */ |
929 | int get_hwpoison_page(struct page *page) |
930 | { |
931 | struct page *head = compound_head(page); |
932 | |
933 | if (!PageHuge(head) && PageTransHuge(head)) { |
934 | /* |
935 | * Non anonymous thp exists only in allocation/free time. We |
936 | * can't handle such a case correctly, so let's give it up. |
937 | * This should be better than triggering BUG_ON when kernel |
938 | * tries to touch the "partially handled" page. |
939 | */ |
940 | if (!PageAnon(head)) { |
941 | pr_err("Memory failure: %#lx: non anonymous thp\n" , |
942 | page_to_pfn(page)); |
943 | return 0; |
944 | } |
945 | } |
946 | |
947 | if (get_page_unless_zero(head)) { |
948 | if (head == compound_head(page)) |
949 | return 1; |
950 | |
951 | pr_info("Memory failure: %#lx cannot catch tail\n" , |
952 | page_to_pfn(page)); |
953 | put_page(head); |
954 | } |
955 | |
956 | return 0; |
957 | } |
958 | EXPORT_SYMBOL_GPL(get_hwpoison_page); |
959 | |
960 | /* |
961 | * Do all that is necessary to remove user space mappings. Unmap |
962 | * the pages and send SIGBUS to the processes if the data was dirty. |
963 | */ |
964 | static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, |
965 | int flags, struct page **hpagep) |
966 | { |
967 | enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; |
968 | struct address_space *mapping; |
969 | LIST_HEAD(tokill); |
970 | bool unmap_success; |
971 | int kill = 1, forcekill; |
972 | struct page *hpage = *hpagep; |
973 | bool mlocked = PageMlocked(hpage); |
974 | |
975 | /* |
976 | * Here we are interested only in user-mapped pages, so skip any |
977 | * other types of pages. |
978 | */ |
979 | if (PageReserved(p) || PageSlab(p)) |
980 | return true; |
981 | if (!(PageLRU(hpage) || PageHuge(p))) |
982 | return true; |
983 | |
984 | /* |
985 | * This check implies we don't kill processes if their pages |
986 | * are in the swap cache early. Those are always late kills. |
987 | */ |
988 | if (!page_mapped(hpage)) |
989 | return true; |
990 | |
991 | if (PageKsm(p)) { |
992 | pr_err("Memory failure: %#lx: can't handle KSM pages.\n" , pfn); |
993 | return false; |
994 | } |
995 | |
996 | if (PageSwapCache(p)) { |
997 | pr_err("Memory failure: %#lx: keeping poisoned page in swap cache\n" , |
998 | pfn); |
999 | ttu |= TTU_IGNORE_HWPOISON; |
1000 | } |
1001 | |
1002 | /* |
1003 | * Propagate the dirty bit from PTEs to struct page first, because we |
1004 | * need this to decide if we should kill or just drop the page. |
1005 | * XXX: the dirty test could be racy: set_page_dirty() may not always |
1006 | * be called inside page lock (it's recommended but not enforced). |
1007 | */ |
1008 | mapping = page_mapping(hpage); |
1009 | if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping && |
1010 | mapping_cap_writeback_dirty(mapping)) { |
1011 | if (page_mkclean(hpage)) { |
1012 | SetPageDirty(hpage); |
1013 | } else { |
1014 | kill = 0; |
1015 | ttu |= TTU_IGNORE_HWPOISON; |
1016 | pr_info("Memory failure: %#lx: corrupted page was clean: dropped without side effects\n" , |
1017 | pfn); |
1018 | } |
1019 | } |
1020 | |
1021 | /* |
1022 | * First collect all the processes that have the page |
1023 | * mapped in dirty form. This has to be done before try_to_unmap, |
1024 | * because ttu takes the rmap data structures down. |
1025 | * |
1026 | * Error handling: We ignore errors here because |
1027 | * there's nothing that can be done. |
1028 | */ |
1029 | if (kill) |
1030 | collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED); |
1031 | |
1032 | unmap_success = try_to_unmap(hpage, ttu); |
1033 | if (!unmap_success) |
1034 | pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n" , |
1035 | pfn, page_mapcount(hpage)); |
1036 | |
1037 | /* |
1038 | * try_to_unmap() might put mlocked page in lru cache, so call |
1039 | * shake_page() again to ensure that it's flushed. |
1040 | */ |
1041 | if (mlocked) |
1042 | shake_page(hpage, 0); |
1043 | |
1044 | /* |
1045 | * Now that the dirty bit has been propagated to the |
1046 | * struct page and all unmaps done we can decide if |
1047 | * killing is needed or not. Only kill when the page |
1048 | * was dirty or the process is not restartable, |
1049 | * otherwise the tokill list is merely |
1050 | * freed. When there was a problem unmapping earlier |
1051 | * use a more force-full uncatchable kill to prevent |
1052 | * any accesses to the poisoned memory. |
1053 | */ |
1054 | forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL); |
1055 | kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); |
1056 | |
1057 | return unmap_success; |
1058 | } |
1059 | |
1060 | static int identify_page_state(unsigned long pfn, struct page *p, |
1061 | unsigned long page_flags) |
1062 | { |
1063 | struct page_state *ps; |
1064 | |
1065 | /* |
1066 | * The first check uses the current page flags which may not have any |
1067 | * relevant information. The second check with the saved page flags is |
1068 | * carried out only if the first check can't determine the page status. |
1069 | */ |
1070 | for (ps = error_states;; ps++) |
1071 | if ((p->flags & ps->mask) == ps->res) |
1072 | break; |
1073 | |
1074 | page_flags |= (p->flags & (1UL << PG_dirty)); |
1075 | |
1076 | if (!ps->mask) |
1077 | for (ps = error_states;; ps++) |
1078 | if ((page_flags & ps->mask) == ps->res) |
1079 | break; |
1080 | return page_action(ps, p, pfn); |
1081 | } |
1082 | |
1083 | static int memory_failure_hugetlb(unsigned long pfn, int flags) |
1084 | { |
1085 | struct page *p = pfn_to_page(pfn); |
1086 | struct page *head = compound_head(p); |
1087 | int res; |
1088 | unsigned long page_flags; |
1089 | |
1090 | if (TestSetPageHWPoison(head)) { |
1091 | pr_err("Memory failure: %#lx: already hardware poisoned\n" , |
1092 | pfn); |
1093 | return 0; |
1094 | } |
1095 | |
1096 | num_poisoned_pages_inc(); |
1097 | |
1098 | if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) { |
1099 | /* |
1100 | * Check "filter hit" and "race with other subpage." |
1101 | */ |
1102 | lock_page(head); |
1103 | if (PageHWPoison(head)) { |
1104 | if ((hwpoison_filter(p) && TestClearPageHWPoison(p)) |
1105 | || (p != head && TestSetPageHWPoison(head))) { |
1106 | num_poisoned_pages_dec(); |
1107 | unlock_page(head); |
1108 | return 0; |
1109 | } |
1110 | } |
1111 | unlock_page(head); |
1112 | dissolve_free_huge_page(p); |
1113 | action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED); |
1114 | return 0; |
1115 | } |
1116 | |
1117 | lock_page(head); |
1118 | page_flags = head->flags; |
1119 | |
1120 | if (!PageHWPoison(head)) { |
1121 | pr_err("Memory failure: %#lx: just unpoisoned\n" , pfn); |
1122 | num_poisoned_pages_dec(); |
1123 | unlock_page(head); |
1124 | put_hwpoison_page(head); |
1125 | return 0; |
1126 | } |
1127 | |
1128 | /* |
1129 | * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so |
1130 | * simply disable it. In order to make it work properly, we need |
1131 | * make sure that: |
1132 | * - conversion of a pud that maps an error hugetlb into hwpoison |
1133 | * entry properly works, and |
1134 | * - other mm code walking over page table is aware of pud-aligned |
1135 | * hwpoison entries. |
1136 | */ |
1137 | if (huge_page_size(page_hstate(head)) > PMD_SIZE) { |
1138 | action_result(pfn, MF_MSG_NON_PMD_HUGE, MF_IGNORED); |
1139 | res = -EBUSY; |
1140 | goto out; |
1141 | } |
1142 | |
1143 | if (!hwpoison_user_mappings(p, pfn, flags, &head)) { |
1144 | action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED); |
1145 | res = -EBUSY; |
1146 | goto out; |
1147 | } |
1148 | |
1149 | res = identify_page_state(pfn, p, page_flags); |
1150 | out: |
1151 | unlock_page(head); |
1152 | return res; |
1153 | } |
1154 | |
1155 | static int memory_failure_dev_pagemap(unsigned long pfn, int flags, |
1156 | struct dev_pagemap *pgmap) |
1157 | { |
1158 | struct page *page = pfn_to_page(pfn); |
1159 | const bool unmap_success = true; |
1160 | unsigned long size = 0; |
1161 | struct to_kill *tk; |
1162 | LIST_HEAD(tokill); |
1163 | int rc = -EBUSY; |
1164 | loff_t start; |
1165 | dax_entry_t cookie; |
1166 | |
1167 | /* |
1168 | * Prevent the inode from being freed while we are interrogating |
1169 | * the address_space, typically this would be handled by |
1170 | * lock_page(), but dax pages do not use the page lock. This |
1171 | * also prevents changes to the mapping of this pfn until |
1172 | * poison signaling is complete. |
1173 | */ |
1174 | cookie = dax_lock_page(page); |
1175 | if (!cookie) |
1176 | goto out; |
1177 | |
1178 | if (hwpoison_filter(page)) { |
1179 | rc = 0; |
1180 | goto unlock; |
1181 | } |
1182 | |
1183 | switch (pgmap->type) { |
1184 | case MEMORY_DEVICE_PRIVATE: |
1185 | case MEMORY_DEVICE_PUBLIC: |
1186 | /* |
1187 | * TODO: Handle HMM pages which may need coordination |
1188 | * with device-side memory. |
1189 | */ |
1190 | goto unlock; |
1191 | default: |
1192 | break; |
1193 | } |
1194 | |
1195 | /* |
1196 | * Use this flag as an indication that the dax page has been |
1197 | * remapped UC to prevent speculative consumption of poison. |
1198 | */ |
1199 | SetPageHWPoison(page); |
1200 | |
1201 | /* |
1202 | * Unlike System-RAM there is no possibility to swap in a |
1203 | * different physical page at a given virtual address, so all |
1204 | * userspace consumption of ZONE_DEVICE memory necessitates |
1205 | * SIGBUS (i.e. MF_MUST_KILL) |
1206 | */ |
1207 | flags |= MF_ACTION_REQUIRED | MF_MUST_KILL; |
1208 | collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED); |
1209 | |
1210 | list_for_each_entry(tk, &tokill, nd) |
1211 | if (tk->size_shift) |
1212 | size = max(size, 1UL << tk->size_shift); |
1213 | if (size) { |
1214 | /* |
1215 | * Unmap the largest mapping to avoid breaking up |
1216 | * device-dax mappings which are constant size. The |
1217 | * actual size of the mapping being torn down is |
1218 | * communicated in siginfo, see kill_proc() |
1219 | */ |
1220 | start = (page->index << PAGE_SHIFT) & ~(size - 1); |
1221 | unmap_mapping_range(page->mapping, start, start + size, 0); |
1222 | } |
1223 | kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags); |
1224 | rc = 0; |
1225 | unlock: |
1226 | dax_unlock_page(page, cookie); |
1227 | out: |
1228 | /* drop pgmap ref acquired in caller */ |
1229 | put_dev_pagemap(pgmap); |
1230 | action_result(pfn, MF_MSG_DAX, rc ? MF_FAILED : MF_RECOVERED); |
1231 | return rc; |
1232 | } |
1233 | |
1234 | /** |
1235 | * memory_failure - Handle memory failure of a page. |
1236 | * @pfn: Page Number of the corrupted page |
1237 | * @flags: fine tune action taken |
1238 | * |
1239 | * This function is called by the low level machine check code |
1240 | * of an architecture when it detects hardware memory corruption |
1241 | * of a page. It tries its best to recover, which includes |
1242 | * dropping pages, killing processes etc. |
1243 | * |
1244 | * The function is primarily of use for corruptions that |
1245 | * happen outside the current execution context (e.g. when |
1246 | * detected by a background scrubber) |
1247 | * |
1248 | * Must run in process context (e.g. a work queue) with interrupts |
1249 | * enabled and no spinlocks hold. |
1250 | */ |
1251 | int memory_failure(unsigned long pfn, int flags) |
1252 | { |
1253 | struct page *p; |
1254 | struct page *hpage; |
1255 | struct page *orig_head; |
1256 | struct dev_pagemap *pgmap; |
1257 | int res; |
1258 | unsigned long page_flags; |
1259 | |
1260 | if (!sysctl_memory_failure_recovery) |
1261 | panic("Memory failure on page %lx" , pfn); |
1262 | |
1263 | if (!pfn_valid(pfn)) { |
1264 | pr_err("Memory failure: %#lx: memory outside kernel control\n" , |
1265 | pfn); |
1266 | return -ENXIO; |
1267 | } |
1268 | |
1269 | pgmap = get_dev_pagemap(pfn, NULL); |
1270 | if (pgmap) |
1271 | return memory_failure_dev_pagemap(pfn, flags, pgmap); |
1272 | |
1273 | p = pfn_to_page(pfn); |
1274 | if (PageHuge(p)) |
1275 | return memory_failure_hugetlb(pfn, flags); |
1276 | if (TestSetPageHWPoison(p)) { |
1277 | pr_err("Memory failure: %#lx: already hardware poisoned\n" , |
1278 | pfn); |
1279 | return 0; |
1280 | } |
1281 | |
1282 | orig_head = hpage = compound_head(p); |
1283 | num_poisoned_pages_inc(); |
1284 | |
1285 | /* |
1286 | * We need/can do nothing about count=0 pages. |
1287 | * 1) it's a free page, and therefore in safe hand: |
1288 | * prep_new_page() will be the gate keeper. |
1289 | * 2) it's part of a non-compound high order page. |
1290 | * Implies some kernel user: cannot stop them from |
1291 | * R/W the page; let's pray that the page has been |
1292 | * used and will be freed some time later. |
1293 | * In fact it's dangerous to directly bump up page count from 0, |
1294 | * that may make page_ref_freeze()/page_ref_unfreeze() mismatch. |
1295 | */ |
1296 | if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) { |
1297 | if (is_free_buddy_page(p)) { |
1298 | action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); |
1299 | return 0; |
1300 | } else { |
1301 | action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); |
1302 | return -EBUSY; |
1303 | } |
1304 | } |
1305 | |
1306 | if (PageTransHuge(hpage)) { |
1307 | lock_page(p); |
1308 | if (!PageAnon(p) || unlikely(split_huge_page(p))) { |
1309 | unlock_page(p); |
1310 | if (!PageAnon(p)) |
1311 | pr_err("Memory failure: %#lx: non anonymous thp\n" , |
1312 | pfn); |
1313 | else |
1314 | pr_err("Memory failure: %#lx: thp split failed\n" , |
1315 | pfn); |
1316 | if (TestClearPageHWPoison(p)) |
1317 | num_poisoned_pages_dec(); |
1318 | put_hwpoison_page(p); |
1319 | return -EBUSY; |
1320 | } |
1321 | unlock_page(p); |
1322 | VM_BUG_ON_PAGE(!page_count(p), p); |
1323 | hpage = compound_head(p); |
1324 | } |
1325 | |
1326 | /* |
1327 | * We ignore non-LRU pages for good reasons. |
1328 | * - PG_locked is only well defined for LRU pages and a few others |
1329 | * - to avoid races with __SetPageLocked() |
1330 | * - to avoid races with __SetPageSlab*() (and more non-atomic ops) |
1331 | * The check (unnecessarily) ignores LRU pages being isolated and |
1332 | * walked by the page reclaim code, however that's not a big loss. |
1333 | */ |
1334 | shake_page(p, 0); |
1335 | /* shake_page could have turned it free. */ |
1336 | if (!PageLRU(p) && is_free_buddy_page(p)) { |
1337 | if (flags & MF_COUNT_INCREASED) |
1338 | action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); |
1339 | else |
1340 | action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED); |
1341 | return 0; |
1342 | } |
1343 | |
1344 | lock_page(p); |
1345 | |
1346 | /* |
1347 | * The page could have changed compound pages during the locking. |
1348 | * If this happens just bail out. |
1349 | */ |
1350 | if (PageCompound(p) && compound_head(p) != orig_head) { |
1351 | action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED); |
1352 | res = -EBUSY; |
1353 | goto out; |
1354 | } |
1355 | |
1356 | /* |
1357 | * We use page flags to determine what action should be taken, but |
1358 | * the flags can be modified by the error containment action. One |
1359 | * example is an mlocked page, where PG_mlocked is cleared by |
1360 | * page_remove_rmap() in try_to_unmap_one(). So to determine page status |
1361 | * correctly, we save a copy of the page flags at this time. |
1362 | */ |
1363 | if (PageHuge(p)) |
1364 | page_flags = hpage->flags; |
1365 | else |
1366 | page_flags = p->flags; |
1367 | |
1368 | /* |
1369 | * unpoison always clear PG_hwpoison inside page lock |
1370 | */ |
1371 | if (!PageHWPoison(p)) { |
1372 | pr_err("Memory failure: %#lx: just unpoisoned\n" , pfn); |
1373 | num_poisoned_pages_dec(); |
1374 | unlock_page(p); |
1375 | put_hwpoison_page(p); |
1376 | return 0; |
1377 | } |
1378 | if (hwpoison_filter(p)) { |
1379 | if (TestClearPageHWPoison(p)) |
1380 | num_poisoned_pages_dec(); |
1381 | unlock_page(p); |
1382 | put_hwpoison_page(p); |
1383 | return 0; |
1384 | } |
1385 | |
1386 | if (!PageTransTail(p) && !PageLRU(p)) |
1387 | goto identify_page_state; |
1388 | |
1389 | /* |
1390 | * It's very difficult to mess with pages currently under IO |
1391 | * and in many cases impossible, so we just avoid it here. |
1392 | */ |
1393 | wait_on_page_writeback(p); |
1394 | |
1395 | /* |
1396 | * Now take care of user space mappings. |
1397 | * Abort on fail: __delete_from_page_cache() assumes unmapped page. |
1398 | * |
1399 | * When the raw error page is thp tail page, hpage points to the raw |
1400 | * page after thp split. |
1401 | */ |
1402 | if (!hwpoison_user_mappings(p, pfn, flags, &hpage)) { |
1403 | action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED); |
1404 | res = -EBUSY; |
1405 | goto out; |
1406 | } |
1407 | |
1408 | /* |
1409 | * Torn down by someone else? |
1410 | */ |
1411 | if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) { |
1412 | action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED); |
1413 | res = -EBUSY; |
1414 | goto out; |
1415 | } |
1416 | |
1417 | identify_page_state: |
1418 | res = identify_page_state(pfn, p, page_flags); |
1419 | out: |
1420 | unlock_page(p); |
1421 | return res; |
1422 | } |
1423 | EXPORT_SYMBOL_GPL(memory_failure); |
1424 | |
1425 | #define MEMORY_FAILURE_FIFO_ORDER 4 |
1426 | #define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER) |
1427 | |
1428 | struct memory_failure_entry { |
1429 | unsigned long pfn; |
1430 | int flags; |
1431 | }; |
1432 | |
1433 | struct memory_failure_cpu { |
1434 | DECLARE_KFIFO(fifo, struct memory_failure_entry, |
1435 | MEMORY_FAILURE_FIFO_SIZE); |
1436 | spinlock_t lock; |
1437 | struct work_struct work; |
1438 | }; |
1439 | |
1440 | static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu); |
1441 | |
1442 | /** |
1443 | * memory_failure_queue - Schedule handling memory failure of a page. |
1444 | * @pfn: Page Number of the corrupted page |
1445 | * @flags: Flags for memory failure handling |
1446 | * |
1447 | * This function is called by the low level hardware error handler |
1448 | * when it detects hardware memory corruption of a page. It schedules |
1449 | * the recovering of error page, including dropping pages, killing |
1450 | * processes etc. |
1451 | * |
1452 | * The function is primarily of use for corruptions that |
1453 | * happen outside the current execution context (e.g. when |
1454 | * detected by a background scrubber) |
1455 | * |
1456 | * Can run in IRQ context. |
1457 | */ |
1458 | void memory_failure_queue(unsigned long pfn, int flags) |
1459 | { |
1460 | struct memory_failure_cpu *mf_cpu; |
1461 | unsigned long proc_flags; |
1462 | struct memory_failure_entry entry = { |
1463 | .pfn = pfn, |
1464 | .flags = flags, |
1465 | }; |
1466 | |
1467 | mf_cpu = &get_cpu_var(memory_failure_cpu); |
1468 | spin_lock_irqsave(&mf_cpu->lock, proc_flags); |
1469 | if (kfifo_put(&mf_cpu->fifo, entry)) |
1470 | schedule_work_on(smp_processor_id(), &mf_cpu->work); |
1471 | else |
1472 | pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n" , |
1473 | pfn); |
1474 | spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); |
1475 | put_cpu_var(memory_failure_cpu); |
1476 | } |
1477 | EXPORT_SYMBOL_GPL(memory_failure_queue); |
1478 | |
1479 | static void memory_failure_work_func(struct work_struct *work) |
1480 | { |
1481 | struct memory_failure_cpu *mf_cpu; |
1482 | struct memory_failure_entry entry = { 0, }; |
1483 | unsigned long proc_flags; |
1484 | int gotten; |
1485 | |
1486 | mf_cpu = this_cpu_ptr(&memory_failure_cpu); |
1487 | for (;;) { |
1488 | spin_lock_irqsave(&mf_cpu->lock, proc_flags); |
1489 | gotten = kfifo_get(&mf_cpu->fifo, &entry); |
1490 | spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); |
1491 | if (!gotten) |
1492 | break; |
1493 | if (entry.flags & MF_SOFT_OFFLINE) |
1494 | soft_offline_page(pfn_to_page(entry.pfn), entry.flags); |
1495 | else |
1496 | memory_failure(entry.pfn, entry.flags); |
1497 | } |
1498 | } |
1499 | |
1500 | static int __init memory_failure_init(void) |
1501 | { |
1502 | struct memory_failure_cpu *mf_cpu; |
1503 | int cpu; |
1504 | |
1505 | for_each_possible_cpu(cpu) { |
1506 | mf_cpu = &per_cpu(memory_failure_cpu, cpu); |
1507 | spin_lock_init(&mf_cpu->lock); |
1508 | INIT_KFIFO(mf_cpu->fifo); |
1509 | INIT_WORK(&mf_cpu->work, memory_failure_work_func); |
1510 | } |
1511 | |
1512 | return 0; |
1513 | } |
1514 | core_initcall(memory_failure_init); |
1515 | |
1516 | #define unpoison_pr_info(fmt, pfn, rs) \ |
1517 | ({ \ |
1518 | if (__ratelimit(rs)) \ |
1519 | pr_info(fmt, pfn); \ |
1520 | }) |
1521 | |
1522 | /** |
1523 | * unpoison_memory - Unpoison a previously poisoned page |
1524 | * @pfn: Page number of the to be unpoisoned page |
1525 | * |
1526 | * Software-unpoison a page that has been poisoned by |
1527 | * memory_failure() earlier. |
1528 | * |
1529 | * This is only done on the software-level, so it only works |
1530 | * for linux injected failures, not real hardware failures |
1531 | * |
1532 | * Returns 0 for success, otherwise -errno. |
1533 | */ |
1534 | int unpoison_memory(unsigned long pfn) |
1535 | { |
1536 | struct page *page; |
1537 | struct page *p; |
1538 | int freeit = 0; |
1539 | static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, |
1540 | DEFAULT_RATELIMIT_BURST); |
1541 | |
1542 | if (!pfn_valid(pfn)) |
1543 | return -ENXIO; |
1544 | |
1545 | p = pfn_to_page(pfn); |
1546 | page = compound_head(p); |
1547 | |
1548 | if (!PageHWPoison(p)) { |
1549 | unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n" , |
1550 | pfn, &unpoison_rs); |
1551 | return 0; |
1552 | } |
1553 | |
1554 | if (page_count(page) > 1) { |
1555 | unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n" , |
1556 | pfn, &unpoison_rs); |
1557 | return 0; |
1558 | } |
1559 | |
1560 | if (page_mapped(page)) { |
1561 | unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n" , |
1562 | pfn, &unpoison_rs); |
1563 | return 0; |
1564 | } |
1565 | |
1566 | if (page_mapping(page)) { |
1567 | unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n" , |
1568 | pfn, &unpoison_rs); |
1569 | return 0; |
1570 | } |
1571 | |
1572 | /* |
1573 | * unpoison_memory() can encounter thp only when the thp is being |
1574 | * worked by memory_failure() and the page lock is not held yet. |
1575 | * In such case, we yield to memory_failure() and make unpoison fail. |
1576 | */ |
1577 | if (!PageHuge(page) && PageTransHuge(page)) { |
1578 | unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n" , |
1579 | pfn, &unpoison_rs); |
1580 | return 0; |
1581 | } |
1582 | |
1583 | if (!get_hwpoison_page(p)) { |
1584 | if (TestClearPageHWPoison(p)) |
1585 | num_poisoned_pages_dec(); |
1586 | unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n" , |
1587 | pfn, &unpoison_rs); |
1588 | return 0; |
1589 | } |
1590 | |
1591 | lock_page(page); |
1592 | /* |
1593 | * This test is racy because PG_hwpoison is set outside of page lock. |
1594 | * That's acceptable because that won't trigger kernel panic. Instead, |
1595 | * the PG_hwpoison page will be caught and isolated on the entrance to |
1596 | * the free buddy page pool. |
1597 | */ |
1598 | if (TestClearPageHWPoison(page)) { |
1599 | unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n" , |
1600 | pfn, &unpoison_rs); |
1601 | num_poisoned_pages_dec(); |
1602 | freeit = 1; |
1603 | } |
1604 | unlock_page(page); |
1605 | |
1606 | put_hwpoison_page(page); |
1607 | if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) |
1608 | put_hwpoison_page(page); |
1609 | |
1610 | return 0; |
1611 | } |
1612 | EXPORT_SYMBOL(unpoison_memory); |
1613 | |
1614 | static struct page *new_page(struct page *p, unsigned long private) |
1615 | { |
1616 | int nid = page_to_nid(p); |
1617 | |
1618 | return new_page_nodemask(p, nid, &node_states[N_MEMORY]); |
1619 | } |
1620 | |
1621 | /* |
1622 | * Safely get reference count of an arbitrary page. |
1623 | * Returns 0 for a free page, -EIO for a zero refcount page |
1624 | * that is not free, and 1 for any other page type. |
1625 | * For 1 the page is returned with increased page count, otherwise not. |
1626 | */ |
1627 | static int __get_any_page(struct page *p, unsigned long pfn, int flags) |
1628 | { |
1629 | int ret; |
1630 | |
1631 | if (flags & MF_COUNT_INCREASED) |
1632 | return 1; |
1633 | |
1634 | /* |
1635 | * When the target page is a free hugepage, just remove it |
1636 | * from free hugepage list. |
1637 | */ |
1638 | if (!get_hwpoison_page(p)) { |
1639 | if (PageHuge(p)) { |
1640 | pr_info("%s: %#lx free huge page\n" , __func__, pfn); |
1641 | ret = 0; |
1642 | } else if (is_free_buddy_page(p)) { |
1643 | pr_info("%s: %#lx free buddy page\n" , __func__, pfn); |
1644 | ret = 0; |
1645 | } else { |
1646 | pr_info("%s: %#lx: unknown zero refcount page type %lx\n" , |
1647 | __func__, pfn, p->flags); |
1648 | ret = -EIO; |
1649 | } |
1650 | } else { |
1651 | /* Not a free page */ |
1652 | ret = 1; |
1653 | } |
1654 | return ret; |
1655 | } |
1656 | |
1657 | static int get_any_page(struct page *page, unsigned long pfn, int flags) |
1658 | { |
1659 | int ret = __get_any_page(page, pfn, flags); |
1660 | |
1661 | if (ret == 1 && !PageHuge(page) && |
1662 | !PageLRU(page) && !__PageMovable(page)) { |
1663 | /* |
1664 | * Try to free it. |
1665 | */ |
1666 | put_hwpoison_page(page); |
1667 | shake_page(page, 1); |
1668 | |
1669 | /* |
1670 | * Did it turn free? |
1671 | */ |
1672 | ret = __get_any_page(page, pfn, 0); |
1673 | if (ret == 1 && !PageLRU(page)) { |
1674 | /* Drop page reference which is from __get_any_page() */ |
1675 | put_hwpoison_page(page); |
1676 | pr_info("soft_offline: %#lx: unknown non LRU page type %lx (%pGp)\n" , |
1677 | pfn, page->flags, &page->flags); |
1678 | return -EIO; |
1679 | } |
1680 | } |
1681 | return ret; |
1682 | } |
1683 | |
1684 | static int soft_offline_huge_page(struct page *page, int flags) |
1685 | { |
1686 | int ret; |
1687 | unsigned long pfn = page_to_pfn(page); |
1688 | struct page *hpage = compound_head(page); |
1689 | LIST_HEAD(pagelist); |
1690 | |
1691 | /* |
1692 | * This double-check of PageHWPoison is to avoid the race with |
1693 | * memory_failure(). See also comment in __soft_offline_page(). |
1694 | */ |
1695 | lock_page(hpage); |
1696 | if (PageHWPoison(hpage)) { |
1697 | unlock_page(hpage); |
1698 | put_hwpoison_page(hpage); |
1699 | pr_info("soft offline: %#lx hugepage already poisoned\n" , pfn); |
1700 | return -EBUSY; |
1701 | } |
1702 | unlock_page(hpage); |
1703 | |
1704 | ret = isolate_huge_page(hpage, &pagelist); |
1705 | /* |
1706 | * get_any_page() and isolate_huge_page() takes a refcount each, |
1707 | * so need to drop one here. |
1708 | */ |
1709 | put_hwpoison_page(hpage); |
1710 | if (!ret) { |
1711 | pr_info("soft offline: %#lx hugepage failed to isolate\n" , pfn); |
1712 | return -EBUSY; |
1713 | } |
1714 | |
1715 | ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, |
1716 | MIGRATE_SYNC, MR_MEMORY_FAILURE); |
1717 | if (ret) { |
1718 | pr_info("soft offline: %#lx: hugepage migration failed %d, type %lx (%pGp)\n" , |
1719 | pfn, ret, page->flags, &page->flags); |
1720 | if (!list_empty(&pagelist)) |
1721 | putback_movable_pages(&pagelist); |
1722 | if (ret > 0) |
1723 | ret = -EIO; |
1724 | } else { |
1725 | /* |
1726 | * We set PG_hwpoison only when the migration source hugepage |
1727 | * was successfully dissolved, because otherwise hwpoisoned |
1728 | * hugepage remains on free hugepage list, then userspace will |
1729 | * find it as SIGBUS by allocation failure. That's not expected |
1730 | * in soft-offlining. |
1731 | */ |
1732 | ret = dissolve_free_huge_page(page); |
1733 | if (!ret) { |
1734 | if (set_hwpoison_free_buddy_page(page)) |
1735 | num_poisoned_pages_inc(); |
1736 | } |
1737 | } |
1738 | return ret; |
1739 | } |
1740 | |
1741 | static int __soft_offline_page(struct page *page, int flags) |
1742 | { |
1743 | int ret; |
1744 | unsigned long pfn = page_to_pfn(page); |
1745 | |
1746 | /* |
1747 | * Check PageHWPoison again inside page lock because PageHWPoison |
1748 | * is set by memory_failure() outside page lock. Note that |
1749 | * memory_failure() also double-checks PageHWPoison inside page lock, |
1750 | * so there's no race between soft_offline_page() and memory_failure(). |
1751 | */ |
1752 | lock_page(page); |
1753 | wait_on_page_writeback(page); |
1754 | if (PageHWPoison(page)) { |
1755 | unlock_page(page); |
1756 | put_hwpoison_page(page); |
1757 | pr_info("soft offline: %#lx page already poisoned\n" , pfn); |
1758 | return -EBUSY; |
1759 | } |
1760 | /* |
1761 | * Try to invalidate first. This should work for |
1762 | * non dirty unmapped page cache pages. |
1763 | */ |
1764 | ret = invalidate_inode_page(page); |
1765 | unlock_page(page); |
1766 | /* |
1767 | * RED-PEN would be better to keep it isolated here, but we |
1768 | * would need to fix isolation locking first. |
1769 | */ |
1770 | if (ret == 1) { |
1771 | put_hwpoison_page(page); |
1772 | pr_info("soft_offline: %#lx: invalidated\n" , pfn); |
1773 | SetPageHWPoison(page); |
1774 | num_poisoned_pages_inc(); |
1775 | return 0; |
1776 | } |
1777 | |
1778 | /* |
1779 | * Simple invalidation didn't work. |
1780 | * Try to migrate to a new page instead. migrate.c |
1781 | * handles a large number of cases for us. |
1782 | */ |
1783 | if (PageLRU(page)) |
1784 | ret = isolate_lru_page(page); |
1785 | else |
1786 | ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE); |
1787 | /* |
1788 | * Drop page reference which is came from get_any_page() |
1789 | * successful isolate_lru_page() already took another one. |
1790 | */ |
1791 | put_hwpoison_page(page); |
1792 | if (!ret) { |
1793 | LIST_HEAD(pagelist); |
1794 | /* |
1795 | * After isolated lru page, the PageLRU will be cleared, |
1796 | * so use !__PageMovable instead for LRU page's mapping |
1797 | * cannot have PAGE_MAPPING_MOVABLE. |
1798 | */ |
1799 | if (!__PageMovable(page)) |
1800 | inc_node_page_state(page, NR_ISOLATED_ANON + |
1801 | page_is_file_cache(page)); |
1802 | list_add(&page->lru, &pagelist); |
1803 | ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, |
1804 | MIGRATE_SYNC, MR_MEMORY_FAILURE); |
1805 | if (ret) { |
1806 | if (!list_empty(&pagelist)) |
1807 | putback_movable_pages(&pagelist); |
1808 | |
1809 | pr_info("soft offline: %#lx: migration failed %d, type %lx (%pGp)\n" , |
1810 | pfn, ret, page->flags, &page->flags); |
1811 | if (ret > 0) |
1812 | ret = -EIO; |
1813 | } |
1814 | } else { |
1815 | pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx (%pGp)\n" , |
1816 | pfn, ret, page_count(page), page->flags, &page->flags); |
1817 | } |
1818 | return ret; |
1819 | } |
1820 | |
1821 | static int soft_offline_in_use_page(struct page *page, int flags) |
1822 | { |
1823 | int ret; |
1824 | int mt; |
1825 | struct page *hpage = compound_head(page); |
1826 | |
1827 | if (!PageHuge(page) && PageTransHuge(hpage)) { |
1828 | lock_page(page); |
1829 | if (!PageAnon(page) || unlikely(split_huge_page(page))) { |
1830 | unlock_page(page); |
1831 | if (!PageAnon(page)) |
1832 | pr_info("soft offline: %#lx: non anonymous thp\n" , page_to_pfn(page)); |
1833 | else |
1834 | pr_info("soft offline: %#lx: thp split failed\n" , page_to_pfn(page)); |
1835 | put_hwpoison_page(page); |
1836 | return -EBUSY; |
1837 | } |
1838 | unlock_page(page); |
1839 | } |
1840 | |
1841 | /* |
1842 | * Setting MIGRATE_ISOLATE here ensures that the page will be linked |
1843 | * to free list immediately (not via pcplist) when released after |
1844 | * successful page migration. Otherwise we can't guarantee that the |
1845 | * page is really free after put_page() returns, so |
1846 | * set_hwpoison_free_buddy_page() highly likely fails. |
1847 | */ |
1848 | mt = get_pageblock_migratetype(page); |
1849 | set_pageblock_migratetype(page, MIGRATE_ISOLATE); |
1850 | if (PageHuge(page)) |
1851 | ret = soft_offline_huge_page(page, flags); |
1852 | else |
1853 | ret = __soft_offline_page(page, flags); |
1854 | set_pageblock_migratetype(page, mt); |
1855 | return ret; |
1856 | } |
1857 | |
1858 | static int soft_offline_free_page(struct page *page) |
1859 | { |
1860 | int rc = 0; |
1861 | struct page *head = compound_head(page); |
1862 | |
1863 | if (PageHuge(head)) |
1864 | rc = dissolve_free_huge_page(page); |
1865 | if (!rc) { |
1866 | if (set_hwpoison_free_buddy_page(page)) |
1867 | num_poisoned_pages_inc(); |
1868 | else |
1869 | rc = -EBUSY; |
1870 | } |
1871 | return rc; |
1872 | } |
1873 | |
1874 | /** |
1875 | * soft_offline_page - Soft offline a page. |
1876 | * @page: page to offline |
1877 | * @flags: flags. Same as memory_failure(). |
1878 | * |
1879 | * Returns 0 on success, otherwise negated errno. |
1880 | * |
1881 | * Soft offline a page, by migration or invalidation, |
1882 | * without killing anything. This is for the case when |
1883 | * a page is not corrupted yet (so it's still valid to access), |
1884 | * but has had a number of corrected errors and is better taken |
1885 | * out. |
1886 | * |
1887 | * The actual policy on when to do that is maintained by |
1888 | * user space. |
1889 | * |
1890 | * This should never impact any application or cause data loss, |
1891 | * however it might take some time. |
1892 | * |
1893 | * This is not a 100% solution for all memory, but tries to be |
1894 | * ``good enough'' for the majority of memory. |
1895 | */ |
1896 | int soft_offline_page(struct page *page, int flags) |
1897 | { |
1898 | int ret; |
1899 | unsigned long pfn = page_to_pfn(page); |
1900 | |
1901 | if (is_zone_device_page(page)) { |
1902 | pr_debug_ratelimited("soft_offline: %#lx page is device page\n" , |
1903 | pfn); |
1904 | if (flags & MF_COUNT_INCREASED) |
1905 | put_page(page); |
1906 | return -EIO; |
1907 | } |
1908 | |
1909 | if (PageHWPoison(page)) { |
1910 | pr_info("soft offline: %#lx page already poisoned\n" , pfn); |
1911 | if (flags & MF_COUNT_INCREASED) |
1912 | put_hwpoison_page(page); |
1913 | return -EBUSY; |
1914 | } |
1915 | |
1916 | get_online_mems(); |
1917 | ret = get_any_page(page, pfn, flags); |
1918 | put_online_mems(); |
1919 | |
1920 | if (ret > 0) |
1921 | ret = soft_offline_in_use_page(page, flags); |
1922 | else if (ret == 0) |
1923 | ret = soft_offline_free_page(page); |
1924 | |
1925 | return ret; |
1926 | } |
1927 | |