memory-failure.c 36.2 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
/*
 * Copyright (C) 2008, 2009 Intel Corporation
 * Authors: Andi Kleen, Fengguang Wu
 *
 * This software may be redistributed and/or modified under the terms of
 * the GNU General Public License ("GPL") version 2 only as published by the
 * Free Software Foundation.
 *
 * High level machine check handler. Handles pages reported by the
 * hardware as being corrupted usually due to a 2bit ECC memory or cache
 * failure.
 *
 * Handles page cache pages in various states.	The tricky part
 * here is that we can access any page asynchronous to other VM
 * users, because memory failures could happen anytime and anywhere,
 * possibly violating some of their assumptions. This is why this code
 * has to be extremely careful. Generally it tries to use normal locking
 * rules, as in get the standard locks, even if that means the
 * error handling takes potentially a long time.
 *
 * The operation to map back from RMAP chains to processes has to walk
 * the complete process list and has non linear complexity with the number
 * mappings. In short it can be quite slow. But since memory corruptions
 * are rare we hope to get away with this.
 */

/*
 * Notebook:
 * - hugetlb needs more code
 * - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
 * - pass bad pages to kdump next kernel
 */
#define DEBUG 1		/* remove me in 2.6.34 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
W
Wu Fengguang 已提交
37
#include <linux/kernel-page-flags.h>
38
#include <linux/sched.h>
H
Hugh Dickins 已提交
39
#include <linux/ksm.h>
40 41 42 43
#include <linux/rmap.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/backing-dev.h>
44 45 46
#include <linux/migrate.h>
#include <linux/page-isolation.h>
#include <linux/suspend.h>
47
#include <linux/slab.h>
48
#include <linux/swapops.h>
49
#include <linux/hugetlb.h>
50 51 52 53 54 55 56 57
#include "internal.h"

int sysctl_memory_failure_early_kill __read_mostly = 0;

int sysctl_memory_failure_recovery __read_mostly = 1;

atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);

58 59
#if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)

60
u32 hwpoison_filter_enable = 0;
W
Wu Fengguang 已提交
61 62
u32 hwpoison_filter_dev_major = ~0U;
u32 hwpoison_filter_dev_minor = ~0U;
W
Wu Fengguang 已提交
63 64
u64 hwpoison_filter_flags_mask;
u64 hwpoison_filter_flags_value;
65
EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
W
Wu Fengguang 已提交
66 67
EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
W
Wu Fengguang 已提交
68 69
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
W
Wu Fengguang 已提交
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

static int hwpoison_filter_dev(struct page *p)
{
	struct address_space *mapping;
	dev_t dev;

	if (hwpoison_filter_dev_major == ~0U &&
	    hwpoison_filter_dev_minor == ~0U)
		return 0;

	/*
	 * page_mapping() does not accept slab page
	 */
	if (PageSlab(p))
		return -EINVAL;

	mapping = page_mapping(p);
	if (mapping == NULL || mapping->host == NULL)
		return -EINVAL;

	dev = mapping->host->i_sb->s_dev;
	if (hwpoison_filter_dev_major != ~0U &&
	    hwpoison_filter_dev_major != MAJOR(dev))
		return -EINVAL;
	if (hwpoison_filter_dev_minor != ~0U &&
	    hwpoison_filter_dev_minor != MINOR(dev))
		return -EINVAL;

	return 0;
}

W
Wu Fengguang 已提交
101 102 103 104 105 106 107 108 109 110 111 112
static int hwpoison_filter_flags(struct page *p)
{
	if (!hwpoison_filter_flags_mask)
		return 0;

	if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
				    hwpoison_filter_flags_value)
		return 0;
	else
		return -EINVAL;
}

A
Andi Kleen 已提交
113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155
/*
 * This allows stress tests to limit test scope to a collection of tasks
 * by putting them under some memcg. This prevents killing unrelated/important
 * processes such as /sbin/init. Note that the target task may share clean
 * pages with init (eg. libc text), which is harmless. If the target task
 * share _dirty_ pages with another task B, the test scheme must make sure B
 * is also included in the memcg. At last, due to race conditions this filter
 * can only guarantee that the page either belongs to the memcg tasks, or is
 * a freed page.
 */
#ifdef	CONFIG_CGROUP_MEM_RES_CTLR_SWAP
u64 hwpoison_filter_memcg;
EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
static int hwpoison_filter_task(struct page *p)
{
	struct mem_cgroup *mem;
	struct cgroup_subsys_state *css;
	unsigned long ino;

	if (!hwpoison_filter_memcg)
		return 0;

	mem = try_get_mem_cgroup_from_page(p);
	if (!mem)
		return -EINVAL;

	css = mem_cgroup_css(mem);
	/* root_mem_cgroup has NULL dentries */
	if (!css->cgroup->dentry)
		return -EINVAL;

	ino = css->cgroup->dentry->d_inode->i_ino;
	css_put(css);

	if (ino != hwpoison_filter_memcg)
		return -EINVAL;

	return 0;
}
#else
static int hwpoison_filter_task(struct page *p) { return 0; }
#endif

W
Wu Fengguang 已提交
156 157
int hwpoison_filter(struct page *p)
{
158 159 160
	if (!hwpoison_filter_enable)
		return 0;

W
Wu Fengguang 已提交
161 162 163
	if (hwpoison_filter_dev(p))
		return -EINVAL;

W
Wu Fengguang 已提交
164 165 166
	if (hwpoison_filter_flags(p))
		return -EINVAL;

A
Andi Kleen 已提交
167 168 169
	if (hwpoison_filter_task(p))
		return -EINVAL;

W
Wu Fengguang 已提交
170 171
	return 0;
}
172 173 174 175 176 177 178
#else
int hwpoison_filter(struct page *p)
{
	return 0;
}
#endif

W
Wu Fengguang 已提交
179 180
EXPORT_SYMBOL_GPL(hwpoison_filter);

181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214
/*
 * Send all the processes who have the page mapped an ``action optional''
 * signal.
 */
static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
			unsigned long pfn)
{
	struct siginfo si;
	int ret;

	printk(KERN_ERR
		"MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
		pfn, t->comm, t->pid);
	si.si_signo = SIGBUS;
	si.si_errno = 0;
	si.si_code = BUS_MCEERR_AO;
	si.si_addr = (void *)addr;
#ifdef __ARCH_SI_TRAPNO
	si.si_trapno = trapno;
#endif
	si.si_addr_lsb = PAGE_SHIFT;
	/*
	 * Don't use force here, it's convenient if the signal
	 * can be temporarily blocked.
	 * This could cause a loop when the user sets SIGBUS
	 * to SIG_IGN, but hopefully noone will do that?
	 */
	ret = send_sig_info(SIGBUS, &si, t);  /* synchronous? */
	if (ret < 0)
		printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
		       t->comm, t->pid, ret);
	return ret;
}

215 216 217 218
/*
 * When a unknown page type is encountered drain as many buffers as possible
 * in the hope to turn the page into a LRU or free page, which we can handle.
 */
219
void shake_page(struct page *p, int access)
220 221 222 223 224 225 226 227 228
{
	if (!PageSlab(p)) {
		lru_add_drain_all();
		if (PageLRU(p))
			return;
		drain_all_pages();
		if (PageLRU(p) || is_free_buddy_page(p))
			return;
	}
229

230
	/*
231 232
	 * Only all shrink_slab here (which would also
	 * shrink other caches) if access is not potentially fatal.
233
	 */
234 235 236 237 238 239 240 241
	if (access) {
		int nr;
		do {
			nr = shrink_slab(1000, GFP_KERNEL, 1000);
			if (page_count(p) == 0)
				break;
		} while (nr > 10);
	}
242 243 244
}
EXPORT_SYMBOL_GPL(shake_page);

245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336
/*
 * Kill all processes that have a poisoned page mapped and then isolate
 * the page.
 *
 * General strategy:
 * Find all processes having the page mapped and kill them.
 * But we keep a page reference around so that the page is not
 * actually freed yet.
 * Then stash the page away
 *
 * There's no convenient way to get back to mapped processes
 * from the VMAs. So do a brute-force search over all
 * running processes.
 *
 * Remember that machine checks are not common (or rather
 * if they are common you have other problems), so this shouldn't
 * be a performance issue.
 *
 * Also there are some races possible while we get from the
 * error detection to actually handle it.
 */

struct to_kill {
	struct list_head nd;
	struct task_struct *tsk;
	unsigned long addr;
	unsigned addr_valid:1;
};

/*
 * Failure handling: if we can't find or can't kill a process there's
 * not much we can do.	We just print a message and ignore otherwise.
 */

/*
 * Schedule a process for later kill.
 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
 * TBD would GFP_NOIO be enough?
 */
static void add_to_kill(struct task_struct *tsk, struct page *p,
		       struct vm_area_struct *vma,
		       struct list_head *to_kill,
		       struct to_kill **tkc)
{
	struct to_kill *tk;

	if (*tkc) {
		tk = *tkc;
		*tkc = NULL;
	} else {
		tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
		if (!tk) {
			printk(KERN_ERR
		"MCE: Out of memory while machine check handling\n");
			return;
		}
	}
	tk->addr = page_address_in_vma(p, vma);
	tk->addr_valid = 1;

	/*
	 * In theory we don't have to kill when the page was
	 * munmaped. But it could be also a mremap. Since that's
	 * likely very rare kill anyways just out of paranoia, but use
	 * a SIGKILL because the error is not contained anymore.
	 */
	if (tk->addr == -EFAULT) {
		pr_debug("MCE: Unable to find user space address %lx in %s\n",
			page_to_pfn(p), tsk->comm);
		tk->addr_valid = 0;
	}
	get_task_struct(tsk);
	tk->tsk = tsk;
	list_add_tail(&tk->nd, to_kill);
}

/*
 * Kill the processes that have been collected earlier.
 *
 * Only do anything when DOIT is set, otherwise just free the list
 * (this is used for clean pages which do not need killing)
 * Also when FAIL is set do a force kill because something went
 * wrong earlier.
 */
static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
			  int fail, unsigned long pfn)
{
	struct to_kill *tk, *next;

	list_for_each_entry_safe (tk, next, to_kill, nd) {
		if (doit) {
			/*
337
			 * In case something went wrong with munmapping
338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388
			 * make sure the process doesn't catch the
			 * signal and then access the memory. Just kill it.
			 */
			if (fail || tk->addr_valid == 0) {
				printk(KERN_ERR
		"MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
					pfn, tk->tsk->comm, tk->tsk->pid);
				force_sig(SIGKILL, tk->tsk);
			}

			/*
			 * In theory the process could have mapped
			 * something else on the address in-between. We could
			 * check for that, but we need to tell the
			 * process anyways.
			 */
			else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
					      pfn) < 0)
				printk(KERN_ERR
		"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
					pfn, tk->tsk->comm, tk->tsk->pid);
		}
		put_task_struct(tk->tsk);
		kfree(tk);
	}
}

static int task_early_kill(struct task_struct *tsk)
{
	if (!tsk->mm)
		return 0;
	if (tsk->flags & PF_MCE_PROCESS)
		return !!(tsk->flags & PF_MCE_EARLY);
	return sysctl_memory_failure_early_kill;
}

/*
 * Collect processes when the error hit an anonymous page.
 */
static void collect_procs_anon(struct page *page, struct list_head *to_kill,
			      struct to_kill **tkc)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk;
	struct anon_vma *av;

	read_lock(&tasklist_lock);
	av = page_lock_anon_vma(page);
	if (av == NULL)	/* Not actually mapped anymore */
		goto out;
	for_each_process (tsk) {
389 390
		struct anon_vma_chain *vmac;

391 392
		if (!task_early_kill(tsk))
			continue;
393 394
		list_for_each_entry(vmac, &av->head, same_anon_vma) {
			vma = vmac->vma;
395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478
			if (!page_mapped_in_vma(page, vma))
				continue;
			if (vma->vm_mm == tsk->mm)
				add_to_kill(tsk, page, vma, to_kill, tkc);
		}
	}
	page_unlock_anon_vma(av);
out:
	read_unlock(&tasklist_lock);
}

/*
 * Collect processes when the error hit a file mapped page.
 */
static void collect_procs_file(struct page *page, struct list_head *to_kill,
			      struct to_kill **tkc)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk;
	struct prio_tree_iter iter;
	struct address_space *mapping = page->mapping;

	/*
	 * A note on the locking order between the two locks.
	 * We don't rely on this particular order.
	 * If you have some other code that needs a different order
	 * feel free to switch them around. Or add a reverse link
	 * from mm_struct to task_struct, then this could be all
	 * done without taking tasklist_lock and looping over all tasks.
	 */

	read_lock(&tasklist_lock);
	spin_lock(&mapping->i_mmap_lock);
	for_each_process(tsk) {
		pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);

		if (!task_early_kill(tsk))
			continue;

		vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff,
				      pgoff) {
			/*
			 * Send early kill signal to tasks where a vma covers
			 * the page but the corrupted page is not necessarily
			 * mapped it in its pte.
			 * Assume applications who requested early kill want
			 * to be informed of all such data corruptions.
			 */
			if (vma->vm_mm == tsk->mm)
				add_to_kill(tsk, page, vma, to_kill, tkc);
		}
	}
	spin_unlock(&mapping->i_mmap_lock);
	read_unlock(&tasklist_lock);
}

/*
 * Collect the processes who have the corrupted page mapped to kill.
 * This is done in two steps for locking reasons.
 * First preallocate one tokill structure outside the spin locks,
 * so that we can kill at least one process reasonably reliable.
 */
static void collect_procs(struct page *page, struct list_head *tokill)
{
	struct to_kill *tk;

	if (!page->mapping)
		return;

	tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
	if (!tk)
		return;
	if (PageAnon(page))
		collect_procs_anon(page, tokill, &tk);
	else
		collect_procs_file(page, tokill, &tk);
	kfree(tk);
}

/*
 * Error handlers for various types of pages.
 */

enum outcome {
479 480
	IGNORED,	/* Error: cannot be handled */
	FAILED,		/* Error: handling failed */
481 482 483 484 485
	DELAYED,	/* Will be handled later */
	RECOVERED,	/* Successfully recovered */
};

static const char *action_name[] = {
486
	[IGNORED] = "Ignored",
487 488 489 490 491
	[FAILED] = "Failed",
	[DELAYED] = "Delayed",
	[RECOVERED] = "Recovered",
};

492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515
/*
 * XXX: It is possible that a page is isolated from LRU cache,
 * and then kept in swap cache or failed to remove from page cache.
 * The page count will stop it from being freed by unpoison.
 * Stress tests should be aware of this memory leak problem.
 */
static int delete_from_lru_cache(struct page *p)
{
	if (!isolate_lru_page(p)) {
		/*
		 * Clear sensible page flags, so that the buddy system won't
		 * complain when the page is unpoison-and-freed.
		 */
		ClearPageActive(p);
		ClearPageUnevictable(p);
		/*
		 * drop the page count elevated by isolate_lru_page()
		 */
		page_cache_release(p);
		return 0;
	}
	return -EIO;
}

516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543
/*
 * Error hit kernel page.
 * Do nothing, try to be lucky and not touch this instead. For a few cases we
 * could be more sophisticated.
 */
static int me_kernel(struct page *p, unsigned long pfn)
{
	return IGNORED;
}

/*
 * Page in unknown state. Do nothing.
 */
static int me_unknown(struct page *p, unsigned long pfn)
{
	printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
	return FAILED;
}

/*
 * Clean (or cleaned) page cache page.
 */
static int me_pagecache_clean(struct page *p, unsigned long pfn)
{
	int err;
	int ret = FAILED;
	struct address_space *mapping;

544 545
	delete_from_lru_cache(p);

546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674
	/*
	 * For anonymous pages we're done the only reference left
	 * should be the one m_f() holds.
	 */
	if (PageAnon(p))
		return RECOVERED;

	/*
	 * Now truncate the page in the page cache. This is really
	 * more like a "temporary hole punch"
	 * Don't do this for block devices when someone else
	 * has a reference, because it could be file system metadata
	 * and that's not safe to truncate.
	 */
	mapping = page_mapping(p);
	if (!mapping) {
		/*
		 * Page has been teared down in the meanwhile
		 */
		return FAILED;
	}

	/*
	 * Truncation is a bit tricky. Enable it per file system for now.
	 *
	 * Open: to take i_mutex or not for this? Right now we don't.
	 */
	if (mapping->a_ops->error_remove_page) {
		err = mapping->a_ops->error_remove_page(mapping, p);
		if (err != 0) {
			printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
					pfn, err);
		} else if (page_has_private(p) &&
				!try_to_release_page(p, GFP_NOIO)) {
			pr_debug("MCE %#lx: failed to release buffers\n", pfn);
		} else {
			ret = RECOVERED;
		}
	} else {
		/*
		 * If the file system doesn't support it just invalidate
		 * This fails on dirty or anything with private pages
		 */
		if (invalidate_inode_page(p))
			ret = RECOVERED;
		else
			printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
				pfn);
	}
	return ret;
}

/*
 * Dirty cache page page
 * Issues: when the error hit a hole page the error is not properly
 * propagated.
 */
static int me_pagecache_dirty(struct page *p, unsigned long pfn)
{
	struct address_space *mapping = page_mapping(p);

	SetPageError(p);
	/* TBD: print more information about the file. */
	if (mapping) {
		/*
		 * IO error will be reported by write(), fsync(), etc.
		 * who check the mapping.
		 * This way the application knows that something went
		 * wrong with its dirty file data.
		 *
		 * There's one open issue:
		 *
		 * The EIO will be only reported on the next IO
		 * operation and then cleared through the IO map.
		 * Normally Linux has two mechanisms to pass IO error
		 * first through the AS_EIO flag in the address space
		 * and then through the PageError flag in the page.
		 * Since we drop pages on memory failure handling the
		 * only mechanism open to use is through AS_AIO.
		 *
		 * This has the disadvantage that it gets cleared on
		 * the first operation that returns an error, while
		 * the PageError bit is more sticky and only cleared
		 * when the page is reread or dropped.  If an
		 * application assumes it will always get error on
		 * fsync, but does other operations on the fd before
		 * and the page is dropped inbetween then the error
		 * will not be properly reported.
		 *
		 * This can already happen even without hwpoisoned
		 * pages: first on metadata IO errors (which only
		 * report through AS_EIO) or when the page is dropped
		 * at the wrong time.
		 *
		 * So right now we assume that the application DTRT on
		 * the first EIO, but we're not worse than other parts
		 * of the kernel.
		 */
		mapping_set_error(mapping, EIO);
	}

	return me_pagecache_clean(p, pfn);
}

/*
 * Clean and dirty swap cache.
 *
 * Dirty swap cache page is tricky to handle. The page could live both in page
 * cache and swap cache(ie. page is freshly swapped in). So it could be
 * referenced concurrently by 2 types of PTEs:
 * normal PTEs and swap PTEs. We try to handle them consistently by calling
 * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
 * and then
 *      - clear dirty bit to prevent IO
 *      - remove from LRU
 *      - but keep in the swap cache, so that when we return to it on
 *        a later page fault, we know the application is accessing
 *        corrupted data and shall be killed (we installed simple
 *        interception code in do_swap_page to catch it).
 *
 * Clean swap cache pages can be directly isolated. A later page fault will
 * bring in the known good data from disk.
 */
static int me_swapcache_dirty(struct page *p, unsigned long pfn)
{
	ClearPageDirty(p);
	/* Trigger EIO in shmem: */
	ClearPageUptodate(p);

675 676 677 678
	if (!delete_from_lru_cache(p))
		return DELAYED;
	else
		return FAILED;
679 680 681 682 683
}

static int me_swapcache_clean(struct page *p, unsigned long pfn)
{
	delete_from_swap_cache(p);
684

685 686 687 688
	if (!delete_from_lru_cache(p))
		return RECOVERED;
	else
		return FAILED;
689 690 691 692 693
}

/*
 * Huge pages. Needs work.
 * Issues:
694 695 696 697
 * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
 *   To narrow down kill region to one page, we need to break up pmd.
 * - To support soft-offlining for hugepage, we need to support hugepage
 *   migration.
698 699 700
 */
static int me_huge_page(struct page *p, unsigned long pfn)
{
701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716
	struct page *hpage = compound_head(p);
	/*
	 * We can safely recover from error on free or reserved (i.e.
	 * not in-use) hugepage by dequeuing it from freelist.
	 * To check whether a hugepage is in-use or not, we can't use
	 * page->lru because it can be used in other hugepage operations,
	 * such as __unmap_hugepage_range() and gather_surplus_pages().
	 * So instead we use page_mapping() and PageAnon().
	 * We assume that this function is called with page lock held,
	 * so there is no race between isolation and mapping/unmapping.
	 */
	if (!(page_mapping(hpage) || PageAnon(hpage))) {
		__isolate_hwpoisoned_huge_page(hpage);
		return RECOVERED;
	}
	return DELAYED;
717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750
}

/*
 * Various page states we can handle.
 *
 * A page state is defined by its current page->flags bits.
 * The table matches them in order and calls the right handler.
 *
 * This is quite tricky because we can access page at any time
 * in its live cycle, so all accesses have to be extremly careful.
 *
 * This is not complete. More states could be added.
 * For any missing state don't attempt recovery.
 */

#define dirty		(1UL << PG_dirty)
#define sc		(1UL << PG_swapcache)
#define unevict		(1UL << PG_unevictable)
#define mlock		(1UL << PG_mlocked)
#define writeback	(1UL << PG_writeback)
#define lru		(1UL << PG_lru)
#define swapbacked	(1UL << PG_swapbacked)
#define head		(1UL << PG_head)
#define tail		(1UL << PG_tail)
#define compound	(1UL << PG_compound)
#define slab		(1UL << PG_slab)
#define reserved	(1UL << PG_reserved)

static struct page_state {
	unsigned long mask;
	unsigned long res;
	char *msg;
	int (*action)(struct page *p, unsigned long pfn);
} error_states[] = {
751
	{ reserved,	reserved,	"reserved kernel",	me_kernel },
752 753 754 755
	/*
	 * free pages are specially detected outside this table:
	 * PG_buddy pages only make a small fraction of all free pages.
	 */
756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788

	/*
	 * Could in theory check if slab page is free or if we can drop
	 * currently unused objects without touching them. But just
	 * treat it as standard kernel for now.
	 */
	{ slab,		slab,		"kernel slab",	me_kernel },

#ifdef CONFIG_PAGEFLAGS_EXTENDED
	{ head,		head,		"huge",		me_huge_page },
	{ tail,		tail,		"huge",		me_huge_page },
#else
	{ compound,	compound,	"huge",		me_huge_page },
#endif

	{ sc|dirty,	sc|dirty,	"swapcache",	me_swapcache_dirty },
	{ sc|dirty,	sc,		"swapcache",	me_swapcache_clean },

	{ unevict|dirty, unevict|dirty,	"unevictable LRU", me_pagecache_dirty},
	{ unevict,	unevict,	"unevictable LRU", me_pagecache_clean},

	{ mlock|dirty,	mlock|dirty,	"mlocked LRU",	me_pagecache_dirty },
	{ mlock,	mlock,		"mlocked LRU",	me_pagecache_clean },

	{ lru|dirty,	lru|dirty,	"LRU",		me_pagecache_dirty },
	{ lru|dirty,	lru,		"clean LRU",	me_pagecache_clean },

	/*
	 * Catchall entry: must be at end.
	 */
	{ 0,		0,		"unknown page state",	me_unknown },
};

789 790 791 792 793 794 795 796 797 798 799 800 801
#undef dirty
#undef sc
#undef unevict
#undef mlock
#undef writeback
#undef lru
#undef swapbacked
#undef head
#undef tail
#undef compound
#undef slab
#undef reserved

802 803
static void action_result(unsigned long pfn, char *msg, int result)
{
804
	struct page *page = pfn_to_page(pfn);
805 806 807

	printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
		pfn,
808
		PageDirty(page) ? "dirty " : "",
809 810 811 812
		msg, action_name[result]);
}

static int page_action(struct page_state *ps, struct page *p,
813
			unsigned long pfn)
814 815
{
	int result;
816
	int count;
817 818 819

	result = ps->action(p, pfn);
	action_result(pfn, ps->msg, result);
820

821
	count = page_count(p) - 1;
822 823 824
	if (ps->action == me_swapcache_dirty && result == DELAYED)
		count--;
	if (count != 0) {
825 826
		printk(KERN_ERR
		       "MCE %#lx: %s page still referenced by %d users\n",
827
		       pfn, ps->msg, count);
828 829
		result = FAILED;
	}
830 831 832 833 834 835

	/* Could do more checks here if page looks ok */
	/*
	 * Could adjust zone counters here to correct for the missing page.
	 */

836
	return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
837 838 839 840 841 842 843 844
}

#define N_UNMAP_TRIES 5

/*
 * Do all that is necessary to remove user space mappings. Unmap
 * the pages and send SIGBUS to the processes if the data was dirty.
 */
W
Wu Fengguang 已提交
845
static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
846 847 848 849 850 851 852 853
				  int trapno)
{
	enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
	struct address_space *mapping;
	LIST_HEAD(tokill);
	int ret;
	int i;
	int kill = 1;
854
	struct page *hpage = compound_head(p);
855

W
Wu Fengguang 已提交
856 857
	if (PageReserved(p) || PageSlab(p))
		return SWAP_SUCCESS;
858 859 860 861 862

	/*
	 * This check implies we don't kill processes if their pages
	 * are in the swap cache early. Those are always late kills.
	 */
863
	if (!page_mapped(hpage))
W
Wu Fengguang 已提交
864 865
		return SWAP_SUCCESS;

866
	if (PageKsm(p))
W
Wu Fengguang 已提交
867
		return SWAP_FAIL;
868 869 870 871 872 873 874 875 876 877

	if (PageSwapCache(p)) {
		printk(KERN_ERR
		       "MCE %#lx: keeping poisoned page in swap cache\n", pfn);
		ttu |= TTU_IGNORE_HWPOISON;
	}

	/*
	 * Propagate the dirty bit from PTEs to struct page first, because we
	 * need this to decide if we should kill or just drop the page.
878 879
	 * XXX: the dirty test could be racy: set_page_dirty() may not always
	 * be called inside page lock (it's recommended but not enforced).
880
	 */
881 882 883 884 885
	mapping = page_mapping(hpage);
	if (!PageDirty(hpage) && mapping &&
	    mapping_cap_writeback_dirty(mapping)) {
		if (page_mkclean(hpage)) {
			SetPageDirty(hpage);
886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903
		} else {
			kill = 0;
			ttu |= TTU_IGNORE_HWPOISON;
			printk(KERN_INFO
	"MCE %#lx: corrupted page was clean: dropped without side effects\n",
				pfn);
		}
	}

	/*
	 * First collect all the processes that have the page
	 * mapped in dirty form.  This has to be done before try_to_unmap,
	 * because ttu takes the rmap data structures down.
	 *
	 * Error handling: We ignore errors here because
	 * there's nothing that can be done.
	 */
	if (kill)
904
		collect_procs(hpage, &tokill);
905 906 907 908 909 910

	/*
	 * try_to_unmap can fail temporarily due to races.
	 * Try a few times (RED-PEN better strategy?)
	 */
	for (i = 0; i < N_UNMAP_TRIES; i++) {
911
		ret = try_to_unmap(hpage, ttu);
912 913 914 915 916 917 918
		if (ret == SWAP_SUCCESS)
			break;
		pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn,  ret);
	}

	if (ret != SWAP_SUCCESS)
		printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
919
				pfn, page_mapcount(hpage));
920 921 922 923 924 925 926 927 928 929

	/*
	 * Now that the dirty bit has been propagated to the
	 * struct page and all unmaps done we can decide if
	 * killing is needed or not.  Only kill when the page
	 * was dirty, otherwise the tokill list is merely
	 * freed.  When there was a problem unmapping earlier
	 * use a more force-full uncatchable kill to prevent
	 * any accesses to the poisoned memory.
	 */
930
	kill_procs_ao(&tokill, !!PageDirty(hpage), trapno,
931
		      ret != SWAP_SUCCESS, pfn);
W
Wu Fengguang 已提交
932 933

	return ret;
934 935
}

936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951
static void set_page_hwpoison_huge_page(struct page *hpage)
{
	int i;
	int nr_pages = 1 << compound_order(hpage);
	for (i = 0; i < nr_pages; i++)
		SetPageHWPoison(hpage + i);
}

static void clear_page_hwpoison_huge_page(struct page *hpage)
{
	int i;
	int nr_pages = 1 << compound_order(hpage);
	for (i = 0; i < nr_pages; i++)
		ClearPageHWPoison(hpage + i);
}

952
int __memory_failure(unsigned long pfn, int trapno, int flags)
953 954 955
{
	struct page_state *ps;
	struct page *p;
956
	struct page *hpage;
957
	int res;
958
	unsigned int nr_pages;
959 960 961 962 963

	if (!sysctl_memory_failure_recovery)
		panic("Memory failure from trap %d on page %lx", trapno, pfn);

	if (!pfn_valid(pfn)) {
964 965 966 967
		printk(KERN_ERR
		       "MCE %#lx: memory outside kernel control\n",
		       pfn);
		return -ENXIO;
968 969 970
	}

	p = pfn_to_page(pfn);
971
	hpage = compound_head(p);
972
	if (TestSetPageHWPoison(p)) {
973
		printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
974 975 976
		return 0;
	}

977 978
	nr_pages = 1 << compound_order(hpage);
	atomic_long_add(nr_pages, &mce_bad_pages);
979 980 981 982 983 984 985 986 987 988 989 990

	/*
	 * We need/can do nothing about count=0 pages.
	 * 1) it's a free page, and therefore in safe hand:
	 *    prep_new_page() will be the gate keeper.
	 * 2) it's part of a non-compound high order page.
	 *    Implies some kernel user: cannot stop them from
	 *    R/W the page; let's pray that the page has been
	 *    used and will be freed some time later.
	 * In fact it's dangerous to directly bump up page count from 0,
	 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
	 */
991
	if (!(flags & MF_COUNT_INCREASED) &&
992
		!get_page_unless_zero(hpage)) {
993 994 995 996 997 998 999
		if (is_free_buddy_page(p)) {
			action_result(pfn, "free buddy", DELAYED);
			return 0;
		} else {
			action_result(pfn, "high order kernel", IGNORED);
			return -EBUSY;
		}
1000 1001
	}

1002 1003 1004 1005 1006 1007 1008 1009
	/*
	 * We ignore non-LRU pages for good reasons.
	 * - PG_locked is only well defined for LRU pages and a few others
	 * - to avoid races with __set_page_locked()
	 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
	 * The check (unnecessarily) ignores LRU pages being isolated and
	 * walked by the page reclaim code, however that's not a big loss.
	 */
1010
	if (!PageLRU(p) && !PageHuge(p))
1011
		shake_page(p, 0);
1012
	if (!PageLRU(p) && !PageHuge(p)) {
1013 1014 1015 1016 1017 1018 1019
		/*
		 * shake_page could have turned it free.
		 */
		if (is_free_buddy_page(p)) {
			action_result(pfn, "free buddy, 2nd try", DELAYED);
			return 0;
		}
1020 1021 1022 1023 1024
		action_result(pfn, "non LRU", IGNORED);
		put_page(p);
		return -EBUSY;
	}

1025 1026 1027 1028 1029
	/*
	 * Lock the page and wait for writeback to finish.
	 * It's very difficult to mess with pages currently under IO
	 * and in many cases impossible, so we just avoid it here.
	 */
1030
	lock_page_nosync(hpage);
W
Wu Fengguang 已提交
1031 1032 1033 1034 1035

	/*
	 * unpoison always clear PG_hwpoison inside page lock
	 */
	if (!PageHWPoison(p)) {
1036
		printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
W
Wu Fengguang 已提交
1037 1038 1039
		res = 0;
		goto out;
	}
W
Wu Fengguang 已提交
1040 1041
	if (hwpoison_filter(p)) {
		if (TestClearPageHWPoison(p))
1042
			atomic_long_sub(nr_pages, &mce_bad_pages);
1043 1044
		unlock_page(hpage);
		put_page(hpage);
W
Wu Fengguang 已提交
1045 1046
		return 0;
	}
W
Wu Fengguang 已提交
1047

1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
	/*
	 * For error on the tail page, we should set PG_hwpoison
	 * on the head page to show that the hugepage is hwpoisoned
	 */
	if (PageTail(p) && TestSetPageHWPoison(hpage)) {
		action_result(pfn, "hugepage already hardware poisoned",
				IGNORED);
		unlock_page(hpage);
		put_page(hpage);
		return 0;
	}
	/*
	 * Set PG_hwpoison on all pages in an error hugepage,
	 * because containment is done in hugepage unit for now.
	 * Since we have done TestSetPageHWPoison() for the head page with
	 * page lock held, we can safely set PG_hwpoison bits on tail pages.
	 */
	if (PageHuge(p))
		set_page_hwpoison_huge_page(hpage);

1068 1069 1070 1071
	wait_on_page_writeback(p);

	/*
	 * Now take care of user space mappings.
W
Wu Fengguang 已提交
1072
	 * Abort on fail: __remove_from_page_cache() assumes unmapped page.
1073
	 */
W
Wu Fengguang 已提交
1074 1075 1076 1077 1078
	if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) {
		printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
		res = -EBUSY;
		goto out;
	}
1079 1080 1081 1082

	/*
	 * Torn down by someone else?
	 */
1083
	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
1084
		action_result(pfn, "already truncated LRU", IGNORED);
1085
		res = -EBUSY;
1086 1087 1088 1089 1090
		goto out;
	}

	res = -EBUSY;
	for (ps = error_states;; ps++) {
1091
		if ((p->flags & ps->mask) == ps->res) {
1092
			res = page_action(ps, p, pfn);
1093 1094 1095 1096
			break;
		}
	}
out:
1097
	unlock_page(hpage);
1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	return res;
}
EXPORT_SYMBOL_GPL(__memory_failure);

/**
 * memory_failure - Handle memory failure of a page.
 * @pfn: Page Number of the corrupted page
 * @trapno: Trap number reported in the signal to user space.
 *
 * This function is called by the low level machine check code
 * of an architecture when it detects hardware memory corruption
 * of a page. It tries its best to recover, which includes
 * dropping pages, killing processes etc.
 *
 * The function is primarily of use for corruptions that
 * happen outside the current execution context (e.g. when
 * detected by a background scrubber)
 *
 * Must run in process context (e.g. a work queue) with interrupts
 * enabled and no spinlocks hold.
 */
void memory_failure(unsigned long pfn, int trapno)
{
	__memory_failure(pfn, trapno, 0);
}
W
Wu Fengguang 已提交
1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140

/**
 * unpoison_memory - Unpoison a previously poisoned page
 * @pfn: Page number of the to be unpoisoned page
 *
 * Software-unpoison a page that has been poisoned by
 * memory_failure() earlier.
 *
 * This is only done on the software-level, so it only works
 * for linux injected failures, not real hardware failures
 *
 * Returns 0 for success, otherwise -errno.
 */
int unpoison_memory(unsigned long pfn)
{
	struct page *page;
	struct page *p;
	int freeit = 0;
1141
	unsigned int nr_pages;
W
Wu Fengguang 已提交
1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153

	if (!pfn_valid(pfn))
		return -ENXIO;

	p = pfn_to_page(pfn);
	page = compound_head(p);

	if (!PageHWPoison(p)) {
		pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn);
		return 0;
	}

1154 1155
	nr_pages = 1 << compound_order(page);

W
Wu Fengguang 已提交
1156 1157
	if (!get_page_unless_zero(page)) {
		if (TestClearPageHWPoison(p))
1158
			atomic_long_sub(nr_pages, &mce_bad_pages);
W
Wu Fengguang 已提交
1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169
		pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn);
		return 0;
	}

	lock_page_nosync(page);
	/*
	 * This test is racy because PG_hwpoison is set outside of page lock.
	 * That's acceptable because that won't trigger kernel panic. Instead,
	 * the PG_hwpoison page will be caught and isolated on the entrance to
	 * the free buddy page pool.
	 */
1170
	if (TestClearPageHWPoison(page)) {
W
Wu Fengguang 已提交
1171
		pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn);
1172
		atomic_long_sub(nr_pages, &mce_bad_pages);
W
Wu Fengguang 已提交
1173 1174
		freeit = 1;
	}
1175 1176
	if (PageHuge(p))
		clear_page_hwpoison_huge_page(page);
W
Wu Fengguang 已提交
1177 1178 1179 1180 1181 1182 1183 1184 1185
	unlock_page(page);

	put_page(page);
	if (freeit)
		put_page(page);

	return 0;
}
EXPORT_SYMBOL(unpoison_memory);
1186 1187 1188

static struct page *new_page(struct page *p, unsigned long private, int **x)
{
1189 1190
	int nid = page_to_nid(p);
	return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359
}

/*
 * Safely get reference count of an arbitrary page.
 * Returns 0 for a free page, -EIO for a zero refcount page
 * that is not free, and 1 for any other page type.
 * For 1 the page is returned with increased page count, otherwise not.
 */
static int get_any_page(struct page *p, unsigned long pfn, int flags)
{
	int ret;

	if (flags & MF_COUNT_INCREASED)
		return 1;

	/*
	 * The lock_system_sleep prevents a race with memory hotplug,
	 * because the isolation assumes there's only a single user.
	 * This is a big hammer, a better would be nicer.
	 */
	lock_system_sleep();

	/*
	 * Isolate the page, so that it doesn't get reallocated if it
	 * was free.
	 */
	set_migratetype_isolate(p);
	if (!get_page_unless_zero(compound_head(p))) {
		if (is_free_buddy_page(p)) {
			pr_debug("get_any_page: %#lx free buddy page\n", pfn);
			/* Set hwpoison bit while page is still isolated */
			SetPageHWPoison(p);
			ret = 0;
		} else {
			pr_debug("get_any_page: %#lx: unknown zero refcount page type %lx\n",
				pfn, p->flags);
			ret = -EIO;
		}
	} else {
		/* Not a free page */
		ret = 1;
	}
	unset_migratetype_isolate(p);
	unlock_system_sleep();
	return ret;
}

/**
 * soft_offline_page - Soft offline a page.
 * @page: page to offline
 * @flags: flags. Same as memory_failure().
 *
 * Returns 0 on success, otherwise negated errno.
 *
 * Soft offline a page, by migration or invalidation,
 * without killing anything. This is for the case when
 * a page is not corrupted yet (so it's still valid to access),
 * but has had a number of corrected errors and is better taken
 * out.
 *
 * The actual policy on when to do that is maintained by
 * user space.
 *
 * This should never impact any application or cause data loss,
 * however it might take some time.
 *
 * This is not a 100% solution for all memory, but tries to be
 * ``good enough'' for the majority of memory.
 */
int soft_offline_page(struct page *page, int flags)
{
	int ret;
	unsigned long pfn = page_to_pfn(page);

	ret = get_any_page(page, pfn, flags);
	if (ret < 0)
		return ret;
	if (ret == 0)
		goto done;

	/*
	 * Page cache page we can handle?
	 */
	if (!PageLRU(page)) {
		/*
		 * Try to free it.
		 */
		put_page(page);
		shake_page(page, 1);

		/*
		 * Did it turn free?
		 */
		ret = get_any_page(page, pfn, 0);
		if (ret < 0)
			return ret;
		if (ret == 0)
			goto done;
	}
	if (!PageLRU(page)) {
		pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n",
				pfn, page->flags);
		return -EIO;
	}

	lock_page(page);
	wait_on_page_writeback(page);

	/*
	 * Synchronized using the page lock with memory_failure()
	 */
	if (PageHWPoison(page)) {
		unlock_page(page);
		put_page(page);
		pr_debug("soft offline: %#lx page already poisoned\n", pfn);
		return -EBUSY;
	}

	/*
	 * Try to invalidate first. This should work for
	 * non dirty unmapped page cache pages.
	 */
	ret = invalidate_inode_page(page);
	unlock_page(page);

	/*
	 * Drop count because page migration doesn't like raised
	 * counts. The page could get re-allocated, but if it becomes
	 * LRU the isolation will just fail.
	 * RED-PEN would be better to keep it isolated here, but we
	 * would need to fix isolation locking first.
	 */
	put_page(page);
	if (ret == 1) {
		ret = 0;
		pr_debug("soft_offline: %#lx: invalidated\n", pfn);
		goto done;
	}

	/*
	 * Simple invalidation didn't work.
	 * Try to migrate to a new page instead. migrate.c
	 * handles a large number of cases for us.
	 */
	ret = isolate_lru_page(page);
	if (!ret) {
		LIST_HEAD(pagelist);

		list_add(&page->lru, &pagelist);
		ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
		if (ret) {
			pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
				pfn, ret, page->flags);
			if (ret > 0)
				ret = -EIO;
		}
	} else {
		pr_debug("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
				pfn, ret, page_count(page), page->flags);
	}
	if (ret)
		return ret;

done:
	atomic_long_add(1, &mce_bad_pages);
	SetPageHWPoison(page);
	/* keep elevated page count for bad page */
	return ret;
}
1360

1361 1362 1363
/*
 * The caller must hold current->mm->mmap_sem in read mode.
 */
1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391
int is_hwpoison_address(unsigned long addr)
{
	pgd_t *pgdp;
	pud_t pud, *pudp;
	pmd_t pmd, *pmdp;
	pte_t pte, *ptep;
	swp_entry_t entry;

	pgdp = pgd_offset(current->mm, addr);
	if (!pgd_present(*pgdp))
		return 0;
	pudp = pud_offset(pgdp, addr);
	pud = *pudp;
	if (!pud_present(pud) || pud_large(pud))
		return 0;
	pmdp = pmd_offset(pudp, addr);
	pmd = *pmdp;
	if (!pmd_present(pmd) || pmd_large(pmd))
		return 0;
	ptep = pte_offset_map(pmdp, addr);
	pte = *ptep;
	pte_unmap(ptep);
	if (!is_swap_pte(pte))
		return 0;
	entry = pte_to_swp_entry(pte);
	return is_hwpoison_entry(entry);
}
EXPORT_SYMBOL_GPL(is_hwpoison_address);