cregit-Linux how code gets into the kernel

Release 4.11 mm/memory-failure.c

Directory: mm
/*
 * 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 multi-bit ECC memory or cache
 * failure.
 * 
 * In addition there is a "soft offline" entry point that allows stop using
 * not-yet-corrupted-by-suspicious pages without killing anything.
 *
 * Handles page cache pages in various states.  The tricky part
 * here is that we can access any page asynchronously in respect to 
 * other VM users, because memory failures could happen anytime and 
 * anywhere. This could violate 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.
 *
 * It can be very tempting to add handling for obscure cases here.
 * In general any code for handling new cases should only be added iff:
 * - You know how to test it.
 * - You have a test that can be added to mce-test
 *   https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
 * - The case actually shows up as a frequent (top 10) page state in
 *   tools/vm/page-types when running a real workload.
 * 
 * There are several operations here with exponential complexity because
 * of unsuitable VM data structures. For example 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. But since memory corruptions
 * are rare we hope to get away with this. This avoids impacting the core 
 * VM.
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/kernel-page-flags.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/ksm.h>
#include <linux/rmap.h>
#include <linux/export.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/backing-dev.h>
#include <linux/migrate.h>
#include <linux/page-isolation.h>
#include <linux/suspend.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memory_hotplug.h>
#include <linux/mm_inline.h>
#include <linux/kfifo.h>
#include <linux/ratelimit.h>
#include "internal.h"
#include "ras/ras_event.h"


int sysctl_memory_failure_early_kill __read_mostly = 0;


int sysctl_memory_failure_recovery __read_mostly = 1;


atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);

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


u32 hwpoison_filter_enable = 0;

u32 hwpoison_filter_dev_major = ~0U;

u32 hwpoison_filter_dev_minor = ~0U;

u64 hwpoison_filter_flags_mask;

u64 hwpoison_filter_flags_value;

EXPORT_SYMBOL_GPL(hwpoison_filter_enable);

EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);

EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);

EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);

EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);




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 pages.
         */
	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;
}


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Andi Kleen10.85%150.00%


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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;
}


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/*
 * 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_MEMCG

u64 hwpoison_filter_memcg;

EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);



static int hwpoison_filter_task(struct page *p)
{
	if (!hwpoison_filter_memcg)
		return 0;

	if (page_cgroup_ino(p) != hwpoison_filter_memcg)
		return -EINVAL;

	return 0;
}

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#else



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

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#endif




int hwpoison_filter(struct page *p)
{
	if (!hwpoison_filter_enable)
		return 0;

	if (hwpoison_filter_dev(p))
		return -EINVAL;

	if (hwpoison_filter_flags(p))
		return -EINVAL;

	if (hwpoison_filter_task(p))
		return -EINVAL;

	return 0;
}

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Haicheng Li814.81%125.00%


Total54100.00%4100.00%



#else



int hwpoison_filter(struct page *p)
{
	return 0;
}

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#endif


EXPORT_SYMBOL_GPL(hwpoison_filter);

/*
 * Send all the processes who have the page mapped a signal.
 * ``action optional'' if they are not immediately affected by the error
 * ``action required'' if error happened in current execution context
 */



static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
			unsigned long pfn, struct page *page, int flags)
{
	struct siginfo si;
	int ret;

	pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n",
		pfn, t->comm, t->pid);
	si.si_signo = SIGBUS;
	si.si_errno = 0;
	si.si_addr = (void *)addr;
#ifdef __ARCH_SI_TRAPNO
	si.si_trapno = trapno;
#endif
	si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT;

	if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
		si.si_code = BUS_MCEERR_AR;
		ret = force_sig_info(SIGBUS, &si, current);
	} else {
		/*
                 * 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 no one will do that?
                 */
		si.si_code = BUS_MCEERR_AO;
		ret = send_sig_info(SIGBUS, &si, t);  /* synchronous? */
	}
	if (ret < 0)
		pr_info("Memory failure: Error sending signal to %s:%d: %d\n",
			t->comm, t->pid, ret);
	return ret;
}


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Wanpeng Li10.55%114.29%


Total182100.00%7100.00%



/*
 * 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.
 */



void shake_page(struct page *p, int access)
{
	if (!PageSlab(p)) {
		lru_add_drain_all();
		if (PageLRU(p))
			return;
		drain_all_pages(page_zone(p));
		if (PageLRU(p) || is_free_buddy_page(p))
			return;
	}

	/*
         * Only call shrink_node_slabs here (which would also shrink
         * other caches) if access is not potentially fatal.
         */
	if (access)
		drop_slab_node(page_to_nid(p));
}

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Johannes Weiner11.47%114.29%


Total68100.00%7100.00%




EXPORT_SYMBOL_GPL(shake_page);

/*
 * 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;
	
char addr_valid;
};

/*
 * 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) {
			pr_err("Memory failure: 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_info("Memory failure: 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);
}


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/*
 * 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(struct list_head *to_kill, int forcekill, int trapno,
			  int fail, struct page *page, unsigned long pfn,
			  int flags)
{
	struct to_kill *tk, *next;

	list_for_each_entry_safe (tk, next, to_kill, nd) {
		if (forcekill) {
			/*
                         * In case something went wrong with munmapping
                         * make sure the process doesn't catch the
                         * signal and then access the memory. Just kill it.
                         */
			if (fail || tk->addr_valid == 0) {
				pr_err("Memory failure: %#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(tk->tsk, tk->addr, trapno,
					      pfn, page, flags) < 0)
				pr_err("Memory failure: %#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);
	}
}


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Total155100.00%7100.00%



/*
 * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
 * on behalf of the thread group. Return task_struct of the (first found)
 * dedicated thread if found, and return NULL otherwise.
 *
 * We already hold read_lock(&tasklist_lock) in the caller, so we don't
 * have to call rcu_read_lock/unlock() in this function.
 */



static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
{
	struct task_struct *t;

	for_each_thread(tsk, t)
		if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
			return t;
	return NULL;
}


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/*
 * Determine whether a given process is "early kill" process which expects
 * to be signaled when some page under the process is hwpoisoned.
 * Return task_struct of the dedicated thread (main thread unless explicitly
 * specified) if the process is "early kill," and otherwise returns NULL.
 */



static struct task_struct *task_early_kill(struct task_struct *tsk,
					   int force_early)
{
	struct task_struct *t;
	if (!tsk->mm)
		return NULL;
	if (force_early)
		return tsk;
	t = find_early_kill_thread(tsk);
	if (t)
		return t;
	if (sysctl_memory_failure_early_kill)
		return tsk;
	return NULL;
}


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Tony Luck914.52%133.33%


Total62100.00%3100.00%



/*
 * 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, int force_early)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk;
	struct anon_vma *av;
	pgoff_t pgoff;

	av = page_lock_anon_vma_read(page);
	if (av == NULL)	/* Not actually mapped anymore */
		return;

	pgoff = page_to_pgoff(page);
	read_lock(&tasklist_lock);
	for_each_process (tsk) {
		struct anon_vma_chain *vmac;
		struct task_struct *t = task_early_kill(tsk, force_early);

		if (!t)
			continue;
		anon_vma_interval_tree_foreach(vmac, &av->rb_root,
					       pgoff, pgoff) {
			vma = vmac->vma;
			if (!page_mapped_in_vma(page, vma))
				continue;
			if (vma->vm_mm == t->mm)
				add_to_kill(t, page, vma, to_kill, tkc);
		}
	}
	read_unlock(&tasklist_lock);
	page_unlock_anon_vma_read(av);
}


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Peter Zijlstra116.75%112.50%


Tony Luck53.07%112.50%


Ingo Molnar21.23%112.50%


Total163100.00%8100.00%



/*
 * 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, int force_early)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk;
	struct address_space *mapping = page->mapping;

	i_mmap_lock_read(mapping);
	read_lock(&tasklist_lock);
	for_each_process(tsk) {
		pgoff_t pgoff = page_to_pgoff(page);
		struct task_struct *t = task_early_kill(tsk, force_early);

		if (!t)
			continue;
		vma_interval_tree_foreach(vma, &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 == t->mm)
				add_to_kill(t, page, vma, to_kill, tkc);
		}
	}
	read_unlock(&tasklist_lock);
	i_mmap_unlock_read(mapping);
}


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Peter Zijlstra96.72%114.29%


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Davidlohr Bueso A21.49%114.29%


Michel Lespinasse10.75%114.29%


Total134100.00%7100.00%



/*
 * 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,
				int force_early)
{
	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, force_early);
	else
		collect_procs_file(page, tokill, &tk, force_early);
	kfree(tk);
}


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static const char *action_name[] = {
	[MF_IGNORED] = "Ignored",
	[MF_FAILED] = "Failed",
	[MF_DELAYED] = "Delayed",
	[MF_RECOVERED] = "Recovered",
};


static const char * const action_page_types[] = {
	[MF_MSG_KERNEL]			= "reserved kernel page",
	[MF_MSG_KERNEL_HIGH_ORDER]	= "high-order kernel page",
	[MF_MSG_SLAB]			= "kernel slab page",
	[MF_MSG_DIFFERENT_COMPOUND]	= "different compound page after locking",
	[MF_MSG_POISONED_HUGE]		= "huge page already hardware poisoned",
	[MF_MSG_HUGE]			= "huge page",
	[MF_MSG_FREE_HUGE]		= "free huge page",
	[MF_MSG_UNMAP_FAILED]		= "unmapping failed page",
	[MF_MSG_DIRTY_SWAPCACHE]	= "dirty swapcache page",
	[MF_MSG_CLEAN_SWAPCACHE]	= "clean swapcache page",
	[MF_MSG_DIRTY_MLOCKED_LRU]	= "dirty mlocked LRU page",
	[MF_MSG_CLEAN_MLOCKED_LRU]	= "clean mlocked LRU page",
	[MF_MSG_DIRTY_UNEVICTABLE_LRU]	= "dirty unevictable LRU page",
	[MF_MSG_CLEAN_UNEVICTABLE_LRU]	= "clean unevictable LRU page",
	[MF_MSG_DIRTY_LRU]		= "dirty LRU page",
	[MF_MSG_CLEAN_LRU]		= "clean LRU page",
	[MF_MSG_TRUNCATED_LRU]		= "already truncated LRU page",
	[MF_MSG_BUDDY]			= "free buddy page",
	[MF_MSG_BUDDY_2ND]		= "free buddy page (2nd try)",
	[MF_MSG_UNKNOWN]		= "unknown page",
};

/*
 * 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()
                 */
		put_page(p);
		return 0;
	}
	return -EIO;
}


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/*
 * 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 MF_IGNORED;
}


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/*
 * Page in unknown state. Do nothing.
 */



static int me_unknown(struct page *p, unsigned long pfn)
{
	pr_err("Memory failure: %#lx: Unknown page state\n", pfn);
	return MF_FAILED;
}


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Total25100.00%4100.00%



/*
 * Clean (or cleaned) page cache page.
 */



static int me_pagecache_clean(struct page *p, unsigned long pfn)
{
	int err;
	int ret = MF_FAILED;
	struct address_space *mapping;

	delete_from_lru_cache(p);

	/*
         * For anonymous pages we're done the only reference left
         * should be the one m_f() holds.
         */
	if (PageAnon(p))
		return MF_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 MF_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) {
			pr_info("Memory failure: %#lx: Failed to punch page: %d\n",
				pfn, err);
		} else if (page_has_private(p) &&
				!try_to_release_page(p, GFP_NOIO)) {
			pr_info("Memory failure: %#lx: failed to release buffers\n",
				pfn);
		} else {
			ret = MF_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 = MF_RECOVERED;
		else
			pr_info("Memory failure: %#lx: Failed to invalidate\n",
				pfn);
	}
	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen14790.74%233.33%


Xie XiuQi53.09%116.67%


Fengguang Wu53.09%116.67%


Chen Yucong31.85%116.67%


Joe Perches21.23%116.67%


Total162100.00%6100.00%



/*
 * Dirty pagecache 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 between 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);
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen5298.11%150.00%


Lucas De Marchi11.89%150.00%


Total53100.00%2100.00%



/*
 * 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);

	if (!delete_from_lru_cache(p))
		return MF_DELAYED;
	else
		return MF_FAILED;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen2868.29%133.33%


Fengguang Wu1126.83%133.33%


Xie XiuQi24.88%133.33%


Total41100.00%3100.00%






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

	if (!delete_from_lru_cache(p))
		return MF_RECOVERED;
	else
		return MF_FAILED;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen2262.86%133.33%


Fengguang Wu1131.43%133.33%


Xie XiuQi25.71%133.33%


Total35100.00%3100.00%



/*
 * Huge pages. Needs work.
 * Issues:
 * - 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.
 */



static int me_huge_page(struct page *p, unsigned long pfn)
{
	int res = 0;
	struct page *hpage = compound_head(p);

	if (!PageHuge(hpage))
		return MF_DELAYED;

	/*
         * 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().
         */
	if (!(page_mapping(hpage) || PageAnon(hpage))) {
		res = dequeue_hwpoisoned_huge_page(hpage);
		if (!res)
			return MF_RECOVERED;
	}
	return MF_DELAYED;
}


Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi5875.32%466.67%


Andi Kleen1722.08%116.67%


Xie XiuQi22.60%116.67%


Total77100.00%6100.00%



/*
 * 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 extremely 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) | (1UL << PG_swapbacked))

#define unevict		(1UL << PG_unevictable)

#define mlock		(1UL << PG_mlocked)

#define writeback	(1UL << PG_writeback)

#define lru		(1UL << PG_lru)

#define head		(1UL << PG_head)

#define slab		(1UL << PG_slab)

#define reserved	(1UL << PG_reserved)


static struct page_state {
	
unsigned long mask;
	
unsigned long res;
	
enum mf_action_page_type type;
	
int (*action)(struct page *p, unsigned long pfn);
} 
error_states[] = {
	{ reserved,	reserved,	MF_MSG_KERNEL,	me_kernel },
	/*
         * free pages are specially detected outside this table:
         * PG_buddy pages only make a small fraction of all free pages.
         */

	/*
         * 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,		MF_MSG_SLAB,	me_kernel },

	{ head,		head,		MF_MSG_HUGE,		me_huge_page },

	{ sc|dirty,	sc|dirty,	MF_MSG_DIRTY_SWAPCACHE,	me_swapcache_dirty },
	{ sc|dirty,	sc,		MF_MSG_CLEAN_SWAPCACHE,	me_swapcache_clean },

	{ mlock|dirty,	mlock|dirty,	MF_MSG_DIRTY_MLOCKED_LRU,	me_pagecache_dirty },
	{ mlock|dirty,	mlock,		MF_MSG_CLEAN_MLOCKED_LRU,	me_pagecache_clean },

	{ unevict|dirty, unevict|dirty,	MF_MSG_DIRTY_UNEVICTABLE_LRU,	me_pagecache_dirty },
	{ unevict|dirty, unevict,	MF_MSG_CLEAN_UNEVICTABLE_LRU,	me_pagecache_clean },

	{ lru|dirty,	lru|dirty,	MF_MSG_DIRTY_LRU,	me_pagecache_dirty },
	{ lru|dirty,	lru,		MF_MSG_CLEAN_LRU,	me_pagecache_clean },

	/*
         * Catchall entry: must be at end.
         */
	{ 0,		0,		MF_MSG_UNKNOWN,	me_unknown },
};


#undef dirty

#undef sc

#undef unevict

#undef mlock

#undef writeback

#undef lru

#undef head

#undef slab

#undef reserved

/*
 * "Dirty/Clean" indication is not 100% accurate due to the possibility of
 * setting PG_dirty outside page lock. See also comment above set_page_dirty().
 */



static void action_result(unsigned long pfn, enum mf_action_page_type type,
			  enum mf_result result)
{
	trace_memory_failure_event(pfn, type, result);

	pr_err("Memory failure: %#lx: recovery action for %s: %s\n",
		pfn, action_page_types[type], action_name[result]);
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen2454.55%114.29%


Xie XiuQi1227.27%342.86%


Naoya Horiguchi715.91%228.57%


Chen Yucong12.27%114.29%


Total44100.00%7100.00%






static int page_action(struct page_state *ps, struct page *p,
			unsigned long pfn)
{
	int result;
	int count;

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

	count = page_count(p) - 1;
	if (ps->action == me_swapcache_dirty && result == MF_DELAYED)
		count--;
	if (count != 0) {
		pr_err("Memory failure: %#lx: %s still referenced by %d users\n",
		       pfn, action_page_types[ps->type], count);
		result = MF_FAILED;
	}
	action_result(pfn, ps->type, result);

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

	return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen6050.85%112.50%


Fengguang Wu3731.36%225.00%


Chen Gong108.47%112.50%


Naoya Horiguchi54.24%112.50%


Xie XiuQi43.39%112.50%


Joe Perches10.85%112.50%


Chen Yucong10.85%112.50%


Total118100.00%8100.00%



/**
 * get_hwpoison_page() - Get refcount for memory error handling:
 * @page:       raw error page (hit by memory error)
 *
 * Return: return 0 if failed to grab the refcount, otherwise true (some
 * non-zero value.)
 */



int get_hwpoison_page(struct page *page)
{
	struct page *head = compound_head(page);

	if (!PageHuge(head) && PageTransHuge(head)) {
		/*
                 * Non anonymous thp exists only in allocation/free time. We
                 * can't handle such a case correctly, so let's give it up.
                 * This should be better than triggering BUG_ON when kernel
                 * tries to touch the "partially handled" page.
                 */
		if (!PageAnon(head)) {
			pr_err("Memory failure: %#lx: non anonymous thp\n",
				page_to_pfn(page));
			return 0;
		}
	}

	if (get_page_unless_zero(head)) {
		if (head == compound_head(page))
			return 1;

		pr_info("Memory failure: %#lx cannot catch tail\n",
			page_to_pfn(page));
		put_page(head);
	}

	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi6364.29%360.00%


Konstantin Khlebnikov3333.67%120.00%


Chen Yucong22.04%120.00%


Total98100.00%5100.00%




EXPORT_SYMBOL_GPL(get_hwpoison_page);

/*
 * Do all that is necessary to remove user space mappings. Unmap
 * the pages and send SIGBUS to the processes if the data was dirty.
 */



static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
				  int trapno, int flags, struct page **hpagep)
{
	enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
	struct address_space *mapping;
	LIST_HEAD(tokill);
	int ret;
	int kill = 1, forcekill;
	struct page *hpage = *hpagep;

	/*
         * Here we are interested only in user-mapped pages, so skip any
         * other types of pages.
         */
	if (PageReserved(p) || PageSlab(p))
		return SWAP_SUCCESS;
	if (!(PageLRU(hpage) || PageHuge(p)))
		return SWAP_SUCCESS;

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

	if (PageKsm(p)) {
		pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn);
		return SWAP_FAIL;
	}

	if (PageSwapCache(p)) {
		pr_err("Memory failure: %#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.
         * XXX: the dirty test could be racy: set_page_dirty() may not always
         * be called inside page lock (it's recommended but not enforced).
         */
	mapping = page_mapping(hpage);
	if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
	    mapping_cap_writeback_dirty(mapping)) {
		if (page_mkclean(hpage)) {
			SetPageDirty(hpage);
		} else {
			kill = 0;
			ttu |= TTU_IGNORE_HWPOISON;
			pr_info("Memory failure: %#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)
		collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);

	ret = try_to_unmap(hpage, ttu);
	if (ret != SWAP_SUCCESS)
		pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
		       pfn, page_mapcount(hpage));

	/*
         * 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 or the process is not restartable,
         * 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.
         */
	forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
	kill_procs(&tokill, forcekill, trapno,
		      ret != SWAP_SUCCESS, p, pfn, flags);

	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen18462.37%213.33%


Naoya Horiguchi4515.25%533.33%


Tony Luck3311.19%320.00%


Fengguang Wu217.12%213.33%


Chen Yucong93.05%213.33%


Joe Perches31.02%16.67%


Total295100.00%15100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi4397.73%150.00%


Wanpeng Li12.27%150.00%


Total44100.00%2100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi4397.73%150.00%


Wanpeng Li12.27%150.00%


Total44100.00%2100.00%



/**
 * 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.
 * @flags: fine tune action taken
 *
 * 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.
 */



int memory_failure(unsigned long pfn, int trapno, int flags)
{
	struct page_state *ps;
	struct page *p;
	struct page *hpage;
	struct page *orig_head;
	int res;
	unsigned int nr_pages;
	unsigned long page_flags;

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

	if (!pfn_valid(pfn)) {
		pr_err("Memory failure: %#lx: memory outside kernel control\n",
			pfn);
		return -ENXIO;
	}

	p = pfn_to_page(pfn);
	orig_head = hpage = compound_head(p);
	if (TestSetPageHWPoison(p)) {
		pr_err("Memory failure: %#lx: already hardware poisoned\n",
			pfn);
		return 0;
	}

	/*
         * Currently errors on hugetlbfs pages are measured in hugepage units,
         * so nr_pages should be 1 << compound_order.  OTOH when errors are on
         * transparent hugepages, they are supposed to be split and error
         * measurement is done in normal page units.  So nr_pages should be one
         * in this case.
         */
	if (PageHuge(p))
		nr_pages = 1 << compound_order(hpage);
	else /* normal page or thp */
		nr_pages = 1;
	num_poisoned_pages_add(nr_pages);

	/*
         * 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 a free hugepage, which is also safe:
         *    an affected hugepage will be dequeued from hugepage freelist,
         *    so there's no concern about reusing it ever after.
         * 3) 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.
         */
	if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
		if (is_free_buddy_page(p)) {
			action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
			return 0;
		} else if (PageHuge(hpage)) {
			/*
                         * Check "filter hit" and "race with other subpage."
                         */
			lock_page(hpage);
			if (PageHWPoison(hpage)) {
				if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
				    || (p != hpage && TestSetPageHWPoison(hpage))) {
					num_poisoned_pages_sub(nr_pages);
					unlock_page(hpage);
					return 0;
				}
			}
			set_page_hwpoison_huge_page(hpage);
			res = dequeue_hwpoisoned_huge_page(hpage);
			action_result(pfn, MF_MSG_FREE_HUGE,
				      res ? MF_IGNORED : MF_DELAYED);
			unlock_page(hpage);
			return res;
		} else {
			action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
			return -EBUSY;
		}
	}

	if (!PageHuge(p) && PageTransHuge(hpage)) {
		lock_page(p);
		if (!PageAnon(p) || unlikely(split_huge_page(p))) {
			unlock_page(p);
			if (!PageAnon(p))
				pr_err("Memory failure: %#lx: non anonymous thp\n",
					pfn);
			else
				pr_err("Memory failure: %#lx: thp split failed\n",
					pfn);
			if (TestClearPageHWPoison(p))
				num_poisoned_pages_sub(nr_pages);
			put_hwpoison_page(p);
			return -EBUSY;
		}
		unlock_page(p);
		VM_BUG_ON_PAGE(!page_count(p), p);
		hpage = compound_head(p);
	}

	/*
         * 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 __SetPageLocked()
         * - 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.
         */
	if (!PageHuge(p)) {
		if (!PageLRU(p))
			shake_page(p, 0);
		if (!PageLRU(p)) {
			/*
                         * shake_page could have turned it free.
                         */
			if (is_free_buddy_page(p)) {
				if (flags & MF_COUNT_INCREASED)
					action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
				else
					action_result(pfn, MF_MSG_BUDDY_2ND,
						      MF_DELAYED);
				return 0;
			}
		}
	}

	lock_page(hpage);

	/*
         * The page could have changed compound pages during the locking.
         * If this happens just bail out.
         */
	if (PageCompound(p) && compound_head(p) != orig_head) {
		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
		res = -EBUSY;
		goto out;
	}

	/*
         * We use page flags to determine what action should be taken, but
         * the flags can be modified by the error containment action.  One
         * example is an mlocked page, where PG_mlocked is cleared by
         * page_remove_rmap() in try_to_unmap_one(). So to determine page status
         * correctly, we save a copy of the page flags at this time.
         */
	page_flags = p->flags;

	/*
         * unpoison always clear PG_hwpoison inside page lock
         */
	if (!PageHWPoison(p)) {
		pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
		num_poisoned_pages_sub(nr_pages);
		unlock_page(hpage);
		put_hwpoison_page(hpage);
		return 0;
	}
	if (hwpoison_filter(p)) {
		if (TestClearPageHWPoison(p))
			num_poisoned_pages_sub(nr_pages);
		unlock_page(hpage);
		put_hwpoison_page(hpage);
		return 0;
	}

	if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p))
		goto identify_page_state;

	/*
         * For error on the tail page, we should set PG_hwpoison
         * on the head page to show that the hugepage is hwpoisoned
         */
	if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
		action_result(pfn, MF_MSG_POISONED_HUGE, MF_IGNORED);
		unlock_page(hpage);
		put_hwpoison_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);

	/*
         * It's very difficult to mess with pages currently under IO
         * and in many cases impossible, so we just avoid it here.
         */
	wait_on_page_writeback(p);

	/*
         * Now take care of user space mappings.
         * Abort on fail: __delete_from_page_cache() assumes unmapped page.
         *
         * When the raw error page is thp tail page, hpage points to the raw
         * page after thp split.
         */
	if (hwpoison_user_mappings(p, pfn, trapno, flags, &hpage)
	    != SWAP_SUCCESS) {
		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
		res = -EBUSY;
		goto out;
	}

	/*
         * Torn down by someone else?
         */
	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
		action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
		res = -EBUSY;
		goto out;
	}

identify_page_state:
	res = -EBUSY;
	/*
         * The first check uses the current page flags which may not have any
         * relevant information. The second check with the saved page flagss is
         * carried out only if the first check can't determine the page status.
         */
	for (ps = error_states;; ps++)
		if ((p->flags & ps->mask) == ps->res)
			break;

	page_flags |= (p->flags & (1UL << PG_dirty));

	if (!ps->mask)
		for (ps = error_states;; ps++)
			if ((page_flags & ps->mask) == ps->res)
				break;
	res = page_action(ps, p, pfn);
out:
	unlock_page(hpage);
	return res;
}

Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi33839.30%1634.78%


Andi Kleen25930.12%510.87%


Fengguang Wu11913.84%919.57%


Wanpeng Li515.93%48.70%


Chen Yucong414.77%36.52%


Xie XiuQi192.21%12.17%


Jin Dongming141.63%24.35%


Kirill A. Shutemov111.28%24.35%


Joe Perches30.35%12.17%


Tony Luck30.35%24.35%


Jens Axboe20.23%12.17%


Total860100.00%46100.00%




EXPORT_SYMBOL_GPL(memory_failure);


#define MEMORY_FAILURE_FIFO_ORDER	4

#define MEMORY_FAILURE_FIFO_SIZE	(1 << MEMORY_FAILURE_FIFO_ORDER)


struct memory_failure_entry {
	
unsigned long pfn;
	
int trapno;
	
int flags;
};


struct memory_failure_cpu {
	DECLARE_KFIFO(fifo, struct memory_failure_entry,
		      MEMORY_FAILURE_FIFO_SIZE);
	
spinlock_t lock;
	
struct work_struct work;
};

static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);

/**
 * memory_failure_queue - Schedule handling memory failure of a page.
 * @pfn: Page Number of the corrupted page
 * @trapno: Trap number reported in the signal to user space.
 * @flags: Flags for memory failure handling
 *
 * This function is called by the low level hardware error handler
 * when it detects hardware memory corruption of a page. It schedules
 * the recovering of error page, including 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)
 *
 * Can run in IRQ context.
 */



void memory_failure_queue(unsigned long pfn, int trapno, int flags)
{
	struct memory_failure_cpu *mf_cpu;
	unsigned long proc_flags;
	struct memory_failure_entry entry = {
		.pfn =		pfn,
		.trapno =	trapno,
		.flags =	flags,
        };

	mf_cpu = &get_cpu_var(memory_failure_cpu);
	spin_lock_irqsave(&mf_cpu->lock, proc_flags);
	if (kfifo_put(&mf_cpu->fifo, entry))
		schedule_work_on(smp_processor_id(), &mf_cpu->work);
	else
		pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
		       pfn);
	spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
	put_cpu_var(memory_failure_cpu);
}

Contributors
PersonTokensPropCommitsCommitProp
Huang Ying10899.08%150.00%


Joe Perches10.92%150.00%


Total109100.00%2100.00%




EXPORT_SYMBOL_GPL(memory_failure_queue);




static void memory_failure_work_func(struct work_struct *work)
{
	struct memory_failure_cpu *mf_cpu;
	struct memory_failure_entry entry = { 0, };
	unsigned long proc_flags;
	int gotten;

	mf_cpu = this_cpu_ptr(&memory_failure_cpu);
	for (;;) {
		spin_lock_irqsave(&mf_cpu->lock, proc_flags);
		gotten = kfifo_get(&mf_cpu->fifo, &entry);
		spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
		if (!gotten)
			break;
		if (entry.flags & MF_SOFT_OFFLINE)
			soft_offline_page(pfn_to_page(entry.pfn), entry.flags);
		else
			memory_failure(entry.pfn, entry.trapno, entry.flags);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Huang Ying9778.86%125.00%


Naveen N. Rao2318.70%125.00%


Christoph Lameter21.63%125.00%


Tony Luck10.81%125.00%


Total123100.00%4100.00%






static int __init memory_failure_init(void)
{
	struct memory_failure_cpu *mf_cpu;
	int cpu;

	for_each_possible_cpu(cpu) {
		mf_cpu = &per_cpu(memory_failure_cpu, cpu);
		spin_lock_init(&mf_cpu->lock);
		INIT_KFIFO(mf_cpu->fifo);
		INIT_WORK(&mf_cpu->work, memory_failure_work_func);
	}

	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Huang Ying61100.00%1100.00%


Total61100.00%1100.00%




core_initcall(memory_failure_init);


#define unpoison_pr_info(fmt, pfn, rs)			\
({                                                      \
        if (__ratelimit(rs))                            \
                pr_info(fmt, pfn);                      \
})

/**
 * 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;
	unsigned int nr_pages;
	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
					DEFAULT_RATELIMIT_BURST);

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

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

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

	if (page_count(page) > 1) {
		unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n",
				 pfn, &unpoison_rs);
		return 0;
	}

	if (page_mapped(page)) {
		unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n",
				 pfn, &unpoison_rs);
		return 0;
	}

	if (page_mapping(page)) {
		unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n",
				 pfn, &unpoison_rs);
		return 0;
	}

	/*
         * unpoison_memory() can encounter thp only when the thp is being
         * worked by memory_failure() and the page lock is not held yet.
         * In such case, we yield to memory_failure() and make unpoison fail.
         */
	if (!PageHuge(page) && PageTransHuge(page)) {
		unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n",
				 pfn, &unpoison_rs);
		return 0;
	}

	nr_pages = 1 << compound_order(page);

	if (!get_hwpoison_page(p)) {
		/*
                 * Since HWPoisoned hugepage should have non-zero refcount,
                 * race between memory failure and unpoison seems to happen.
                 * In such case unpoison fails and memory failure runs
                 * to the end.
                 */
		if (PageHuge(page)) {
			unpoison_pr_info("Unpoison: Memory failure is now running on free hugepage %#lx\n",
					 pfn, &unpoison_rs);
			return 0;
		}
		if (TestClearPageHWPoison(p))
			num_poisoned_pages_dec();
		unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n",
				 pfn, &unpoison_rs);
		return 0;
	}

	lock_page(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.
         */
	if (TestClearPageHWPoison(page)) {
		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
				 pfn, &unpoison_rs);
		num_poisoned_pages_sub(nr_pages);
		freeit = 1;
		if (PageHuge(page))
			clear_page_hwpoison_huge_page(page);
	}
	unlock_page(page);

	put_hwpoison_page(page);
	if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
		put_hwpoison_page(page);

	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi14543.41%850.00%


Fengguang Wu13640.72%16.25%


Wanpeng Li4413.17%531.25%


Chen Yucong82.40%16.25%


Jens Axboe10.30%16.25%


Total334100.00%16100.00%




EXPORT_SYMBOL(unpoison_memory);




static struct page *new_page(struct page *p, unsigned long private, int **x)
{
	int nid = page_to_nid(p);
	if (PageHuge(p))
		return alloc_huge_page_node(page_hstate(compound_head(p)),
						   nid);
	else
		return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen3962.90%250.00%


Naoya Horiguchi2235.48%125.00%


Vlastimil Babka11.61%125.00%


Total62100.00%4100.00%



/*
 * 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;

	/*
         * When the target page is a free hugepage, just remove it
         * from free hugepage list.
         */
	if (!get_hwpoison_page(p)) {
		if (PageHuge(p)) {
			pr_info("%s: %#lx free huge page\n", __func__, pfn);
			ret = 0;
		} else if (is_free_buddy_page(p)) {
			pr_info("%s: %#lx free buddy page\n", __func__, pfn);
			ret = 0;
		} else {
			pr_info("%s: %#lx: unknown zero refcount page type %lx\n",
				__func__, pfn, p->flags);
			ret = -EIO;
		}
	} else {
		/* Not a free page */
		ret = 1;
	}
	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen8773.73%342.86%


Naoya Horiguchi2218.64%342.86%


Borislav Petkov97.63%114.29%


Total118100.00%7100.00%






static int get_any_page(struct page *page, unsigned long pfn, int flags)
{
	int ret = __get_any_page(page, pfn, flags);

	if (ret == 1 && !PageHuge(page) &&
	    !PageLRU(page) && !__PageMovable(page)) {
		/*
                 * Try to free it.
                 */
		put_hwpoison_page(page);
		shake_page(page, 1);

		/*
                 * Did it turn free?
                 */
		ret = __get_any_page(page, pfn, 0);
		if (ret == 1 && !PageLRU(page)) {
			/* Drop page reference which is from __get_any_page() */
			put_hwpoison_page(page);
			pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
				pfn, page->flags);
			return -EIO;
		}
	}
	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi10689.08%240.00%


Wanpeng Li75.88%240.00%


Yisheng Xie65.04%120.00%


Total119100.00%5100.00%






static int soft_offline_huge_page(struct page *page, int flags)
{
	int ret;
	unsigned long pfn = page_to_pfn(page);
	struct page *hpage = compound_head(page);
	LIST_HEAD(pagelist);

	/*
         * This double-check of PageHWPoison is to avoid the race with
         * memory_failure(). See also comment in __soft_offline_page().
         */
	lock_page(hpage);
	if (PageHWPoison(hpage)) {
		unlock_page(hpage);
		put_hwpoison_page(hpage);
		pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
		return -EBUSY;
	}
	unlock_page(hpage);

	ret = isolate_huge_page(hpage, &pagelist);
	/*
         * get_any_page() and isolate_huge_page() takes a refcount each,
         * so need to drop one here.
         */
	put_hwpoison_page(hpage);
	if (!ret) {
		pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
		return -EBUSY;
	}

	ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
				MIGRATE_SYNC, MR_MEMORY_FAILURE);
	if (ret) {
		pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
			pfn, ret, page->flags);
		/*
                 * We know that soft_offline_huge_page() tries to migrate
                 * only one hugepage pointed to by hpage, so we need not
                 * run through the pagelist here.
                 */
		putback_active_hugepage(hpage);
		if (ret > 0)
			ret = -EIO;
	} else {
		/* overcommit hugetlb page will be freed to buddy */
		if (PageHuge(page)) {
			set_page_hwpoison_huge_page(hpage);
			dequeue_hwpoisoned_huge_page(hpage);
			num_poisoned_pages_add(1 << compound_order(hpage));
		} else {
			SetPageHWPoison(page);
			num_poisoned_pages_inc();
		}
	}
	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi16576.04%535.71%


Jianguo Wu198.76%17.14%


Xishi Qiu188.29%17.14%


Wanpeng Li94.15%321.43%


Aneesh Kumar K.V20.92%17.14%


David Rientjes20.92%17.14%


JoonSoo Kim10.46%17.14%


Dean Nelson10.46%17.14%


Total217100.00%14100.00%






static int __soft_offline_page(struct page *page, int flags)
{
	int ret;
	unsigned long pfn = page_to_pfn(page);

	/*
         * Check PageHWPoison again inside page lock because PageHWPoison
         * is set by memory_failure() outside page lock. Note that
         * memory_failure() also double-checks PageHWPoison inside page lock,
         * so there's no race between soft_offline_page() and memory_failure().
         */
	lock_page(page);
	wait_on_page_writeback(page);
	if (PageHWPoison(page)) {
		unlock_page(page);
		put_hwpoison_page(page);
		pr_info("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);
	/*
         * RED-PEN would be better to keep it isolated here, but we
         * would need to fix isolation locking first.
         */
	if (ret == 1) {
		put_hwpoison_page(page);
		pr_info("soft_offline: %#lx: invalidated\n", pfn);
		SetPageHWPoison(page);
		num_poisoned_pages_inc();
		return 0;
	}

	/*
         * Simple invalidation didn't work.
         * Try to migrate to a new page instead. migrate.c
         * handles a large number of cases for us.
         */
	if (PageLRU(page))
		ret = isolate_lru_page(page);
	else
		ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
	/*
         * Drop page reference which is came from get_any_page()
         * successful isolate_lru_page() already took another one.
         */
	put_hwpoison_page(page);
	if (!ret) {
		LIST_HEAD(pagelist);
		/*
                 * After isolated lru page, the PageLRU will be cleared,
                 * so use !__PageMovable instead for LRU page's mapping
                 * cannot have PAGE_MAPPING_MOVABLE.
                 */
		if (!__PageMovable(page))
			inc_node_page_state(page, NR_ISOLATED_ANON +
						page_is_file_cache(page));
		list_add(&page->lru, &pagelist);
		ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
					MIGRATE_SYNC, MR_MEMORY_FAILURE);
		if (ret) {
			if (!list_empty(&pagelist))
				putback_movable_pages(&pagelist);

			pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
				pfn, ret, page->flags);
			if (ret > 0)
				ret = -EIO;
		}
	} else {
		pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
			pfn, ret, page_count(page), page->flags);
	}
	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen13649.64%214.29%


Naoya Horiguchi6724.45%214.29%


Yisheng Xie2810.22%17.14%


MinChan Kim114.01%17.14%


Konstantin Khlebnikov103.65%17.14%


JoonSoo Kim93.28%17.14%


Mel Gorman41.46%321.43%


Andrea Arcangeli41.46%17.14%


Wanpeng Li31.09%17.14%


David Rientjes20.73%17.14%


Total274100.00%14100.00%






static int soft_offline_in_use_page(struct page *page, int flags)
{
	int ret;
	struct page *hpage = compound_head(page);

	if (!PageHuge(page) && PageTransHuge(hpage)) {
		lock_page(hpage);
		if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
			unlock_page(hpage);
			if (!PageAnon(hpage))
				pr_info("soft offline: %#lx: non anonymous thp\n", page_to_pfn(page));
			else
				pr_info("soft offline: %#lx: thp split failed\n", page_to_pfn(page));
			put_hwpoison_page(hpage);
			return -EBUSY;
		}
		unlock_page(hpage);
		get_hwpoison_page(page);
		put_hwpoison_page(hpage);
	}

	if (PageHuge(page))
		ret = soft_offline_huge_page(page, flags);
	else
		ret = __soft_offline_page(page, flags);

	return ret;
}


Contributors
PersonTokensPropCommitsCommitProp
Wanpeng Li8857.89%333.33%


Naoya Horiguchi5536.18%444.44%


Kirill A. Shutemov85.26%111.11%


David Rientjes10.66%111.11%


Total152100.00%9100.00%






static void soft_offline_free_page(struct page *page)
{
	if (PageHuge(page)) {
		struct page *hpage = compound_head(page);

		set_page_hwpoison_huge_page(hpage);
		if (!dequeue_hwpoisoned_huge_page(hpage))
			num_poisoned_pages_add(1 << compound_order(hpage));
	} else {
		if (!TestSetPageHWPoison(page))
			num_poisoned_pages_inc();
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Wanpeng Li3653.73%125.00%


Naoya Horiguchi3146.27%375.00%


Total67100.00%4100.00%



/**
 * 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);

	if (PageHWPoison(page)) {
		pr_info("soft offline: %#lx page already poisoned\n", pfn);
		if (flags & MF_COUNT_INCREASED)
			put_hwpoison_page(page);
		return -EBUSY;
	}

	get_online_mems();
	ret = get_any_page(page, pfn, flags);
	put_online_mems();

	if (ret > 0)
		ret = soft_offline_in_use_page(page, flags);
	else if (ret == 0)
		soft_offline_free_page(page);

	return ret;
}

Contributors
PersonTokensPropCommitsCommitProp
Naoya Horiguchi9996.12%150.00%


Wanpeng Li43.88%150.00%


Total103100.00%2100.00%




Overall Contributors
PersonTokensPropCommitsCommitProp
Andi Kleen233040.47%1711.41%


Naoya Horiguchi157127.28%4026.85%


Fengguang Wu63411.01%149.40%


Huang Ying3375.85%21.34%


Wanpeng Li2454.25%128.05%


Tony Luck1242.15%53.36%


Xie XiuQi881.53%32.01%


Chen Yucong721.25%32.01%


Konstantin Khlebnikov430.75%21.34%


Yisheng Xie340.59%10.67%


Naveen N. Rao230.40%10.67%


Peter Zijlstra200.35%10.67%


Kirill A. Shutemov200.35%32.01%


Jianguo Wu190.33%10.67%


Xishi Qiu190.33%21.34%


Haicheng Li180.31%10.67%


Joe Perches160.28%21.34%


MinChan Kim140.24%10.67%


Jin Dongming140.24%21.34%


Michel Lespinasse130.23%21.34%


Rik Van Riel120.21%10.67%


JoonSoo Kim100.17%21.34%


Chen Gong100.17%10.67%


Borislav Petkov90.16%10.67%


Vlastimil Babka70.12%32.01%


Ingo Molnar60.10%32.01%


Vladimir Davydov50.09%21.34%


David Rientjes50.09%21.34%


Dave Chinner40.07%10.67%


Tejun Heo40.07%21.34%


Andrea Arcangeli40.07%10.67%


Mel Gorman40.07%32.01%


Jens Axboe30.05%10.67%


Paul Gortmaker30.05%10.67%


Hugh Dickins30.05%10.67%


Motohiro Kosaki30.05%10.67%


Davidlohr Bueso A20.03%10.67%


Lucas De Marchi20.03%10.67%


Aneesh Kumar K.V20.03%10.67%


Christoph Lameter20.03%10.67%


Zhi Yong Wu10.02%10.67%


Nicholas Piggin10.02%10.67%


Johannes Weiner10.02%10.67%


Dean Nelson10.02%10.67%


Total5758100.00%149100.00%


Directory: mm



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