* 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
+ * 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 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.
+ * 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.
+ *
+ * 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.
*/
/*
* - 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>
+#include <linux/kernel-page-flags.h>
#include <linux/sched.h>
#include <linux/ksm.h>
#include <linux/rmap.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 "internal.h"
int sysctl_memory_failure_early_kill __read_mostly = 0;
atomic_long_t mce_bad_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;
+}
+
+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;
+}
+
+/*
+ * 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
+
+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;
+}
+#else
+int hwpoison_filter(struct page *p)
+{
+ return 0;
+}
+#endif
+
+EXPORT_SYMBOL_GPL(hwpoison_filter);
+
/*
* 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)
+ unsigned long pfn, struct page *page)
{
struct siginfo si;
int ret;
#ifdef __ARCH_SI_TRAPNO
si.si_trapno = trapno;
#endif
- si.si_addr_lsb = PAGE_SHIFT;
+ si.si_addr_lsb = compound_trans_order(compound_head(page)) + 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?
+ * to SIG_IGN, but hopefully no one will do that?
*/
ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
if (ret < 0)
return ret;
}
+/*
+ * 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();
+ if (PageLRU(p) || is_free_buddy_page(p))
+ return;
+ }
+
+ /*
+ * Only call shrink_slab here (which would also shrink other caches) if
+ * access is not potentially fatal.
+ */
+ if (access) {
+ int nr;
+ do {
+ struct shrink_control shrink = {
+ .gfp_mask = GFP_KERNEL,
+ };
+
+ nr = shrink_slab(&shrink, 1000, 1000);
+ if (page_count(p) == 1)
+ break;
+ } while (nr > 10);
+ }
+}
+EXPORT_SYMBOL_GPL(shake_page);
+
/*
* Kill all processes that have a poisoned page mapped and then isolate
* the page.
struct list_head nd;
struct task_struct *tsk;
unsigned long addr;
- unsigned addr_valid:1;
+ char addr_valid;
};
/*
* 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",
+ pr_info("MCE: Unable to find user space address %lx in %s\n",
page_to_pfn(p), tsk->comm);
tk->addr_valid = 0;
}
* wrong earlier.
*/
static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
- int fail, unsigned long pfn)
+ int fail, struct page *page, unsigned long pfn)
{
struct to_kill *tk, *next;
list_for_each_entry_safe (tk, next, to_kill, nd) {
if (doit) {
/*
- * In case something went wrong with munmaping
+ * In case something went wrong with munmapping
* make sure the process doesn't catch the
* signal and then access the memory. Just kill it.
- * the signal handlers
*/
if (fail || tk->addr_valid == 0) {
printk(KERN_ERR
* process anyways.
*/
else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
- pfn) < 0)
+ pfn, page) < 0)
printk(KERN_ERR
"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
pfn, tk->tsk->comm, tk->tsk->pid);
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;
+ return;
+
+ read_lock(&tasklist_lock);
for_each_process (tsk) {
+ struct anon_vma_chain *vmac;
+
if (!task_early_kill(tsk))
continue;
- list_for_each_entry (vma, &av->head, anon_vma_node) {
+ list_for_each_entry(vmac, &av->head, same_anon_vma) {
+ vma = vmac->vma;
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);
+ page_unlock_anon_vma(av);
}
/*
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.
- */
-
+ mutex_lock(&mapping->i_mmap_mutex);
read_lock(&tasklist_lock);
- spin_lock(&mapping->i_mmap_lock);
for_each_process(tsk) {
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
add_to_kill(tsk, page, vma, to_kill, tkc);
}
}
- spin_unlock(&mapping->i_mmap_lock);
read_unlock(&tasklist_lock);
+ mutex_unlock(&mapping->i_mmap_mutex);
}
/*
*/
enum outcome {
- FAILED, /* Error handling failed */
+ IGNORED, /* Error: cannot be handled */
+ FAILED, /* Error: handling failed */
DELAYED, /* Will be handled later */
- IGNORED, /* Error safely ignored */
RECOVERED, /* Successfully recovered */
};
static const char *action_name[] = {
+ [IGNORED] = "Ignored",
[FAILED] = "Failed",
[DELAYED] = "Delayed",
- [IGNORED] = "Ignored",
[RECOVERED] = "Recovered",
};
/*
- * Error hit kernel page.
- * Do nothing, try to be lucky and not touch this instead. For a few cases we
- * could be more sophisticated.
+ * 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 me_kernel(struct page *p, unsigned long pfn)
+static int delete_from_lru_cache(struct page *p)
{
- return DELAYED;
+ 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;
}
/*
- * Already poisoned page.
+ * 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_ignore(struct page *p, unsigned long pfn)
+static int me_kernel(struct page *p, unsigned long pfn)
{
return IGNORED;
}
return FAILED;
}
-/*
- * Free memory
- */
-static int me_free(struct page *p, unsigned long pfn)
-{
- return DELAYED;
-}
-
/*
* Clean (or cleaned) page cache page.
*/
int ret = FAILED;
struct address_space *mapping;
- if (!isolate_lru_page(p))
- page_cache_release(p);
+ delete_from_lru_cache(p);
/*
* For anonymous pages we're done the only reference left
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);
+ pr_info("MCE %#lx: failed to release buffers\n", pfn);
} else {
ret = RECOVERED;
}
* 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
+ * and the page is dropped between then the error
* will not be properly reported.
*
* This can already happen even without hwpoisoned
*/
static int me_swapcache_dirty(struct page *p, unsigned long pfn)
{
- int ret = FAILED;
-
ClearPageDirty(p);
/* Trigger EIO in shmem: */
ClearPageUptodate(p);
- if (!isolate_lru_page(p)) {
- page_cache_release(p);
- ret = DELAYED;
- }
-
- return ret;
+ if (!delete_from_lru_cache(p))
+ return DELAYED;
+ else
+ return FAILED;
}
static int me_swapcache_clean(struct page *p, unsigned long pfn)
{
- int ret = FAILED;
-
- if (!isolate_lru_page(p)) {
- page_cache_release(p);
- ret = RECOVERED;
- }
delete_from_swap_cache(p);
- return ret;
+
+ if (!delete_from_lru_cache(p))
+ return RECOVERED;
+ else
+ return FAILED;
}
/*
* Huge pages. Needs work.
* Issues:
- * No rmap support so we cannot find the original mapper. In theory could walk
- * all MMs and look for the mappings, but that would be non atomic and racy.
- * Need rmap for hugepages for this. Alternatively we could employ a heuristic,
- * like just walking the current process and hoping it has it mapped (that
- * should be usually true for the common "shared database cache" case)
- * Should handle free huge pages and dequeue them too, but this needs to
- * handle huge page accounting correctly.
+ * - 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)
{
- return FAILED;
+ int res = 0;
+ 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))) {
+ res = dequeue_hwpoisoned_huge_page(hpage);
+ if (!res)
+ return RECOVERED;
+ }
+ return DELAYED;
}
/*
* 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.
+ * 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 tail (1UL << PG_tail)
#define compound (1UL << PG_compound)
#define slab (1UL << PG_slab)
-#define buddy (1UL << PG_buddy)
#define reserved (1UL << PG_reserved)
static struct page_state {
char *msg;
int (*action)(struct page *p, unsigned long pfn);
} error_states[] = {
- { reserved, reserved, "reserved kernel", me_ignore },
- { buddy, buddy, "free kernel", me_free },
+ { reserved, reserved, "reserved 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
{ unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
{ unevict, unevict, "unevictable LRU", me_pagecache_clean},
-#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
{ mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
{ mlock, mlock, "mlocked LRU", me_pagecache_clean },
-#endif
{ lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
{ lru|dirty, lru, "clean LRU", me_pagecache_clean },
- { swapbacked, swapbacked, "anonymous", me_pagecache_clean },
/*
* Catchall entry: must be at end.
{ 0, 0, "unknown page state", me_unknown },
};
+#undef dirty
+#undef sc
+#undef unevict
+#undef mlock
+#undef writeback
#undef lru
+#undef swapbacked
+#undef head
+#undef tail
+#undef compound
+#undef slab
+#undef reserved
static void action_result(unsigned long pfn, char *msg, int result)
{
- struct page *page = NULL;
- if (pfn_valid(pfn))
- page = pfn_to_page(pfn);
+ struct page *page = pfn_to_page(pfn);
printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
pfn,
- page && PageDirty(page) ? "dirty " : "",
+ PageDirty(page) ? "dirty " : "",
msg, action_name[result]);
}
static int page_action(struct page_state *ps, struct page *p,
- unsigned long pfn, int ref)
+ unsigned long pfn)
{
int result;
+ int count;
result = ps->action(p, pfn);
action_result(pfn, ps->msg, result);
- if (page_count(p) != 1 + ref)
+
+ count = page_count(p) - 1;
+ if (ps->action == me_swapcache_dirty && result == DELAYED)
+ count--;
+ if (count != 0) {
printk(KERN_ERR
"MCE %#lx: %s page still referenced by %d users\n",
- pfn, ps->msg, page_count(p) - 1);
+ pfn, ps->msg, count);
+ result = FAILED;
+ }
/* Could do more checks here if page looks ok */
/*
* Could adjust zone counters here to correct for the missing page.
*/
- return result == RECOVERED ? 0 : -EBUSY;
+ return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
}
-#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.
*/
-static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
+static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
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;
+ struct page *hpage = compound_head(p);
+ struct page *ppage;
- if (PageReserved(p) || PageCompound(p) || PageSlab(p) || PageKsm(p))
- return;
-
- if (!PageLRU(p))
- lru_add_drain_all();
+ if (PageReserved(p) || PageSlab(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(p))
- return;
+ if (!page_mapped(hpage))
+ return SWAP_SUCCESS;
+
+ if (PageKsm(p))
+ return SWAP_FAIL;
if (PageSwapCache(p)) {
printk(KERN_ERR
/*
* 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(p);
- if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) {
- if (page_mkclean(p)) {
- SetPageDirty(p);
+ mapping = page_mapping(hpage);
+ if (!PageDirty(hpage) && mapping &&
+ mapping_cap_writeback_dirty(mapping)) {
+ if (page_mkclean(hpage)) {
+ SetPageDirty(hpage);
} else {
kill = 0;
ttu |= TTU_IGNORE_HWPOISON;
}
}
+ /*
+ * ppage: poisoned page
+ * if p is regular page(4k page)
+ * ppage == real poisoned page;
+ * else p is hugetlb or THP, ppage == head page.
+ */
+ ppage = hpage;
+
+ if (PageTransHuge(hpage)) {
+ /*
+ * Verify that this isn't a hugetlbfs head page, the check for
+ * PageAnon is just for avoid tripping a split_huge_page
+ * internal debug check, as split_huge_page refuses to deal with
+ * anything that isn't an anon page. PageAnon can't go away fro
+ * under us because we hold a refcount on the hpage, without a
+ * refcount on the hpage. split_huge_page can't be safely called
+ * in the first place, having a refcount on the tail isn't
+ * enough * to be safe.
+ */
+ if (!PageHuge(hpage) && PageAnon(hpage)) {
+ if (unlikely(split_huge_page(hpage))) {
+ /*
+ * FIXME: if splitting THP is failed, it is
+ * better to stop the following operation rather
+ * than causing panic by unmapping. System might
+ * survive if the page is freed later.
+ */
+ printk(KERN_INFO
+ "MCE %#lx: failed to split THP\n", pfn);
+
+ BUG_ON(!PageHWPoison(p));
+ return SWAP_FAIL;
+ }
+ /* THP is split, so ppage should be the real poisoned page. */
+ ppage = p;
+ }
+ }
+
/*
* First collect all the processes that have the page
* mapped in dirty form. This has to be done before try_to_unmap,
* there's nothing that can be done.
*/
if (kill)
- collect_procs(p, &tokill);
+ collect_procs(ppage, &tokill);
- /*
- * 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++) {
- ret = try_to_unmap(p, ttu);
- if (ret == SWAP_SUCCESS)
- break;
- pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn, ret);
- }
+ if (hpage != ppage)
+ lock_page(ppage);
+ ret = try_to_unmap(ppage, ttu);
if (ret != SWAP_SUCCESS)
printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
- pfn, page_mapcount(p));
+ pfn, page_mapcount(ppage));
+
+ if (hpage != ppage)
+ unlock_page(ppage);
/*
* Now that the dirty bit has been propagated to the
* use a more force-full uncatchable kill to prevent
* any accesses to the poisoned memory.
*/
- kill_procs_ao(&tokill, !!PageDirty(p), trapno,
- ret != SWAP_SUCCESS, pfn);
+ kill_procs_ao(&tokill, !!PageDirty(ppage), trapno,
+ ret != SWAP_SUCCESS, p, pfn);
+
+ return ret;
}
-int __memory_failure(unsigned long pfn, int trapno, int ref)
+static void set_page_hwpoison_huge_page(struct page *hpage)
+{
+ int i;
+ int nr_pages = 1 << compound_trans_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_trans_order(hpage);
+ for (i = 0; i < nr_pages; i++)
+ ClearPageHWPoison(hpage + i);
+}
+
+int __memory_failure(unsigned long pfn, int trapno, int flags)
{
struct page_state *ps;
struct page *p;
+ struct page *hpage;
int res;
+ unsigned int nr_pages;
if (!sysctl_memory_failure_recovery)
panic("Memory failure from trap %d on page %lx", trapno, pfn);
if (!pfn_valid(pfn)) {
- action_result(pfn, "memory outside kernel control", IGNORED);
- return -EIO;
+ printk(KERN_ERR
+ "MCE %#lx: memory outside kernel control\n",
+ pfn);
+ return -ENXIO;
}
p = pfn_to_page(pfn);
+ hpage = compound_head(p);
if (TestSetPageHWPoison(p)) {
- action_result(pfn, "already hardware poisoned", IGNORED);
+ printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn);
return 0;
}
- atomic_long_add(1, &mce_bad_pages);
+ nr_pages = 1 << compound_trans_order(hpage);
+ atomic_long_add(nr_pages, &mce_bad_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 part of a non-compound high order page.
+ * 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 (!get_page_unless_zero(compound_head(p))) {
- action_result(pfn, "free or high order kernel", IGNORED);
- return PageBuddy(compound_head(p)) ? 0 : -EBUSY;
+ if (!(flags & MF_COUNT_INCREASED) &&
+ !get_page_unless_zero(hpage)) {
+ if (is_free_buddy_page(p)) {
+ action_result(pfn, "free buddy", DELAYED);
+ return 0;
+ } else if (PageHuge(hpage)) {
+ /*
+ * Check "just unpoisoned", "filter hit", and
+ * "race with other subpage."
+ */
+ lock_page(hpage);
+ if (!PageHWPoison(hpage)
+ || (hwpoison_filter(p) && TestClearPageHWPoison(p))
+ || (p != hpage && TestSetPageHWPoison(hpage))) {
+ atomic_long_sub(nr_pages, &mce_bad_pages);
+ return 0;
+ }
+ set_page_hwpoison_huge_page(hpage);
+ res = dequeue_hwpoisoned_huge_page(hpage);
+ action_result(pfn, "free huge",
+ res ? IGNORED : DELAYED);
+ unlock_page(hpage);
+ return res;
+ } else {
+ action_result(pfn, "high order kernel", IGNORED);
+ return -EBUSY;
+ }
+ }
+
+ /*
+ * 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.
+ */
+ if (!PageHuge(p) && !PageTransCompound(p)) {
+ if (!PageLRU(p))
+ shake_page(p, 0);
+ if (!PageLRU(p)) {
+ /*
+ * shake_page could have turned it free.
+ */
+ if (is_free_buddy_page(p)) {
+ action_result(pfn, "free buddy, 2nd try",
+ DELAYED);
+ return 0;
+ }
+ action_result(pfn, "non LRU", IGNORED);
+ put_page(p);
+ return -EBUSY;
+ }
}
/*
* It's very difficult to mess with pages currently under IO
* and in many cases impossible, so we just avoid it here.
*/
- lock_page_nosync(p);
+ lock_page(hpage);
+
+ /*
+ * unpoison always clear PG_hwpoison inside page lock
+ */
+ if (!PageHWPoison(p)) {
+ printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
+ res = 0;
+ goto out;
+ }
+ if (hwpoison_filter(p)) {
+ if (TestClearPageHWPoison(p))
+ atomic_long_sub(nr_pages, &mce_bad_pages);
+ unlock_page(hpage);
+ put_page(hpage);
+ return 0;
+ }
+
+ /*
+ * 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, "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);
+
wait_on_page_writeback(p);
/*
* Now take care of user space mappings.
+ * Abort on fail: __delete_from_page_cache() assumes unmapped page.
*/
- hwpoison_user_mappings(p, pfn, trapno);
+ 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;
+ }
/*
* Torn down by someone else?
*/
if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
action_result(pfn, "already truncated LRU", IGNORED);
- res = 0;
+ res = -EBUSY;
goto out;
}
res = -EBUSY;
for (ps = error_states;; ps++) {
if ((p->flags & ps->mask) == ps->res) {
- res = page_action(ps, p, pfn, ref);
+ res = page_action(ps, p, pfn);
break;
}
}
out:
- unlock_page(p);
+ unlock_page(hpage);
return res;
}
EXPORT_SYMBOL_GPL(__memory_failure);
{
__memory_failure(pfn, trapno, 0);
}
+
+#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 0x%#lx\n",
+ pfn);
+ spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
+ put_cpu_var(memory_failure_cpu);
+}
+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 = &__get_cpu_var(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;
+ __memory_failure(entry.pfn, entry.trapno, entry.flags);
+ }
+}
+
+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;
+}
+core_initcall(memory_failure_init);
+
+/**
+ * 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;
+
+ if (!pfn_valid(pfn))
+ return -ENXIO;
+
+ p = pfn_to_page(pfn);
+ page = compound_head(p);
+
+ if (!PageHWPoison(p)) {
+ pr_info("MCE: Page was already unpoisoned %#lx\n", pfn);
+ return 0;
+ }
+
+ nr_pages = 1 << compound_trans_order(page);
+
+ if (!get_page_unless_zero(page)) {
+ /*
+ * 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)) {
+ pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn);
+ return 0;
+ }
+ if (TestClearPageHWPoison(p))
+ atomic_long_sub(nr_pages, &mce_bad_pages);
+ pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
+ 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)) {
+ pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
+ atomic_long_sub(nr_pages, &mce_bad_pages);
+ freeit = 1;
+ if (PageHuge(page))
+ clear_page_hwpoison_huge_page(page);
+ }
+ unlock_page(page);
+
+ put_page(page);
+ if (freeit)
+ put_page(page);
+
+ return 0;
+}
+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_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
+}
+
+/*
+ * 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_memory_hotplug prevents a race with memory hotplug.
+ * This is a big hammer, a better would be nicer.
+ */
+ lock_memory_hotplug();
+
+ /*
+ * Isolate the page, so that it doesn't get reallocated if it
+ * was free.
+ */
+ set_migratetype_isolate(p);
+ /*
+ * When the target page is a free hugepage, just remove it
+ * from free hugepage list.
+ */
+ if (!get_page_unless_zero(compound_head(p))) {
+ if (PageHuge(p)) {
+ pr_info("get_any_page: %#lx free huge page\n", pfn);
+ ret = dequeue_hwpoisoned_huge_page(compound_head(p));
+ } else if (is_free_buddy_page(p)) {
+ pr_info("get_any_page: %#lx free buddy page\n", pfn);
+ /* Set hwpoison bit while page is still isolated */
+ SetPageHWPoison(p);
+ ret = 0;
+ } else {
+ pr_info("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_memory_hotplug();
+ return ret;
+}
+
+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);
+
+ ret = get_any_page(page, pfn, flags);
+ if (ret < 0)
+ return ret;
+ if (ret == 0)
+ goto done;
+
+ if (PageHWPoison(hpage)) {
+ put_page(hpage);
+ pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn);
+ return -EBUSY;
+ }
+
+ /* Keep page count to indicate a given hugepage is isolated. */
+
+ list_add(&hpage->lru, &pagelist);
+ ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0,
+ true);
+ if (ret) {
+ struct page *page1, *page2;
+ list_for_each_entry_safe(page1, page2, &pagelist, lru)
+ put_page(page1);
+
+ pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
+ pfn, ret, page->flags);
+ if (ret > 0)
+ ret = -EIO;
+ return ret;
+ }
+done:
+ if (!PageHWPoison(hpage))
+ atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
+ set_page_hwpoison_huge_page(hpage);
+ dequeue_hwpoisoned_huge_page(hpage);
+ /* keep elevated page count for bad page */
+ 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);
+
+ if (PageHuge(page))
+ return soft_offline_huge_page(page, flags);
+
+ 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_info("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_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_page(page);
+ ret = 0;
+ pr_info("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);
+ /*
+ * Drop page reference which is came from get_any_page()
+ * successful isolate_lru_page() already took another one.
+ */
+ put_page(page);
+ if (!ret) {
+ LIST_HEAD(pagelist);
+ inc_zone_page_state(page, NR_ISOLATED_ANON +
+ page_is_file_cache(page));
+ list_add(&page->lru, &pagelist);
+ ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
+ 0, true);
+ if (ret) {
+ putback_lru_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);
+ }
+ if (ret)
+ return ret;
+
+done:
+ atomic_long_add(1, &mce_bad_pages);
+ SetPageHWPoison(page);
+ /* keep elevated page count for bad page */
+ return ret;
+}
Code Review / linux-2.6.git / blobdiff