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mm: soft-offline: close the race against page allocation

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A process can be killed with SIGBUS(BUS_MCEERR_AR) when it tries to
allocate a page that was just freed on the way of soft-offline.  This is
undesirable because soft-offline (which is about corrected error) is
less aggressive than hard-offline (which is about uncorrected error),
and we can make soft-offline fail and keep using the page for good
reason like "system is busy."

Two main changes of this patch are:

- setting migrate type of the target page to MIGRATE_ISOLATE. As done
  in free_unref_page_commit(), this makes kernel bypass pcplist when
  freeing the page. So we can assume that the page is in freelist just
  after put_page() returns,

- setting PG_hwpoison on free page under zone->lock which protects
  freelists, so this allows us to avoid setting PG_hwpoison on a page
  that is decided to be allocated soon.

[akpm@linux-foundation.org: tweak set_hwpoison_free_buddy_page() comment]
Link: http://lkml.kernel.org/r/1531452366-11661-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com>
Tested-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <zy.zhengyi@alibaba-inc.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naoya Horiguchi
2018-08-23 17:00:42 -07:00
committed by Linus Torvalds
parent 6bc9b56433
commit d4ae9916ea
5 changed files with 57 additions and 16 deletions
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30
mm/page_alloc.c
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@@ -8096,3 +8096,33 @@ bool is_free_buddy_page(struct page *page)
return order < MAX_ORDER;
}
#ifdef CONFIG_MEMORY_FAILURE
/*
* Set PG_hwpoison flag if a given page is confirmed to be a free page. This
* test is performed under the zone lock to prevent a race against page
* allocation.
*/
bool set_hwpoison_free_buddy_page(struct page *page)
{
struct zone *zone = page_zone(page);
unsigned long pfn = page_to_pfn(page);
unsigned long flags;
unsigned int order;
bool hwpoisoned = false;
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
struct page *page_head = page - (pfn & ((1 << order) - 1));
if (PageBuddy(page_head) && page_order(page_head) >= order) {
if (!TestSetPageHWPoison(page))
hwpoisoned = true;
break;
}
}
spin_unlock_irqrestore(&zone->lock, flags);
return hwpoisoned;
}
#endif