mm/memory-failure: call shake_page() when error hits thp tail page
authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tue, 5 May 2015 23:23:35 +0000 (16:23 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 6 May 2015 00:10:10 +0000 (17:10 -0700)
commit09789e5de18e4e442870b2d700831f5cb802eb05
treef553ab9f299e17d7391be42f846de00cb5b4bbe1
parent7d616e4ddb9c0754ed6245a43332d5b867e4db11
mm/memory-failure: call shake_page() when error hits thp tail page

Currently memory_failure() calls shake_page() to sweep pages out from
pcplists only when the victim page is 4kB LRU page or thp head page.
But we should do this for a thp tail page too.

Consider that a memory error hits a thp tail page whose head page is on
a pcplist when memory_failure() runs.  Then, the current kernel skips
shake_pages() part, so hwpoison_user_mappings() returns without calling
split_huge_page() nor try_to_unmap() because PageLRU of the thp head is
still cleared due to the skip of shake_page().

As a result, me_huge_page() runs for the thp, which is broken behavior.

One effect is a leak of the thp.  And another is to fail to isolate the
memory error, so later access to the error address causes another MCE,
which kills the processes which used the thp.

This patch fixes this problem by calling shake_page() for thp tail case.

Fixes: 385de35722c9 ("thp: allow a hwpoisoned head page to be put back to LRU")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Dean Nelson <dnelson@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jin Dongming <jin.dongming@np.css.fujitsu.com>
Cc: <stable@vger.kernel.org> [3.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory-failure.c