mm/memory-failure.c: fix memory leak by race between poison and unpoison
authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Thu, 22 May 2014 18:54:21 +0000 (11:54 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 23 May 2014 16:37:30 +0000 (09:37 -0700)
commit3e030ecc0fc7de10fd0da10c1c19939872a31717
tree031646bc5b484c0c90ebb88803d9eeda6ec77691
parentad0f614e4723db8cead439cf414108cbf975b224
mm/memory-failure.c: fix memory leak by race between poison and unpoison

When a memory error happens on an in-use page or (free and in-use)
hugepage, the victim page is isolated with its refcount set to one.

When you try to unpoison it later, unpoison_memory() calls put_page()
for it twice in order to bring the page back to free page pool (buddy or
free hugepage list).  However, if another memory error occurs on the
page which we are unpoisoning, memory_failure() returns without
releasing the refcount which was incremented in the same call at first,
which results in memory leak and unconsistent num_poisoned_pages
statistics.  This patch fixes it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@vger.kernel.org> [2.6.32+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory-failure.c