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)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 11 Jun 2014 18:54:08 +0000 (11:54 -0700)
commit362225376da72c45248fb879178100a4aeda78f5
treed44abfa9ad0f7c97390b2b552c6aff4156ac4f2c
parentf3a9846d7ae15244093f490f19ecb2f932494bc7
mm/memory-failure.c: fix memory leak by race between poison and unpoison

commit 3e030ecc0fc7de10fd0da10c1c19939872a31717 upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm/memory-failure.c