mm: mempolicy: fix mbind_range() && vma_adjust() interaction
authorOleg Nesterov <oleg@redhat.com>
Wed, 31 Jul 2013 20:53:28 +0000 (13:53 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 31 Jul 2013 21:41:02 +0000 (14:41 -0700)
commit3964acd0dbec123aa0a621973a2a0580034b4788
treeeb5bcfb186354c2ebfa6b0b07c37156b34d21e9e
parent36f571e9ed0419e73d127e18aa8992ced867268c
mm: mempolicy: fix mbind_range() && vma_adjust() interaction

vma_adjust() does vma_set_policy(vma, vma_policy(next)) and this
is doubly wrong:

1. This leaks vma->vm_policy if it is not NULL and not equal to
   next->vm_policy.

   This can happen if vma_merge() expands "area", not prev (case 8).

2. This sets the wrong policy if vma_merge() joins prev and area,
   area is the vma the caller needs to update and it still has the
   old policy.

Revert commit 1444f92c8498 ("mm: merging memory blocks resets
mempolicy") which introduced these problems.

Change mbind_range() to recheck mpol_equal() after vma_merge() to fix
the problem that commit tried to address.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven T Hampson <steven.t.hampson@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mempolicy.c
mm/mmap.c