tmpfs: fix oops on mounts with mpol=default
commitc67cc76d1b8da6a7eb74716255c2f0db20d66d64
authorRavikiran G Thirumalai <kiran@scalex86.org>
Tue, 23 Mar 2010 20:35:28 +0000 (23 13:35 -0700)
committerGreg Kroah-Hartman <gregkh@suse.de>
Thu, 1 Apr 2010 22:58:25 +0000 (1 15:58 -0700)
tree861a52c6dbd460af73416abea79c08014d740613
parent25b6e384dc523fdfff039405defd415c6e067108
tmpfs: fix oops on mounts with mpol=default

commit 413b43deab8377819aba1dbad2abf0c15d59b491 upstream.

Fix an 'oops' when a tmpfs mount point is mounted with the mpol=default
mempolicy.

Upon remounting a tmpfs mount point with 'mpol=default' option, the mount
code crashed with a null pointer dereference.  The initial problem report
was on 2.6.27, but the problem exists in mainline 2.6.34-rc as well.  On
examining the code, we see that mpol_new returns NULL if default mempolicy
was requested.  This 'NULL' mempolicy is accessed to store the node mask
resulting in oops.

The following patch fixes it.

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
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@suse.de>
mm/mempolicy.c