| From 413b43deab8377819aba1dbad2abf0c15d59b491 Mon Sep 17 00:00:00 2001 |
| From: Ravikiran G Thirumalai <kiran@scalex86.org> |
| Date: Tue, 23 Mar 2010 13:35:28 -0700 |
| Subject: tmpfs: fix oops on mounts with mpol=default |
| |
| From: Ravikiran G Thirumalai <kiran@scalex86.org> |
| |
| 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 | 9 +++++++-- |
| 1 file changed, 7 insertions(+), 2 deletions(-) |
| |
| --- a/mm/mempolicy.c |
| +++ b/mm/mempolicy.c |
| @@ -2187,10 +2187,15 @@ int mpol_parse_str(char *str, struct mem |
| goto out; |
| mode = MPOL_PREFERRED; |
| break; |
| - |
| + case MPOL_DEFAULT: |
| + /* |
| + * Insist on a empty nodelist |
| + */ |
| + if (!nodelist) |
| + err = 0; |
| + goto out; |
| /* |
| * case MPOL_BIND: mpol_new() enforces non-empty nodemask. |
| - * case MPOL_DEFAULT: mpol_new() enforces empty nodemask, ignores flags. |
| */ |
| } |
| |
