| Date | Tue, 30 Mar 2010 15:55:30 -0700 | From | Greg KH <> | Subject | [052/116] tmpfs: fix oops on mounts with mpol=default |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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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 @@ -2142,10 +2142,15 @@ 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. */ }
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