On Tue, 2010-03-16 at 14:49 +0900, KOSAKI Motohiro wrote: > ChangeLog from Ravikiran's original one > - Fix the patch description. the problem is in mount, not only remount. > - Skip mpol_new() simply, instead adding NULL check. > > > ========================= > From: Ravikiran G Thirumalai <kiran@xxxxxxxxxxxx> > > 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@xxxxxxxxxxxx> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> > Cc: Mel Gorman <mel@xxxxxxxxx> > Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx> > Cc: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxx> Acked-by: Lee Schermerhorn <lee.schermerhorn@xxxxxx> > --- > mm/mempolicy.c | 9 +++++++-- > 1 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index bda230e..25a0c0f 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -2213,10 +2213,15 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context) > 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. > */ > } > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>