Messages in this thread | | | Date | Wed, 18 Jan 2017 10:31:31 +0100 | From | Michal Hocko <> | Subject | Re: [RFC 1/4] mm, page_alloc: fix check for NULL preferred_zone |
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On Tue 17-01-17 23:16:07, Vlastimil Babka wrote: > Since commit c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in > a zonelist twice") we have a wrong check for NULL preferred_zone, which can > theoretically happen due to concurrent cpuset modification. We check the > zoneref pointer which is never NULL and we should check the zone pointer. > > Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice") > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 34ada718ef47..593a11d8bc6b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3763,7 +3763,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > */ > ac.preferred_zoneref = first_zones_zonelist(ac.zonelist, > ac.high_zoneidx, ac.nodemask); > - if (!ac.preferred_zoneref) { > + if (!ac.preferred_zoneref->zone) {
When can the ->zone be NULL?
> page = NULL; > goto no_zone; > } > -- > 2.11.0
-- Michal Hocko SUSE Labs
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