On Wed, Dec 10, 2014 at 09:38:42PM +0800, Weijie Yang wrote: > On Tue, Dec 9, 2014 at 5:59 PM, Mel Gorman <mgorman@xxxxxxx> wrote: > > On Tue, Dec 09, 2014 at 03:40:35PM +0800, Weijie Yang wrote: > >> If the free page and its buddy has different zone id, the current > >> zone->lock cann't prevent buddy page getting allocated, this could > >> trigger VM_BUG_ON_PAGE in a very tiny chance: > >> > > > > Under what circumstances can a buddy page be allocated without the > > zone->lock? Any parallel allocation from that zone that takes place will > > be from the per-cpu allocator and should not be affected by this. Have > > you actually hit this race? > > My description maybe not clear, if the free page and its buddy is not > at the same zone, the holding zone->lock cann't prevent buddy page > getting allocated. You're right, the description is not clear but now I see your point. Thanks. Acked-by: Mel Gorman <mgorman@xxxxxxx> -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>