On Fri, Jun 03, 2016 at 09:57:22AM +0200, Geert Uytterhoeven wrote: > Hi Andrew, Mel, > > On Thu, Jun 2, 2016 at 8:43 PM, Andrew Morton <[email protected]> > wrote: > > On Thu, 2 Jun 2016 13:19:36 +0100 Mel Gorman <[email protected]> > > wrote: > >> > >Signed-off-by: Mel Gorman <[email protected]> > >> > > >> > Acked-by: Vlastimil Babka <[email protected]> > >> > > >> > >> Thanks. > > > > I queued this. A tested-by:Geert would be nice? > > > > > > From: Mel Gorman <[email protected]> > > Subject: mm, page_alloc: recalculate the preferred zoneref if the context > > can ignore memory policies > > > > The optimistic fast path may use cpuset_current_mems_allowed instead of of > > a NULL nodemask supplied by the caller for cpuset allocations. The > > preferred zone is calculated on this basis for statistic purposes and as a > > starting point in the zonelist iterator. > > > > However, if the context can ignore memory policies due to being atomic or > > being able to ignore watermarks then the starting point in the zonelist > > iterator is no longer correct. This patch resets the zonelist iterator in > > the allocator slowpath if the context can ignore memory policies. This > > will alter the zone used for statistics but only after it is known that it > > makes sense for that context. Resetting it before entering the slowpath > > would potentially allow an ALLOC_CPUSET allocation to be accounted for > > against the wrong zone. Note that while nodemask is not explicitly set to > > the original nodemask, it would only have been overwritten if > > cpuset_enabled() and it was reset before the slowpath was entered. > > > > Link: http://lkml.kernel.org/r/[email protected] > > Fixes: c33d6c06f60f710 ("mm, page_alloc: avoid looking up the first zone in > > a zonelist twice") > > My understanding was that this was an an additional patch, not fixing > the problem in-se? >
It doesn't fix the problem you had, it is a follow-on patch that potentially affects. > Indeed, after applying this patch (without the other one that added > "z = ac->preferred_zoneref;" to the reset_fair block of > get_page_from_freelist()) I still get crashes... > The patch you have is the only one required for the crash. This patch handles a corner case with atomic allocations that can ignore memory policies. > Now testing with both applied... Thanks. -- Mel Gorman SUSE Labs
