Hi Mel, On Fri, Jun 3, 2016 at 10:41 AM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, Jun 03, 2016 at 09:57:22AM +0200, Geert Uytterhoeven wrote: >> On Thu, Jun 2, 2016 at 8:43 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: >> > On Thu, 2 Jun 2016 13:19:36 +0100 Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: >> >> > >Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> >> >> > >> >> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> >> >> >> >> Thanks. >> > >> > I queued this. A tested-by:Geert would be nice? >> > >> > From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> >> > 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/20160602103936.GU2527@xxxxxxxxxxxxxxxxxxx >> > 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. Thanks for confirming! >> 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. OK. In the mean time my tests completed successfully with both patches applied. Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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>