From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f197.google.com (mail-ig0-f197.google.com [209.85.213.197]) by kanga.kvack.org (Postfix) with ESMTP id 9F7056B007E for ; Fri, 3 Jun 2016 05:00:32 -0400 (EDT) Received: by mail-ig0-f197.google.com with SMTP id q18so111511528igr.2 for ; Fri, 03 Jun 2016 02:00:32 -0700 (PDT) Received: from mail-io0-x236.google.com (mail-io0-x236.google.com. [2607:f8b0:4001:c06::236]) by mx.google.com with ESMTPS id u124si5702022ioe.106.2016.06.03.02.00.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Jun 2016 02:00:31 -0700 (PDT) Received: by mail-io0-x236.google.com with SMTP id k19so55802833ioi.3 for ; Fri, 03 Jun 2016 02:00:31 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20160603084142.GY2527@techsingularity.net> References: <20160530155644.GP2527@techsingularity.net> <574E05B8.3060009@suse.cz> <20160601091921.GT2527@techsingularity.net> <574EB274.4030408@suse.cz> <20160602103936.GU2527@techsingularity.net> <0eb1f112-65d4-f2e5-911e-697b21324b9f@suse.cz> <20160602121936.GV2527@techsingularity.net> <20160602114341.e3b974640fc3f8cbcb54898b@linux-foundation.org> <20160603084142.GY2527@techsingularity.net> From: Geert Uytterhoeven Date: Fri, 3 Jun 2016 11:00:30 +0200 Message-ID: Subject: Re: BUG: scheduling while atomic: cron/668/0x10c9a0c0 Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Vlastimil Babka , Linux Kernel Mailing List , Linux MM , linux-m68k Hi Mel, On Fri, Jun 3, 2016 at 10:41 AM, Mel Gorman 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 wrote: >> > On Thu, 2 Jun 2016 13:19:36 +0100 Mel Gorman wrote: >> >> > >Signed-off-by: Mel Gorman >> >> > >> >> > Acked-by: Vlastimil Babka >> >> >> >> Thanks. >> > >> > I queued this. A tested-by:Geert would be nice? >> > >> > From: Mel Gorman >> > 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@techsingularity.net >> > 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@linux-m68k.org 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@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org