From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f200.google.com (mail-ot0-f200.google.com [74.125.82.200]) by kanga.kvack.org (Postfix) with ESMTP id 7E9CE6B0005 for ; Fri, 2 Mar 2018 20:08:29 -0500 (EST) Received: by mail-ot0-f200.google.com with SMTP id u46so6203746otg.16 for ; Fri, 02 Mar 2018 17:08:29 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 205sor2888641oib.181.2018.03.02.17.08.28 for (Google Transport Security); Fri, 02 Mar 2018 17:08:28 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20180302164052.5eea1b896e3a7125d1e1f23a@linux-foundation.org> References: <1519908465-12328-1-git-send-email-neelx@redhat.com> <0485727b2e82da7efbce5f6ba42524b429d0391a.1520011945.git.neelx@redhat.com> <20180302164052.5eea1b896e3a7125d1e1f23a@linux-foundation.org> From: Daniel Vacek Date: Sat, 3 Mar 2018 02:08:27 +0100 Message-ID: Subject: Re: [PATCH v3 2/2] mm/page_alloc: fix memmap_init_zone pageblock alignment Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Vlastimil Babka , Mel Gorman , Pavel Tatashin , Paul Burton , stable@vger.kernel.org On Sat, Mar 3, 2018 at 1:40 AM, Andrew Morton wrote: > On Sat, 3 Mar 2018 01:12:26 +0100 Daniel Vacek wrote: > >> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns >> where possible") introduced a bug where move_freepages() triggers a >> VM_BUG_ON() on uninitialized page structure due to pageblock alignment. > > b92df1de5d28 was merged a year ago. Can you suggest why this hasn't > been reported before now? Yeah. I was surprised myself I couldn't find a fix to backport to RHEL. But actually customers started to report this as soon as 7.4 (where b92df1de5d28 was merged in RHEL) was released. I remember reports from September/October-ish times. It's not easily reproduced and happens on a handful of machines only. I guess that's why. But that does not make it less serious, I think. Though there actually is a report here: https://bugzilla.kernel.org/show_bug.cgi?id=196443 And there are reports for Fedora from July: https://bugzilla.redhat.com/show_bug.cgi?id=1473242 and CentOS: https://bugs.centos.org/view.php?id=13964 and we internally track several dozens reports for RHEL bug https://bugzilla.redhat.com/show_bug.cgi?id=1525121 Enough? ;-) > This makes me wonder whether a -stable backport is really needed... For some machines it definitely is. Won't hurt either, IMHO. --nX -- 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