From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f54.google.com (mail-la0-f54.google.com [209.85.215.54]) by kanga.kvack.org (Postfix) with ESMTP id A04BD6B0031 for ; Tue, 8 Jul 2014 17:15:09 -0400 (EDT) Received: by mail-la0-f54.google.com with SMTP id mc6so4448158lab.13 for ; Tue, 08 Jul 2014 14:15:08 -0700 (PDT) Received: from mail-lb0-x233.google.com (mail-lb0-x233.google.com [2a00:1450:4010:c04::233]) by mx.google.com with ESMTPS id n7si23761847lah.78.2014.07.08.14.15.08 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Jul 2014 14:15:08 -0700 (PDT) Received: by mail-lb0-f179.google.com with SMTP id z11so4363623lbi.38 for ; Tue, 08 Jul 2014 14:15:08 -0700 (PDT) Date: Wed, 9 Jul 2014 01:15:06 +0400 From: Cyrill Gorcunov Subject: Re: [PATCH] mm: Don't forget to set softdirty on file mapped fault Message-ID: <20140708211506.GI17860@moon.sw.swsoft.com> References: <20140708192151.GD17860@moon.sw.swsoft.com> <20140708131920.2a857d573e8cc89780c9fa1c@linux-foundation.org> <20140708204017.GG17860@moon.sw.swsoft.com> <20140708134511.4a32b7400a952541a31e9078@linux-foundation.org> <20140708205448.GH17860@moon.sw.swsoft.com> <20140708140501.6c293226bfd87e4dff7ef7fb@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140708140501.6c293226bfd87e4dff7ef7fb@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: LKML , Linux MM , Pavel Emelyanov On Tue, Jul 08, 2014 at 02:05:01PM -0700, Andrew Morton wrote: > > > > In case if page fault happend on dirty filemapping the newly created pte > > may loose softdirty bit thus if a userspace program is tracking memory > > changes with help of a memory tracker (CONFIG_MEM_SOFT_DIRTY) it might > > miss modification of a memory page (which in worts case may lead to > > data inconsistency). > > Much better, thanks. > > It's a rather gross-looking bug and data inconsistency sounds serious. > Do you think a -stable backport is needed? It seems the memory tracker is not that widespread in userspace programs (I mean at the moment as far as I know only we use it intensively) so I don't consider it as critical but moving it into stable won't hurt. Still I fear in 3.16 the mm/memory.c code has been significantly reworked so this patch won't apply on its own. I can prepare a patch for 3.15 though, just say a word. -- 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