From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bk0-f47.google.com (mail-bk0-f47.google.com [209.85.214.47]) by kanga.kvack.org (Postfix) with ESMTP id DAC976B0035 for ; Thu, 23 Jan 2014 01:27:50 -0500 (EST) Received: by mail-bk0-f47.google.com with SMTP id d7so201118bkh.20 for ; Wed, 22 Jan 2014 22:27:50 -0800 (PST) Received: from mail-la0-x231.google.com (mail-la0-x231.google.com [2a00:1450:4010:c03::231]) by mx.google.com with ESMTPS id pj2si8993098bkb.195.2014.01.22.22.27.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 22 Jan 2014 22:27:50 -0800 (PST) Received: by mail-la0-f49.google.com with SMTP id y1so1096555lam.22 for ; Wed, 22 Jan 2014 22:27:49 -0800 (PST) Date: Thu, 23 Jan 2014 10:27:46 +0400 From: Cyrill Gorcunov Subject: Re: [Bug 67651] Bisected: Lots of fragmented mmaps cause gimp to fail in 3.12 after exceeding vm_max_map_count Message-ID: <20140123062746.GT1574@moon> References: <20140122190816.GB4963@suse.de> <52E04A21.3050101@mit.edu> <20140123055906.GS1574@moon> <20140122220910.198121ee.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140122220910.198121ee.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Andy Lutomirski , Mel Gorman , Pavel Emelyanov , gnome@rvzt.net, drawoc@darkrefraction.com, alan@lxorguk.ukuu.org.uk, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org On Wed, Jan 22, 2014 at 10:09:10PM -0800, Andrew Morton wrote: > > > > > > That being said, this could cause vma blowups for programs that are > > > actually using this thing. > > > > Hi Andy, indeed, this could happen. The easiest way is to ignore softdirty bit > > when we're trying to merge vmas and set it one new merged. I think this should > > be correct. Once I finish I'll send the patch. > > Hang on. We think the problem is that gimp is generating vmas which > *should* be merged, but for unknown reasons they differ in > VM_SOFTDIRTY, yes? Yes. One place where I forgot to set softdirty bit is setup_arg_pages. But it called once on elf load, so it can't cause such effect (but should be fixed too). Also there is do_brk where vmasoftdirty is missed too :/ Another problem is the potential scenario when we have a bunch of vmas and clear vma-softdirty bit on them, then we try to map new one, flags won't match and instead of extending old vma the new one will be created. I think (if only I'm not missing something) that vma-softdirty should be ignored in such case (ie inside is_mergeable_vma) and once vma extended it should be marked as dirty one. Again, I need to think and test more. > Shouldn't we work out where we're forgetting to set VM_SOFTDIRTY? > Putting bandaids over this error when we come to trying to merge the > vmas sounds very wrong? I'm looking into this as well. Cyrill -- 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