Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752760AbdCBM10 (ORCPT ); Thu, 2 Mar 2017 07:27:26 -0500 Received: from mx2.suse.de ([195.135.220.15]:40024 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751617AbdCBMZz (ORCPT ); Thu, 2 Mar 2017 07:25:55 -0500 Date: Thu, 2 Mar 2017 11:35:20 +0100 From: Michal Hocko To: Tetsuo Handa Cc: Xiong Zhou , Christoph Hellwig , linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: mm allocation failure and hang when running xfstests generic/269 on xfs Message-ID: <20170302103520.GC1404@dhcp22.suse.cz> References: <20170301044634.rgidgdqqiiwsmfpj@XZHOUW.usersys.redhat.com> <20170302003731.GB24593@infradead.org> <20170302051900.ct3xbesn2ku7ezll@XZHOUW.usersys.redhat.com> <42eb5d53-5ceb-a9ce-791a-9469af30810c@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42eb5d53-5ceb-a9ce-791a-9469af30810c@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1759 Lines: 51 On Thu 02-03-17 19:04:48, Tetsuo Handa wrote: [...] > So, commit 5d17a73a2ebeb8d1("vmalloc: back off when the current task is > killed") implemented __GFP_KILLABLE flag and automatically applied that > flag. As a result, those who are not ready to fail upon SIGKILL are > confused. ;-) You are right! The function is documented it might fail but the code doesn't really allow that. This seems like a bug to me. What do you think about the following? --- >From d02cb0285d8ce3344fd64dc7e2912e9a04bef80d Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Thu, 2 Mar 2017 11:31:11 +0100 Subject: [PATCH] xfs: allow kmem_zalloc_greedy to fail Even though kmem_zalloc_greedy is documented it might fail the current code doesn't really implement this properly and loops on the smallest allowed size for ever. This is a problem because vzalloc might fail permanently. Since 5d17a73a2ebe ("vmalloc: back off when the current task is killed") such a failure is much more probable than it used to be. Fix this by bailing out if the minimum size request failed. This has been noticed by a hung generic/269 xfstest by Xiong Zhou. Reported-by: Xiong Zhou Analyzed-by: Tetsuo Handa Signed-off-by: Michal Hocko --- fs/xfs/kmem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c index 339c696bbc01..ee95f5c6db45 100644 --- a/fs/xfs/kmem.c +++ b/fs/xfs/kmem.c @@ -34,6 +34,8 @@ kmem_zalloc_greedy(size_t *size, size_t minsize, size_t maxsize) size_t kmsize = maxsize; while (!(ptr = vzalloc(kmsize))) { + if (kmsize == minsize) + break; if ((kmsize >>= 1) <= minsize) kmsize = minsize; } -- 2.11.0 -- Michal Hocko SUSE Labs