From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756635AbdKGImm (ORCPT ); Tue, 7 Nov 2017 03:42:42 -0500 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:44642 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754969AbdKGIml (ORCPT ); Tue, 7 Nov 2017 03:42:41 -0500 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.184 X-Original-MAILFROM: byungchul.park@lge.com Subject: Re: possible deadlock in generic_file_write_iter To: Dmitry Vyukov Cc: Peter Zijlstra , Al Viro , Jan Kara , syzbot , Andrew Morton , Johannes Weiner , jlayton@redhat.com, LKML , linux-mm@kvack.org, npiggin@gmail.com, rgoldwyn@suse.com, ross.zwisler@linux.intel.com, syzkaller-bugs@googlegroups.com, Ingo Molnar , kernel-team@lge.com References: <94eb2c05f6a018dc21055d39c05b@google.com> <20171106032941.GR21978@ZenIV.linux.org.uk> <20171106131544.GB4359@quack2.suse.cz> <20171106133304.GS21978@ZenIV.linux.org.uk> <20171106160107.GA20227@worktop.programming.kicks-ass.net> <20171107005442.GA1405@X58A-UD3R> <20171107081143.GD3326@worktop> <8352ad42-8437-4e25-29f4-c3b93c6eed18@lge.com> From: Byungchul Park Message-ID: <9cac5a72-e3ff-1b59-4903-a98167728a7a@lge.com> Date: Tue, 7 Nov 2017 17:42:36 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: ko Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 11/7/2017 5:31 PM에 Dmitry Vyukov 이(가) 쓴 글: > On Tue, Nov 7, 2017 at 9:30 AM, Byungchul Park wrote: >> 11/7/2017 5:11 PM에 Peter Zijlstra 이(가) 쓴 글: >> >>> On Tue, Nov 07, 2017 at 09:54:42AM +0900, Byungchul Park wrote: >>>>> >>>>> The best I could come up with is something like the below; its not >>>>> at all pretty and I could see people objecting; least of all myself for >>>>> the __complete() thing, but I ran out of creative naming juice. >>>> >>>> >>>> Patches assigning a lock_class per gendisk were already applied in tip. >>>> I believe that solves this. >>>> >>>> e319e1fbd9d42420ab6eec0bfd75eb9ad7ca63b1 >>>> block, locking/lockdep: Assign a lock_class per gendisk used for >>>> wait_for_completion() >>>> >>>> I think the following proposal makes kernel too hacky. >>> >>> >>> Ah, I tough this was with those included... >> >> >> Please CC me for issues wrt. crossrelease. > > Hi Byungchul, > > Whom are you asking? And what is crossrelease? Hi Dmitry, Actually, I asked Peter since he know I am the author of crossrelease which is a feature enhancing lockdep detection. That makes deadlocks caused by wait_for_completion() or lock_page() detectable. The feature was merged and disabled by default for now in vanilla because of its performance regression, though that was fixed and enabled in tip latest. -- Thanks, Byungchul