From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: INFO: task hung in wb_shutdown (2) To: Tetsuo Handa , torvalds@linux-foundation.org Cc: jack@suse.cz, tj@kernel.org, syzbot+c0cf869505e03bdf1a24@syzkaller.appspotmail.com, christophe.jaillet@wanadoo.fr, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, zhangweiping@didichuxing.com, akpm@linux-foundation.org, dvyukov@google.com, linux-block@vger.kernel.org References: <94eb2c05b2d83650030568cc8bd9@google.com> <43302799-1c50-4cab-b974-9fe1ca584813@I-love.SAKURA.ne.jp> <201805020714.FDD52145.OOJtOFVFSMLQFH@I-love.SAKURA.ne.jp> From: Jens Axboe Message-ID: <9cafa39a-aa2e-f4f0-02ae-a11e7ddace8d@kernel.dk> Date: Thu, 3 May 2018 09:25:13 -0600 MIME-Version: 1.0 In-Reply-To: <201805020714.FDD52145.OOJtOFVFSMLQFH@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=utf-8 List-ID: On 5/1/18 4:14 PM, Tetsuo Handa wrote: >>>>From 1b90d7f71d60e743c69cdff3ba41edd1f9f86f93 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa > Date: Wed, 2 May 2018 07:07:55 +0900 > Subject: [PATCH v2] bdi: wake up concurrent wb_shutdown() callers. > > syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in > wb_shutdown() [1]. This seems to be because commit 5318ce7d46866e1d ("bdi: > Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call > wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down). > > Introduce a helper function clear_and_wake_up_bit() and use it, in order > to avoid similar errors in future. Queued up, thanks Tetsuo! -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751445AbeECPZU (ORCPT ); Thu, 3 May 2018 11:25:20 -0400 Received: from mail-it0-f66.google.com ([209.85.214.66]:33692 "EHLO mail-it0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbeECPZQ (ORCPT ); Thu, 3 May 2018 11:25:16 -0400 X-Google-Smtp-Source: AB8JxZpQ4Wm5Rvz3uO5cZMXvAPNeV6CyGqpEmFijUH6dIAy89MdeEZfIiUyg3rNtJI8vP+9Dkwm42Q== Subject: Re: INFO: task hung in wb_shutdown (2) To: Tetsuo Handa , torvalds@linux-foundation.org Cc: jack@suse.cz, tj@kernel.org, syzbot+c0cf869505e03bdf1a24@syzkaller.appspotmail.com, christophe.jaillet@wanadoo.fr, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, zhangweiping@didichuxing.com, akpm@linux-foundation.org, dvyukov@google.com, linux-block@vger.kernel.org References: <94eb2c05b2d83650030568cc8bd9@google.com> <43302799-1c50-4cab-b974-9fe1ca584813@I-love.SAKURA.ne.jp> <201805020714.FDD52145.OOJtOFVFSMLQFH@I-love.SAKURA.ne.jp> From: Jens Axboe Message-ID: <9cafa39a-aa2e-f4f0-02ae-a11e7ddace8d@kernel.dk> Date: Thu, 3 May 2018 09:25:13 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <201805020714.FDD52145.OOJtOFVFSMLQFH@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/1/18 4:14 PM, Tetsuo Handa wrote: >>>From 1b90d7f71d60e743c69cdff3ba41edd1f9f86f93 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa > Date: Wed, 2 May 2018 07:07:55 +0900 > Subject: [PATCH v2] bdi: wake up concurrent wb_shutdown() callers. > > syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in > wb_shutdown() [1]. This seems to be because commit 5318ce7d46866e1d ("bdi: > Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call > wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down). > > Introduce a helper function clear_and_wake_up_bit() and use it, in order > to avoid similar errors in future. Queued up, thanks Tetsuo! -- Jens Axboe