From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2B1DFD21E1 for ; Mon, 30 Jul 2018 15:08:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B7E920893 for ; Mon, 30 Jul 2018 15:08:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B7E920893 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727667AbeG3Qnx (ORCPT ); Mon, 30 Jul 2018 12:43:53 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:26850 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726651AbeG3Qnx (ORCPT ); Mon, 30 Jul 2018 12:43:53 -0400 Received: from fsav403.sakura.ne.jp (fsav403.sakura.ne.jp [133.242.250.102]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id w6UF7RWt092649; Tue, 31 Jul 2018 00:07:27 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav403.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav403.sakura.ne.jp); Tue, 31 Jul 2018 00:07:27 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav403.sakura.ne.jp) Received: from [192.168.1.8] (softbank126074194044.bbtec.net [126.74.194.44]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id w6UF7Qbx092642 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 31 Jul 2018 00:07:26 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: INFO: task hung in generic_file_write_iter To: Andrew Morton Cc: Alexander Viro , syzbot , linux-mm@kvack.org, mgorman@techsingularity.net, Michal Hocko , ak@linux.intel.com, jack@suse.cz, jlayton@redhat.com, linux-kernel@vger.kernel.org, mawilcox@microsoft.com, syzkaller-bugs@googlegroups.com, tim.c.chen@linux.intel.com, linux-fsdevel References: <0000000000009ce88d05714242a8@google.com> <4b349bff-8ad4-6410-250d-593b13d8d496@I-love.SAKURA.ne.jp> <9b9fcdda-c347-53ee-fdbb-8a7d11cf430e@I-love.SAKURA.ne.jp> <20180720130602.f3d6dc4c943558875a36cb52@linux-foundation.org> From: Tetsuo Handa Message-ID: Date: Tue, 31 Jul 2018 00:07:22 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180720130602.f3d6dc4c943558875a36cb52@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/07/21 5:06, Andrew Morton wrote: > On Fri, 20 Jul 2018 19:36:23 +0900 Tetsuo Handa wrote: > >>> >>> This report is stalling after mount() completed and process used remap_file_pages(). >>> I think that we might need to use debug printk(). But I don't know what to examine. >>> >> >> Andrew, can you pick up this debug printk() patch? >> I guess we can get the result within one week. > > Sure, let's toss it in -next for a while. > >> >From 8f55e00b21fefffbc6abd9085ac503c52a302464 Mon Sep 17 00:00:00 2001 >> From: Tetsuo Handa >> Date: Fri, 20 Jul 2018 19:29:06 +0900 >> Subject: [PATCH] fs/buffer.c: add debug print for __getblk_gfp() stall problem >> >> Among syzbot's unresolved hung task reports, 18 out of 65 reports contain >> __getblk_gfp() line in the backtrace. Since there is a comment block that >> says that __getblk_gfp() will lock up the machine if try_to_free_buffers() >> attempt from grow_dev_page() is failing, let's start from checking whether >> syzbot is hitting that case. This change will be removed after the bug is >> fixed. > > I'm not sure that grow_dev_page() is hanging. It has often been > suspected, but always is proven innocent. Lets see. syzbot reproduced this problem ( https://syzkaller.appspot.com/text?tag=CrashLog&x=11f2fc44400000 ) . It says that grow_dev_page() is returning 1 but __find_get_block() is failing forever. Any idea?