From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id 38E3C6B7242 for ; Wed, 5 Sep 2018 04:55:49 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id h10-v6so2315289eda.9 for ; Wed, 05 Sep 2018 01:55:49 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h25-v6si1447104edr.245.2018.09.05.01.55.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Sep 2018 01:55:47 -0700 (PDT) Date: Wed, 5 Sep 2018 10:55:45 +0200 From: Jan Kara Subject: Re: linux-next test error Message-ID: <20180905085545.GD24902@quack2.suse.cz> References: <0000000000004f6b5805751a8189@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000004f6b5805751a8189@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: syzbot Cc: ak@linux.intel.com, akpm@linux-foundation.org, jack@suse.cz, jrdr.linux@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mawilcox@microsoft.com, mgorman@techsingularity.net, syzkaller-bugs@googlegroups.com, tim.c.chen@linux.intel.com, zwisler@kernel.org On Wed 05-09-18 00:13:02, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 387ac6229ecf Add linux-next specific files for 20180905 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=149c67a6400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=ad5163873ecfbc32 > dashboard link: https://syzkaller.appspot.com/bug?extid=87a05ae4accd500f5242 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+87a05ae4accd500f5242@syzkaller.appspotmail.com > > INFO: task hung in do_page_mkwriteINFO: task syz-fuzzer:4876 blocked for > more than 140 seconds. > Not tainted 4.19.0-rc2-next-20180905+ #56 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > syz-fuzzer D21704 4876 4871 0x00000000 > Call Trace: > context_switch kernel/sched/core.c:2825 [inline] > __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 > schedule+0xfb/0x450 kernel/sched/core.c:3517 > io_schedule+0x1c/0x70 kernel/sched/core.c:5140 > wait_on_page_bit_common mm/filemap.c:1100 [inline] > __lock_page+0x5b7/0x7a0 mm/filemap.c:1273 > lock_page include/linux/pagemap.h:483 [inline] > do_page_mkwrite+0x429/0x520 mm/memory.c:2391 Waiting for page lock after ->page_mkwrite callback. Which means ->page_mkwrite did not return VM_FAULT_LOCKED but 0. Looking into linux-next... indeed "fs: convert return type int to vm_fault_t" has busted block_page_mkwrite(). It has to return VM_FAULT_LOCKED and not 0 now. Souptick, can I ask you to run 'fstests' for at least common filesystems like ext4, xfs, btrfs when you change generic filesystem code please? That would catch a bug like this immediately. Thanks. Honza -- Jan Kara SUSE Labs, CR