From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 0A6746B0038 for ; Mon, 15 Jan 2018 08:57:06 -0500 (EST) Received: by mail-io0-f199.google.com with SMTP id v15so11875601iob.22 for ; Mon, 15 Jan 2018 05:57:06 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id d3si38838itg.163.2018.01.15.05.57.04 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 15 Jan 2018 05:57:05 -0800 (PST) Subject: Re: INFO: task hung in filemap_fault From: Tetsuo Handa References: <201801081948.HAE82801.FQOSHtMOFVLFOJ@I-love.SAKURA.ne.jp> <201801151944.FII09821.FMVQFJtHOOOSLF@I-love.SAKURA.ne.jp> In-Reply-To: Message-Id: <201801152256.HDH17623.tSJHFLFOFMVOQO@I-love.SAKURA.ne.jp> Date: Mon, 15 Jan 2018 22:56:42 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: dvyukov@google.com Cc: bot+980f5e5fc060c37505bd65abb49a963518b269d9@syzkaller.appspotmail.com, ak@linux.intel.com, akpm@linux-foundation.org, jack@suse.cz, jlayton@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mgorman@techsingularity.net, mingo@kernel.org, npiggin@gmail.com, rgoldwyn@suse.com, syzkaller-bugs@googlegroups.com, axboe@kernel.dk, tom.leiming@gmail.com, hare@suse.de, osandov@fb.com, shli@fb.com Dmitry Vyukov wrote: > > No problem. In the "tty: User triggerable soft lockup." case, I manually > > trimmed the reproducer at https://marc.info/?l=linux-mm&m=151368630414963 . > > That is, > > > > (1) Can the problem be reproduced even if setup_tun(0, true); is commented out? > > > > (2) Can the problem be reproduced even if NONFAILING(A = B); is replaced with > > plain A = B; assignment? > > > > (3) Can the problem be reproduced even if install_segv_handler(); is commented > > out? > > > > (4) Can the problem be reproduced even if some syscalls (e.g. __NR_memfd_create, > > __NR_getsockopt, __NR_perf_event_open) are replaced with no-op? > > > > and so on. Then, I finally reached a reproducer which I sent, and the bug was fixed. > > > > What is important is that everyone can try simplifying the reproducer written > > in plain C in order to narrow down the culprit. Providing a (e.g.) CGI service > > which generates plain C reproducer like gistfile1.txt will be helpful to me. > > I am not completely following. You previously mentioned raw.log, which > is a collection of multiple programs, but now you seem to be talking > about a single reproducer. When syzbot manages to reproduce the bug > only with syzkaller program but not with a corresponding C program, it > provides only syzkaller program. It such case it can sense to convert. > But the case you pointed to actually contains C program. So there is > no need to do the conversion at all... What am I missing? > raw.log is not readable for me. I want to see C program even if syzbot did not manage to reproduce the bug. If C program is available, everyone can try reproducing the bug with manually trimmed C program. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org