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 F0CD4C43387 for ; Sat, 5 Jan 2019 10:50:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4DF4214D8 for ; Sat, 5 Jan 2019 10:50:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726241AbfAEKt7 (ORCPT ); Sat, 5 Jan 2019 05:49:59 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:14802 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726100AbfAEKt7 (ORCPT ); Sat, 5 Jan 2019 05:49:59 -0500 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 x05AnCTf010933; Sat, 5 Jan 2019 19:49:12 +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); Sat, 05 Jan 2019 19:49:12 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav403.sakura.ne.jp) Received: from [192.168.1.8] (softbank126126163036.bbtec.net [126.126.163.36]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x05AnBrY010929 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Sat, 5 Jan 2019 19:49:11 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: INFO: rcu detected stall in ndisc_alloc_skb From: Tetsuo Handa To: Dmitry Vyukov Cc: syzbot , David Miller , Alexey Kuznetsov , LKML , netdev , syzkaller-bugs , Hideaki YOSHIFUJI , Linux-MM References: <0000000000007beca9057e4c8c14@google.com> Message-ID: <8cdbcb63-d2f7-cace-0eda-d73255fd47e7@i-love.sakura.ne.jp> Date: Sat, 5 Jan 2019 19:49:11 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: 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 2019/01/03 2:06, Tetsuo Handa wrote: > On 2018/12/31 17:24, Dmitry Vyukov wrote: >>>> Since this involves OOMs and looks like a one-off induced memory corruption: >>>> >>>> #syz dup: kernel panic: corrupted stack end in wb_workfn >>>> >>> >>> Why? >>> >>> RCU stall in this case is likely to be latency caused by flooding of printk(). >> >> Just a hypothesis. OOMs lead to arbitrary memory corruptions, so can >> cause stalls as well. But can be what you said too. I just thought >> that cleaner dashboard is more useful than a large assorted pile of >> crashes. If you think it's actionable in some way, feel free to undup. >> > > We don't know why bpf tree is hitting this problem. > Let's continue monitoring this problem. > > #syz undup > A report at 2019/01/05 10:08 from "no output from test machine (2)" ( https://syzkaller.appspot.com/text?tag=CrashLog&x=1700726f400000 ) says that there are flood of memory allocation failure messages. Since continuous memory allocation failure messages itself is not recognized as a crash, we might be misunderstanding that this problem is not occurring recently. It will be nice if we can run testcases which are executed on bpf-next tree.