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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 7911EC43460 for ; Thu, 22 Apr 2021 16:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 486F661406 for ; Thu, 22 Apr 2021 16:13:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237961AbhDVQOA (ORCPT ); Thu, 22 Apr 2021 12:14:00 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:55415 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236637AbhDVQN4 (ORCPT ); Thu, 22 Apr 2021 12:13:56 -0400 Received: from fsav103.sakura.ne.jp (fsav103.sakura.ne.jp [27.133.134.230]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 13MGD7e3035656; Fri, 23 Apr 2021 01:13:07 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav103.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav103.sakura.ne.jp); Fri, 23 Apr 2021 01:13:07 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav103.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 13MGD7ND035619 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Fri, 23 Apr 2021 01:13:07 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [syzbot] unexpected kernel reboot (4) To: Dmitry Vyukov Cc: Andrey Konovalov , syzbot , LKML , syzkaller-bugs , "open list:HID CORE LAYER" , syzkaller References: <000000000000301a4d05bfe14b8f@google.com> From: Tetsuo Handa Message-ID: Date: Fri, 23 Apr 2021 01:13:03 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/04/22 23:20, Dmitry Vyukov wrote: > I've prepared this syzkaller change: > https://github.com/google/syzkaller/pull/2550/files OK. Please merge and let's see whether syzkaller can find different ways. In my environment, this problem behaves very puzzling. While the reproducer I use is single threaded, changing timing via CONFIG_DEBUG_KOBJECT=y or even https://syzkaller.appspot.com/x/patch.diff?x=13d69ffed00000 avoids this problem. I can't narrow down what is happening. > > Re hibernation/suspend configs, you said disabling them is not > helping, right? Does it still make sense to disable them? > If these configs are enabled, we can at least find some bugs in the > preparation for suspend code. However, as you noted, it will > immediately lead to "lost connection". > Ideally we somehow tweak hibernation/suspend to get to the > hibernation/suspend point and then immediately and automatically > resume. That will be one of disable-specific-functionality changes. > This way we could test both suspend and unsuspend code, which > I assume can lead to bugs, and don't cause "lost connection" at the > same time. I guess such a mode does not exist today... and I am not > sure what happens with TCP connections after this. I don't know whether ssh sessions can survive 10 seconds of hibernation/suspend. But maybe disabling hibernation/suspend configs until disable-specific-functionality changes are accepted makes sense.