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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 28F03C433ED for ; Mon, 12 Apr 2021 07:25:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F171961207 for ; Mon, 12 Apr 2021 07:25:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236858AbhDLHZf (ORCPT ); Mon, 12 Apr 2021 03:25:35 -0400 Received: from mxout01.lancloud.ru ([45.84.86.81]:54282 "EHLO mxout01.lancloud.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231274AbhDLHZb (ORCPT ); Mon, 12 Apr 2021 03:25:31 -0400 Received: from LanCloud DKIM-Filter: OpenDKIM Filter v2.11.0 mxout01.lancloud.ru 64D7720CF94C Received: from LanCloud Received: from LanCloud Subject: Re: Mutual debugging of 2 processes can stuck in unkillable stopped state From: Igor Zhbanov To: Oleg Nesterov CC: , References: <20210329164900.GB24849@redhat.com> <4124a89e-a62e-0c51-1f46-8409867a626a@omprussia.ru> <20210329173848.GC24849@redhat.com> Message-ID: Date: Mon, 12 Apr 2021 10:25:06 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: ru-RU Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.11.198] X-ClientProxiedBy: LFEXT02.lancloud.ru (fd00:f066::142) To LFEX15.lancloud.ru (fd00:f066::45) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Oleg, So what is the cause of this problem? Thank you. On 29.03.2021 20:44, Igor Zhbanov wrote: > > Here is the processes stack before sending any signals to them: > > izh@suse2:~> sudo cat /proc/1751/stack > [<0>] ptrace_stop+0x14e/0x260 > [<0>] ptrace_do_notify+0x91/0xb0 > [<0>] ptrace_notify+0x4e/0x70 > [<0>] syscall_slow_exit_work+0x90/0x150 > [<0>] do_syscall_64+0x129/0x1f0 > [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > izh@suse2:~> sudo cat /proc/1979/stack > [<0>] ptrace_stop+0x14e/0x260 > [<0>] get_signal+0x4d5/0x840 > [<0>] do_signal+0x30/0x6a0 > [<0>] exit_to_usermode_loop+0x8b/0x120 > [<0>] do_syscall_64+0x1c3/0x1f0 > [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > >> Igor, thanks for your report, but (I think) this has nothing to do >> with mutual debugging. I'll return to this problem in a couple of >> days, I'm a bit busy right now.