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=-8.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 4EDDCC433E1 for ; Fri, 17 Jul 2020 12:40:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 28FAD206F4 for ; Fri, 17 Jul 2020 12:40:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="A0MQw1Qv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726442AbgGQMk1 (ORCPT ); Fri, 17 Jul 2020 08:40:27 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:42825 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726090AbgGQMk1 (ORCPT ); Fri, 17 Jul 2020 08:40:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594989625; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Rttk+XtaMzhFwuc22uPWendfKEFz7sRFjPiSryu4BTU=; b=A0MQw1QvLzirihvGhclDrQddQf1TsZqHJsMPvTtwu4jXEYPE1wsDF2ZhaqsVshIzqu47jK 7G2Kq4kBycuhIaPPLo6IaQSytzlc8X0YU8Sc5NuoCGW7MOlpb6K3e+sD3US4Pd4yF+LKBG eyJXjI3k0/hwKvNXbv+0J1mupfwprMU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-218-V3DTRKEAOC6GeQp4geiNLw-1; Fri, 17 Jul 2020 08:40:21 -0400 X-MC-Unique: V3DTRKEAOC6GeQp4geiNLw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F52D19200C0; Fri, 17 Jul 2020 12:40:20 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.194.199]) by smtp.corp.redhat.com (Postfix) with SMTP id 3114B19C58; Fri, 17 Jul 2020 12:40:19 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 17 Jul 2020 14:40:20 +0200 (CEST) Date: Fri, 17 Jul 2020 14:40:18 +0200 From: Oleg Nesterov To: Jiri Slaby Cc: christian@brauner.io, "Eric W. Biederman" , Linux kernel mailing list Subject: Re: 5.8-rc*: kernel BUG at kernel/signal.c:1917 Message-ID: <20200717124017.GB6067@redhat.com> References: <6b253b55-586d-0bc4-9f58-c45c631abc60@kernel.org> <5a8c4c38-7aeb-981a-8d3b-a7a5c8ca5564@kernel.org> <20200717122651.GA6067@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717122651.GA6067@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/17, Oleg Nesterov wrote: > > On 07/17, Jiri Slaby wrote: > > > > On 17. 07. 20, 12:45, Jiri Slaby wrote: > > > Hi, > > > > > > the strace testsuite triggers this on 5.8-rc4 and -rc5 both on x86_64 > > > and i586: > > > > make check needs -jsomething, running is sequentially (-j1) doesn't > > trigger it. After the error, I cannot run anything. Like ps to find out > > what test caused the crash... > > Strange... I'll try to reproduce but I can't do this till Monday. > > Meanwhile, could you try the patch below? It needs CONFIG_DEBUG_ATOMIC_SLEEP. please see the updated patch below, lets check ptrace_unfreeze() too. Oleg. diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 43d6179508d6..71c76bc7dec6 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -180,6 +180,7 @@ static bool ptrace_freeze_traced(struct task_struct *task) spin_lock_irq(&task->sighand->siglock); if (task_is_traced(task) && !__fatal_signal_pending(task)) { + task->task_state_change = _THIS_IP_; task->state = __TASK_TRACED; ret = true; } @@ -203,8 +204,10 @@ static void ptrace_unfreeze_traced(struct task_struct *task) if (task->state == __TASK_TRACED) { if (__fatal_signal_pending(task)) wake_up_state(task, __TASK_TRACED); - else + else { + task->task_state_change = _THIS_IP_; task->state = TASK_TRACED; + } } spin_unlock_irq(&task->sighand->siglock); } diff --git a/kernel/signal.c b/kernel/signal.c index ee22ec78fd6d..ba4c4c9ed9b5 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1914,7 +1914,9 @@ bool do_notify_parent(struct task_struct *tsk, int sig) BUG_ON(sig == -1); /* do_notify_parent_cldstop should have been called instead. */ - BUG_ON(task_is_stopped_or_traced(tsk)); + WARN(task_is_stopped_or_traced(tsk), + "exist with state=%ld set at %pS", + tsk->state, (void*)tsk->task_state_change); BUG_ON(!tsk->ptrace && (tsk->group_leader != tsk || !thread_group_empty(tsk))); @@ -2214,6 +2216,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t preempt_enable_no_resched(); freezable_schedule(); cgroup_leave_frozen(true); + WARN_ON(current->state); } else { /* * By the time we got the lock, our tracer went away. @@ -2393,6 +2396,7 @@ static bool do_signal_stop(int signr) /* Now we don't run again until woken by SIGCONT or SIGKILL */ cgroup_enter_frozen(); freezable_schedule(); + WARN_ON(current->state); return true; } else { /*