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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14ACEC433EF for ; Thu, 28 Apr 2022 18:53:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236767AbiD1S4k (ORCPT ); Thu, 28 Apr 2022 14:56:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234374AbiD1S4h (ORCPT ); Thu, 28 Apr 2022 14:56:37 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 24225B53F8 for ; Thu, 28 Apr 2022 11:53:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651172000; 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=rSgLveFDCQt97fdY0v/KXXdMC87h+iGQQ3KjG9Dmh38=; b=GsiFS9lxDa7nP2CQfk5FxrBp061Bu0lowO7Y4vXiqkNf7nIdKruCjo5XGhwngvXj1OvBM8 QLSlsDgJOVbe2y/8y5eywfBd6sEcJs4dF93lmumxrEQGVZnrNjEbD0Ya1VWew9UvAcB+Ql i1FyIYmhnqT2iv/YqQ4y/UAHxUOYC40= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-39-_yFZ8gkLNFqQdtiQkAf15A-1; Thu, 28 Apr 2022 14:53:18 -0400 X-MC-Unique: _yFZ8gkLNFqQdtiQkAf15A-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C9D633C0CD50; Thu, 28 Apr 2022 18:53:17 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.151]) by smtp.corp.redhat.com (Postfix) with SMTP id DAEE314A5060; Thu, 28 Apr 2022 18:53:12 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 28 Apr 2022 20:53:17 +0200 (CEST) Date: Thu, 28 Apr 2022 20:53:11 +0200 From: Oleg Nesterov To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn Subject: Re: [PATCH 9/9] ptrace: Don't change __state Message-ID: <20220428185311.GF15485@redhat.com> References: <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org> <20220426225211.308418-9-ebiederm@xmission.com> <87czh2160k.fsf@email.froward.int.ebiederm.org> <20220428151110.GB15485@redhat.com> <875ymtywxg.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <875ymtywxg.fsf@email.froward.int.ebiederm.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/28, Eric W. Biederman wrote: > > Oleg Nesterov writes: > > >> The bug appears when the TRACEE makes it to schedule(). Inside > >> schedule there is a call to signal_pending_state() which notices > >> a SIGKILL is pending and refuses to sleep. > > > > And I think this is fine. This doesn't really differ from the case > > when the tracee was killed before it takes siglock. > > Hmm. Maybe. I hope ;) > Previously we were actually guaranteed in ptrace_check_attach that after > ptrace_freeze_traced would succeed as any pending fatal signal would > cause ptrace_freeze_traced to fail. Any incoming fatal signal would not > stop schedule from sleeping. Yes. So let me repeat, 7/9 "ptrace: Simplify the wait_task_inactive call in ptrace_check_attach" looks good to me (except it should use wait_task_inactive(__TASK_TRACED)), but it should come before other meaningfull changes and the changelog should be updated. And then we will probably need to reconsider this wait_task_inactive() and WARN_ON() around it, but depends on what will we finally do. > I think in my tired mind yesterday I got lost too ;) > Still I would like to be able to > let wait_task_inactive not care about the state of the process it is > going to sleep for. Not sure... but to be honest I didn't really pay attention to the wait_task_inactive(match_state => 0) part... Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nk9GY-008ETN-P8 for linux-um@lists.infradead.org; Thu, 28 Apr 2022 18:53:28 +0000 Date: Thu, 28 Apr 2022 20:53:11 +0200 From: Oleg Nesterov Subject: Re: [PATCH 9/9] ptrace: Don't change __state Message-ID: <20220428185311.GF15485@redhat.com> References: <878rrrh32q.fsf_-_@email.froward.int.ebiederm.org> <20220426225211.308418-9-ebiederm@xmission.com> <87czh2160k.fsf@email.froward.int.ebiederm.org> <20220428151110.GB15485@redhat.com> <875ymtywxg.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <875ymtywxg.fsf@email.froward.int.ebiederm.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn On 04/28, Eric W. Biederman wrote: > > Oleg Nesterov writes: > > >> The bug appears when the TRACEE makes it to schedule(). Inside > >> schedule there is a call to signal_pending_state() which notices > >> a SIGKILL is pending and refuses to sleep. > > > > And I think this is fine. This doesn't really differ from the case > > when the tracee was killed before it takes siglock. > > Hmm. Maybe. I hope ;) > Previously we were actually guaranteed in ptrace_check_attach that after > ptrace_freeze_traced would succeed as any pending fatal signal would > cause ptrace_freeze_traced to fail. Any incoming fatal signal would not > stop schedule from sleeping. Yes. So let me repeat, 7/9 "ptrace: Simplify the wait_task_inactive call in ptrace_check_attach" looks good to me (except it should use wait_task_inactive(__TASK_TRACED)), but it should come before other meaningfull changes and the changelog should be updated. And then we will probably need to reconsider this wait_task_inactive() and WARN_ON() around it, but depends on what will we finally do. > I think in my tired mind yesterday I got lost too ;) > Still I would like to be able to > let wait_task_inactive not care about the state of the process it is > going to sleep for. Not sure... but to be honest I didn't really pay attention to the wait_task_inactive(match_state => 0) part... Oleg. _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um