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 5705FC433EF for ; Mon, 18 Apr 2022 17:20:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346963AbiDRRWw (ORCPT ); Mon, 18 Apr 2022 13:22:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346991AbiDRRWh (ORCPT ); Mon, 18 Apr 2022 13:22:37 -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 D9A1911A34 for ; Mon, 18 Apr 2022 10:19:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650302396; 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=BOeDwm19QZU5bj1yBihjhswrckaR7N4xxWK6qgyPxIA=; b=ZCgurH657/diQCpZwxz0p2PUXks1fuUjzV2vVjVWeptahCfhdy45efJLaxS2FZGIkK134G vyltAow0XPHCRmntnDKI8DELFmFentnefEuMyYPnWw4K0HFOMpeZOZfxuT6kCgJwsRXAu4 ZfpW1y0dacuBarmtuzvRt49sqNgCA0Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-437-7tjVyLDfNhGYyJThbh6otQ-1; Mon, 18 Apr 2022 13:19:52 -0400 X-MC-Unique: 7tjVyLDfNhGYyJThbh6otQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4AC56811E78; Mon, 18 Apr 2022 17:19:46 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.13]) by smtp.corp.redhat.com (Postfix) with SMTP id 34F3840FD37C; Mon, 18 Apr 2022 17:19:43 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 18 Apr 2022 19:19:45 +0200 (CEST) Date: Mon, 18 Apr 2022 19:19:42 +0200 From: Oleg Nesterov To: Peter Zijlstra Cc: rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, ebiederm@xmission.com, bigeasy@linutronix.de, Will Deacon , linux-kernel@vger.kernel.org, tj@kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT_RT Message-ID: <20220418171941.GB16199@redhat.com> References: <20220413185909.GB30360@redhat.com> <20220413192053.GY2731@worktop.programming.kicks-ass.net> <20220413195612.GC2762@worktop.programming.kicks-ass.net> <20220414115410.GA32752@redhat.com> <20220414183433.GC32752@redhat.com> <20220415101644.GA10421@redhat.com> <20220415105755.GA15217@redhat.com> <20220418170104.GA16199@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220418170104.GA16199@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/18, Oleg Nesterov wrote: > > static int ptrace_check_attach(struct task_struct *child, bool ignore_state) > { ... > + if (!traced) > + return -ESRCH; > + > + WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED); > + if (ignore_state) > + return 0; > + > + if (!task_is_traced(child)) > + return -ESRCH; This is the new check V1 didn't have, we need it to unsure that check_attach can't miss the change in child->jobctl and call wait_task_inactive() before the child marks itself as "traced" and clears JOBCTL_TRACED_XXX. Oleg.