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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 C0A8DC43603 for ; Fri, 20 Dec 2019 20:37:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C0C62072B for ; Fri, 20 Dec 2019 20:37:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CPOUv+lu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727509AbfLTUhC (ORCPT ); Fri, 20 Dec 2019 15:37:02 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:29945 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726525AbfLTUhB (ORCPT ); Fri, 20 Dec 2019 15:37:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576874220; 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=4jjRnLYjGrqgF7WL+aNzr4dW0tQZdCM9Qqr1PxQyLYQ=; b=CPOUv+luqofKZe6ideEHXXcBsW3L4JPJKOxZSWOLEzNIqorxihmH7DX20/QiFvEZbw/oXY OgeIexMwwdPL7Ar5aOK9UdWOWoTzXsiVY82r9FG3pokzhelvGsYqgUssOYcpmM2i0t7DnD GX2/D6kcUnlioYNtT4iC4Q0Fdivl1jU= 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-432-eyXY7Fg4MeWQIpg8Nlm4TQ-1; Fri, 20 Dec 2019 15:36:57 -0500 X-MC-Unique: eyXY7Fg4MeWQIpg8Nlm4TQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 676271005513; Fri, 20 Dec 2019 20:36:54 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (ovpn-204-70.brq.redhat.com [10.40.204.70]) by smtp.corp.redhat.com (Postfix) with SMTP id 899A17C839; Fri, 20 Dec 2019 20:36:51 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 20 Dec 2019 21:36:54 +0100 (CET) Date: Fri, 20 Dec 2019 21:36:50 +0100 From: Oleg Nesterov To: Christian Brauner Cc: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Ingo Molnar , Johannes Weiner , Li Zefan , Peter Zijlstra , cgroups@vger.kernel.org Subject: Re: [PATCH 2/3] clone3: allow spawning processes into cgroups Message-ID: <20191220203650.GA15133@redhat.com> References: <20191218173516.7875-1-christian.brauner@ubuntu.com> <20191218173516.7875-3-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191218173516.7875-3-christian.brauner@ubuntu.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/18, Christian Brauner wrote: > > This adds support for creating a process in a different cgroup than its > parent. Cough... I will not comment the intent ;) I can't review the cgroup patches anyway. However, > +int cgroup_lock_fork(struct kernel_clone_args *kargs) > + __acquires(&cgroup_mutex) > +{ > + struct cgroup *cgrp; > + > + if (!(kargs->flags & CLONE_INTO_CGROUP)) > + return 0; > + > + cgrp = kargs->cgrp; > + if (!cgrp) > + return 0; > + > + mutex_lock(&cgroup_mutex); > + > + if (!cgroup_is_dead(cgrp)) > + return 0; > + > + mutex_unlock(&cgroup_mutex); > + return -ENODEV; ... > @@ -2172,7 +2172,7 @@ static __latent_entropy struct task_struct *copy_process( > * between here and cgroup_post_fork() if an organisation operation is in > * progress. > */ > - retval = cgroup_can_fork(p); > + retval = cgroup_can_fork(current, p, args); > if (retval) > goto bad_fork_cgroup_threadgroup_change_end; > > @@ -2226,6 +2226,10 @@ static __latent_entropy struct task_struct *copy_process( > goto bad_fork_cancel_cgroup; > } > > + retval = cgroup_lock_fork(args); mutex_lock() under spin_lock() ?? just in case, note that mutex_lock(&cgroup_mutex) is not safe even under cgroup_threadgroup_change_begin(), this can deadlock. Oleg.