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=-11.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 561C3C34049 for ; Tue, 18 Feb 2020 20:01:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 251A02465D for ; Tue, 18 Feb 2020 20:01:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582056088; bh=Tn/SrJ/oXq7x45pUrAWtvbL//v+33hRQW4wAMEPfRO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X9V8uXPLd2Ft7cGibOPIkAnm50xLQNiMzmccTeQ3gg/XtQtJto18funNFcHIo3b7q VtPTEb1x0HPR2JrhIyf/0EDzRyqvQzyRP7i8Bt5WCASLnh5dE5CG8E9S3Lbhn0giZh Cg1ZC6h0uJDXdDlsQHKfxEXG1GE7UsAjnuKMKLM4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728763AbgBRUB1 (ORCPT ); Tue, 18 Feb 2020 15:01:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:41022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728761AbgBRUBY (ORCPT ); Tue, 18 Feb 2020 15:01:24 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3C7302464E; Tue, 18 Feb 2020 20:01:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582056083; bh=Tn/SrJ/oXq7x45pUrAWtvbL//v+33hRQW4wAMEPfRO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rf5EiqX91Tol+al3gQiToxUXQqtDX/eTvQjTr0GfEEQJkZFoQpc8NpZCN8nlTqcVo cDNWIB/Ei/uO3HRRxVJnhD6tinN0PNhSGIqqkScz/BJPQ0l1OSmQWOzJ758eW1sbYy RxUVSwd//T9z9Tw453jKDcbr6jYkxlU1496tuqxQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tejun Heo Subject: [PATCH 5.5 28/80] cgroup: init_tasks shouldnt be linked to the root cgroup Date: Tue, 18 Feb 2020 20:54:49 +0100 Message-Id: <20200218190435.137599128@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200218190432.043414522@linuxfoundation.org> References: <20200218190432.043414522@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tejun Heo commit 0cd9d33ace336bc424fc30944aa3defd6786e4fe upstream. 5153faac18d2 ("cgroup: remove cgroup_enable_task_cg_lists() optimization") removed lazy initialization of css_sets so that new tasks are always lniked to its css_set. In the process, it incorrectly ended up adding init_tasks to root css_set. They show up as PID 0's in root's cgroup.procs triggering warnings in systemd and generally confusing people. Fix it by skip css_set linking for init_tasks. Signed-off-by: Tejun Heo Reported-by: https://github.com/joanbm Link: https://github.com/systemd/systemd/issues/14682 Fixes: 5153faac18d2 ("cgroup: remove cgroup_enable_task_cg_lists() optimization") Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cgroup.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5932,11 +5932,14 @@ void cgroup_post_fork(struct task_struct spin_lock_irq(&css_set_lock); - WARN_ON_ONCE(!list_empty(&child->cg_list)); - cset = task_css_set(current); /* current is @child's parent */ - get_css_set(cset); - cset->nr_tasks++; - css_set_move_task(child, NULL, cset, false); + /* init tasks are special, only link regular threads */ + if (likely(child->pid)) { + WARN_ON_ONCE(!list_empty(&child->cg_list)); + cset = task_css_set(current); /* current is @child's parent */ + get_css_set(cset); + cset->nr_tasks++; + css_set_move_task(child, NULL, cset, false); + } /* * If the cgroup has to be frozen, the new task has too. Let's set