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=-12.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 5999DC2D0DB for ; Thu, 30 Jan 2020 16:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E4322083E for ; Thu, 30 Jan 2020 16:47:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580402842; bh=i8A9qAzt/VXM+MP0WemAo06gYyO10bD7Y/0oYPeF7CU=; h=Date:From:To:Cc:Subject:List-ID:From; b=f7OqZpME/m1OyFEYkyTTt6FxTOhNZqVPgAJkfYFFFDXeTFYGr51GsxLpcJCMKm58b o0lmJrzbMEIWPBSP3FPWvGbdd2ocmt8u//uv4g/bBt+yDJ2dm17x3e606SfJ3S6ms1 mWDW++EOz7HlscevYsaUG7LdYmdIXsvbEnTQF9P0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727380AbgA3QrV (ORCPT ); Thu, 30 Jan 2020 11:47:21 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:36375 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727186AbgA3QrV (ORCPT ); Thu, 30 Jan 2020 11:47:21 -0500 Received: by mail-qt1-f195.google.com with SMTP id t13so3006040qto.3; Thu, 30 Jan 2020 08:47:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=cRkmfZ70e1FN/dai6WJTy1Ty8v4BIDTiaHK0pQLcbpM=; b=msmlzcdjC+TyANKBhZKTl1h2yOagQ43WqHjcbrMtcNUrNzFU/gaLY2HBa5xN/2WODX h6+ZcRFdLaex3hEqFCWiVEGhC+QV99QFD9W9wOcspZRPS53Q3+iJe/MhBvWz94UMeViM vWjDkkpxkBSr7yDexhoHJoUGfy58IVK8w3Yd3eO3yVJtt8omAFB4Xxa90XCI8gjeDJpA 0QKylSioDjUDa49oOuBRM6YPDiqfMHq3qM8OuqFeP4ZBOBtEMDDzrmlOAJYbGXc7vh93 L+GzYcO2xV/5CnDlVJfq6hy5QoyR/BvcSzHOByrmhKlMurzLQ6JTBtemCSDu4yv7HRUn f4nQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mime-version:content-disposition; bh=cRkmfZ70e1FN/dai6WJTy1Ty8v4BIDTiaHK0pQLcbpM=; b=Lmyhv5oVp4VY1rwefrlU44ZV+Lq+zctRSvZd9ulmDpXsi+zZhYB1iilKOWQBXeI6+k UCFrRCPMpxmiytDTAJIHCSooRfYoDhd8SYuUbdDaUK77wa7EbQ5YNYvoREcdb6ZunCrO ZUukNAxipg5K/OUMxvoE2ZEW9hqdh8m/4HwTvCuW08TyyAQT7RwYdiG1RP9eENVAXQoI cYCYtfwZiDLjpXlzmcFIbgaAQMuag5+kNGF+QbVIDpHBujn4BWBG2Y8cenfWh4HAZgqn O5k1UDLMiW075eHsWlLNQdBFa8wZGmZ7g7SaHdRS3tXGTeem4haPc4dnkRLgTi24GCmH VmVA== X-Gm-Message-State: APjAAAXRvmWA+6vMzIWpH/yD0MPmYYnVXnJ57J2f0s9+hNb0Dk/rEAFq p+Zh6qZHkbGVNKhwwD5xQlY= X-Google-Smtp-Source: APXvYqwrPTcNF2ywjVNYtwaeuLl+A5vMAx1dYlbTD+IMjVdAYmJyjIuPy0oCF2C5XcVNzkfDBTRzQQ== X-Received: by 2002:ac8:7352:: with SMTP id q18mr5631408qtp.125.1580402838461; Thu, 30 Jan 2020 08:47:18 -0800 (PST) Received: from localhost ([2620:10d:c091:480::139]) by smtp.gmail.com with ESMTPSA id b22sm2950594qka.121.2020.01.30.08.47.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jan 2020 08:47:17 -0800 (PST) Date: Thu, 30 Jan 2020 11:47:17 -0500 From: Tejun Heo To: Li Zefan Cc: Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Oleg Nesterov Subject: [PATCH cgroup/for-5.6-fixes] cgroup: init_tasks shouldn't be linked to the root cgroup Message-ID: <20200130164717.GE180576@mtj.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >From 0cd9d33ace336bc424fc30944aa3defd6786e4fe Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 30 Jan 2020 11:37:33 -0500 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+ --- kernel/cgroup/cgroup.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index b3744872263e..cf8a36bdf5c8 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5932,11 +5932,14 @@ void cgroup_post_fork(struct task_struct *child) 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 -- 2.24.1