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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 F0A63C5ACC6 for ; Tue, 16 Oct 2018 17:20:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B30582098A for ; Tue, 16 Oct 2018 17:20:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vb351d9p" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B30582098A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730625AbeJQBLr (ORCPT ); Tue, 16 Oct 2018 21:11:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:57148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729552AbeJQBLr (ORCPT ); Tue, 16 Oct 2018 21:11:47 -0400 Received: from localhost (ip-213-127-77-176.ip.prioritytelecom.net [213.127.77.176]) (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 6DE4D20866; Tue, 16 Oct 2018 17:20:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1539710421; bh=nzJLxSSL0UcoAM8r7mnekJjnVQ7N1tYNKcJSWlCuFMI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vb351d9pYS3/hlVM5oCwgdVcdIZsEdBUlgbmtOIQdM/py4clLXRKFru+5UVAo6qHj t8edr/WB+w0BXVxwh46jsg5xy7nsKAaSemrNbh5pkze3GGpl/ovHmwOuUuVPl1NDdH x+ojm8J5JfoV4KNZ7ETtwB9ruIeMbNqKoMQNyllQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tejun Heo , Amin Jamali , Joao De Almeida Pereira Subject: [PATCH 4.14 072/109] cgroup: Fix dom_cgrp propagation when enabling threaded mode Date: Tue, 16 Oct 2018 19:05:40 +0200 Message-Id: <20181016170528.712843436@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181016170524.530541524@linuxfoundation.org> References: <20181016170524.530541524@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tejun Heo commit 479adb89a97b0a33e5a9d702119872cc82ca21aa upstream. A cgroup which is already a threaded domain may be converted into a threaded cgroup if the prerequisite conditions are met. When this happens, all threaded descendant should also have their ->dom_cgrp updated to the new threaded domain cgroup. Unfortunately, this propagation was missing leading to the following failure. # cd /sys/fs/cgroup/unified # cat cgroup.subtree_control # show that no controllers are enabled # mkdir -p mycgrp/a/b/c # echo threaded > mycgrp/a/b/cgroup.type At this point, the hierarchy looks as follows: mycgrp [d] a [dt] b [t] c [inv] Now let's make node "a" threaded (and thus "mycgrp" s made "domain threaded"): # echo threaded > mycgrp/a/cgroup.type By this point, we now have a hierarchy that looks as follows: mycgrp [dt] a [t] b [t] c [inv] But, when we try to convert the node "c" from "domain invalid" to "threaded", we get ENOTSUP on the write(): # echo threaded > mycgrp/a/b/c/cgroup.type sh: echo: write error: Operation not supported This patch fixes the problem by * Moving the opencoded ->dom_cgrp save and restoration in cgroup_enable_threaded() into cgroup_{save|restore}_control() so that mulitple cgroups can be handled. * Updating all threaded descendants' ->dom_cgrp to point to the new dom_cgrp when enabling threaded mode. Signed-off-by: Tejun Heo Reported-and-tested-by: "Michael Kerrisk (man-pages)" Reported-by: Amin Jamali Reported-by: Joao De Almeida Pereira Link: https://lore.kernel.org/r/CAKgNAkhHYCMn74TCNiMJ=ccLd7DcmXSbvw3CbZ1YREeG7iJM5g@mail.gmail.com Fixes: 454000adaa2a ("cgroup: introduce cgroup->dom_cgrp and threaded css_set handling") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman --- include/linux/cgroup-defs.h | 1 + kernel/cgroup/cgroup.c | 25 ++++++++++++++++--------- 2 files changed, 17 insertions(+), 9 deletions(-) --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -353,6 +353,7 @@ struct cgroup { * specific task are charged to the dom_cgrp. */ struct cgroup *dom_cgrp; + struct cgroup *old_dom_cgrp; /* used while enabling threaded */ /* * list of pidlists, up to two for each namespace (one for procs, one --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2780,11 +2780,12 @@ restart: } /** - * cgroup_save_control - save control masks of a subtree + * cgroup_save_control - save control masks and dom_cgrp of a subtree * @cgrp: root of the target subtree * - * Save ->subtree_control and ->subtree_ss_mask to the respective old_ - * prefixed fields for @cgrp's subtree including @cgrp itself. + * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the + * respective old_ prefixed fields for @cgrp's subtree including @cgrp + * itself. */ static void cgroup_save_control(struct cgroup *cgrp) { @@ -2794,6 +2795,7 @@ static void cgroup_save_control(struct c cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { dsct->old_subtree_control = dsct->subtree_control; dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; + dsct->old_dom_cgrp = dsct->dom_cgrp; } } @@ -2819,11 +2821,12 @@ static void cgroup_propagate_control(str } /** - * cgroup_restore_control - restore control masks of a subtree + * cgroup_restore_control - restore control masks and dom_cgrp of a subtree * @cgrp: root of the target subtree * - * Restore ->subtree_control and ->subtree_ss_mask from the respective old_ - * prefixed fields for @cgrp's subtree including @cgrp itself. + * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the + * respective old_ prefixed fields for @cgrp's subtree including @cgrp + * itself. */ static void cgroup_restore_control(struct cgroup *cgrp) { @@ -2833,6 +2836,7 @@ static void cgroup_restore_control(struc cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { dsct->subtree_control = dsct->old_subtree_control; dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; + dsct->dom_cgrp = dsct->old_dom_cgrp; } } @@ -3140,6 +3144,8 @@ static int cgroup_enable_threaded(struct { struct cgroup *parent = cgroup_parent(cgrp); struct cgroup *dom_cgrp = parent->dom_cgrp; + struct cgroup *dsct; + struct cgroup_subsys_state *d_css; int ret; lockdep_assert_held(&cgroup_mutex); @@ -3169,12 +3175,13 @@ static int cgroup_enable_threaded(struct */ cgroup_save_control(cgrp); - cgrp->dom_cgrp = dom_cgrp; + cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) + if (dsct == cgrp || cgroup_is_threaded(dsct)) + dsct->dom_cgrp = dom_cgrp; + ret = cgroup_apply_control(cgrp); if (!ret) parent->nr_threaded_children++; - else - cgrp->dom_cgrp = cgrp; cgroup_finalize_control(cgrp, ret); return ret;