From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751447AbeEVOlW (ORCPT ); Tue, 22 May 2018 10:41:22 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:39048 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751199AbeEVOlS (ORCPT ); Tue, 22 May 2018 10:41:18 -0400 From: Roman Gushchin To: Tejun Heo CC: Roman Gushchin , , , , Subject: [PATCH] cgroup, docs: add a note about returning EBUSY in some cases Date: Tue, 22 May 2018 15:36:48 +0100 Message-ID: <20180522143648.29508-1-guro@fb.com> X-Mailer: git-send-email 2.14.3 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [2620:10d:c092:200::1:c39d] X-ClientProxiedBy: AM5PR0602CA0004.eurprd06.prod.outlook.com (2603:10a6:203:a3::14) To DM3PR15MB1084.namprd15.prod.outlook.com (2603:10b6:0:12::10) X-MS-PublicTrafficType: Email X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(5600026)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7153060)(7193020);SRVR:DM3PR15MB1084; 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and writing into cgroup.subtree_control if there are attached processes. The return code might be slightly surprising, and because there is nothing obviously better, let's document it at least. Signed-off-by: Roman Gushchin Cc: Tejun Heo Cc: kernel-team@fb.com Cc: cgroups@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Documentation/cgroup-v2.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index 74cdeaed9f7a..57302f88a4ad 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -799,6 +799,9 @@ All cgroup core files are prefixed with "cgroup." When delegating a sub-hierarchy, write access to this file should be granted along with the containing directory. + If the target cgroup has enabled controllers, writing to this + file will fail with EBUSY. + In a threaded cgroup, reading this file fails with EOPNOTSUPP as all the processes belong to the thread root. Writing is supported and moves every thread of the process to the cgroup. @@ -850,6 +853,9 @@ All cgroup core files are prefixed with "cgroup." the last one is effective. When multiple enable and disable operations are specified, either all succeed or all fail. + If the cgroup has attached tasks, writing to this file will + fail with EBUSY. + cgroup.events A read-only flat-keyed file which exists on non-root cgroups. The following entries are defined. Unless specified -- 2.14.3