From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751851AbdLARAr (ORCPT ); Fri, 1 Dec 2017 12:00:47 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:47234 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750965AbdLARAo (ORCPT ); Fri, 1 Dec 2017 12:00:44 -0500 Date: Fri, 1 Dec 2017 17:00:09 +0000 From: Roman Gushchin To: Michal Hocko CC: Vladimir Davydov , Johannes Weiner , Tetsuo Handa , David Rientjes , Andrew Morton , Tejun Heo , , , , , Subject: Re: [PATCH v13 5/7] mm, oom: add cgroup v2 mount option for cgroup-aware OOM killer Message-ID: <20171201170004.GA27436@castle.DHCP.thefacebook.com> References: <20171130152824.1591-1-guro@fb.com> <20171130152824.1591-6-guro@fb.com> <20171201084113.47lnuo3diwxts732@dhcp22.suse.cz> <20171201131530.GA7741@castle.DHCP.thefacebook.com> <20171201133145.w4b4cekruklcgtol@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; 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ENOTSUP sounds better to me. > -- > Michal Hocko > SUSE Labs >>From 78bf2c00abf450bcd993d02a7dc1783144005fbd Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Fri, 1 Dec 2017 14:30:14 +0000 Subject: [PATCH] mm, oom: return error on access to memory.oom_group if groupoom is disabled Cgroup-aware OOM killer depends on cgroup mount option and is turned off by default, despite the user interface (memory.oom_group file) is always present. As it might be confusing to a user, let's return -ENOTSUPP on an attempt to access to memory.oom_group if groupoom is not enabled globally. Example: $ cd /sys/fs/cgroup/user.slice/ $ cat memory.oom_group cat: memory.oom_group: Unknown error 524 $ echo 1 > memory.oom_group -bash: echo: write error: Unknown error 524 $ mount -o remount,groupoom /sys/fs/cgroup $ echo 1 > memory.oom_group $ cat memory.oom_group 1 Signed-off-by: Roman Gushchin Cc: Andrew Morton Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Tejun Heo Cc: kernel-team@fb.com Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c76d5fb55c5c..b709ee4f914b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5482,6 +5482,9 @@ static int memory_oom_group_show(struct seq_file *m, void *v) struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); bool oom_group = memcg->oom_group; + if (!(cgrp_dfl_root.flags & CGRP_GROUP_OOM)) + return -ENOTSUPP; + seq_printf(m, "%d\n", oom_group); return 0; @@ -5495,6 +5498,9 @@ static ssize_t memory_oom_group_write(struct kernfs_open_file *of, int oom_group; int err; + if (!(cgrp_dfl_root.flags & CGRP_GROUP_OOM)) + return -ENOTSUPP; + err = kstrtoint(strstrip(buf), 0, &oom_group); if (err) return err; -- 2.14.3