From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f175.google.com (mail-pf0-f175.google.com [209.85.192.175]) by kanga.kvack.org (Postfix) with ESMTP id 7FFA06B0005 for ; Tue, 1 Mar 2016 11:56:42 -0500 (EST) Received: by mail-pf0-f175.google.com with SMTP id w128so71238814pfb.2 for ; Tue, 01 Mar 2016 08:56:42 -0800 (PST) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id z63si51512736pfi.63.2016.03.01.08.56.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 01 Mar 2016 08:56:41 -0800 (PST) Date: Tue, 1 Mar 2016 19:56:30 +0300 From: Vladimir Davydov Subject: Re: [PATCH 2/2] cgroup: reset css on destruction Message-ID: <20160301165630.GB2426@esperanza> References: <69629961aefc48c021b895bb0c8297b56c11a577.1456830735.git.vdavydov@virtuozzo.com> <92b11b89791412df49e73597b87912e8f143a3f7.1456830735.git.vdavydov@virtuozzo.com> <20160301163018.GE3965@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20160301163018.GE3965@htj.duckdns.org> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Andrew Morton , Johannes Weiner , Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Mar 01, 2016 at 11:30:18AM -0500, Tejun Heo wrote: > On Tue, Mar 01, 2016 at 02:13:13PM +0300, Vladimir Davydov wrote: > > @@ -5138,6 +5138,8 @@ static void kill_css(struct cgroup_subsys_state *css) > > * See seq_css() for details. > > */ > > css_clear_dir(css, NULL); > > + if (css->ss->css_reset) > > + css->ss->css_reset(css); > > I think the better spot for this is in offline_css() right before > ->css_offline() is called. Okay, here it goes. --- From: Vladimir Davydov Subject: [PATCH] cgroup: reset css on destruction An associated css can be around for quite a while after a cgroup directory has been removed. In general, it makes sense to reset it to defaults so as not to worry about any remnants. For instance, memory cgroup needs to reset memory.low, otherwise pages charged to a dead cgroup might never get reclaimed. There's ->css_reset callback, which would fit perfectly for the purpose. Currently, it's only called when a subsystem is disabled in the unified hierarchy and there are other subsystems dependant on it. Let's call it on css destruction as well. Suggested-by: Johannes Weiner Signed-off-by: Vladimir Davydov diff --git a/kernel/cgroup.c b/kernel/cgroup.c index cc40463e7b69..bb1900b70b01 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4876,6 +4876,9 @@ static void offline_css(struct cgroup_subsys_state *css) if (!(css->flags & CSS_ONLINE)) return; + if (ss->css_reset) + ss->css_reset(css); + if (ss->css_offline) ss->css_offline(css); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org