From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754688AbcHARk7 (ORCPT ); Mon, 1 Aug 2016 13:40:59 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:36355 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753936AbcHARkZ (ORCPT ); Mon, 1 Aug 2016 13:40:25 -0400 Date: Mon, 1 Aug 2016 19:39:56 +0200 From: Michal Hocko To: Johannes Weiner Cc: Vladimir Davydov , Andrew Morton , linux-mm@kvack.org, LKML Subject: Re: [PATCH] memcg: put soft limit reclaim out of way if the excess tree is empty Message-ID: <20160801173956.GA31957@dhcp22.suse.cz> References: <1470045621-14335-1-git-send-email-mhocko@kernel.org> <20160801135757.GB19395@esperanza> <20160801141227.GI13544@dhcp22.suse.cz> <20160801150343.GA7603@cmpxchg.org> <20160801152454.GK13544@dhcp22.suse.cz> <20160801171717.GB8724@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160801171717.GB8724@cmpxchg.org> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 01-08-16 13:17:17, Johannes Weiner wrote: > On Mon, Aug 01, 2016 at 05:24:54PM +0200, Michal Hocko wrote: > > @@ -2564,7 +2559,13 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, > > return 0; > > > > mctz = soft_limit_tree_node(pgdat->node_id); > > - if (soft_limit_tree_empty(mctz)) > > + > > + /* > > + * Do not even bother to check the largest node if the node > > root Fixed > > > + * is empty. Do it lockless to prevent lock bouncing. Races > > + * are acceptable as soft limit is best effort anyway. > > + */ > > + if (RB_EMPTY_ROOT(&mctz->rb_root)) > > return 0; > > Other than that, looks good. Please retain my > > Acked-by: Johannes Weiner Thanks. -- Michal Hocko SUSE Labs