Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756815Ab1EMGz1 (ORCPT ); Fri, 13 May 2011 02:55:27 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:59690 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756590Ab1EMGzZ (ORCPT ); Fri, 13 May 2011 02:55:25 -0400 Date: Fri, 13 May 2011 08:54:59 +0200 From: Johannes Weiner To: KAMEZAWA Hiroyuki Cc: Daisuke Nishimura , Balbir Singh , Ying Han , Michal Hocko , Andrew Morton , Rik van Riel , Minchan Kim , KOSAKI Motohiro , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [rfc patch 3/6] mm: memcg-aware global reclaim Message-ID: <20110513065459.GA18610@cmpxchg.org> References: <1305212038-15445-1-git-send-email-hannes@cmpxchg.org> <1305212038-15445-4-git-send-email-hannes@cmpxchg.org> <20110513094050.6a01dad8.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110513094050.6a01dad8.kamezawa.hiroyu@jp.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1312 Lines: 36 On Fri, May 13, 2011 at 09:40:50AM +0900, KAMEZAWA Hiroyuki wrote: > > @@ -1954,6 +1952,19 @@ restart: > > goto restart; > > > > throttle_vm_writeout(sc->gfp_mask); > > +} > > + > > +static void shrink_zone(int priority, struct zone *zone, > > + struct scan_control *sc) > > +{ > > + struct mem_cgroup *root = sc->memcg; > > + struct mem_cgroup *mem = NULL; > > + > > + do { > > + mem_cgroup_hierarchy_walk(root, &mem); > > + sc->current_memcg = mem; > > + do_shrink_zone(priority, zone, sc); > > If I don't miss something, css_put() against mem->css will be required somewhere. That's a bit of a hack. mem_cgroup_hierarchy_walk() always does css_put() on *mem before advancing to the next child. At the last iteration, it returns mem == root. Since the caller must have a reference on root to begin with, it does not css_get() root. So when mem == root, there are no outstanding references from the walk anymore. This only works since it always does the full hierarchy walk, so it's going away anyway when the hierarchy walk becomes intermittent. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/