From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755963Ab2FTNrm (ORCPT ); Wed, 20 Jun 2012 09:47:42 -0400 Received: from cantor2.suse.de ([195.135.220.15]:50473 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291Ab2FTNrl (ORCPT ); Wed, 20 Jun 2012 09:47:41 -0400 Date: Wed, 20 Jun 2012 15:47:38 +0200 From: Michal Hocko To: Glauber Costa Cc: linux-mm@kvack.org, Pekka Enberg , Cristoph Lameter , David Rientjes , cgroups@vger.kernel.org, devel@openvz.org, kamezawa.hiroyu@jp.fujitsu.com, linux-kernel@vger.kernel.org, Frederic Weisbecker , Suleiman Souhlal Subject: Re: [PATCH v4 07/25] memcg: Reclaim when more than one page needed. Message-ID: <20120620134738.GG5541@tiehlicka.suse.cz> References: <1340015298-14133-1-git-send-email-glommer@parallels.com> <1340015298-14133-8-git-send-email-glommer@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1340015298-14133-8-git-send-email-glommer@parallels.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 18-06-12 14:28:00, Glauber Costa wrote: > From: Suleiman Souhlal > > mem_cgroup_do_charge() was written before slab accounting, and expects > three cases: being called for 1 page, being called for a stock of 32 pages, > or being called for a hugepage. If we call for 2 or 3 pages (and several > slabs used in process creation are such, at least with the debug options I > had), it assumed it's being called for stock and just retried without reclaiming. > > Fix that by passing down a minsize argument in addition to the csize. > > And what to do about that (csize == PAGE_SIZE && ret) retry? If it's > needed at all (and presumably is since it's there, perhaps to handle > races), then it should be extended to more than PAGE_SIZE, yet how far? > And should there be a retry count limit, of what? For now retry up to > COSTLY_ORDER (as page_alloc.c does), stay safe with a cond_resched(), > and make sure not to do it if __GFP_NORETRY. > > [v4: fixed nr pages calculation pointed out by Christoph Lameter ] > > Signed-off-by: Suleiman Souhlal > Signed-off-by: Glauber Costa > Reviewed-by: Kamezawa Hiroyuki I think this is not ready to be merged yet. Two comments below. [...] > @@ -2210,18 +2211,18 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > } else > mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); > /* > - * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch > - * of regular pages (CHARGE_BATCH), or a single regular page (1). > - * > * Never reclaim on behalf of optional batching, retry with a > * single page instead. > */ > - if (nr_pages == CHARGE_BATCH) > + if (nr_pages > min_pages) > return CHARGE_RETRY; > > if (!(gfp_mask & __GFP_WAIT)) > return CHARGE_WOULDBLOCK; > > + if (gfp_mask & __GFP_NORETRY) > + return CHARGE_NOMEM; This is kmem specific and should be preparated out in case this should be merged before the rest. Btw. I assume that oom==false when called from kmem... > + > ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); > if (mem_cgroup_margin(mem_over_limit) >= nr_pages) > return CHARGE_RETRY; > @@ -2234,8 +2235,10 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > * unlikely to succeed so close to the limit, and we fall back > * to regular pages anyway in case of failure. > */ > - if (nr_pages == 1 && ret) > + if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret) { > + cond_resched(); > return CHARGE_RETRY; > + } What prevents us from looping for unbounded amount of time here? Maybe you need to consider the number of reclaimed pages here. > > /* > * At task move, charge accounts can be doubly counted. So, it's > @@ -2369,7 +2372,8 @@ again: > nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; > } > > - ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check); > + ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, nr_pages, > + oom_check); > switch (ret) { > case CHARGE_OK: > break; > -- > 1.7.10.2 > > -- > 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 -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic