Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757276Ab2FYOSP (ORCPT ); Mon, 25 Jun 2012 10:18:15 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:29306 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757093Ab2FYOSL (ORCPT ); Mon, 25 Jun 2012 10:18:11 -0400 From: Glauber Costa To: Cc: , Andrew Morton , , Frederic Weisbecker , David Rientjes , Pekka Enberg , Michal Hocko , Johannes Weiner , Christoph Lameter , , , Tejun Heo , Suleiman Souhlal , Glauber Costa Subject: [PATCH 02/11] memcg: Reclaim when more than one page needed. Date: Mon, 25 Jun 2012 18:15:19 +0400 Message-Id: <1340633728-12785-3-git-send-email-glommer@parallels.com> X-Mailer: git-send-email 1.7.10.2 In-Reply-To: <1340633728-12785-1-git-send-email-glommer@parallels.com> References: <1340633728-12785-1-git-send-email-glommer@parallels.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3543 Lines: 98 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 --- mm/memcontrol.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9304db2..8e601e8 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2158,8 +2158,16 @@ enum { CHARGE_OOM_DIE, /* the current is killed because of OOM */ }; +/* + * We need a number that is small enough to be likely to have been + * reclaimed even under pressure, but not too big to trigger unnecessary + * retries + */ +#define NR_PAGES_TO_RETRY 2 + static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, - unsigned int nr_pages, bool oom_check) + unsigned int nr_pages, unsigned int min_pages, + bool oom_check) { unsigned long csize = nr_pages * PAGE_SIZE; struct mem_cgroup *mem_over_limit; @@ -2182,18 +2190,18 @@ 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; + ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) return CHARGE_RETRY; @@ -2206,7 +2214,7 @@ 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 <= NR_PAGES_TO_RETRY && ret) return CHARGE_RETRY; /* @@ -2341,7 +2349,8 @@ 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 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/