Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753232Ab1CWHN0 (ORCPT ); Wed, 23 Mar 2011 03:13:26 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:38497 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752442Ab1CWHNZ (ORCPT ); Wed, 23 Mar 2011 03:13:25 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Minchan Kim Subject: Re: [PATCH 1/5] vmscan: remove all_unreclaimable check from direct reclaim path completely Cc: kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org, Andrew Morton , David Rientjes , Linus Torvalds , Rik van Riel , Oleg Nesterov , linux-mm , Andrey Vagin , Hugh Dickins , KAMEZAWA Hiroyuki , Nick Piggin , Johannes Weiner In-Reply-To: References: <20110323142133.1AC6.A69D9226@jp.fujitsu.com> Message-Id: <20110323161354.1AD2.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Wed, 23 Mar 2011 16:13:21 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2225 Lines: 74 > Okay. I got it. > > The problem is following as. > By the race the free_pcppages_bulk and balance_pgdat, it is possible > zone->all_unreclaimable = 1 and zone->pages_scanned = 0. > DMA zone have few LRU pages and in case of no-swap and big memory > pressure, there could be a just a page in inactive file list like your > example. (anon lru pages isn't important in case of non-swap system) > In such case, shrink_zones doesn't scan the page at all until priority > become 0 as get_scan_count does scan >>= priority(it's mostly zero). Nope. if (zone->all_unreclaimable && priority != DEF_PRIORITY) continue; This tow lines mean, all_unreclaimable prevent priority 0 reclaim. > And although priority become 0, nr_scan_try_batch returns zero until > saved pages become 32. So for scanning the page, at least, we need 32 > times iteration of priority 12..0. If system has fork-bomb, it is > almost livelock. Therefore, 1000 times get_scan_count(DEF_PRIORITY) takes 1000 times no-op. > > If is is right, how about this? Boo. You seems forgot why you introduced current all_unreclaimable() function. While hibernation, we can't trust all_unreclaimable. That's the reason why I proposed following patch when you introduced all_unreclaimable(). --- mm/vmscan.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index c391c32..1919d8a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include @@ -1931,7 +1932,7 @@ out: return sc->nr_reclaimed; /* top priority shrink_zones still had more to do? don't OOM, then */ - if (scanning_global_lru(sc) && !all_unreclaimable) + if (scanning_global_lru(sc) && !all_unreclaimable && !oom_killer_disabled) return 1; return 0; -- 1.6.5.2 -- 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/