Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754327Ab1CKAFA (ORCPT ); Thu, 10 Mar 2011 19:05:00 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:34419 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753825Ab1CKAE6 (ORCPT ); Thu, 10 Mar 2011 19:04:58 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 11 Mar 2011 08:58:33 +0900 From: KAMEZAWA Hiroyuki To: Minchan Kim Cc: Andrew Morton , Andrew Vagin , Andrey Vagin , Mel Gorman , KOSAKI Motohiro , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable() Message-Id: <20110311085833.874c6c0e.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <1299325456-2687-1-git-send-email-avagin@openvz.org> <20110305152056.GA1918@barrios-desktop> <4D72580D.4000208@gmail.com> <20110305155316.GB1918@barrios-desktop> <4D7267B6.6020406@gmail.com> <20110305170759.GC1918@barrios-desktop> <20110307135831.9e0d7eaa.akpm@linux-foundation.org> <20110309143704.194e8ee1.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.1.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4078 Lines: 128 On Thu, 10 Mar 2011 15:58:29 +0900 Minchan Kim wrote: > Hi Kame, > > Sorry for late response. > I had a time to test this issue shortly because these day I am very busy. > This issue was interesting to me. > So I hope taking a time for enough testing when I have a time. > I should find out root cause of livelock. > Thanks. I and Kosaki-san reproduced the bug with swapless system. Now, Kosaki-san is digging and found some issue with scheduler boost at OOM and lack of enough "wait" in vmscan.c. I myself made patch like attached one. This works well for returning TRUE at all_unreclaimable() but livelock(deadlock?) still happens. I wonder vmscan itself isn't a key for fixing issue. Then, I'd like to wait for Kosaki-san's answer ;) I'm now wondering how to catch fork-bomb and stop it (without using cgroup). I think the problem is that fork-bomb is faster than killall... Thanks, -Kame == This is just a debug patch. --- mm/vmscan.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 54 insertions(+), 4 deletions(-) Index: mmotm-0303/mm/vmscan.c =================================================================== --- mmotm-0303.orig/mm/vmscan.c +++ mmotm-0303/mm/vmscan.c @@ -1983,9 +1983,55 @@ static void shrink_zones(int priority, s } } -static bool zone_reclaimable(struct zone *zone) +static bool zone_seems_empty(struct zone *zone, struct scan_control *sc) { - return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; + unsigned long nr, wmark, free, isolated, lru; + + /* + * If scanned, zone->pages_scanned is incremented and this can + * trigger OOM. + */ + if (sc->nr_scanned) + return false; + + free = zone_page_state(zone, NR_FREE_PAGES); + isolated = zone_page_state(zone, NR_ISOLATED_FILE); + if (nr_swap_pages) + isolated += zone_page_state(zone, NR_ISOLATED_ANON); + + /* In we cannot do scan, don't count LRU pages. */ + if (!zone->all_unreclaimable) { + lru = zone_page_state(zone, NR_ACTIVE_FILE); + lru += zone_page_state(zone, NR_INACTIVE_FILE); + if (nr_swap_pages) { + lru += zone_page_state(zone, NR_ACTIVE_ANON); + lru += zone_page_state(zone, NR_INACTIVE_ANON); + } + } else + lru = 0; + nr = free + isolated + lru; + wmark = min_wmark_pages(zone); + wmark += zone->lowmem_reserve[gfp_zone(sc->gfp_mask)]; + wmark += 1 << sc->order; + printk("thread %d/%ld all %d scanned %ld pages %ld/%ld/%ld/%ld/%ld/%ld\n", + current->pid, sc->nr_scanned, zone->all_unreclaimable, + zone->pages_scanned, + nr,free,isolated,lru, + zone_reclaimable_pages(zone), wmark); + /* + * In some case (especially noswap), almost all page cache are paged out + * and we'll see the amount of reclaimable+free pages is smaller than + * zone->min. In this case, we canoot expect any recovery other + * than OOM-KILL. We can't reclaim memory enough for usual tasks. + */ + + return nr <= wmark; +} + +static bool zone_reclaimable(struct zone *zone, struct scan_control *sc) +{ + /* zone_reclaimable_pages() can return 0, we need <= */ + return zone->pages_scanned <= zone_reclaimable_pages(zone) * 6; } /* @@ -2006,11 +2052,15 @@ static bool all_unreclaimable(struct zon continue; if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) continue; - if (zone_reclaimable(zone)) { + if (zone_seems_empty(zone, sc)) + continue; + if (zone_reclaimable(zone, sc)) { all_unreclaimable = false; break; } } + if (all_unreclaimable) + printk("all_unreclaimable() returns TRUE\n"); return all_unreclaimable; } @@ -2456,7 +2506,7 @@ loop_again: if (zone->all_unreclaimable) continue; if (!compaction && nr_slab == 0 && - !zone_reclaimable(zone)) + !zone_reclaimable(zone, &sc)) zone->all_unreclaimable = 1; /* * If we've done a decent amount of scanning and -- 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/