Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751973Ab1EXFpa (ORCPT ); Tue, 24 May 2011 01:45:30 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:45229 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750921Ab1EXFp3 (ORCPT ); Tue, 24 May 2011 01:45:29 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Message-ID: <4DDB45EF.2080803@jp.fujitsu.com> Date: Tue, 24 May 2011 14:45:19 +0900 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; ja; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: minchan.kim@gmail.com CC: abarry@cray.com, akpm@linux-foundation.org, linux-mm@kvack.org, mgorman@suse.de, riel@redhat.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org Subject: Re: Unending loop in __alloc_pages_slowpath following OOM-kill; rfc: patch. References: <4DCDA347.9080207@cray.com> <4DD2991B.5040707@cray.com> <20110520164924.GB2386@barrios-desktop> <4DDB3A1E.6090206@jp.fujitsu.com> In-Reply-To: <4DDB3A1E.6090206@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3465 Lines: 79 (2011/05/24 13:54), KOSAKI Motohiro wrote: >> >From 8bd3f16736548375238161d1bd85f7d7c381031f Mon Sep 17 00:00:00 2001 >> From: Minchan Kim >> Date: Sat, 21 May 2011 01:37:41 +0900 >> Subject: [PATCH] Prevent unending loop in __alloc_pages_slowpath >> >> From: Andrew Barry >> >> I believe I found a problem in __alloc_pages_slowpath, which allows a process to >> get stuck endlessly looping, even when lots of memory is available. >> >> Running an I/O and memory intensive stress-test I see a 0-order page allocation >> with __GFP_IO and __GFP_WAIT, running on a system with very little free memory. >> Right about the same time that the stress-test gets killed by the OOM-killer, >> the utility trying to allocate memory gets stuck in __alloc_pages_slowpath even >> though most of the systems memory was freed by the oom-kill of the stress-test. >> >> The utility ends up looping from the rebalance label down through the >> wait_iff_congested continiously. Because order=0, __alloc_pages_direct_compact >> skips the call to get_page_from_freelist. Because all of the reclaimable memory >> on the system has already been reclaimed, __alloc_pages_direct_reclaim skips the >> call to get_page_from_freelist. Since there is no __GFP_FS flag, the block with >> __alloc_pages_may_oom is skipped. The loop hits the wait_iff_congested, then >> jumps back to rebalance without ever trying to get_page_from_freelist. This loop >> repeats infinitely. >> >> The test case is pretty pathological. Running a mix of I/O stress-tests that do >> a lot of fork() and consume all of the system memory, I can pretty reliably hit >> this on 600 nodes, in about 12 hours. 32GB/node. >> >> Signed-off-by: Andrew Barry >> Reviewed-by: Minchan Kim >> Cc: Mel Gorman >> --- >> mm/page_alloc.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 3f8bce2..e78b324 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -2064,6 +2064,7 @@ restart: >> first_zones_zonelist(zonelist, high_zoneidx, NULL, >> &preferred_zone); >> >> +rebalance: >> /* This is the last chance, in general, before the goto nopage. */ >> page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist, >> high_zoneidx, alloc_flags & ~ALLOC_NO_WATERMARKS, >> @@ -2071,7 +2072,6 @@ restart: >> if (page) >> goto got_pg; >> >> -rebalance: >> /* Allocate without watermarks if the context allows */ >> if (alloc_flags & ALLOC_NO_WATERMARKS) { >> page = __alloc_pages_high_priority(gfp_mask, order, > > I'm sorry I missed this thread long time. > > In this case, I think we should call drain_all_pages(). then following > patch is better. > However I also think your patch is valuable. because while the task is > sleeping in wait_iff_congested(), an another task may free some pages. > thus, rebalance path should try to get free pages. iow, you makes sense. > > So, I'd like to propose to merge both your and my patch. I forgot to write important thing. Your patch looks good to me. Reviewed-by: KOSAKI Motohiro -- 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/