From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id C47A56B0011 for ; Tue, 24 May 2011 01:45:31 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 260583EE0AE for ; Tue, 24 May 2011 14:45:28 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id F311245DF49 for ; Tue, 24 May 2011 14:45:27 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id D366745DF46 for ; Tue, 24 May 2011 14:45:27 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id C7038E08001 for ; Tue, 24 May 2011 14:45:27 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 84918E08002 for ; Tue, 24 May 2011 14:45:27 +0900 (JST) Message-ID: <4DDB45EF.2080803@jp.fujitsu.com> Date: Tue, 24 May 2011 14:45:19 +0900 From: KOSAKI Motohiro MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 (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, 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org