From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227])
	by kanga.kvack.org (Postfix) with SMTP id F312162008E
	for <linux-mm@kvack.org>; Wed,  7 Apr 2010 22:57:23 -0400 (EDT)
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: [PATCH 63 of 67] disable migreate_prep()
Message-Id: <34a31b5dcd314ad1bd89.1270691506@v2.random>
In-Reply-To: <patchbomb.1270691443@v2.random>
References: <patchbomb.1270691443@v2.random>
Date: Thu, 08 Apr 2010 03:51:46 +0200
From: Andrea Arcangeli <aarcange@redhat.com>
Sender: owner-linux-mm@kvack.org
To: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>, Izik Eidus <ieidus@redhat.com>, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Nick Piggin <npiggin@suse.de>, Rik van Riel <riel@redhat.com>, Mel Gorman <mel@csn.ul.ie>, Dave Hansen <dave@linux.vnet.ibm.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Ingo Molnar <mingo@elte.hu>, Mike Travis <travis@sgi.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Christoph Lameter <cl@linux-foundation.org>, Chris Wright <chrisw@sous-sol.org>, bpicco@redhat.com, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Balbir Singh <balbir@linux.vnet.ibm.com>, Arnd Bergmann <arnd@arndb.de>, "Michael S. Tsirkin" <mst@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Johannes Weiner <hannes@cmpxchg.org>, Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>, Chris Mason <chris.mason@oracle.com>
List-ID: <linux-mm.kvack.org>

From: Andrea Arcangeli <aarcange@redhat.com>

I get trouble from lockdep if I leave it enabled:

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.34-rc3 #50
-------------------------------------------------------
largepages/4965 is trying to acquire lock:
 (events){+.+.+.}, at: [<ffffffff8105b788>] flush_work+0x38/0x130

 but task is already holding lock:
  (&mm->mmap_sem){++++++}, at: [<ffffffff8141b022>] do_page_fault+0xd2/0x430


flush_work apparently wants to run free from lock and it bugs in:

	lock_map_acquire(&cwq->wq->lockdep_map);

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -379,7 +379,9 @@ static int compact_zone(struct zone *zon
 	cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
 	cc->free_pfn &= ~(pageblock_nr_pages-1);
 
+#if 0
 	migrate_prep();
+#endif
 
 	while ((ret = compact_finished(zone, cc)) == COMPACT_INCOMPLETE) {
 		unsigned long nr_migrate, nr_remaining;

--
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/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>