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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, rientjes@google.com, clameter@sgi.com
Subject: Re: [PATCH 0/6] Use two zonelists per node instead of multiple zonelists v11r2
Date: Thu, 13 Dec 2007 09:23:38 +0900	[thread overview]
Message-ID: <20071213092338.8b10944c.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <1197495172.5029.62.camel@localhost>

On Wed, 12 Dec 2007 16:32:51 -0500
Lee Schermerhorn <Lee.Schermerhorn@hp.com> wrote:

> Just this afternoon, I hit a null pointer deref in
> __mem_cgroup_remove_list() [called from mem_cgroup_uncharge() if I can
> trust the stack trace] attempting to unmap a page for migration.  I'm
> just starting to investigate this.
> 
> I'll replace the series I have [~V10] with V11r2 and continue testing in
> anticipation of the day that we can get this into -mm.
> 
Hi, Lee-san.

Could you know what is the caller of page migration ?
system call ? hot removal ? or some new thing ?

Note: 2.6.24-rc4-mm1's cgroup/migration logic.

In 2.6.24-rc4-mm1, in page migration, mem_cgroup_prepare_migration() increments
page_cgroup's refcnt before calling try_to_unmap(). This extra refcnt guarantees 
the page_cgroup's refcnt will not drop to 0 in sequence of
unmap_and_move() -> try_to_unmap() -> page_remove_rmap() -> mem_cgroup_unchage(). 

Thanks,
-Kame

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  reply	other threads:[~2007-12-13  0:23 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-11 20:21 Mel Gorman
2007-12-11 20:22 ` [PATCH 1/6] Use zonelists instead of zones when direct reclaiming pages Mel Gorman
2007-12-11 20:22 ` [PATCH 2/6] Introduce node_zonelist() for accessing the zonelist for a GFP mask Mel Gorman
2007-12-11 20:22 ` [PATCH 3/6] Remember what the preferred zone is for zone_statistics Mel Gorman
2007-12-11 20:23 ` [PATCH 4/6] Use two zonelist that are filtered by GFP mask Mel Gorman
2007-12-11 20:23 ` [PATCH 5/6] Have zonelist contains structs with both a zone pointer and zone_idx Mel Gorman
2007-12-11 20:23 ` [PATCH 6/6] Filter based on a nodemask as well as a gfp_mask Mel Gorman
2007-12-11 21:51 ` [PATCH 0/6] Use two zonelists per node instead of multiple zonelists v11r2 Andrew Morton
2007-12-12 21:32 ` Lee Schermerhorn
2007-12-13  0:23   ` KAMEZAWA Hiroyuki [this message]
2007-12-13 16:16     ` Lee Schermerhorn

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