Re: [stable] [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous

From: Greg KH <greg@kroah.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: akpm@linux-foundation.org, Andrea Arcangeli <aarcange@redhat.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Ury Stankevich <urykhy@gmail.com>,
	stable@kernel.org
Subject: Re: [stable] [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous
Date: Mon, 30 May 2011 22:45:02 +0800	[thread overview]
Message-ID: <20110530144502.GA2689@kroah.com> (raw)
In-Reply-To: <20110530131300.GQ5044@csn.ul.ie>

On Mon, May 30, 2011 at 02:13:00PM +0100, Mel Gorman wrote:
> Asynchronous compaction is used when promoting to huge pages. This is
> all very nice but if there are a number of processes in compacting
> memory, a large number of pages can be isolated. An "asynchronous"
> process can stall for long periods of time as a result with a user
> reporting that firefox can stall for 10s of seconds. This patch aborts
> asynchronous compaction if too many pages are isolated as it's better to
> fail a hugepage promotion than stall a process.
> 
> If accepted, this should also be considered for 2.6.39-stable. It should
> also be considered for 2.6.38-stable but ideally [11bc82d6: mm:
> compaction: Use async migration for __GFP_NO_KSWAPD and enforce no
> writeback] would be applied to 2.6.38 before consideration.
> 
> Reported-and-Tested-by: Ury Stankevich <urykhy@gmail.com>
> Signed-off-by: Mel Gorman <mgorman@suse.de>
> ---
>  mm/compaction.c |   32 ++++++++++++++++++++++++++------
>  1 files changed, 26 insertions(+), 6 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>