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Message-ID: <20110427084319.GM4658@suse.de>
Date: Wed, 27 Apr 2011 09:43:19 +0100
From: Mel Gorman <mgorman@...e.de>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Linux-MM <linux-mm@...ck.org>,
Linux-Netdev <netdev@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
David Miller <davem@...emloft.net>, Neil Brown <neilb@...e.de>
Subject: Re: [PATCH 00/13] Swap-over-NBD without deadlocking
On Tue, Apr 26, 2011 at 04:50:49PM +0200, Peter Zijlstra wrote:
> On Tue, 2011-04-26 at 15:46 +0100, Mel Gorman wrote:
> >
> > I did find that only a few route-cache entries should be required. In
> > the original patches I worked with, there was a reservation for the
> > maximum possible number of route-cache entries. I thought this was
> > overkill and instead reserved 1-per-active-swapfile-backed-by-NFS.
>
> Right, so the thing I was worried about was a route-cache poison attack
> where someone would spam the machine such that it would create a lot of
> route cache entries and might flush the one we needed just as we needed
> it.
>
> Pinning the one entry we need would solve that (if possible).
That is a possibility all right, nice thoughts there. Ok, as I do
not want this series to grow to the point where it is unreviewable,
I'll mark pinning the routing cache entry for a follow-on series.
In this series, the throttling logic should allow a new routing cache
entry to be allocated by kswapd as it's immune to the throttle.
Thanks.
--
Mel Gorman
SUSE Labs
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