Re: [00/41] Large Blocksize Support V7 (adds memmap support)
From: Nick Piggin
Date: Tue Sep 11 2007 - 17:48:21 EST
On Wednesday 12 September 2007 07:41, Christoph Lameter wrote:
> On Tue, 11 Sep 2007, Nick Piggin wrote:
> > I think I would have as good a shot as any to write a fragmentation
> > exploit, yes. I think I've given you enough info to do the same, so I'd
> > like to hear a reason why it is not a problem.
>
> No you have not explained why the theoretical issues continue to exist
> given even just considering Lumpy Reclaim in .23 nor what effect the
> antifrag patchset would have.
So how does lumpy reclaim, your slab patches, or anti-frag have
much effect on the worst case situation? Or help much against a
targetted fragmentation attack?
> And you have used a 2M pagesize which is
> irrelevant to this patchset that deals with blocksizes up to 64k. In my
> experience the use of blocksize < PAGE_COSTLY_ORDER (32k) is reasonably
> safe.
I used EXACTLY the page sizes that you brought up in your patch
description (ie. 64K and 2MB).
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