linux-kernel - Re: [PATCH 03/33] mm: slub: add knowledge of reserve pages

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Message-Id: <200710311437.28630.nickpiggin@yahoo.com.au>
Date:	Wed, 31 Oct 2007 14:37:28 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	netdev@...r.kernel.org, trond.myklebust@....uio.no
Subject: Re: [PATCH 03/33] mm: slub: add knowledge of reserve pages

On Wednesday 31 October 2007 03:04, Peter Zijlstra wrote:
> Restrict objects from reserve slabs (ALLOC_NO_WATERMARKS) to allocation
> contexts that are entitled to it.
>
> Care is taken to only touch the SLUB slow path.
>
> This is done to ensure reserve pages don't leak out and get consumed.

I think this is generally a good idea (to prevent slab allocators
from stealing reserve). However I naively think the implementation
is a bit overengineered and thus has a few holes.

Humour me, what was the problem with failing the slab allocation
(actually, not fail but just call into the page allocator to do
correct waiting  / reclaim) in the slowpath if the process fails the
watermark checks?
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