linux-kernel - Re: [PATCH 2/2] mempool: fix first round failure behavior

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Date:	Wed, 21 Dec 2011 16:34:55 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mempool: fix first round failure behavior

Hello, Andrew.

On Wed, Dec 21, 2011 at 4:32 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> This is a significant change in behaviour.  Previously the mempool code
> would preserve emergency pools while waiting for someone to return an
> item.  Now, it will permit many more items to be allocated, chewing
> into the emergency pools.
>
> We *know* that items will soon become available, so why not wait for
> that to happen rather than consuming memory which less robust callers
> could have utilised?
>
> IOW, this change appears to make the kernel more vulnerable to memory
> exhaustion failures?

Yeah, that's me misreading the code.  mempool allocator doesn't retry
with the original gfp mask.  It does with umm... less modified one, so
the patch description is wrong but the behavior w.r.t. emergency pool
doesn't change. I'm rewriting the commit message.

Thanks.

-- 
tejun
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