linux-kernel - Re: [PATCH 01/10] zcache: fix preemptable memory allocation in atomic context

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Message-ID: <4FE08C1A.2020308@linux.vnet.ibm.com>
Date:	Tue, 19 Jun 2012 09:26:34 -0500
From:	Seth Jennings <sjenning@...ux.vnet.ibm.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH 01/10] zcache: fix preemptable memory allocation in atomic
 context

On 06/19/2012 03:32 AM, Xiao Guangrong wrote:

> zcache_do_preload uses ZCACHE_GFP_MASK to allocate memory that will be sleep,
> but zcache_do_preload is called in zcache_put_page where IRQ is disabled
> 
> Fix it by use GFP_ATOMIC flag


Did you get a might_sleep warning on this?  I haven't seen this being an
issue.

GFP_ATOMIC only modifies the existing mask to allow allocation use the
emergency pool.  It is __GFP_WAIT not being set that prevents sleep.  We
don't want to use the emergency pool since we make large, long lived
allocations with this mask.

--
Seth

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