linux-kernel - Re: [PATCH v3 2/3] resource: Add release_mem_region

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Date:	Wed, 10 Apr 2013 15:08:29 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Toshi Kani <toshi.kani@...com>
cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linuxram@...ibm.com,
	guz.fnst@...fujitsu.com, tmac@...com,
	isimatu.yasuaki@...fujitsu.com, wency@...fujitsu.com,
	tangchen@...fujitsu.com, jiang.liu@...wei.com
Subject: Re: [PATCH v3 2/3] resource: Add release_mem_region_adjustable()

On Wed, 10 Apr 2013, Toshi Kani wrote:

> > I'll switch it to GFP_ATOMIC.  Which is horridly lame but the
> > allocation is small and alternatives are unobvious.
> 
> Great!  Again, thanks for the update!

release_mem_region_adjustable() allocates at most one struct resource, so 
why not do kmalloc(sizeof(struct resource), GFP_KERNEL) before taking 
resource_lock and then testing whether it's NULL or not when splitting?  
It unnecessarily allocates memory when there's no split, but 
__remove_pages() shouldn't be a hotpath.
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