linux-kernel - Re: [PATCH 2/2] ARM: dma-mapping: fix alloc/free for coherent + CMA + gfp=0

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Message-ID: <20160223153003.GB22447@lnxrabinv.se.axis.com>
Date:	Tue, 23 Feb 2016 16:30:03 +0100
From:	Rabin Vincent <rabin@....in>
To:	Michal Nazarewicz <mina86@...a86.com>
Cc:	Rabin Vincent <rabin.vincent@...s.com>, linux@....linux.org.uk,
	akpm@...ux-foundation.org, linux-arm-kernel@...ts.infradead.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ARM: dma-mapping: fix alloc/free for coherent + CMA
 + gfp=0

On Fri, Feb 19, 2016 at 02:50:52PM +0100, Michal Nazarewicz wrote:
> I haven’t looked closely at the code, but why not:
> 
> 	struct cma *cma = 
>         if (!cma_release(dev_get_cma_area(dev), page, size >> PAGE_SHIFT)) {
> 		// ... do whatever other non-CMA free
> 	}

The page tables changes need to be done before we release the area with
cma_release().  With the v2 patchset which I've sent to LAKML we won't
need a new in_cma() function since we'll now record how we allocated the
buffer and use this information in the free routine.