linux-kernel - Re: [PATCH 4/4] ARM: remove consistent dma region and use common vmalloc range for dma allocations

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Message-ID: <20120413183813.GO24211@n2100.arm.linux.org.uk>
Date:	Fri, 13 Apr 2012 19:38:13 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	linaro-mm-sig@...ts.linaro.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Arnd Bergmann <arnd@...db.de>,
	Chunsang Jeong <chunsang.jeong@...aro.org>,
	Krishna Reddy <vdumpa@...dia.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Hiroshi Doyu <hdoyu@...dia.com>,
	Subash Patel <subashrp@...il.com>
Subject: Re: [PATCH 4/4] ARM: remove consistent dma region and use common
	vmalloc range for dma allocations

On Fri, Apr 13, 2012 at 04:05:50PM +0200, Marek Szyprowski wrote:
> This patch changes dma-mapping subsystem to use generic vmalloc areas
> for all consistent dma allocations. This increases the total size limit
> of the consistent allocations and removes platform hacks and a lot of
> duplicated code.

NAK.  I don't think you appreciate the contexts from which the dma coherent
code can be called from, and the reason why we pre-allocate the page
tables (so that IRQ-based allocations work.)

The vmalloc region doesn't allow that because page tables are allocated
using GFP_KERNEL not GFP_ATOMIC.

Sorry.
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