linux-kernel - Re: [PATCH] MIPS: Fix DMA contiguous allocation

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Date:	Wed, 9 Dec 2015 14:32:46 +0000
From:	Qais Yousef <qais.yousef@...tec.com>
To:	Mel Gorman <mgorman@...hsingularity.net>,
	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-mips@...ux-mips.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, <ralf@...ux-mips.org>
Subject: Re: [PATCH] MIPS: Fix DMA contiguous allocation

On 12/09/2015 11:36 AM, Mel Gorman wrote:
> On Tue, Dec 08, 2015 at 02:19:39PM -0800, Andrew Morton wrote:
>> On Tue, 8 Dec 2015 10:18:50 +0000 Qais Yousef <qais.yousef@...tec.com> wrote:
>>
>>> --- a/arch/mips/mm/dma-default.c
>>> +++ b/arch/mips/mm/dma-default.c
>>> @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size,
>>>   
>>>   	gfp = massage_gfp_flags(dev, gfp);
>>>   
>>> -	if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC))
>>> +	if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC))
>>>   		page = dma_alloc_from_contiguous(dev,
>>>   					count, get_order(size));
>>>   	if (!page)
>> hm.  It seems that the code is asking "can I do a potentially-sleeping
>> memory allocation"?
>>
>> The way to do that under the new regime is
>>
>> 	if (IS_ENABLED(CONFIG_DMA_CMA) && gfpflags_allow_blocking(gfp))
>>
>> Mel, can you please confirm?
> Yes, this is the correct way it should be checked. The full flags cover
> watermark and kswapd treatment which potentially could be altered by
> the caller.
>

OK thanks both. I'll send a revised version with this change.

Thanks,
Qais
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