linux-kernel - Re: [PATCH] ARM: DMA: Fix kzalloc flags in __iommu_alloc

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Message-ID: <CAAVeFuL-x1-vmaViYou6ViRR+ipCnz5WdwbmKC4Cu5ViD+pVNA@mail.gmail.com>
Date:	Tue, 13 Jan 2015 17:45:16 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Cc:	Alexandre Courbot <acourbot@...dia.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thierry Reding <treding@...dia.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [PATCH] ARM: DMA: Fix kzalloc flags in __iommu_alloc_buffer()

Ping? This patch still seems to be needed as of today...

On Thu, Dec 11, 2014 at 8:12 PM, Marek Szyprowski
<m.szyprowski@...sung.com> wrote:
>
> On 2014-12-08 09:39, Alexandre Courbot wrote:
>>
>> There doesn't seem to be any valid reason to allocate the pages array
>> with the same flags as the buffer itself. Doing so can eventually lead
>> to the following safeguard in mm/slab.c to be hit:
>>
>> BUG_ON(flags & GFP_SLAB_BUG_MASK);
>>
>> This happens when buffers are allocated with __GFP_DMA32 or
>> __GFP_HIGHMEM.
>>
>> Fix this by allocating the pages array with GFP_KERNEL to follow what is
>> done elsewhere in this file. Using GFP_KERNEL in __iommu_alloc_buffer()
>> is safe because atomic allocations are handled by __iommu_alloc_atomic().
>>
>> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
>> Cc: Russell King <linux@....linux.org.uk>
>> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: Thierry Reding <treding@...dia.com>
>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
>
>
> Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>
>
>> ---
>>   arch/arm/mm/dma-mapping.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
>> index e8907117861e..bc495354c802 100644
>> --- a/arch/arm/mm/dma-mapping.c
>> +++ b/arch/arm/mm/dma-mapping.c
>> @@ -1106,7 +1106,7 @@ static struct page **__iommu_alloc_buffer(struct
>> device *dev, size_t size,
>>         int i = 0;
>>         if (array_size <= PAGE_SIZE)
>> -               pages = kzalloc(array_size, gfp);
>> +               pages = kzalloc(array_size, GFP_KERNEL);
>>         else
>>                 pages = vzalloc(array_size);
>>         if (!pages)
>
>
> Best regards
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>
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