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

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Message-ID: <CAAVeFuKn6nE+KOSexGSK_=r5iv8bYBEheVU7=HyODGszEz+NAw@mail.gmail.com>
Date:	Thu, 22 Jan 2015 13:41:25 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	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()

On Tue, Jan 13, 2015 at 8:20 PM, Marek Szyprowski
<m.szyprowski@...sung.com> wrote:
> Hello,
>
> On 2015-01-13 09:45, Alexandre Courbot wrote:
>>
>> Ping? This patch still seems to be needed as of today...
>
>
> Arnd, could you take this patch together with your other pending
> dma-mapping.h changes?

Arnd, gentle ping on this?

>
>
>> 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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