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SubjectRE: [RFC 2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP_ATOMIC
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Hello,

On Wednesday, August 22, 2012 3:37 PM Hiroshi Doyu wrote:

> KyongHo Cho <pullip.cho@samsung.com> wrote @ Wed, 22 Aug 2012 14:47:00 +0200:
>
> > vzalloc() call in __iommu_alloc_buffer() also causes BUG() in atomic context.
>
> Right.
>
> I've been thinking that kzalloc() may be enough here, since
> vzalloc() was introduced to avoid allocation failure for big chunk of
> memory, but I think that it's unlikely that the number of page array
> can be so big. So I propose to drop vzalloc() here, and just simply to
> use kzalloc only as below(*1).

We already had a discussion about this, so I don't think it makes much sense to
change it back to kzalloc. This vmalloc() call won't hurt anyone. It should not
be considered a problem for atomic allocations, because no sane driver will try
to allocate buffers larger than a dozen KiB with GFP_ATOMIC flag. I would call
such try a serious bug, which we should not care here.

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center





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