Hi Hiroshi,

On Thursday, August 23, 2012 8:15 AM Hiroshi Doyu wrote:

On Thu, 23 Aug 2012 07:58:34 +0200
Marek Szyprowski [off-list ref] wrote:

quoted

Hello,

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

quoted

KyongHo Cho [off-list ref] wrote @ Wed, 22 Aug 2012 14:47:00 +0200:

quoted

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.

Ok, I've already sent v2 just now, where, instead of changing it back,
just with GFP_ATOMIC, kzalloc() would be selected, just in case. I guess
that this would be ok(a bit safer?)

I've posted some comments to v2. If you agree with my suggestion, no changes around
those vmalloc() calls will be needed.

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



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