Re: [PATCH] mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls

Marek Szyprowski
2012-11-20T10:49:01Z

Hello,

On 11/19/2012 11:48 PM, Andrew Morton wrote:
> On Sun, 18 Nov 2012 19:18:46 -0500
> Jason Cooper <jason@lakedaemon.net> wrote:
>
> > I've added the maintainers for mm/*. Hopefully they can let us know if
> > this is good for v3.8...
>
> As Marek has inexplicably put this patch into linux-next via his tree,
> we don't appear to be getting a say in the matter!

I've just put this patch to linux-next via my dma-mapping tree to give it
some testing asap to check if other changes to arm dma-mapping are required
or not.

> The patch looks good to me. That open-coded wait loop predates the
> creation of bitkeeper tree(!) but doesn't appear to be needed. There
> will perhaps be some behavioural changes observable for GFP_KERNEL
> callers as dma_pool_alloc() will no longer dip into page reserves but I
> see nothing special about dma_pool_alloc() which justifies doing that
> anyway.
>
> The patch makes pool->waitq and its manipulation obsolete, but it
> failed to remove all that stuff.

Right, I missed that part, I will update it asap.

> The changelog failed to describe the problem which Soren reported.
> That should be included, and as the problem sounds fairly serious we
> might decide to backport the fix into -stable kernels.

Ok, I will extend the changelog.

> dma_pool_alloc()'s use of a local "struct dma_page *page" is
> distressing - MM developers very much expect a local called "page" to
> have type "struct page *". But that's a separate issue.

I will prepare a separate patch cleaning it. I was also a bit surprised
by such naming scheme, but it is probably related to the fact that this
come has not been touched much since a very ancient times.

> As this patch is already in -next and is stuck there for two more
> weeks I can't (or at least won't) merge this patch, so I can't help
> with any of the above.

I will fix both issues in the next version of the patch. Would like to
merge it to your tree or should I keep it in my dma-mapping tree?

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