Re: CMA broken in next-20120926

From: Mark Brown
Date: Thu Sep 27 2012 - 13:50:03 EST


On Thu, Sep 27, 2012 at 05:59:19PM +0200, Marek Szyprowski wrote:
> On Thursday, September 27, 2012 1:29 PM Thierry Reding wrote:

> > any idea why CMA might be broken in next-20120926. I see that there
> > haven't been any major changes to CMA itself, but there's been quite a
> > bit of restructuring of various memory allocation bits lately. I wasn't
> > able to track the problem down, though.

> > What I see is this during boot (with CMA_DEBUG enabled):

> > [ 0.266904] cma: dma_alloc_from_contiguous(cma db474f80, count 64, align 6)
> > [ 0.284469] cma: dma_alloc_from_contiguous(): memory range at c09d7000 is busy, retrying
> > [ 0.293648] cma: dma_alloc_from_contiguous(): memory range at c09d7800 is busy, retrying
> > ...
> > [ 2.648619] DMA: failed to allocate 256 KiB pool for atomic coherent allocation
> > ...
> > [ 4.196193] WARNING: at /home/thierry.reding/src/kernel/linux-ipmp.git/arch/arm/mm/dma-
> > mapping.c:485 __alloc_from_pool+0xdc/0x110()
> > [ 4.207988] coherent pool not initialised!

> > So the pool isn't getting initialized properly because CMA can't get at
> > the memory. Do you have any hints as to what might be going on? If it's
> > any help, I started seeing this with next-20120926 and it is in today's
> > next as well.

> Thanks for the report, I will check this issue asap.

Myself and Peter have seen the same thing, though neither of us drilled
down enough to make a sensible report.
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