Re: [PATCH v2] mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls

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On 15.01.2013 22:56, Jason Cooper wrote:
Soeren,

On Tue, Jan 15, 2013 at 03:16:17PM -0500, Jason Cooper wrote:
If my understanding is correct, one of the drivers (most likely one)
either asks for too small of a dma buffer, or is not properly
deallocating blocks from the per-device pool.  Either case leads to
exhaustion, and falling back to the atomic pool.  Which subsequently
gets wiped out as well.

If my hunch is right, could you please try each of the three dvb drivers
in turn and see which one (or more than one) causes the error?


In fact I use only 2 types of DVB sticks: em28xx usb bridge plus drxk
demodulator, and dib0700 usb bridge plus dib7000p demod.

I would bet for em28xx causing the error, but this is not thoroughly
tested. Unfortunately testing with removed sticks is not easy, because
this is a production system and disabling some services for the long
time we need to trigger this error will certainly result in unhappy
users.

I will see what I can do here. Is there an easy way to track the buffer
usage without having to wait for complete exhaustion?

In linux-3.5.x there is no such problem. Can we use all available memory
for dma buffers here on armv5 architectures, in contrast to newer
kernels?

Regards,
Soeren

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