2011/11/18 Michal Nazarewicz [off-list ref]:

On Fri, 18 Nov 2011 22:20:48 +0100, sandeep patil [off-list ref]
wrote:

quoted

I am running a simple test to allocate contiguous regions and write a log
on
in a file on sdcard simultaneously. I can reproduce this migration failure
100%
times with it.
when I tracked the pages that failed to migrate, I found them on the
buffer head lru
list with a reference held on the buffer_head in the page, which
causes drop_buffers()
to fail.

So, i guess my question is, until all the migration failures are
tracked down and fixed,
is there a plan to retry the contiguous allocation from a new range in
the CMA region?

No. ?Current CMA implementation will stick to the same range of pages also
on consequent allocations of the same size.

Doesn't that mean the drivers that fail to allocate from contiguous DMA region
will fail, if the migration fails?

~ sandeep