Re: [Linaro-mm-sig] [PATCHv17 0/11] Contiguous Memory Allocator

[sandeep patil]

On Fri, Nov 18, 2011 at 8:43 AM, Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
> Welcome everyone once again,

> Please notice that this patch series is aimed to start further
> discussion. There are still few issues that need to be resolved before
> CMA will be really ready. The most hot problem is the issue with movable
> pages that causes migration to fail from time to time. Our investigation
> leads us to the point that these rare pages cannot be migrated because
> there are some pending io operations on them.


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?

~ sandeep
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