On 6/30/17 5:57 PM, Jerome Glisse wrote:
On Fri, Jun 30, 2017 at 04:19:25PM -0700, Evgeny Baskakov wrote:
Hi Jerome,
It seems that the kernel can pass 0 in src_pfns for pages that it cannot
migrate (i.e. the kernel knows that they cannot migrate prior to calling
alloc_and_copy).
So, a zero in src_pfns can mean either "the page is not allocated yet" or
"the page cannot migrate".
Can migrate_vma set the MIGRATE_PFN_MIGRATE flag for not allocated pages? On
the driver side it is difficult to differentiate between the cases.
So this is what is happening in v24. For thing that can not be migrated you
get 0 and for things that are not allocated you get MIGRATE_PFN_MIGRATE like
the updated comments in migrate.h explain.
Cheers,
Jérôme
Yes, I see the updated documentation in migrate.h. The issue seems to be gone now in v24.
Thanks!
Evgeny Baskakov
NVIDIA
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