On Sat, Jun 16, 2018 at 08:08:53AM +0900, Linus Torvalds wrote:

On Fri, Jun 15, 2018 at 2:08 PM Wei Wang [off-list ref] wrote:

quoted

This patch adds a function to get free pages blocks from a free page
list. The obtained free page blocks are hints about free pages, because
there is no guarantee that they are still on the free page list after
the function returns.

...

quoted

+uint32_t get_from_free_page_list(int order, __le64 buf[], uint32_t size)

...

Ack. This is the kind of simple interface where I don't need to worry
about the MM code calling out to random drivers or subsystems.

I think that "order" should be checked for validity, but from a MM
standpoint I think this is fine.

                Linus

The only issue seems to be getting hold of buf that's large enough -
and we don't really know what the size is, or whether one
buf would be enough.

Linus, do you think it would be ok to have get_from_free_page_list
actually pop entries from the free list and use them as the buffer
to store PAs?

Caller would be responsible for freeing the returned entries.

-- 
MST