mm/ksm: add ksm_get_folio

Patch series "transfer page to folio in KSM".

This is the first part of page to folio transfer on KSM.  Since only
single page could be stored in KSM, we could safely transfer stable tree
pages to folios.  

This patchset could reduce ksm.o 57kbytes from 2541776 bytes on latest
akpm/mm-stable branch with CONFIG_DEBUG_VM enabled.  It pass the KSM
testing in LTP and kernel selftest.

Thanks for Matthew Wilcox and David Hildenbrand's suggestions and
comments!


This patch (of 10):

The ksm only contains single pages, so we could add a new func
ksm_get_folio for get_ksm_page to use folio instead of pages to save a
couple of compound_head calls.

After all caller replaced, get_ksm_page will be removed.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alex Shi (tencent) <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Izik Eidus <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Chris Wright <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions