mm: numa: Add THP migration for the NUMA working set scanning fault case.

Note: This is very heavily based on a patch from Peter Zijlstra with
	fixes from Ingo Molnar, Hugh Dickins and Johannes Weiner.  That patch
	put a lot of migration logic into mm/huge_memory.c where it does
	not belong. This version puts tries to share some of the migration
	logic with migrate_misplaced_page.  However, it should be noted
	that now migrate.c is doing more with the pagetable manipulation
	than is preferred. The end result is barely recognisable so as
	before, the signed-offs had to be removed but will be re-added if
	the original authors are ok with it.

Add THP migration for the NUMA working set scanning fault case.

It uses the page lock to serialize. No migration pte dance is
necessary because the pte is already unmapped when we decide
to migrate.

[dhillf@gmail.com: Fix memory leak on isolation failure]
[dhillf@gmail.com: Fix transfer of last_nid information]
Signed-off-by: Mel Gorman <mgorman@suse.de>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 91556889adac..51eac4bdc606 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -79,6 +79,12 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 extern int migrate_misplaced_page(struct page *page, int node);
 extern int migrate_misplaced_page(struct page *page, int node);
 extern bool migrate_ratelimited(int node);
+extern int migrate_misplaced_transhuge_page(struct mm_struct *mm,
+                        struct vm_area_struct *vma,
+                        pmd_t *pmd, pmd_t entry,
+                        unsigned long address,
+                        struct page *page, int node);
+
 #else
 static inline int migrate_misplaced_page(struct page *page, int node)
 {
@@ -88,6 +94,15 @@ static inline bool migrate_ratelimited(int node)
 {
         return false;
 }
+
+static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm,
+                        struct vm_area_struct *vma,
+                        pmd_t *pmd, pmd_t entry,
+                        unsigned long address,
+                        struct page *page, int node)
+{
+        return -EAGAIN;
+}
 #endif /* CONFIG_NUMA_BALANCING */
 
 #endif /* _LINUX_MIGRATE_H */