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, 5 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dd39ba000b31..d97af9636ab2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3288,15 +3288,18 @@ void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
                                   struct mem_cgroup **memcgp)
 {
         struct mem_cgroup *memcg = NULL;
+        unsigned int nr_pages = 1;
         struct page_cgroup *pc;
         enum charge_type ctype;
 
         *memcgp = NULL;
 
-        VM_BUG_ON(PageTransHuge(page));
         if (mem_cgroup_disabled())
                 return;
 
+        if (PageTransHuge(page))
+                nr_pages <<= compound_order(page);
+
         pc = lookup_page_cgroup(page);
         lock_page_cgroup(pc);
         if (PageCgroupUsed(pc)) {
@@ -3358,7 +3361,7 @@ void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
          * charged to the res_counter since we plan on replacing the
          * old one and only one page is going to be left afterwards.
          */
-        __mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);
+        __mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false);
 }
 
 /* remove redundant charge if migration failed*/