mm: numa: Copy cpupid on page migration

After page migration, the new page has the nidpid unset. This makes
every fault on a recently migrated page look like a first numa fault,
leading to another page migration.

Copying over the nidpid at page migration time should prevent erroneous
migrations of recently migrated pages.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-46-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index ff537749d3b465539435f6b9cd991989b740817f..44c1fa9d6f5456e429f33ea515d2f66697f40a99 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -443,6 +443,8 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
  */
 void migrate_page_copy(struct page *newpage, struct page *page)
 {
+       int cpupid;
+
        if (PageHuge(page) || PageTransHuge(page))
                copy_huge_page(newpage, page);
        else
@@ -479,6 +481,13 @@ void migrate_page_copy(struct page *newpage, struct page *page)
                        __set_page_dirty_nobuffers(newpage);
        }
 
+       /*
+        * Copy NUMA information to the new page, to prevent over-eager
+        * future migrations of this same page.
+        */
+       cpupid = page_cpupid_xchg_last(page, -1);
+       page_cpupid_xchg_last(newpage, cpupid);
+
        mlock_migrate_page(newpage, page);
        ksm_migrate_page(newpage, page);
        /*