From: Mel Gorman <mgorman@suse.de>
Date: Wed, 20 Feb 2013 02:14:37 +0000 (+1100)
Subject: mm: numa: take THP into account when migrating pages for NUMA balancing
X-Git-Tag: next-20130220~1^2~472
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4e089822144dcdfdb02edbbc85b72f1e135cc7ed;p=karo-tx-linux.git

mm: numa: take THP into account when migrating pages for NUMA balancing

Wanpeng Li pointed out that numamigrate_isolate_page() assumes that only
one base page is being migrated when in fact it can also be checking THP.
The consequences are that a migration will be attempted when a target node
is nearly full and fail later.  It's unlikely to be user-visible but it
should be fixed.  While we are there, migrate_balanced_pgdat() should
treat nr_migrate_pages as an unsigned long as it is treated as a
watermark.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Suggested-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Simon Jeons <simon.jeons@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/migrate.c b/mm/migrate.c
index 2fd8b4af4744..77f4e70df24d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1461,7 +1461,7 @@ int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
  * pages. Currently it only checks the watermarks which crude
  */
 static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
-				   int nr_migrate_pages)
+				   unsigned long nr_migrate_pages)
 {
 	int z;
 	for (z = pgdat->nr_zones - 1; z >= 0; z--) {
@@ -1559,8 +1559,10 @@ int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 {
 	int ret = 0;
 
+	VM_BUG_ON(compound_order(page) && !PageTransHuge(page));
+
 	/* Avoid migrating to a node that is nearly full */
-	if (migrate_balanced_pgdat(pgdat, 1)) {
+	if (migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) {
 		int page_lru;
 
 		if (isolate_lru_page(page)) {