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Subject[-mm][PATCH 8/10] fix shmem page migration incorrectness on memcgroup

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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

mem_cgroup_uncharge() against old page is done after radix-tree-replacement.
And there were special handling to ingore swap-cache page. But, shmem can
be swap-cache and file-cache at the same time. Chekcing PageSwapCache() is
not correct here. Check PageAnon() instead.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

---
mm/migrate.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
Index: b/mm/migrate.c
===================================================================
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -332,7 +332,13 @@ static int migrate_page_move_mapping(str
__inc_zone_page_state(newpage, NR_FILE_PAGES);

spin_unlock_irq(&mapping->tree_lock);
- if (!PageSwapCache(newpage))
+
+ /*
+ * The page is removed from radix-tree implicitly.
+ * We uncharge it here but swap cache of anonymous page should be
+ * uncharged by mem_cgroup_ucharge_page().
+ */
+ if (!PageAnon(newpage))
mem_cgroup_uncharge_cache_page(page);

return 0;
@@ -381,7 +387,8 @@ static void migrate_page_copy(struct pag
/*
* SwapCache is removed implicitly. Uncharge against swapcache
* should be called after ClearPageSwapCache() because
- * mem_cgroup_uncharge_page checks the flag.
+ * mem_cgroup_uncharge_page checks the flag. shmem's swap cache
+ * is uncharged before here.
*/
mem_cgroup_uncharge_page(page);
}



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