memcg: move_lists on page not page_cgroup

Each caller of mem_cgroup_move_lists is having to use page_get_page_cgroup:
it's more convenient if it acts upon the page itself not the page_cgroup; and
in a later patch this becomes important to handle within memcontrol.c.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 9 insertions, 7 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e4247c83c1c7..56432ff8d4e3 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -36,7 +36,7 @@ extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask);
 extern void mem_cgroup_uncharge(struct page_cgroup *pc);
 extern void mem_cgroup_uncharge_page(struct page *page);
-extern void mem_cgroup_move_lists(struct page_cgroup *pc, bool active);
+extern void mem_cgroup_move_lists(struct page *page, bool active);
 extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
                                         struct list_head *dst,
                                         unsigned long *scanned, int order,
@@ -106,8 +106,7 @@ static inline void mem_cgroup_uncharge_page(struct page *page)
 {
 }
 
-static inline void mem_cgroup_move_lists(struct page_cgroup *pc,
-                                                bool active)
+static inline void mem_cgroup_move_lists(struct page *page, bool active)
 {
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 41041c0a6898..afdd406f618a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -407,11 +407,13 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
 /*
  * This routine assumes that the appropriate zone's lru lock is already held
  */
-void mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
+void mem_cgroup_move_lists(struct page *page, bool active)
 {
+        struct page_cgroup *pc;
         struct mem_cgroup_per_zone *mz;
         unsigned long flags;
 
+        pc = page_get_page_cgroup(page);
         if (!pc)
                 return;
 
diff --git a/mm/swap.c b/mm/swap.c
index 710a20bb9749..d4ec59aa5c46 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -176,7 +176,7 @@ void activate_page(struct page *page)
                 SetPageActive(page);
                 add_page_to_active_list(zone, page);
                 __count_vm_event(PGACTIVATE);
-                mem_cgroup_move_lists(page_get_page_cgroup(page), true);
+                mem_cgroup_move_lists(page, true);
         }
         spin_unlock_irq(&zone->lru_lock);
 }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 106ba10e1ac6..45711585684e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1128,7 +1128,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
                 ClearPageActive(page);
 
                 list_move(&page->lru, &zone->inactive_list);
-                mem_cgroup_move_lists(page_get_page_cgroup(page), false);
+                mem_cgroup_move_lists(page, false);
                 pgmoved++;
                 if (!pagevec_add(&pvec, page)) {
                         __mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
@@ -1156,8 +1156,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
                 VM_BUG_ON(PageLRU(page));
                 SetPageLRU(page);
                 VM_BUG_ON(!PageActive(page));
+
                 list_move(&page->lru, &zone->active_list);
-                mem_cgroup_move_lists(page_get_page_cgroup(page), true);
+                mem_cgroup_move_lists(page, true);
                 pgmoved++;
                 if (!pagevec_add(&pvec, page)) {
                         __mod_zone_page_state(zone, NR_ACTIVE, pgmoved);