mm: memcg: push down PageSwapCache check into uncharge entry functions
authorJohannes Weiner <hannes@cmpxchg.org>
Tue, 31 Jul 2012 23:45:31 +0000 (16:45 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 1 Aug 2012 01:42:48 +0000 (18:42 -0700)
Not all uncharge paths need to check if the page is swapcache, some of
them can know for sure.

Push down the check into all callsites of uncharge_common() so that the
patch that removes some of them is more obvious.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memcontrol.c

index 7eadcdad06f31bb7ed7b86fd321d4aebf5fbb595..87c2ec49b4825303b1ba48b98b844c88fb3bab76 100644 (file)
@@ -2987,8 +2987,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
        if (mem_cgroup_disabled())
                return NULL;
 
-       if (PageSwapCache(page))
-               return NULL;
+       VM_BUG_ON(PageSwapCache(page));
 
        if (PageTransHuge(page)) {
                nr_pages <<= compound_order(page);
@@ -3085,6 +3084,8 @@ void mem_cgroup_uncharge_page(struct page *page)
        if (page_mapped(page))
                return;
        VM_BUG_ON(page->mapping && !PageAnon(page));
+       if (PageSwapCache(page))
+               return;
        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
 }
 
@@ -3092,6 +3093,8 @@ void mem_cgroup_uncharge_cache_page(struct page *page)
 {
        VM_BUG_ON(page_mapped(page));
        VM_BUG_ON(page->mapping);
+       if (PageSwapCache(page))
+               return;
        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
 }
 
@@ -3156,6 +3159,8 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
        if (!swapout) /* this was a swap cache but the swap is unused ! */
                ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
 
+       if (PageSwapCache(page))
+               return;
        memcg = __mem_cgroup_uncharge_common(page, ctype, false);
 
        /*
@@ -3345,10 +3350,11 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg,
                unused = oldpage;
        }
        anon = PageAnon(used);
-       __mem_cgroup_uncharge_common(unused,
-               anon ? MEM_CGROUP_CHARGE_TYPE_ANON
-                    : MEM_CGROUP_CHARGE_TYPE_CACHE,
-               true);
+       if (!PageSwapCache(unused))
+               __mem_cgroup_uncharge_common(unused,
+                                            anon ? MEM_CGROUP_CHARGE_TYPE_ANON
+                                            : MEM_CGROUP_CHARGE_TYPE_CACHE,
+                                            true);
        css_put(&memcg->css);
        /*
         * We disallowed uncharge of pages under migration because mapcount