mm: simplify lock_page_memcg()

Now that migration doesn't clear page->mem_cgroup of live pages anymore,
it's safe to make lock_page_memcg() and the memcg stat functions take
pages, and spare the callers from memcg objects.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index 51a24f6a555d..87311af936f2 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -519,7 +519,6 @@ EXPORT_SYMBOL(invalidate_mapping_pages);
 static int
 invalidate_complete_page2(struct address_space *mapping, struct page *page)
 {
-        struct mem_cgroup *memcg;
         unsigned long flags;
 
         if (page->mapping != mapping)
@@ -528,15 +527,15 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
         if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
                 return 0;
 
-        memcg = lock_page_memcg(page);
+        lock_page_memcg(page);
         spin_lock_irqsave(&mapping->tree_lock, flags);
         if (PageDirty(page))
                 goto failed;
 
         BUG_ON(page_has_private(page));
-        __delete_from_page_cache(page, NULL, memcg);
+        __delete_from_page_cache(page, NULL);
         spin_unlock_irqrestore(&mapping->tree_lock, flags);
-        unlock_page_memcg(memcg);
+        unlock_page_memcg(page);
 
         if (mapping->a_ops->freepage)
                 mapping->a_ops->freepage(page);
@@ -545,7 +544,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
         return 1;
 failed:
         spin_unlock_irqrestore(&mapping->tree_lock, flags);
-        unlock_page_memcg(memcg);
+        unlock_page_memcg(page);
         return 0;
 }