mm: memcontrol: cleanup kmem charge functions

 - Handle memcg_kmem_enabled check out to the caller. This reduces the
   number of function definitions making the code easier to follow. At
   the same time it doesn't result in code bloat, because all of these
   functions are used only in one or two places.

 - Move __GFP_ACCOUNT check to the caller as well so that one wouldn't
   have to dive deep into memcg implementation to see which allocations
   are charged and which are not.

 - Refresh comments.

Link: http://lkml.kernel.org/r/52882a28b542c1979fd9a033b4dc8637fc347399.1464079537.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 13cf4c665321..de2491c42d4f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4009,7 +4009,8 @@ struct page *alloc_kmem_pages(gfp_t gfp_mask, unsigned int order)
         struct page *page;
 
         page = alloc_pages(gfp_mask, order);
-        if (page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
+        if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) &&
+            page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
                 __free_pages(page, order);
                 page = NULL;
         }
@@ -4021,7 +4022,8 @@ struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
         struct page *page;
 
         page = alloc_pages_node(nid, gfp_mask, order);
-        if (page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
+        if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) &&
+            page && memcg_kmem_charge(page, gfp_mask, order) != 0) {
                 __free_pages(page, order);
                 page = NULL;
         }
@@ -4034,7 +4036,8 @@ struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
  */
 void __free_kmem_pages(struct page *page, unsigned int order)
 {
-        memcg_kmem_uncharge(page, order);
+        if (memcg_kmem_enabled())
+                memcg_kmem_uncharge(page, order);
         __free_pages(page, order);
 }