thp: compound_trans_order

Read compound_trans_order safe. Noop for CONFIG_TRANSPARENT_HUGEPAGE=n.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f4ea3410fb4d..741206ffdace 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1027,10 +1027,6 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 {
         struct page_cgroup *pc;
         struct mem_cgroup_per_zone *mz;
-        int page_size = PAGE_SIZE;
-
-        if (PageTransHuge(page))
-                page_size <<= compound_order(page);
 
         if (mem_cgroup_disabled())
                 return NULL;
@@ -2286,8 +2282,10 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
         int ret;
         int page_size = PAGE_SIZE;
 
-        if (PageTransHuge(page))
+        if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
+                VM_BUG_ON(!PageTransHuge(page));
+        }
 
         pc = lookup_page_cgroup(page);
         /* can happen at boot */
@@ -2558,8 +2556,10 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         if (PageSwapCache(page))
                 return NULL;
 
-        if (PageTransHuge(page))
+        if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
+                VM_BUG_ON(!PageTransHuge(page));
+        }
 
         count = page_size >> PAGE_SHIFT;
         /*