memcontrol: add vm_match_cgroup()

mm_cgroup() is exclusively used to test whether an mm's mem_cgroup pointer
is pointing to a specific cgroup.  Instead of returning the pointer, we can
just do the test itself in a new macro:

	vm_match_cgroup(mm, cgroup)

returns non-zero if the mm's mem_cgroup points to cgroup.  Otherwise it
returns zero.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index a0e92a263d12..8fd527c4e2bf 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -321,7 +321,7 @@ static int page_referenced_anon(struct page *page,
                  * counting on behalf of references from different
                  * cgroups
                  */
-                if (mem_cont && (mm_cgroup(vma->vm_mm) != mem_cont))
+                if (mem_cont && !vm_match_cgroup(vma->vm_mm, mem_cont))
                         continue;
                 referenced += page_referenced_one(page, vma, &mapcount);
                 if (!mapcount)
@@ -382,7 +382,7 @@ static int page_referenced_file(struct page *page,
                  * counting on behalf of references from different
                  * cgroups
                  */
-                if (mem_cont && (mm_cgroup(vma->vm_mm) != mem_cont))
+                if (mem_cont && !vm_match_cgroup(vma->vm_mm, mem_cont))
                         continue;
                 if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
                                   == (VM_LOCKED|VM_MAYSHARE)) {