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>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 9815951..925d57b 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -51,10 +51,8 @@ extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                        gfp_t gfp_mask);
 int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
 
-static inline struct mem_cgroup *mm_cgroup(const struct mm_struct *mm)
-{
-       return rcu_dereference(mm->mem_cgroup);
-}
+#define vm_match_cgroup(mm, cgroup)    \
+       ((cgroup) == rcu_dereference((mm)->mem_cgroup))
 
 extern int mem_cgroup_prepare_migration(struct page *page);
 extern void mem_cgroup_end_migration(struct page *page);
@@ -123,9 +121,9 @@ static inline int mem_cgroup_cache_charge(struct page *page,
        return 0;
 }
 
-static inline struct mem_cgroup *mm_cgroup(const struct mm_struct *mm)
+static inline int vm_match_cgroup(struct mm_struct *mm, struct mem_cgroup *mem)
 {
-       return NULL;
+       return 1;
 }
 
 static inline int task_in_mem_cgroup(struct task_struct *task,

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c2c702..6bded84 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -399,7 +399,7 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
        int ret;
 
        task_lock(task);
-       ret = task->mm && mm_cgroup(task->mm) == mem;
+       ret = task->mm && vm_match_cgroup(task->mm, mem);
        task_unlock(task);
        return ret;
 }

diff --git a/mm/rmap.c b/mm/rmap.c
index a0e92a2..8fd527c 100644 (file)
--- 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)) {