memcontrol: move oom task exclusion to tasklist scan

Creates a helper function to return non-zero if a task is a member of a
memory controller:

	int task_in_mem_cgroup(const struct task_struct *task,
			       const struct mem_cgroup *mem);

When the OOM killer is constrained by the memory controller, the exclusion
of tasks that are not a member of that controller was previously misplaced
and appeared in the badness scoring function.  It should be excluded
during the tasklist scan in select_bad_process() instead.

[akpm@linux-foundation.org: build fix]
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4f580268b1b7..42536c737d9c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -48,6 +48,7 @@ extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
 extern void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask);
 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)
 {
@@ -110,6 +111,12 @@ static inline struct mem_cgroup *mm_cgroup(const struct mm_struct *mm)
         return NULL;
 }
 
+static inline int task_in_mem_cgroup(struct task_struct *task,
+                                     const struct mem_cgroup *mem)
+{
+        return 1;
+}
+
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
 #endif /* _LINUX_MEMCONTROL_H */