oom: make oom_unkillable_task() helper function

Presently we have the same task check in two places. Unify it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 11 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b9816ea2eb8f..2c993e47487f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -101,6 +101,26 @@ static struct task_struct *find_lock_task_mm(struct task_struct *p)
         return NULL;
 }
 
+/* return true if the task is not adequate as candidate victim task. */
+static bool oom_unkillable_task(struct task_struct *p, struct mem_cgroup *mem,
+                           const nodemask_t *nodemask)
+{
+        if (is_global_init(p))
+                return true;
+        if (p->flags & PF_KTHREAD)
+                return true;
+
+        /* When mem_cgroup_out_of_memory() and p is not member of the group */
+        if (mem && !task_in_mem_cgroup(p, mem))
+                return true;
+
+        /* p may not have freeable memory in nodemask */
+        if (!has_intersects_mems_allowed(p, nodemask))
+                return true;
+
+        return false;
+}
+
 /**
  * badness - calculate a numeric value for how bad this task has been
  * @p: task struct of which task we should calculate
@@ -295,12 +315,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
         for_each_process(p) {
                 unsigned long points;
 
-                /* skip the init task and kthreads */
-                if (is_global_init(p) || (p->flags & PF_KTHREAD))
-                        continue;
-                if (mem && !task_in_mem_cgroup(p, mem))
-                        continue;
-                if (!has_intersects_mems_allowed(p, nodemask))
+                if (oom_unkillable_task(p, mem, nodemask))
                         continue;
 
                 /*
@@ -467,11 +482,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 
                         if (child->mm == p->mm)
                                 continue;
-                        if (child->flags & PF_KTHREAD)
-                                continue;
-                        if (mem && !task_in_mem_cgroup(child, mem))
-                                continue;
-                        if (!has_intersects_mems_allowed(child, nodemask))
+                        if (oom_unkillable_task(p, mem, nodemask))
                                 continue;
 
                         /* badness() returns 0 if the thread is unkillable */