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>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b9816ea2eb8f7dbd3d89cd0b435f81ee9efc7480..2c993e47487f9d0d9e40dc1527fc38fc26007dcf 100644 (file)
--- 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 */