[PATCH 3/9] oom: make oom_unkillable_task() helper function

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

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

Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 mm/oom_kill.c |   33 ++++++++++++++++++++++-----------
 1 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index dc8589e..afcbf17 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -277,6 +277,26 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
 }
 #endif
 
+/* 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;
+}
+
 /*
  * Simple selection loop. We chose the process with the highest
  * number of 'points'. We expect the caller will lock the tasklist.
@@ -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 */
-- 
1.6.5.2



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