oom: /proc/<pid>/oom_score treat kernel thread honestly
If a kernel thread is using use_mm(), badness() returns a positive value.
This is not a big issue because caller take care of it correctly. But
there is one exception, /proc/<pid>/oom_score calls badness() directly and
doesn't care that the task is a regular process.
Another example, /proc/1/oom_score return !0 value. But it's unkillable.
This incorrectness makes administration a little confusing.
This patch fixes it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: 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 3999747a..867bd26 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -139,8 +139,8 @@
* algorithm has been meticulously tuned to meet the principle
* of least surprise ... (be careful when you change it)
*/
-
-unsigned long badness(struct task_struct *p, unsigned long uptime)
+unsigned long badness(struct task_struct *p, struct mem_cgroup *mem,
+ const nodemask_t *nodemask, unsigned long uptime)
{
unsigned long points, cpu_time, run_time;
struct task_struct *child;
@@ -150,6 +150,8 @@
unsigned long utime;
unsigned long stime;
+ if (oom_unkillable_task(p, mem, nodemask))
+ return 0;
if (oom_adj == OOM_DISABLE)
return 0;
@@ -351,7 +353,7 @@
if (p->signal->oom_adj == OOM_DISABLE)
continue;
- points = badness(p, uptime.tv_sec);
+ points = badness(p, mem, nodemask, uptime.tv_sec);
if (points > *ppoints || !chosen) {
chosen = p;
*ppoints = points;
@@ -482,11 +484,10 @@
if (child->mm == p->mm)
continue;
- if (oom_unkillable_task(p, mem, nodemask))
- continue;
/* badness() returns 0 if the thread is unkillable */
- child_points = badness(child, uptime.tv_sec);
+ child_points = badness(child, mem, nodemask,
+ uptime.tv_sec);
if (child_points > victim_points) {
victim = child;
victim_points = child_points;