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Commit 26ebc984 authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
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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: default avatarKOSAKI 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f88ccad5

fs/proc/base.c

+3 −2
Original line number Diff line number Diff line
@@ -428,7 +428,8 @@ static const struct file_operations proc_lstats_operations = { 
#endif



/* The badness from the OOM killer */

unsigned long badness(struct task_struct *p, unsigned long uptime);

unsigned long badness(struct task_struct *p, struct mem_cgroup *mem,

		      nodemask_t *nodemask, unsigned long uptime);

static int proc_oom_score(struct task_struct *task, char *buffer)

{

	unsigned long points = 0;
@@ -437,7 +438,7 @@ static int proc_oom_score(struct task_struct *task, char *buffer) 
	do_posix_clock_monotonic_gettime(&uptime);

	read_lock(&tasklist_lock);

	if (pid_alive(task))

		points = badness(task, uptime.tv_sec);

		points = badness(task, NULL, NULL, uptime.tv_sec);

	read_unlock(&tasklist_lock);

	return sprintf(buffer, "%lu\n", points);

}

mm/oom_kill.c

+7 −6
Original line number Diff line number Diff line
@@ -139,8 +139,8 @@ static bool oom_unkillable_task(struct task_struct *p, struct mem_cgroup *mem, 
 *    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 badness(struct task_struct *p, unsigned long uptime) 
	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 @@ static struct task_struct *select_bad_process(unsigned long *ppoints, 
		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 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 


			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;