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Commit 61eafb00 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, oom: fix and cleanup oom score calculations 



The divide in p->signal->oom_score_adj * totalpages / 1000 within
oom_badness() was causing an overflow of the signed long data type.

This adds both the root bias and p->signal->oom_score_adj before doing the
normalization which fixes the issue and also cleans up the calculation.

Tested-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fbb24a3a

mm/oom_kill.c

+7 −8
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, 
			  const nodemask_t *nodemask, unsigned long totalpages)

{

	long points;

	long adj;



	if (oom_unkillable_task(p, memcg, nodemask))

		return 0;
@@ -192,7 +193,8 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, 
	if (!p)

		return 0;



	if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {

	adj = p->signal->oom_score_adj;

	if (adj == OOM_SCORE_ADJ_MIN) {

		task_unlock(p);

		return 0;

	}
@@ -210,14 +212,11 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, 
	 * implementation used by LSMs.

	 */

	if (has_capability_noaudit(p, CAP_SYS_ADMIN))

		points -= 30 * totalpages / 1000;

		adj -= 30;



	/*

	 * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may

	 * either completely disable oom killing or always prefer a certain

	 * task.

	 */

	points += p->signal->oom_score_adj * totalpages / 1000;

	/* Normalize to oom_score_adj units */

	adj *= totalpages / 1000;

	points += adj;



	/*

	 * Never return 0 for an eligible task regardless of the root bonus and