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mm, oom: fix and cleanup oom score calculations

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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: Dave Jones <davej@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2012-06-20 12:52:58 -07:00 committed by Linus Torvalds
parent fbb24a3a91
commit 61eafb00d5
1 changed files with 7 additions and 8 deletions
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15
mm/oom_kill.c
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@ -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