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mm, oom: fix badness score underflow

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If the privileges given to root threads (3% of allowable memory) or a
negative value of /proc/pid/oom_score_adj happen to exceed the amount of
rss of a thread, its badness score overflows as a result of commit
a7f638f999 ("mm, oom: normalize oom scores to oom_score_adj scale only
for userspace").

Fix this by making the type signed and return 1, meaning the thread is
still eligible for kill, if the value is negative.

Reported-by: Dave Jones <davej@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes
2012-06-08 13:21:26 -07:00
committed by Linus Torvalds
parent 7249450449
commit 1e11ad8dc4
1 changed files with 2 additions and 2 deletions
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4
mm/oom_kill.c
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@@ -183,7 +183,7 @@ static bool oom_unkillable_task(struct task_struct *p,
unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg, unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
const nodemask_t *nodemask, unsigned long totalpages) const nodemask_t *nodemask, unsigned long totalpages)
{ {
unsigned long points; long points;
if (oom_unkillable_task(p, memcg, nodemask)) if (oom_unkillable_task(p, memcg, nodemask))
return 0; return 0;
@@ -223,7 +223,7 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
* Never return 0 for an eligible task regardless of the root bonus and * Never return 0 for an eligible task regardless of the root bonus and
* oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here). * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
*/ */
return points ? points : 1; return points > 0 ? points : 1;
} }
/* /*