diff options
| author | Chris Redpath <chris.redpath@arm.com> | 2014-06-11 14:08:40 +0100 |
|---|---|---|
| committer | Jon Medhurst <tixy@linaro.org> | 2014-06-11 15:08:35 +0100 |
| commit | 4378062f289e67259f017f6b176ee385dc974836 (patch) | |
| tree | 0797cd6fc66c81a5b55d71f660b8fd2c7a95c957 | |
| parent | d1df056f9e6dd9707037ed74621e170dfa8f4c52 (diff) | |
sched: hmp: fix out-of-range CPU possiblebig-LITTLE-MP-14.06
If someone hotplugs all the little CPUs while another CPU is handling
a wakeup, we can potentially return new_cpu == NR_CPUS from
hmp_select_slower_cpu (which is called internally by
hmp_best_little_cpu as well). We will use this to deref the
per_cpu rq array in hmp_next_down_delay which can go boom.
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
| -rw-r--r-- | kernel/sched/fair.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ffa643ce911..26c43b46301 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4456,7 +4456,11 @@ unlock: #else new_cpu = hmp_select_slower_cpu(p, prev_cpu); #endif - if (new_cpu != prev_cpu) { + /* + * we might have no suitable CPU + * in which case new_cpu == NR_CPUS + */ + if (new_cpu < NR_CPUS && new_cpu != prev_cpu) { hmp_next_down_delay(&p->se, new_cpu); trace_sched_hmp_migrate(p, new_cpu, HMP_MIGRATE_WAKEUP); return new_cpu; |