The race is in unlocked task_rq() access. In pair with parallel
call of sched_setaffinity() it may be a reason of corruption
of internal rq's data.
Signed-off-by: Kirill Tkhai <tkhai@xxxxxxxxx>
CC: Juri Lelli <juri.lelli@xxxxxxxxx>
CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.14
---
kernel/sched/deadline.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 800e99b..ffb023a 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -513,9 +513,16 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
struct sched_dl_entity,
dl_timer);
struct task_struct *p = dl_task_of(dl_se);
- struct rq *rq = task_rq(p);
+ struct rq *rq;
+again:
+ rq = task_rq(p);
raw_spin_lock(&rq->lock);
+ if (unlikely(rq != task_rq(p))) {
+ raw_spin_unlock(&rq->lock);
+ goto again;
+ }
+
/*
* We need to take care of a possible races here. In fact, the
* task might have changed its scheduling policy to something
--
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