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| author | luca abeni <[email protected]> | 2019-03-25 13:15:30 +0000 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2019-04-16 14:54:58 +0000 |
| commit | 1b02cd6a2d7f3e2a6a5262887d2cb2912083e42f (patch) | |
| tree | 1dfd4308ddb2928cd277a314e6c281766a1cd6c5 | |
| parent | sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup (diff) | |
| download | kernel-1b02cd6a2d7f3e2a6a5262887d2cb2912083e42f.tar.gz kernel-1b02cd6a2d7f3e2a6a5262887d2cb2912083e42f.zip | |
sched/deadline: Correctly handle active 0-lag timers
syzbot reported the following warning:
[ ] WARNING: CPU: 4 PID: 17089 at kernel/sched/deadline.c:255 task_non_contending+0xae0/0x1950
line 255 of deadline.c is:
WARN_ON(hrtimer_active(&dl_se->inactive_timer));
in task_non_contending().
Unfortunately, in some cases (for example, a deadline task
continuosly blocking and waking immediately) it can happen that
a task blocks (and task_non_contending() is called) while the
0-lag timer is still active.
In this case, the safest thing to do is to immediately decrease
the running bandwidth of the task, without trying to re-arm the 0-lag timer.
Signed-off-by: luca abeni <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: chengjian (D) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | kernel/sched/deadline.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 6a73e41a2016..43901fa3f269 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -252,7 +252,6 @@ static void task_non_contending(struct task_struct *p) if (dl_entity_is_special(dl_se)) return; - WARN_ON(hrtimer_active(&dl_se->inactive_timer)); WARN_ON(dl_se->dl_non_contending); zerolag_time = dl_se->deadline - @@ -269,7 +268,7 @@ static void task_non_contending(struct task_struct *p) * If the "0-lag time" already passed, decrease the active * utilization now, instead of starting a timer */ - if (zerolag_time < 0) { + if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) { if (dl_task(p)) sub_running_bw(dl_se, dl_rq); if (!dl_task(p) || p->state == TASK_DEAD) { |