diff options
| author | luca abeni <luca.abeni@santannapisa.it> | 2019-03-25 14:15:30 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-02 09:40:32 +0200 |
| commit | c22cb4bd1a35fb86ef00547031b975e3235201e8 (patch) | |
| tree | 1ebb5a9efd942a4c8ad90b3b94e722632c237755 /kernel | |
| parent | 33c6b9ca70a8b066a613e2a3d0331ae8f82aa31a (diff) | |
sched/deadline: Correctly handle active 0-lag timers
commit 1b02cd6a2d7f3e2a6a5262887d2cb2912083e42f upstream.
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 <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: chengjian (D) <cj.chengjian@huawei.com>
Link: https://lkml.kernel.org/r/20190325131530.34706-1-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -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 b2589c7e9439..22770168bff8 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -217,7 +217,6 @@ static void task_non_contending(struct task_struct *p) if (dl_se->dl_runtime == 0) return; - WARN_ON(hrtimer_active(&dl_se->inactive_timer)); WARN_ON(dl_se->dl_non_contending); zerolag_time = dl_se->deadline - @@ -234,7 +233,7 @@ 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_bw, dl_rq); if (!dl_task(p) || p->state == TASK_DEAD) { |