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| author | Frederic Weisbecker <frederic@kernel.org> | 2024-01-29 15:56:36 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-16 19:10:55 +0100 |
| commit | 4abccba26f639395d94c126b5444cd4046d237b8 (patch) | |
| tree | 2e46fa1f0c03e3535ce48c6900285701b4d8300f /kernel/time | |
| parent | f0b1398669a3925d19da6d1b4607648fd3fc4326 (diff) | |
| download | linux-4abccba26f639395d94c126b5444cd4046d237b8.tar.gz linux-4abccba26f639395d94c126b5444cd4046d237b8.tar.bz2 linux-4abccba26f639395d94c126b5444cd4046d237b8.zip | |
hrtimer: Report offline hrtimer enqueue
commit dad6a09f3148257ac1773cd90934d721d68ab595 upstream.
The hrtimers migration on CPU-down hotplug process has been moved
earlier, before the CPU actually goes to die. This leaves a small window
of opportunity to queue an hrtimer in a blind spot, leaving it ignored.
For example a practical case has been reported with RCU waking up a
SCHED_FIFO task right before the CPUHP_AP_IDLE_DEAD stage, queuing that
way a sched/rt timer to the local offline CPU.
Make sure such situations never go unnoticed and warn when that happens.
Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240129235646.3171983-4-boqun.feng@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/hrtimer.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 760793998cdd..edb0f821dcea 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -1085,6 +1085,7 @@ static int enqueue_hrtimer(struct hrtimer *timer, enum hrtimer_mode mode) { debug_activate(timer, mode); + WARN_ON_ONCE(!base->cpu_base->online); base->cpu_base->active_bases |= 1 << base->index; @@ -2183,6 +2184,7 @@ int hrtimers_prepare_cpu(unsigned int cpu) cpu_base->softirq_next_timer = NULL; cpu_base->expires_next = KTIME_MAX; cpu_base->softirq_expires_next = KTIME_MAX; + cpu_base->online = 1; hrtimer_cpu_base_init_expiry_lock(cpu_base); return 0; } @@ -2250,6 +2252,7 @@ int hrtimers_cpu_dying(unsigned int dying_cpu) smp_call_function_single(ncpu, retrigger_next_event, NULL, 0); raw_spin_unlock(&new_base->lock); + old_base->online = 0; raw_spin_unlock(&old_base->lock); return 0; |