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| author | Frederic Weisbecker <frederic@kernel.org> | 2024-01-29 15:56:36 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-23 08:12:55 +0100 |
| commit | 1aa4f696306dfe4f0d453eeb1e90f26cd10d8ed5 (patch) | |
| tree | 5fdaef4c00465ed0f67aa388e1b50cd2ca64772b | |
| parent | 95eab1039625d54d1770665756dd34e9fe926638 (diff) | |
| download | linux-stable-1aa4f696306dfe4f0d453eeb1e90f26cd10d8ed5.tar.gz linux-stable-1aa4f696306dfe4f0d453eeb1e90f26cd10d8ed5.tar.bz2 linux-stable-1aa4f696306dfe4f0d453eeb1e90f26cd10d8ed5.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>
| -rw-r--r-- | include/linux/hrtimer.h | 4 | ||||
| -rw-r--r-- | kernel/time/hrtimer.c | 3 |
2 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 3bdaa92a2cab..88496ba45c48 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -182,6 +182,7 @@ enum hrtimer_base_type { * @hang_detected: The last hrtimer interrupt detected a hang * @softirq_activated: displays, if the softirq is raised - update of softirq * related settings is not required then. + * @online: CPU is online from an hrtimers point of view * @nr_events: Total number of hrtimer interrupt events * @nr_retries: Total number of hrtimer interrupt retries * @nr_hangs: Total number of hrtimer interrupt hangs @@ -206,7 +207,8 @@ struct hrtimer_cpu_base { unsigned int hres_active : 1, in_hrtirq : 1, hang_detected : 1, - softirq_activated : 1; + softirq_activated : 1, + online : 1; #ifdef CONFIG_HIGH_RES_TIMERS unsigned int nr_events; unsigned short nr_retries; diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index bf74f43e42af..0eb5b6cc6d93 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -970,6 +970,7 @@ 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; @@ -1887,6 +1888,7 @@ 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; return 0; } @@ -1953,6 +1955,7 @@ 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; |