This is a note to let you know that I've just added the patch titled
timers/nohz: Switch to ONESHOT_STOPPED in the low-res handler when the tick is stopped
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
timers-nohz-switch-to-oneshot_stopped-in-the-low-res-handler-when-the-tick-is-stopped.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 62c1256d544747b38e77ca9b5bfe3a26f9592576 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Sat, 23 Apr 2022 00:14:46 +1000
Subject: timers/nohz: Switch to ONESHOT_STOPPED in the low-res handler when the tick is stopped
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit 62c1256d544747b38e77ca9b5bfe3a26f9592576 upstream.
When tick_nohz_stop_tick() stops the tick and high resolution timers are
disabled, then the clock event device is not put into ONESHOT_STOPPED
mode. This can lead to spurious timer interrupts with some clock event
device drivers that don't shut down entirely after firing.
Eliminate these by putting the device into ONESHOT_STOPPED mode at points
where it is not being reprogrammed. When there are no timers active, then
tick_program_event() with KTIME_MAX can be used to stop the device. When
there is a timer active, the device can be stopped at the next tick (any
new timer added by timers will reprogram the tick).
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220422141446.915024-1-npiggin@xxxxxxxxx
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/tick-sched.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -884,6 +884,8 @@ static void tick_nohz_stop_tick(struct t
if (unlikely(expires == KTIME_MAX)) {
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_cancel(&ts->sched_timer);
+ else
+ tick_program_event(KTIME_MAX, 1);
return;
}
@@ -1274,9 +1276,15 @@ static void tick_nohz_handler(struct clo
tick_sched_do_timer(ts, now);
tick_sched_handle(ts, regs);
- /* No need to reprogram if we are running tickless */
- if (unlikely(ts->tick_stopped))
+ if (unlikely(ts->tick_stopped)) {
+ /*
+ * The clockevent device is not reprogrammed, so change the
+ * clock event device to ONESHOT_STOPPED to avoid spurious
+ * interrupts on devices which might not be truly one shot.
+ */
+ tick_program_event(KTIME_MAX, 1);
return;
+ }
hrtimer_forward(&ts->sched_timer, now, TICK_NSEC);
tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1);
Patches currently in stable-queue which might be from npiggin@xxxxxxxxx are
queue-5.10/timers-nohz-switch-to-oneshot_stopped-in-the-low-res-handler-when-the-tick-is-stopped.patch
