When some CPUs cycle out of s2idle due to non-wakeup IRQs, it's possible
for them to run while the CPU responsible for jiffies updates remains idle.
This can delay the execution of timers indefinitely until the CPU managing
the jiffies updates finally wakes up, by which point everything could be
dead if enough time passes.
Fix it by handing off timekeeping duties when the timekeeping CPU enters
s2idle and freezes its tick. When all CPUs are in s2idle, the first one to
wake up for any reason (either from a wakeup IRQ or non-wakeup IRQ) will
assume responsibility for the timekeeping tick.
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Panchajanya1999 <kernel@panchajanya.dev>
(cherry picked from commit 717100653a78c63fe56b95721fffee5fad96ee91)
(cherry picked from commit 83196f829f9e2d4aef6a4d30ac449a7bfc985208)
(cherry picked from commit ab251b18b95c2fe80f457dabdf2e7132a6b0ea27)
(cherry picked from commit e58369f386e19f02bc5db1a155040e54dd201a60)
commit 07c54cc5988f19c9642fd463c2dbdac7fc52f777 upstream.
After the recent commit 5097cbcb38e6 ("sched/isolation: Prevent boot crash
when the boot CPU is nohz_full") the kernel no longer crashes, but there is
another problem.
In this case tick_setup_device() calls tick_take_do_timer_from_boot() to
update tick_do_timer_cpu and this triggers the WARN_ON_ONCE(irqs_disabled)
in smp_call_function_single().
Kill tick_take_do_timer_from_boot() and just use WRITE_ONCE(), the new
comment explains why this is safe (thanks Thomas!).
Fixes: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240528122019.GA28794@redhat.com
Link: https://lore.kernel.org/all/20240522151742.GA10400@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
