A cleanup patch from my legacy timer series broke ia64 and led
to RCU stall errors and a fast system clock:
[ 909.360108] INFO: task systemd-sysv-ge:200 blocked for more than 127 seconds.
[ 909.360108] Not tainted 5.10.0+ #130
[ 909.360108] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 909.360108] task:systemd-sysv-ge state:D stack: 0 pid: 200 ppid: 189 flags:0x00000000
[ 909.364108]
[ 909.364108] Call Trace:
[ 909.364423] [<a00000010109b210>] __schedule+0x890/0x21e0
[ 909.364423] sp=e0000100487d7b70 bsp=e0000100487d1748
[ 909.368423] [<a00000010109cc00>] schedule+0xa0/0x240
[ 909.368423] sp=e0000100487d7b90 bsp=e0000100487d16e0
[ 909.368558] [<a00000010109ce70>] io_schedule+0x70/0xa0
[ 909.368558] sp=e0000100487d7b90 bsp=e0000100487d16c0
[ 909.372290] [<a00000010109e1c0>] bit_wait_io+0x20/0xe0
[ 909.372290] sp=e0000100487d7b90 bsp=e0000100487d1698
[ 909.374168] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[ 909.376290] [<a00000010109d860>] __wait_on_bit+0xc0/0x1c0
[ 909.376290] sp=e0000100487d7b90 bsp=e0000100487d1648
[ 909.374168] rcu: 3-....: (2 ticks this GP) idle=19e/1/0x4000000000000002 softirq=1581/1581 fqs=2
[ 909.374168] (detected by 0, t=5661 jiffies, g=1089, q=3)
[ 909.376290] [<a00000010109da80>] out_of_line_wait_on_bit+0x120/0x140
[ 909.376290] sp=e0000100487d7b90 bsp=e0000100487d1610
[ 909.374168] Task dump for CPU 3:
[ 909.374168] task:khungtaskd state:R running task
Revert most of my patch to make this work again, including the extra
update_process_times()/profile_tick() and the local_irq_enable() in the
loop that I expected not to be needed here.
I have not found out exactly what goes wrong, and would suggest that
someone with hardware access tries to convert this code into a singleshot
clockevent driver, which should give better behavior in all cases.
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Fixes: 2b49ddcef2 ("ia64: convert to legacy_timer_tick")
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
796130b1de