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| author | Arnd Bergmann <arnd@arndb.de> | 2020-12-19 12:05:45 +0300 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2021-01-12 19:01:42 +0300 |
| commit | 796130b1de29575e2e3fc3b0da4bda162b750db7 (patch) | |
| tree | 0cd0887b05497c5a8f3a9c445ee1e20e179182b8 /arch/ia64 | |
| parent | 5c8fe583cce542aa0b84adc939ce85293de36e5e (diff) | |
| download | linux-796130b1de29575e2e3fc3b0da4bda162b750db7.tar.xz | |
ia64: fix timer cleanup regression
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: 2b49ddcef297 ("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>
Diffstat (limited to 'arch/ia64')
| -rw-r--r-- | arch/ia64/kernel/time.c | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index ed9fc3d057a6..43e8050145be 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c @@ -171,29 +171,34 @@ void vtime_account_hardirq(struct task_struct *tsk) static irqreturn_t timer_interrupt (int irq, void *dev_id) { - unsigned long cur_itm, new_itm, ticks; + unsigned long new_itm; if (cpu_is_offline(smp_processor_id())) { return IRQ_HANDLED; } new_itm = local_cpu_data->itm_next; - cur_itm = ia64_get_itc(); - if (!time_after(cur_itm, new_itm)) { + if (!time_after(ia64_get_itc(), new_itm)) printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n", - cur_itm, new_itm); - ticks = 1; - } else { - ticks = DIV_ROUND_UP(cur_itm - new_itm, - local_cpu_data->itm_delta); - new_itm += ticks * local_cpu_data->itm_delta; - } + ia64_get_itc(), new_itm); + + while (1) { + new_itm += local_cpu_data->itm_delta; + + legacy_timer_tick(smp_processor_id() == time_keeper_id); - if (smp_processor_id() != time_keeper_id) - ticks = 0; + local_cpu_data->itm_next = new_itm; - legacy_timer_tick(ticks); + if (time_after(new_itm, ia64_get_itc())) + break; + + /* + * Allow IPIs to interrupt the timer loop. + */ + local_irq_enable(); + local_irq_disable(); + } do { /* |