* [RFC PATCH] rtc: add a schedule point in 'rtc_timer_do_work'
@ 2019-07-25 11:30 Xiongfeng Wang
2019-08-06 6:07 ` Kefeng Wang
0 siblings, 1 reply; 2+ messages in thread
From: Xiongfeng Wang @ 2019-07-25 11:30 UTC (permalink / raw)
To: a.zummo, alexandre.belloni
Cc: linux-rtc, linux-kernel, wangxiongfeng2, wangkefeng.wang
When I ran the syzkaller testsuite, it prints out the following calltrace.
[ 138.350029] rcu: INFO: rcu_sched self-detected stall on CPU
[ 138.354703] rcu: 2-....: (104998 ticks this GP) idle=ece/1/0x4000000000000002 softirq=2825/2825 fqs=26250
[ 138.357771] (t=105005 jiffies g=8033 q=1)
[ 138.358952] NMI backtrace for cpu 2
[ 138.359954] CPU: 2 PID: 170 Comm: kworker/2:1 Not tainted 5.2.0-514.55.6.9.x86_64 #64
[ 138.362212] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014
[ 138.365818] Workqueue: events rtc_timer_do_work
[ 138.367122] Call Trace:
[ 138.367815] <IRQ>
[ 138.368420] dump_stack+0xa7/0xf9
[ 138.369372] nmi_cpu_backtrace+0xc2/0xd0
[ 138.370516] ? lapic_can_unplug_cpu+0xa0/0xa0
[ 138.371747] nmi_trigger_cpumask_backtrace+0x14e/0x190
[ 138.373201] rcu_dump_cpu_stacks+0x97/0xc5
[ 138.374376] rcu_sched_clock_irq+0x819/0x8d0
[ 138.375571] ? tick_sched_do_timer+0xb0/0xb0
[ 138.376787] ? tick_sched_do_timer+0xb0/0xb0
[ 138.377991] update_process_times+0x2d/0x60
[ 138.379176] tick_sched_handle+0x2f/0x70
[ 138.381088] tick_sched_timer+0x41/0x90
[ 138.382170] __hrtimer_run_queues+0x11b/0x580
[ 138.383386] hrtimer_interrupt+0x11b/0x280
[ 138.384585] smp_apic_timer_interrupt+0x7a/0x230
[ 138.385909] apic_timer_interrupt+0xf/0x20
[ 138.387066] </IRQ>
[ 138.387668] RIP: 0010:debug_lockdep_rcu_enabled+0x6/0x30
[ 138.389149] Code: 1f 44 00 00 0f 1f 44 00 00 f0 ff 05 94 08 32 01 c3 0f 1f 00 0f 1f 44 00 00 f0 ff 0d 84 08 32 01 c3 0f 1f 00 8b 0d 2e 59 54 01 <31> c0 85 c9 74 21 8b 15 c2 b8 54 01 85 d2 74 17 65 48 8b 04 25 c0
[ 138.394395] RSP: 0018:ffffc9000080fd30 EFLAGS: 00000203 ORIG_RAX: ffffffffffffff13
[ 138.397117] RAX: 0000000000000000 RBX: ffff88813b77de10 RCX: 0000000000000002
[ 138.399104] RDX: 0000000000000000 RSI: ffffffff81886439 RDI: ffff88813b77de10
[ 138.401128] RBP: ffffc9000080fe38 R08: 0000000000000000 R09: 0000000000000000
[ 138.403149] R10: 0000000000000001 R11: 0000000000000013 R12: ffff88813b77de98
[ 138.405147] R13: ffff88813bab0c00 R14: 1a15e2eb5cd98000 R15: 000000003b9aca00
[ 138.407118] ? rtc_timer_do_work+0x349/0x710
[ 138.408344] rtc_timer_do_work+0x35c/0x710
[ 138.409516] ? graph_unlock+0x41/0x80
[ 138.410591] ? process_one_work+0x1d4/0x710
[ 138.412062] process_one_work+0x272/0x710
[ 138.413193] ? process_one_work+0x1d4/0x710
[ 138.414376] worker_thread+0x58/0x520
[ 138.415405] kthread+0x120/0x160
[ 138.416337] ? process_one_work+0x710/0x710
[ 138.417486] ? kthread_bind+0x20/0x20
[ 138.418526] ret_from_fork+0x24/0x30
After looking into the syzkaller log, I found out it is caused by the
following procedure. Firstly, enable the update interrupt through ioctl
'RTC_UIE_ON'. Secondly, set the rtc time to be a far further time
through ioctl 'RTC_SET_TIME'. This will cause we stuck in
'rtc_timer_do_work()' because the expiring time of 'UIE' is far less
than the current rtc time. This patch add a schedule point to avoid the
RCU calltrace.
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
---
drivers/rtc/interface.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 72b7ddc4..0c8339d 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -911,6 +911,8 @@ void rtc_timer_do_work(struct work_struct *work)
timerqueue_add(&rtc->timerqueue, &timer->node);
trace_rtc_timer_enqueue(timer);
}
+
+ cond_resched();
}
/* Set next alarm */
--
1.7.12.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] rtc: add a schedule point in 'rtc_timer_do_work'
2019-07-25 11:30 [RFC PATCH] rtc: add a schedule point in 'rtc_timer_do_work' Xiongfeng Wang
@ 2019-08-06 6:07 ` Kefeng Wang
0 siblings, 0 replies; 2+ messages in thread
From: Kefeng Wang @ 2019-08-06 6:07 UTC (permalink / raw)
To: Xiongfeng Wang, a.zummo, alexandre.belloni
Cc: linux-rtc, linux-kernel, puranjay12, arnd, Andy Shevchenko,
wangkefeng wang
Kindly ping...
On 2019/7/25 19:30, Xiongfeng Wang wrote:
> When I ran the syzkaller testsuite, it prints out the following calltrace.
>
> [ 138.350029] rcu: INFO: rcu_sched self-detected stall on CPU
> [ 138.354703] rcu: 2-....: (104998 ticks this GP) idle=ece/1/0x4000000000000002 softirq=2825/2825 fqs=26250
> [ 138.357771] (t=105005 jiffies g=8033 q=1)
> [ 138.358952] NMI backtrace for cpu 2
> [ 138.359954] CPU: 2 PID: 170 Comm: kworker/2:1 Not tainted 5.2.0-514.55.6.9.x86_64 #64
> [ 138.362212] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014
> [ 138.365818] Workqueue: events rtc_timer_do_work
> [ 138.367122] Call Trace:
> [ 138.367815] <IRQ>
> [ 138.368420] dump_stack+0xa7/0xf9
> [ 138.369372] nmi_cpu_backtrace+0xc2/0xd0
> [ 138.370516] ? lapic_can_unplug_cpu+0xa0/0xa0
> [ 138.371747] nmi_trigger_cpumask_backtrace+0x14e/0x190
> [ 138.373201] rcu_dump_cpu_stacks+0x97/0xc5
> [ 138.374376] rcu_sched_clock_irq+0x819/0x8d0
> [ 138.375571] ? tick_sched_do_timer+0xb0/0xb0
> [ 138.376787] ? tick_sched_do_timer+0xb0/0xb0
> [ 138.377991] update_process_times+0x2d/0x60
> [ 138.379176] tick_sched_handle+0x2f/0x70
> [ 138.381088] tick_sched_timer+0x41/0x90
> [ 138.382170] __hrtimer_run_queues+0x11b/0x580
> [ 138.383386] hrtimer_interrupt+0x11b/0x280
> [ 138.384585] smp_apic_timer_interrupt+0x7a/0x230
> [ 138.385909] apic_timer_interrupt+0xf/0x20
> [ 138.387066] </IRQ>
> [ 138.387668] RIP: 0010:debug_lockdep_rcu_enabled+0x6/0x30
> [ 138.389149] Code: 1f 44 00 00 0f 1f 44 00 00 f0 ff 05 94 08 32 01 c3 0f 1f 00 0f 1f 44 00 00 f0 ff 0d 84 08 32 01 c3 0f 1f 00 8b 0d 2e 59 54 01 <31> c0 85 c9 74 21 8b 15 c2 b8 54 01 85 d2 74 17 65 48 8b 04 25 c0
> [ 138.394395] RSP: 0018:ffffc9000080fd30 EFLAGS: 00000203 ORIG_RAX: ffffffffffffff13
> [ 138.397117] RAX: 0000000000000000 RBX: ffff88813b77de10 RCX: 0000000000000002
> [ 138.399104] RDX: 0000000000000000 RSI: ffffffff81886439 RDI: ffff88813b77de10
> [ 138.401128] RBP: ffffc9000080fe38 R08: 0000000000000000 R09: 0000000000000000
> [ 138.403149] R10: 0000000000000001 R11: 0000000000000013 R12: ffff88813b77de98
> [ 138.405147] R13: ffff88813bab0c00 R14: 1a15e2eb5cd98000 R15: 000000003b9aca00
> [ 138.407118] ? rtc_timer_do_work+0x349/0x710
> [ 138.408344] rtc_timer_do_work+0x35c/0x710
> [ 138.409516] ? graph_unlock+0x41/0x80
> [ 138.410591] ? process_one_work+0x1d4/0x710
> [ 138.412062] process_one_work+0x272/0x710
> [ 138.413193] ? process_one_work+0x1d4/0x710
> [ 138.414376] worker_thread+0x58/0x520
> [ 138.415405] kthread+0x120/0x160
> [ 138.416337] ? process_one_work+0x710/0x710
> [ 138.417486] ? kthread_bind+0x20/0x20
> [ 138.418526] ret_from_fork+0x24/0x30
>
> After looking into the syzkaller log, I found out it is caused by the
> following procedure. Firstly, enable the update interrupt through ioctl
> 'RTC_UIE_ON'. Secondly, set the rtc time to be a far further time
> through ioctl 'RTC_SET_TIME'. This will cause we stuck in
> 'rtc_timer_do_work()' because the expiring time of 'UIE' is far less
> than the current rtc time. This patch add a schedule point to avoid the
> RCU calltrace.
>
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> ---
> drivers/rtc/interface.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index 72b7ddc4..0c8339d 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -911,6 +911,8 @@ void rtc_timer_do_work(struct work_struct *work)
> timerqueue_add(&rtc->timerqueue, &timer->node);
> trace_rtc_timer_enqueue(timer);
> }
> +
> + cond_resched();
> }
>
> /* Set next alarm */
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2019-08-06 6:08 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-25 11:30 [RFC PATCH] rtc: add a schedule point in 'rtc_timer_do_work' Xiongfeng Wang
2019-08-06 6:07 ` Kefeng Wang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).