Hi,

We gathered the output of of 'sysrq-trigger t'  again.

Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2021/08/18

> Hi,
> 
> fstests btrfs/232 cause kworker rcu_gp CPU stalls on linux 5.4.141
> 
>   PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
>     219 root      20   0       0      0      0 R 100.0   0.0  13:46.88 kworker/4:2+rcu_gp
> 
> stalls task:
> [  293.488867] kworker/4:2     R  running task        0   219      2 0x80004000
> [  293.497059] Workqueue: rcu_gp process_srcu
> [  293.502011] Call Trace:
> [  293.505063]  ? process_srcu+0x15e/0x4a0
> [  293.509694]  ? __queue_work+0x13d/0x3e0
> [  293.514298]  ? process_one_work+0x1a7/0x360
> [  293.519335]  ? worker_thread+0x30/0x390
> [  293.523982]  ? create_worker+0x1a0/0x1a0
> [  293.528675]  ? kthread+0x112/0x130
> [  293.532784]  ? __kthread_cancel_work+0x40/0x40
> [  293.538061]  ? ret_from_fork+0x1f/0x40
> 
> Kernel version: 5.4.141
> this does not happen in 5.4.116 ( the last well tested kernel version here)
> we just began to test 5.4.141
> It is yet not clear whether it is a btrfs bug or RCU bug?
> 
> Reproduce count: 2 times.
> 
> Server: No ECC Error
> 	Product Name: PowerEdge T620
> 	BIOS Version: 2.9.0
> 
> Storage: No smartctl Error
> 	Model Number:                       Dell Express Flash NVMe SM1715 800GB SFF
> 	Firmware Version:                   IPV0AD3Q
> 
> The output of of 'sysrq-trigger t' is in file rcu_gp.stalls.dmesg.txt.
> 
> And /var/log/messages in rcu_gp.stalls.messages.txt
> 
> Best Regards
> Wang Yugui (wangyugui@e16-tech.com)
> 2021/08/18
>