Subject: Re: kselftest: net: tls: hangs

From: Jakub Kicinski <[email-masked]>
Date: Thu, 31 Mar 2022 11:54:10 -0700

On Thu, 31 Mar 2022 13:18:56 +0530 Naresh Kamboju wrote:
> Hi Jakub,
> 
> > Can you check where the process is stuck and it's state?
> > /proc/$pid/stack and run that thru scripts/decode_stacktrace
> >  
> 
> Steps to reproduce:
>           - cd /opt/kselftests/default-in-kernel/net
>           - ./tls &
>           - tests_pid=$!
>           - echo $tests_pid
>           - sleep 90
>           - cat /proc/$tests_pid/stack | tee tests_pid_stack.log
>           - cat tests_pid_stack.log
> 
> [<0>] do_wait+0x191/0x3a0
> [<0>] kernel_wait4+0xaf/0x160
> [<0>] __do_sys_wait4+0x85/0x90
> [<0>] __x64_sys_wait4+0x1c/0x20
> [<0>] do_syscall_64+0x5c/0x80
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae

The kernel test harness runs the tests in a separate process,
this is the stack trace for the main process. We'll need a stack trace
for the child, so:

	main_pid=$!
	tests_pid=$(pgrep -P $main_pid)

Also since each test runs in a separate child, we can try to catch the
one that got stuck for longer than 30 sec:

	pp=$(pgrep -P $main_pid)
	while true; do 
		sleep 30
		p=$(pgrep -P $main_pid)
		if [ $p != $pp ]; then
			pp=$p
			echo "New PID $p, continue waiting..."
			continue
		fi

		echo "PID $p is stuck!"
		cat /proc/$p/stack
	done

> Detail test log can be found here in this link [1]
> 
> I do not see any output from
> ./scripts/decode_stacktrace.sh  stack-dump.txt
> 
> 
> - Naresh
> 
> [1] https://lkft.validation.linaro.org/scheduler/job/4812800#L2256