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Message-ID: <877426e1-fc7e-467f-944c-9d6c450f11dd@alu.unizg.hr>
Date: Sat, 9 Mar 2024 15:25:02 +0100
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Subject: Re: [BUG net-next selftests/pidfd] Hang in ./pidfd_setns_test
 pidfd_send_signal()
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From: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
To: Christian Brauner <brauner@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>, linux-kernel@vger.kernel.org,
 linux-kselftest@vger.kernel.org
References: <e2ba3f8c-80e6-477d-9cea-1c9af820e0ed@alu.unizg.hr>
In-Reply-To: <e2ba3f8c-80e6-477d-9cea-1c9af820e0ed@alu.unizg.hr>
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Hi,

There seems to be some additional insight.

Trying to kill the processes so the testsuite might hopefully continue, this was
the result: unkillable (-SIGKILL) processes, which can also not be traced with
strace, and neither the selftest suite continued.

root     1000955    2931  0 01:05 pts/2    00:00:00 ./pidfd_setns_test
root     1000956 1000955 99 01:05 pts/2    14:09:03 [pidfd_setns_tes] <defunct>
root     1037946 1005609  0 15:19 pts/3    00:00:00 grep --color=auto pidfd_setns_tes
root@defiant:/home/marvin/linux/kernel/net-next# strace -p 1000955
strace: Could not attach to process. If your uid matches the uid of the target process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try again as the root user. For more details, see /etc/sysctl.d/10-ptrace.conf: Operation not permitted
strace: attach: ptrace(PTRACE_SEIZE, 1000955): Operation not permitted
root@defiant:/home/marvin/linux/kernel/net-next# strace -p 1000956
strace: Could not attach to process. If your uid matches the uid of the target process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try again as the root user. For more details, see /etc/sysctl.d/10-ptrace.conf: Operation not permitted
strace: attach: ptrace(PTRACE_SEIZE, 1000956): Operation not permitted
root@defiant:/home/marvin/linux/kernel/net-next#

Hope this helps.

It would be very interesting to see now what exactly eats 99% of a CPU core, but
I am not enough technologically savvy for this task ATM.

Best regards,
Mirsad Todorovac