linux-kernel - Re: Mutual debugging of 2 processes can stuck in unkillable stopped state

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Message-ID: <f7c84257-70a3-e482-0d3a-8ea95cbc8b62@omprussia.ru>
Date:   Mon, 12 Apr 2021 10:25:06 +0300
From:   Igor Zhbanov <i.zhbanov@...russia.ru>
To:     Oleg Nesterov <oleg@...hat.com>
CC:     <linux-trace-devel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: Mutual debugging of 2 processes can stuck in unkillable stopped
 state

Hi Oleg,

So what is the cause of this problem?

Thank you.

On 29.03.2021 20:44, Igor Zhbanov wrote:
> 
> Here is the processes stack before sending any signals to them:
> 
> izh@...e2:~> sudo cat /proc/1751/stack
> [<0>] ptrace_stop+0x14e/0x260
> [<0>] ptrace_do_notify+0x91/0xb0
> [<0>] ptrace_notify+0x4e/0x70
> [<0>] syscall_slow_exit_work+0x90/0x150
> [<0>] do_syscall_64+0x129/0x1f0
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> izh@...e2:~> sudo cat /proc/1979/stack
> [<0>] ptrace_stop+0x14e/0x260
> [<0>] get_signal+0x4d5/0x840
> [<0>] do_signal+0x30/0x6a0
> [<0>] exit_to_usermode_loop+0x8b/0x120
> [<0>] do_syscall_64+0x1c3/0x1f0
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
>> Igor, thanks for your report, but (I think) this has nothing to do
>> with mutual debugging. I'll return to this problem in a couple of
>> days, I'm a bit busy right now.