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Date:   Fri, 12 Mar 2021 17:23:45 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Qianli Zhao <zhaoqianligood@gmail.com>
Cc:     christian@brauner.io, axboe@kernel.dk, ebiederm@xmission.com,
        tglx@linutronix.de, pcc@google.com, linux-kernel@vger.kernel.org,
        zhaoqianli@xiaomi.com
Subject: Re: [PATCH V2] exit: trigger panic when global init has exited
Message-ID: <20210312162344.GB27820@redhat.com>
References: <1615519478-178620-1-git-send-email-zhaoqianligood@gmail.com>
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On 03/12, Qianli Zhao wrote:
>
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -767,6 +767,17 @@ void __noreturn do_exit(long code)
>  	validate_creds_for_do_exit(tsk);
>  
>  	/*
> +	 * If global init has exited,
> +	 * panic immediately to get a useable coredump.
> +	 */
> +	if (unlikely(is_global_init(tsk) &&
> +	    (thread_group_empty(tsk) ||
> +	    (tsk->signal->flags & SIGNAL_GROUP_EXIT)))) {
> +			panic("Attempted to kill init! exitcode=0x%08x\n",
> +				tsk->signal->group_exit_code ?: (int)code);

See our discussion with Eric, this is not right.
https://lore.kernel.org/lkml/20210310173236.GB8973@redhat.com/

Oleg.