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Date: Sat, 2 Oct 2021 18:04:10 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Alexander Popov <alex.popov@linux.com>
Cc: Jonathan Corbet <corbet@lwn.net>, Paul McKenney <paulmck@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
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	Randy Dunlap <rdunlap@infradead.org>,
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Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter
Message-ID: <YVifGtn3LctrWOwg@zeniv-ca.linux.org.uk>
References: <20210929185823.499268-1-alex.popov@linux.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Wed, Sep 29, 2021 at 09:58:23PM +0300, Alexander Popov wrote:

> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -53,6 +53,7 @@ static int pause_on_oops_flag;
>  static DEFINE_SPINLOCK(pause_on_oops_lock);
>  bool crash_kexec_post_notifiers;
>  int panic_on_warn __read_mostly;
> +int pkill_on_warn __read_mostly;
>  unsigned long panic_on_taint;
>  bool panic_on_taint_nousertaint = false;
>  
> @@ -610,6 +611,9 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
>  
>  	print_oops_end_marker();
>  
> +	if (pkill_on_warn && system_state >= SYSTEM_RUNNING)
> +		do_group_exit(SIGKILL);
> +

Wait a sec...  do_group_exit() is very much not locking-neutral.
Aren't you introducing a bunch of potential deadlocks by adding
that?