From: Petr Mladek <pmladek@suse.com>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH printk v4 14/14] dump_stack: Do not get cpu_sync for panic CPU
Date: Wed, 7 Feb 2024 17:16:18 +0100 [thread overview]
Message-ID: <ZcOs0nG3KvkGKyF0@alley> (raw)
In-Reply-To: <20240207134103.1357162-15-john.ogness@linutronix.de>
On Wed 2024-02-07 14:47:03, John Ogness wrote:
> dump_stack() is called in panic(). If for some reason another CPU
> is holding the printk_cpu_sync and is unable to release it, the
> panic CPU will be unable to continue and print the stacktrace.
>
> Since non-panic CPUs are not allowed to store new printk messages
> anyway, there is no need to synchronize the stacktrace output in
> a panic situation.
>
> For the panic CPU, do not get the printk_cpu_sync because it is
> not needed and avoids a potential deadlock scenario in panic().
>
> Link: https://lore.kernel.org/lkml/ZcIGKU8sxti38Kok@alley
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
Makes sense.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
next prev parent reply other threads:[~2024-02-07 16:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 13:40 [PATCH printk v4 00/14] fix console flushing John Ogness
2024-02-07 13:40 ` [PATCH printk v4 01/14] printk: nbcon: Relocate 32bit seq macros John Ogness
2024-02-07 13:40 ` [PATCH printk v4 02/14] printk: Adjust mapping for " John Ogness
2024-02-07 13:40 ` [PATCH printk v4 03/14] printk: Use prb_first_seq() as base " John Ogness
2024-02-07 13:40 ` [PATCH printk v4 04/14] printk: ringbuffer: Do not skip non-finalized records with prb_next_seq() John Ogness
2024-02-07 16:00 ` Petr Mladek
2024-02-07 13:40 ` [PATCH printk v4 05/14] printk: ringbuffer: Clarify special lpos values John Ogness
2024-02-07 13:40 ` [PATCH printk v4 06/14] printk: For @suppress_panic_printk check for other CPU in panic John Ogness
2024-02-07 13:40 ` [PATCH printk v4 07/14] printk: Add this_cpu_in_panic() John Ogness
2024-02-07 13:40 ` [PATCH printk v4 08/14] printk: ringbuffer: Cleanup reader terminology John Ogness
2024-02-07 13:40 ` [PATCH printk v4 09/14] printk: Wait for all reserved records with pr_flush() John Ogness
2024-02-07 13:40 ` [PATCH printk v4 10/14] printk: ringbuffer: Skip non-finalized records in panic John Ogness
2024-02-07 13:41 ` [PATCH printk v4 11/14] printk: Disable passing console lock owner completely during panic() John Ogness
2024-02-07 13:41 ` [PATCH printk v4 12/14] printk: Avoid non-panic CPUs writing to ringbuffer John Ogness
2024-02-07 13:41 ` [PATCH printk v4 13/14] panic: Flush kernel log buffer at the end John Ogness
2024-02-07 13:41 ` [PATCH printk v4 14/14] dump_stack: Do not get cpu_sync for panic CPU John Ogness
2024-02-07 16:16 ` Petr Mladek [this message]
2024-02-07 16:18 ` [PATCH printk v4 00/14] fix console flushing Petr Mladek
2024-02-07 16:53 ` Petr Mladek
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