From: John Ogness <john.ogness@linutronix.de>
To: Stephen Brennan <stephen.s.brennan@oracle.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Petr Mladek <pmladek@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Brennan <stephen.s.brennan@oracle.com>,
Sebastian Reichel <sre@kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Luis Chamberlain <mcgrof@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] printk: Drop console_sem during panic
Date: Thu, 27 Jan 2022 10:28:53 +0106 [thread overview]
Message-ID: <87fsp9pm6q.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <20220126230236.750229-5-stephen.s.brennan@oracle.com>
On 2022-01-26, Stephen Brennan <stephen.s.brennan@oracle.com> wrote:
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2759,7 +2782,7 @@ void console_unlock(void)
> * flush, no worries.
> */
> retry = prb_read_valid(prb, next_seq, NULL);
> - if (retry && console_trylock())
> + if (retry && !abandon_console_lock_in_panic() && console_trylock())
As Sergey suggested [0], I would like to see the call to
abandon_console_lock_in_panic() move inside console_trylock(). This will
help to avoid the race between NMI CPU halt and the internal sema.lock
spinlock.
John Ogness
[0] https://lore.kernel.org/all/YfJFjHdg%2FkhNXiRd@google.com
next prev parent reply other threads:[~2022-01-27 9:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 23:02 [PATCH v2 0/4] printk: reduce deadlocks " Stephen Brennan
2022-01-26 23:02 ` [PATCH v2 1/4] panic: Add panic_in_progress helper Stephen Brennan
2022-01-27 14:34 ` Petr Mladek
2022-01-27 16:02 ` Stephen Brennan
2022-01-28 8:24 ` Petr Mladek
2022-01-26 23:02 ` [PATCH v2 2/4] printk: disable optimistic spin during panic Stephen Brennan
2022-01-26 23:02 ` [PATCH v2 3/4] printk: Avoid livelock with heavy printk " Stephen Brennan
2022-01-27 14:50 ` Petr Mladek
2022-01-27 16:19 ` Stephen Brennan
2022-01-26 23:02 ` [PATCH v2 4/4] printk: Drop console_sem " Stephen Brennan
2022-01-27 9:22 ` John Ogness [this message]
2022-01-27 15:03 ` Petr Mladek
2022-01-28 5:55 ` Sergey Senozhatsky
2022-01-27 15:12 ` Petr Mladek
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