From: Steven Rostedt <rostedt@goodmis.org>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] printk: wake up klogd in vprintk_emit
Date: Wed, 18 Apr 2018 10:29:43 -0400 [thread overview]
Message-ID: <20180418102943.5aa0ffc4@gandalf.local.home> (raw)
In-Reply-To: <20180414030145.26304-1-sergey.senozhatsky@gmail.com>
On Sat, 14 Apr 2018 12:01:45 +0900
Sergey Senozhatsky <sergey.senozhatsky@gmail.com> wrote:
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1888,6 +1888,7 @@ asmlinkage int vprintk_emit(int facility, int level,
>
> printed_len = log_output(facility, level, lflags, dict, dictlen, text, text_len);
>
> + wake_up_klogd();
> logbuf_unlock_irqrestore(flags);
You can't do this, because the scheduler can call printk_deferred()
with the rq lock held, and printk_deferred() will grab the logbuf lock.
Calling wake_up_klogd() will grab the rq lock and give us a A-B<->B-A
locking order.
-- Steve
next prev parent reply other threads:[~2018-04-18 14:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-14 3:01 Sergey Senozhatsky
2018-04-18 14:04 ` Petr Mladek
2018-04-19 1:23 ` Sergey Senozhatsky
2018-04-19 9:54 ` Petr Mladek
2018-04-18 14:29 ` Steven Rostedt [this message]
2018-04-18 15:02 ` Petr Mladek
2018-04-18 15:10 ` Steven Rostedt
2018-04-19 1:17 ` Sergey Senozhatsky
2018-04-19 1:42 ` [PATCHv2] " Sergey Senozhatsky
2018-04-19 10:02 ` Petr Mladek
2018-04-20 1:52 ` Sergey Senozhatsky
2018-04-20 8:18 ` Petr Mladek
2018-04-25 13:23 ` Petr Mladek
2018-04-26 1:44 ` Sergey Senozhatsky
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