From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org, "4 . 13+" <stable@vger.kernel.org>
Subject: Re: [PATCH] printk/nmi: Prevent deadlock when serializing NMI backtraces
Date: Wed, 23 May 2018 11:01:07 +0900 [thread overview]
Message-ID: <20180523020107.GA8465@jagdpanzerIV> (raw)
In-Reply-To: <20180522174320.10ced885@gandalf.local.home>
On (05/22/18 17:43), Steven Rostedt wrote:
> > CPU0 CPU1 CPU2
> >
> > printk()
> > vprintk_emit()
> > spin_lock(&logbuf_lock)
> >
> > trigger_all_cpu_backtrace()
> > raise()
> >
> > nmi_enter()
> > printk_nmi_enter()
> > if (this_cpu_read(printk_context)
> > & PRINTK_SAFE_CONTEXT_MASK)
> > // false
> > else
> > // looks safe to use printk_deferred()
> > this_cpu_or(printk_context,
> > PRINTK_NMI_DEFERRED_CONTEXT_MASK);
> >
> > nmi_cpu_backtrace()
> > arch_spin_lock(&lock);
>
> What branch is this based on, because I can't find the
> "arch_spin_lock()" you are talking about here.
This arch_spin_lock() is in lib/nmi_backtrace.c
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/nmi_backtrace.c?h=v4.17-rc6#n94
-ss
next prev parent reply other threads:[~2018-05-23 2:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 14:39 [PATCH] printk/nmi: Prevent deadlock when serializing NMI backtraces Petr Mladek
2018-05-18 2:07 ` Sergey Senozhatsky
2018-05-18 6:38 ` Sergey Senozhatsky
2018-05-18 8:10 ` Petr Mladek
2018-05-22 21:43 ` Steven Rostedt
2018-05-23 2:01 ` Sergey Senozhatsky [this message]
2018-05-28 12:27 ` Petr Mladek
2018-06-05 12:47 ` Petr Mladek
2018-06-06 5:10 ` Sergey Senozhatsky
2018-06-06 10:33 ` Sergey Senozhatsky
2018-06-08 10:48 ` Petr Mladek
2018-06-18 6:37 ` Sergey Senozhatsky
2018-06-18 9:39 ` Petr Mladek
2018-06-18 10:07 ` Sergey Senozhatsky
2018-06-19 7:52 ` Petr Mladek
2018-06-19 8:27 ` Sergey Senozhatsky
2018-06-19 13:23 ` Steven Rostedt
2018-06-20 1:58 ` Sergey Senozhatsky
2018-06-20 2:32 ` Steven Rostedt
2018-06-20 4:17 ` Sergey Senozhatsky
2018-06-06 11:15 ` Petr Mladek
2018-06-07 5:40 ` Sergey Senozhatsky
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