From: cmetcalf@mellanox.com (Chris Metcalf)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods
Date: Thu, 17 Mar 2016 20:17:59 -0400 [thread overview]
Message-ID: <56EB4937.1010404@mellanox.com> (raw)
In-Reply-To: <20160317225557.GA4287@linux.vnet.ibm.com>
On 3/17/2016 6:55 PM, Paul E. McKenney wrote:
> The RCU stall-warn stack traces can be ugly, agreed.
>
> That said, RCU used to use NMI-based stack traces, but switched to the
> current scheme due to the NMIs having the unfortunate habit of locking
> things up, which IIRC often meant no stack traces at all. If I recall
> correctly, one of the problems was self-deadlock in printk().
Steven Rostedt enabled the per_cpu printk func support in June 2014, and
the nmi_backtrace code uses it to just capture printk output to percpu
buffers, so I think it's going to be a lot more robust than earlier attempts.
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
WARNING: multiple messages have this Message-ID (diff)
From: Chris Metcalf <cmetcalf@mellanox.com>
To: <paulmck@linux.vnet.ibm.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Aaron Tomlin <atomlin@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@osdl.org>,
Daniel Thompson <daniel.thompson@linaro.org>, <x86@kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods
Date: Thu, 17 Mar 2016 20:17:59 -0400 [thread overview]
Message-ID: <56EB4937.1010404@mellanox.com> (raw)
In-Reply-To: <20160317225557.GA4287@linux.vnet.ibm.com>
On 3/17/2016 6:55 PM, Paul E. McKenney wrote:
> The RCU stall-warn stack traces can be ugly, agreed.
>
> That said, RCU used to use NMI-based stack traces, but switched to the
> current scheme due to the NMIs having the unfortunate habit of locking
> things up, which IIRC often meant no stack traces at all. If I recall
> correctly, one of the problems was self-deadlock in printk().
Steven Rostedt enabled the per_cpu printk func support in June 2014, and
the nmi_backtrace code uses it to just capture printk output to percpu
buffers, so I think it's going to be a lot more robust than earlier attempts.
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
next prev parent reply other threads:[~2016-03-18 0:17 UTC|newest]
Thread overview: 121+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 21:40 [PATCH 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-02-29 21:40 ` Chris Metcalf
2016-02-29 21:40 ` [PATCH 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods Chris Metcalf
2016-02-29 21:40 ` Chris Metcalf
2016-02-29 21:40 ` [PATCH 2/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-01 14:23 ` Daniel Thompson
2016-03-01 16:01 ` Chris Metcalf
2016-03-07 8:26 ` Daniel Thompson
2016-03-07 17:05 ` Chris Metcalf
2016-03-07 9:48 ` Peter Zijlstra
2016-03-07 17:38 ` Chris Metcalf
2016-03-07 20:43 ` Peter Zijlstra
2016-03-16 17:02 ` [PATCH v2 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-17 19:36 ` Peter Zijlstra
2016-03-17 19:36 ` Peter Zijlstra
2016-03-17 22:31 ` Chris Metcalf
2016-03-17 22:31 ` Chris Metcalf
2016-03-17 22:38 ` Peter Zijlstra
2016-03-17 22:38 ` Peter Zijlstra
2016-03-17 22:41 ` Chris Metcalf
2016-03-17 22:41 ` Chris Metcalf
2016-03-17 23:14 ` Peter Zijlstra
2016-03-17 23:14 ` Peter Zijlstra
2016-03-17 22:55 ` Paul E. McKenney
2016-03-17 22:55 ` Paul E. McKenney
2016-03-17 23:09 ` Peter Zijlstra
2016-03-17 23:09 ` Peter Zijlstra
2016-03-17 23:11 ` Peter Zijlstra
2016-03-17 23:11 ` Peter Zijlstra
2016-03-18 0:28 ` Paul E. McKenney
2016-03-18 0:28 ` Paul E. McKenney
2016-03-18 0:17 ` Chris Metcalf [this message]
2016-03-18 0:17 ` Chris Metcalf
2016-03-18 0:33 ` Paul E. McKenney
2016-03-18 0:33 ` Paul E. McKenney
2016-03-18 9:40 ` Daniel Thompson
2016-03-18 9:40 ` Daniel Thompson
2016-03-18 23:54 ` Paul E. McKenney
2016-03-18 23:54 ` Paul E. McKenney
2016-03-16 17:02 ` [PATCH v2 2/4] nmi_backtrace: do a local dump_stack() instead of a self-NMI Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` [PATCH v2 3/4] arch/tile: adopt the new nmi_backtrace framework Chris Metcalf
2016-03-16 17:02 ` [PATCH v2 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 17:02 ` Chris Metcalf
2016-03-16 18:46 ` kbuild test robot
2016-03-16 18:46 ` kbuild test robot
2016-03-16 18:46 ` kbuild test robot
2016-03-16 18:46 ` kbuild test robot
2016-03-21 15:38 ` Peter Zijlstra
2016-03-21 15:38 ` Peter Zijlstra
2016-03-21 15:38 ` Peter Zijlstra
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:46 ` Chris Metcalf
2016-03-21 15:42 ` Peter Zijlstra
2016-03-21 15:42 ` Peter Zijlstra
2016-03-21 16:15 ` Chris Metcalf
2016-03-21 16:15 ` Chris Metcalf
2016-03-21 16:15 ` Chris Metcalf
2016-03-21 16:32 ` Peter Zijlstra
2016-03-21 16:32 ` Peter Zijlstra
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:12 ` Chris Metcalf
2016-03-21 17:17 ` Peter Zijlstra
2016-03-21 17:17 ` Peter Zijlstra
2016-03-21 16:48 ` Peter Zijlstra
2016-03-21 16:48 ` Peter Zijlstra
2016-03-21 21:49 ` Peter Zijlstra
2016-03-21 21:49 ` Peter Zijlstra
2016-03-22 17:19 ` [PATCH v3 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` [PATCH v3 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` [PATCH v3 2/4] nmi_backtrace: do a local dump_stack() instead of a self-NMI Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` [PATCH v3 3/4] arch/tile: adopt the new nmi_backtrace framework Chris Metcalf
2016-03-22 17:19 ` [PATCH v3 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:19 ` Chris Metcalf
2016-03-22 17:30 ` Peter Zijlstra
2016-03-22 17:30 ` Peter Zijlstra
2016-03-22 22:28 ` Rafael J. Wysocki
2016-03-22 22:28 ` Rafael J. Wysocki
2016-03-22 22:31 ` Rafael J. Wysocki
2016-03-22 22:31 ` Rafael J. Wysocki
2016-03-22 22:45 ` Peter Zijlstra
2016-03-22 22:45 ` Peter Zijlstra
2016-03-23 0:50 ` Rafael J. Wysocki
2016-03-23 0:50 ` Rafael J. Wysocki
2016-03-23 7:53 ` Peter Zijlstra
2016-03-23 7:53 ` Peter Zijlstra
2016-03-30 17:16 ` [PATCH v4 0/4] improvements to the nmi_backtrace code Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` [PATCH v4 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` [PATCH v4 2/4] nmi_backtrace: do a local dump_stack() instead of a self-NMI Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` [PATCH v4 3/4] arch/tile: adopt the new nmi_backtrace framework Chris Metcalf
2016-03-30 17:16 ` [PATCH v4 4/4] nmi_backtrace: generate one-line reports for idle cpus Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-03-30 17:16 ` Chris Metcalf
2016-02-29 21:40 ` [PATCH 3/4] nmi_backtrace: do a local dump_stack() instead of a self-NMI Chris Metcalf
2016-02-29 21:40 ` Chris Metcalf
2016-02-29 21:40 ` [PATCH 4/4] arch/tile: adopt the new nmi_backtrace framework Chris Metcalf
2016-03-01 0:49 ` [PATCH 0/4] improvements to the nmi_backtrace code Andrew Morton
2016-03-01 0:49 ` Andrew Morton
2016-03-01 10:01 ` Petr Mladek
2016-03-01 10:01 ` Petr Mladek
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