From: Peter Zijlstra <peterz@infradead.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Jiang Liu <jiang.liu@linux.intel.com>,
mingo@kernel.org, "Rafael J. Wysocki" <rafael@kernel.org>,
Tejun Heo <tj@kernel.org>,
linux hotplug mailing <linux-hotplug@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: Possible deadlock related to CPU hotplug and kernfs
Date: Tue, 8 Sep 2015 12:40:08 +0200 [thread overview]
Message-ID: <20150908104008.GD3644@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <2165815.z3RZSlC1oy@vostro.rjw.lan>
On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote:
> On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote:
> Peter, Ingo, some help from lockdep expert is needed.
>
> We have a splat that almost certainly is a false positive (the original report
> is here http://marc.info/?l=linux-kernel&m=144109156901959&w=4) and no ideas
> how to make it go away. Can you please have a look and advise?
I can't even find the relevant code :/
>From that email I get kernfs_fop_write() which calls
kernfs_get_active(), but that does _NOT_ call cpu_up(), so that
callchain is shite.
The actual lockdep splat is also not really helpful, and is spraying
names over: acpi, device, sysfs and kernfs (do we really need that many
layeres of obfuscation for a simple file?)
So, please, start by explaining the thing proper such that simple people
like me know what to look for.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Jiang Liu <jiang.liu@linux.intel.com>,
mingo@kernel.org, "Rafael J. Wysocki" <rafael@kernel.org>,
Tejun Heo <tj@kernel.org>,
linux hotplug mailing <linux-hotplug@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: Possible deadlock related to CPU hotplug and kernfs
Date: Tue, 08 Sep 2015 10:40:08 +0000 [thread overview]
Message-ID: <20150908104008.GD3644@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <2165815.z3RZSlC1oy@vostro.rjw.lan>
On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote:
> On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote:
> Peter, Ingo, some help from lockdep expert is needed.
>
> We have a splat that almost certainly is a false positive (the original report
> is here http://marc.info/?l=linux-kernel&m\x144109156901959&w=4) and no ideas
> how to make it go away. Can you please have a look and advise?
I can't even find the relevant code :/
From that email I get kernfs_fop_write() which calls
kernfs_get_active(), but that does _NOT_ call cpu_up(), so that
callchain is shite.
The actual lockdep splat is also not really helpful, and is spraying
names over: acpi, device, sysfs and kernfs (do we really need that many
layeres of obfuscation for a simple file?)
So, please, start by explaining the thing proper such that simple people
like me know what to look for.
next prev parent reply other threads:[~2015-09-08 10:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-01 7:12 Possible deadlock related to CPU hotplug and kernfs Jiang Liu
2015-09-01 7:12 ` Jiang Liu
2015-09-02 16:14 ` Tejun Heo
2015-09-02 16:14 ` Tejun Heo
2015-09-03 0:58 ` Rafael J. Wysocki
2015-09-03 0:58 ` Rafael J. Wysocki
2015-09-03 16:19 ` Tejun Heo
2015-09-03 16:19 ` Tejun Heo
2015-09-03 20:08 ` Rafael J. Wysocki
2015-09-03 20:08 ` Rafael J. Wysocki
2015-09-04 7:20 ` Jiang Liu
2015-09-04 7:20 ` Jiang Liu
2015-09-04 14:16 ` Rafael J. Wysocki
2015-09-04 14:16 ` Rafael J. Wysocki
2015-09-07 3:11 ` Jiang Liu
2015-09-07 3:11 ` Jiang Liu
2015-09-07 21:33 ` Rafael J. Wysocki
2015-09-07 21:33 ` Rafael J. Wysocki
2015-09-08 10:40 ` Peter Zijlstra [this message]
2015-09-08 10:40 ` Peter Zijlstra
2015-09-08 22:28 ` Rafael J. Wysocki
2015-09-08 22:28 ` Rafael J. Wysocki
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