From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Saravana Kannan <skannan@codeaurora.org>,
Linux PM list <linux-pm@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [BUG] Kernel splat when taking CPUs offline
Date: Thu, 9 Jul 2015 09:34:45 +0530 [thread overview]
Message-ID: <20150709040445.GG1805@linux> (raw)
In-Reply-To: <1625417.XZkzNdoaJA@vostro.rjw.lan>
On 09-07-15, 02:13, Rafael J. Wysocki wrote:
> So the cpufreq driver's ->get() callback returns 0 for the given CPU and
> that's what triggers the WARN_ON(). And it most likely returns 0, because
> its internal data structure for that CPU is not present.
>
> I *guess* that before the above commit policy was NULL in cpufreq_update_policy()
> and we didn't get to the point where ->get() was called.
I am not sure if that behavior should have changed at all.. Earlier we
were clearing per-cpu cpufreq_cpu_data for offline CPUs and so policy
would have been NULL for offline CPUs.
Now that per-cpu variable isn't cleared, but cpufreq_cpu_get() does
check if the CPU is part of policy->cpus or not, i.e. if it is
offline. And so policy should still be NULL for offline CPUs.
I think it might be related to what I chased down yesterday:
http://marc.info/?l=linux-kernel&m=143633485824975&w=2
@Steven: Can you please give this a try ?
--
viresh
next prev parent reply other threads:[~2015-07-09 4:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 19:24 [BUG] Kernel splat when taking CPUs offline Steven Rostedt
2015-07-09 0:13 ` Rafael J. Wysocki
2015-07-09 3:34 ` Steven Rostedt
2015-07-09 4:04 ` Viresh Kumar [this message]
2015-07-09 4:25 ` Steven Rostedt
2015-07-09 4:57 ` Viresh Kumar
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