From: Borislav Petkov <bp@alien8.de>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: tony.luck@intel.com, tglx@linutronix.de, mingo@redhat.com,
hpa@zytor.com, x86@kernel.org, linux-edac@vger.kernel.org,
linux-kernel@vger.kernel.org,
Chris Wilson <chris@chris-wilson.co.uk>
Subject: Re: [PATCH] x86/mce/therm_throt: Handle case where throttle_active_work() is called on behalf of an offline CPU
Date: Sat, 22 Feb 2020 18:51:51 +0100 [thread overview]
Message-ID: <20200222175151.GD11284@zn.tnic> (raw)
In-Reply-To: <20200222162432.497201-1-srinivas.pandruvada@linux.intel.com>
On Sat, Feb 22, 2020 at 08:24:32AM -0800, Srinivas Pandruvada wrote:
> During cpu-hotplug test with CONFIG_PREEMPTION and CONFIG_DEBUG_PREEMPT
> enabled, Chris reported error:
>
> BUG: using smp_processor_id() in preemptible [00000000] code: kworker/1:0/17
> caller is throttle_active_work+0x12/0x280
>
> Here throttle_active_work() is a work queue callback scheduled with
> schedule_delayed_work_on(). This will not cause this error for the use
> of smp_processor_id() under normal conditions as there is a check for
> "current->nr_cpus_allowed == 1".
> But when the target CPU is offline the workqueue becomes unbound.
> Then the work queue callback can be scheduled on another CPU and the
> error is printed for the use of smp_processor_id() in preemptible context.
So what's wrong with simply doing:
if (cpu_is_offline(this_cpu))
return;
?
You don't need to run the callback on an offlined CPU anyway...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-02-22 17:52 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-22 16:24 [PATCH] x86/mce/therm_throt: Handle case where throttle_active_work() is called on behalf of an offline CPU Srinivas Pandruvada
2020-02-22 16:53 ` Chris Wilson
2020-02-22 17:51 ` Borislav Petkov [this message]
2020-02-23 0:25 ` Srinivas Pandruvada
2020-02-24 12:55 ` Borislav Petkov
2020-02-24 16:01 ` Thomas Gleixner
2020-02-24 19:25 ` Thomas Gleixner
2020-02-24 21:05 ` Pandruvada, Srinivas
2020-02-25 9:46 ` Srinivas Pandruvada
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