lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 20 May 2013 14:58:24 +0800
From:	Michael Wang <>
To:	Borislav Petkov <>
CC:	Tejun Heo <>,
	"Paul E. McKenney" <>,
	Jiri Kosina <>,
	Frederic Weisbecker <>,
	Tony Luck <>,,, Thomas Gleixner <>
Subject: Re: NOHZ: WARNING: at arch/x86/kernel/smp.c:123 native_smp_send_reschedule,
 round 2

On 05/20/2013 02:47 PM, Borislav Petkov wrote:
> On Mon, May 20, 2013 at 02:23:37PM +0800, Michael Wang wrote:
>> On 05/20/2013 12:50 PM, Borislav Petkov wrote:
>>> On Mon, May 20, 2013 at 11:16:33AM +0800, Michael Wang wrote:
>>>> I suppose the reason is that the cpu we passed to
>>>> mod_delayed_work_on() has a chance to become offline before we
>>>> disabled irq, what about check it before send resched ipi? like:
>>> I think this is only addressing the symptoms - what we should be doing
>>> instead is asking ourselves why are we even scheduling work on a cpu if
>>> the machine goes offline?
>>> I don't know though who should be responsible for killing all that
>>> work - the workqueue itself or the guy who created it, i.e. cpufreq
>>> governor...
>> So there are two questions here:
>> 1. Is gov_queue_work() want to queue the work on offline cpu?
>> 2. Is mod_delayed_work_on() allow offline cpu?
>> I guess both should be false?
> Well, if we don't allow queueing work on a cpu which goes offline, i.e.
> #2, the problem should be solved.

I've take a look at the usage of queue_delayed_work_on() and
mod_delayed_work_on(), mostly passed this_cpu, or those in online mask,
I think offline cpu is not by designed.

Besides, the cpu gov_queue_work() is using 'policy->cpus' which seems to
be updated during UP DOWN notify, I think they are supposed to be online.

But we need expert in cpufreq to confirm all these...

Michael Wang

> Tejun?
> Here are the splats:

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists