Date: Wed, 12 Jul 2017 10:44:54 -0500 (CDT)
From: Christopher Lameter <cl@linux.com>
To: Andre Wild <wild@linux.vnet.ibm.com>
cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        heiko.carstens@de.ibm.com
Subject: Re: BUG: using __this_cpu_read() in preemptible [00000000] code:
 mm_percpu_wq/7
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References: <b7cc8709-5bbf-8a9a-a155-0ea804641e9a@linux.vnet.ibm.com>
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On Wed, 7 Jun 2017, Andre Wild wrote:

> I'm currently seeing the following message running kernel version 4.11.0.
> It looks like it was introduced with the patch
> 4037d452202e34214e8a939fa5621b2b3bbb45b7.

A 2007 patch? At that point we did not have __this_cpu_read() nor
refresh_cpu_vmstats.... Is this on s390 or some such architecture?


> Can you please take a look at this problem?

Could you give me a bit more context?


> [Tue Jun  6 15:27:03 2017] BUG: using __this_cpu_read() in preemptible
> [00000000] code: mm_percpu_wq/7
> [Tue Jun  6 15:27:03 2017] caller is refresh_cpu_vm_stats+0x198/0x3d8
> [Tue Jun  6 15:27:03 2017] CPU: 0 PID: 7 Comm: mm_percpu_wq Tainted: G
> W       4.11.0-20170529.0.ae409ab.224a322.fc25.s390xdefault #1
> [Tue Jun  6 15:27:03 2017] Workqueue: mm_percpu_wq vmstat_update

It is run in preemptible mode but this from a kworker
context so the processor cannot change (see vmstat_refresh()).

Even on s390 or so this should be fine.