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Groups > linux.kernel > #1600767
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] cpu/hotplug: Serialize callback invocations proper |
| Date | 2017-03-14 18:50 +0100 |
| Message-ID | <tkYK5-3xL-7@gated-at.bofh.it> (permalink) |
| References | <sofxg-7Za-21@gated-at.bofh.it> <tiljP-6LS-3@gated-at.bofh.it> <tkWfh-1T2-57@gated-at.bofh.it> <tkYK5-3xL-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, 14 Mar 2017, Bart Van Assche wrote:
> On Tue, 2017-03-14 at 16:06 +0100, Sebastian Andrzej Siewior wrote:
> > The setup/remove_state/instance() functions in the hotplug core code are
> > serialized against concurrent CPU hotplug, but unfortunately not serialized
> > against themself.
> >
> > As a consequence a concurrent invocation of these function results in
> > corruption of the callback machinery because two instances try to invoke
> > callbacks on remote cpus at the same time. This results in missing callback
> > invocations and initiator threads waiting forever on the completion.
> >
> > The obvious solution to replace get_cpu_online() with cpu_hotplug_begin()
> > is not possible because at least one callsite calls into these functions
> > from a get_online_cpu() locked region.
> >
> > Extend the protection scope of the cpuhp_state_mutex from solely protecting
> > the state arrays to cover the callback invocation machinery as well.
> >
> > Reported-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
> > Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface")
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> Tested-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
>
> So this regression was introduced in kernel v4.6? Anyway, thanks for the patch!
And it's very timing sensitive ....
Thanks for trying to bisect this!
tglx
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[PATCH] cpu/hotplug: Serialize callback invocations proper Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-03-14 16:10 +0100 Re: [PATCH] cpu/hotplug: Serialize callback invocations proper Thomas Gleixner <tglx@linutronix.de> - 2017-03-14 18:50 +0100 [tip:smp/urgent] cpu/hotplug: Serialize callback invocations proper tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-03-14 19:30 +0100
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