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SubjectRe: mm: deadlock between get_online_cpus/pcpu_alloc
On Tue, Feb 07, 2017 at 10:23:31AM +0100, Vlastimil Babka wrote:
>
> > cpu offlining. I have to check the code but my impression was that WQ
> > code will ignore the cpu requested by the work item when the cpu is
> > going offline. If the offline happens while the worker function already
> > executes then it has to wait as we run with preemption disabled so we
> > should be safe here. Or am I missing something obvious?
>
> Tejun suggested an alternative solution to avoiding get_online_cpus() in
> this thread:
> https://lkml.kernel.org/r/<20170123170329.GA7820@htj.duckdns.org>

I was hoping it would not really be necessary to sync against the cpu
offline callback if we know we don't really have to guarantee we run on
the correct CPU.

--
Mel Gorman
SUSE Labs

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