Re: [PATCH] sched: fix scheduler_disable() with core scheduling

[Dario Faggioli <dfaggioli@xxxxxxxx>]

On Thu, 2020-04-09 at 14:50 +0200, Jürgen Groß wrote:
> On 09.04.20 11:41, Sergey Dyasli wrote:
> > In core-scheduling mode, Xen might crash when entering ACPI S5
> > state.
> > This happens in sched_slave() during is_idle_unit(next) check
> > because
> > next->vcpu_list is stale and points to an already freed memory.
> > 
> > This situation happens shortly after scheduler_disable() is called
> > if
> > some CPU is still inside sched_slave() softirq. Current logic
> > simply
> > returns prev->next_task from sched_wait_rendezvous_in() which
> > causes
> > the described crash because next_task->vcpu_list has become
> > invalid.
> > 
> > Fix the crash by returning NULL from sched_wait_rendezvous_in() in
> > the case when scheduler_disable() has been called.
> > 
> > Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
> 
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> 
Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>

Thanks and Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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