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

[Jürgen Groß <jgross@xxxxxxxx>]

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>
Good catch!

Have you seen any further problems (e.g. with cpu on/offlining) with
this patch applied?

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen