On 17/05/2019 15:17, Jan Beulich wrote:
>>>> On 08.05.19 at 13:31, <jgr...@suse.com> wrote:
>> Commit 753ba43d6d16e688 ("xen/sched: fix credit2 smt idle handling")
>> introduced a regression when switching cpus between cpupools.
>>
>> When assigning a cpu to a cpupool with credit2 being the default
>> scheduler csched2_deinit_pdata() is called for the credit2 private data
>> after the new scheduler's private data has been hooked to the per-cpu
>> scheduler data. Unfortunately csched2_deinit_pdata() will cycle through
>> all per-cpu scheduler areas it knows of for removing the cpu from the
>> respective sibling masks including the area of the just moved cpu. This
>> will (depending on the new scheduler) either clobber the data of the
>> new scheduler or in case of sched_rt lead to a crash.
>>
>> Avoid that by removing the cpu from the list of active cpus in credit2
>> data first.
>>
>> The opposite problem is occurring when removing a cpu from a cpupool:
>> init_pdata() of credit2 will access the per-cpu data of the old
>> scheduler.
>>
>> Signed-off-by: Juergen Gross <jgr...@suse.com>
>
> May I ask what the disposition of this is? I've noticed too late
> that I've backported the commit being fixed here without
> waiting for this fix to go in. I'd prefer the stable trees, in
> particular 4.11 for the impending 4.11.2 release, to be able
> to pick this up soon.
Dario already gave his Reviewed-by:
Juergen
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