[PATCH v2 3/4] sparc64: remove mm_cpumask clearing to fix kthread_use_mm race

[David Miller]

From: Nicholas Piggin <npiggin at gmail.com>
Date: Tue, 15 Sep 2020 13:24:07 +1000

> Excerpts from David Miller's message of September 15, 2020 5:59 am:
>> From: Nicholas Piggin <npiggin at gmail.com>
>> Date: Mon, 14 Sep 2020 14:52:18 +1000
>> 
>>  ...
>>> The basic fix for sparc64 is to remove its mm_cpumask clearing code. The
>>> optimisation could be effectively restored by sending IPIs to mm_cpumask
>>> members and having them remove themselves from mm_cpumask. This is more
>>> tricky so I leave it as an exercise for someone with a sparc64 SMP.
>>> powerpc has a (currently similarly broken) example.
>>> 
>>> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
>> 
>> Sad to see this optimization go away, but what can I do:
>> 
>> Acked-by: David S. Miller <davem at davemloft.net>
>> 
> 
> Thanks Dave, any objection if we merge this via the powerpc tree
> to keep the commits together?

No objection.