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

[David Miller]

From: Nicholas Piggin <npiggin@xxxxxxxxx>
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@xxxxxxxxx>

Sad to see this optimization go away, but what can I do:

Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>