[PATCH v2 1/4] mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race

[Michael Ellerman]

Nicholas Piggin <npiggin at gmail.com> writes:
> Excerpts from peterz at infradead.org's message of September 14, 2020 8:56 pm:
>> On Mon, Sep 14, 2020 at 02:52:16PM +1000, Nicholas Piggin wrote:
>>> Reading and modifying current->mm and current->active_mm and switching
>>> mm should be done with irqs off, to prevent races seeing an intermediate
>>> state.
...
>>> 
>>> This is a bit ugly, but in the interest of fixing the bug and backporting
>>> before all architectures are converted this is a compromise.
>>> 
>>> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
>> 
>> Acked-by: Peter Zijlstra (Intel) <peterz at infradead.org>
>> 
>> I'm thinking we want this selected on x86 as well. Andy?
>
> Thanks for the ack. The plan was to take it through the powerpc tree,
> but if you'd want x86 to select it, maybe a topic branch?

I've put this series in a topic branch based on v5.9-rc2:

  https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/log/?h=topic/irqs-off-activate-mm

I plan to merge it into the powerpc/next tree for v5.10, but if anyone
else wants to merge it that's fine too.

cheers