On Tue, May 6, 2014 at 3:29 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> So you forgot to CC Linus, Linus has expressed some dislike for
> preemptible mmu_notifiers in the recent past:
Indeed. I think we *really* should change that anonvma rwsem into an
rwlock. We had performance numbers that showed it needs to be done.
The *last* thing we want is to have random callbacks that can block in
this critical region. So now I think making it an rwlock is a good
idea just to make sure that never happens.
Seriously, the mmu_notifiers were misdesigned to begin with, and much
too deep. We're not screwing up the VM any more because of them.
Linus
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