Re: [PATCH] mm/mmu_notifier: Remove non_block_start/end() from notifier invocation

[Jason Gunthorpe]

On Tue, Aug 11, 2026 at 03:33:18PM +0100, David Woodhouse wrote:
> > At the cost of completely destroying the mm shootdown performance with
> > 1s RCU grace period waits every mm operation. No thanks.
> 
> I feel like we're not talking about the same things here.
> 
> The KVM patch which this enables does *not* behave as you have
> described. Have you looked at it?

It does, it calls synchronize_rcu() from
kvm_mmu_notifier_invalidate_range_start() - don't do that...

> Nobody's suggesting that we force any *other* MMU notifiers to do
> anything that they don't do today.

Sure, but nobody should implement their own notifiers with such a
heavy locking primitive.

Jason