On Tue, Feb 01, 2022 at 02:20:39AM +0000, Matthew Wilcox wrote: > On Mon, Jan 31, 2022 at 05:14:34PM -0800, Andrew Morton wrote: > > On Fri, 28 Jan 2022 05:09:31 -0800 Michel Lespinasse <michel@xxxxxxxxxxxxxx> wrote: > > > The next step is to walk down the existing page table tree to find the > > > current pte entry. This is done with interrupts disabled to avoid > > > races with munmap(). > > > > Sebastian, could you please comment on this from the CONFIG_PREEMPT_RT > > point of view? > > I am not a fan of this approach. For other reasons, I think we want to > switch to RCU-freed page tables, and then we can walk the page tables > with the RCU lock held. Some architectures already RCU-free the page > tables, so I think it's just a matter of converting the rest. Note - I have no problem with switching to RCU-freed page tables everywhere when and if we end up needing to. I just don't see that this need comes from the SPF patchset, so I don't think this should be introduced as an artificial dependency. -- Michel "walken" Lespinasse
