On Fri, Jul 25, 2014 at 01:16:39PM -0700, Jesse Barnes wrote: > On Thu, 24 Jul 2014 16:35:39 +0200 > Joerg Roedel <joro@xxxxxxxxxx> wrote: > > > From: Joerg Roedel <jroedel@xxxxxxx> > > > > This notifier closes an important gap with the current > > invalidate_range_start()/end() notifiers. The _start() part > > is called when all pages are still mapped while the _end() > > notifier is called when all pages are potentially unmapped > > and already freed. > > > > This does not allow to manage external (non-CPU) hardware > > TLBs with MMU-notifiers because there is no way to prevent > > that hardware will establish new TLB entries between the > > calls of these two functions. But this is a requirement to > > the subsytem that implements these existing notifiers. > > > > To allow managing external TLBs the MMU-notifiers need to > > catch the moment when pages are unmapped but not yet freed. > > This new notifier catches that moment and notifies the > > interested subsytem when pages that were unmapped are about > > to be freed. The new notifier will only be called between > > invalidate_range_start()/end(). > > So if we were actually sharing page tables, we should be able to make > start/end no-ops and just use this new callback, assuming we didn't > need to do any other serialization or debug stuff, right? > > Seems like a good addition, and saves us a bunch of trouble... Pondering on that i think there is a missing call to mmu_notifier_invalidate_range inside move_huge_pmd which is call by move_page_tables. But otherwise yes, you should not need to register range_start/end() callback. It should be enought to only register the invalidate_range callback. Note that on my side i will remain an user of range_start/end() but other listener like kvm or xen or sgi might want to revisit there code with this new callback. Cheers, Jérôme > > Thanks, > -- > Jesse Barnes, Intel Open Source Technology Center > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>