On Sat, Mar 05, 2022, Paolo Bonzini wrote: > On 3/5/22 01:34, Sean Christopherson wrote: > > On Fri, Mar 04, 2022, Paolo Bonzini wrote: > > > On 3/4/22 17:02, Sean Christopherson wrote: > > > > On Fri, Mar 04, 2022, Paolo Bonzini wrote: > > > > > On 3/3/22 22:32, Sean Christopherson wrote: > > > > > I didn't remove the paragraph from the commit message, but I think it's > > > > > unnecessary now. The workqueue is flushed in kvm_mmu_zap_all_fast() and > > > > > kvm_mmu_uninit_tdp_mmu(), unlike the buggy patch, so it doesn't need to take > > > > > a reference to the VM. > > > > > > > > > > I think I don't even need to check kvm->users_count in the defunct root > > > > > case, as long as kvm_mmu_uninit_tdp_mmu() flushes and destroys the workqueue > > > > > before it checks that the lists are empty. > > > > > > > > Yes, that should work. IIRC, the WARN_ONs will tell us/you quite quickly if > > > > we're wrong :-) mmu_notifier_unregister() will call the "slow" kvm_mmu_zap_all() > > > > and thus ensure all non-root pages zapped, but "leaking" a worker will trigger > > > > the WARN_ON that there are no roots on the list. > > > > > > Good, for the record these are the commit messages I have: > > I'm seeing some hangs in ~50% of installation jobs, both Windows and Linux. > I have not yet tried to reproduce outside the automated tests, or to bisect, > but I'll try to push at least the first part of the series for 5.18. Out of curiosity, what was the bug? I see this got pushed to kvm/next.
