On 25/06/2018 09:57, Michal Hocko wrote: > On Sun 24-06-18 10:11:21, Paolo Bonzini wrote: >> On 22/06/2018 17:02, Michal Hocko wrote: >>> @@ -7215,6 +7216,8 @@ void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, >>> apic_address = gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); >>> if (start <= apic_address && apic_address < end) >>> kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); >>> + >>> + return 0; >> >> This is wrong, gfn_to_hva can sleep. > > Hmm, I have tried to crawl the call chain and haven't found any > sleepable locks taken. Maybe I am just missing something. > __kvm_memslots has a complex locking assert. I do not see we would take > slots_lock anywhere from the notifier call path. IIUC that means that > users_count has to be zero at that time. I have no idea how that is > guaranteed. Nevermind, ENOCOFFEE. This is gfn_to_hva, not gfn_to_pfn. It only needs SRCU. Paolo
