On Fri, Jul 17, 2020 at 01:00:25AM -0700, Ram Pai wrote: > > +int kvmppc_uv_migrate_mem_slot(struct kvm *kvm, > + const struct kvm_memory_slot *memslot) Don't see any callers for this outside of this file, so why not static? > +{ > + unsigned long gfn = memslot->base_gfn; > + struct vm_area_struct *vma; > + unsigned long start, end; > + int ret = 0; > + > + while (kvmppc_next_nontransitioned_gfn(memslot, kvm, &gfn)) { So you checked the state of gfn under uvmem_lock above, but release it too. > + > + mmap_read_lock(kvm->mm); > + start = gfn_to_hva(kvm, gfn); > + if (kvm_is_error_hva(start)) { > + ret = H_STATE; > + goto next; > + } > + > + end = start + (1UL << PAGE_SHIFT); > + vma = find_vma_intersection(kvm->mm, start, end); > + if (!vma || vma->vm_start > start || vma->vm_end < end) { > + ret = H_STATE; > + goto next; > + } > + > + mutex_lock(&kvm->arch.uvmem_lock); > + ret = kvmppc_svm_migrate_page(vma, start, end, > + (gfn << PAGE_SHIFT), kvm, PAGE_SHIFT, false); What is the guarantee that the gfn is in the same earlier state when you do do migration here? Regards, Bharata.