FAILED: patch "[PATCH] KVM: x86: map/unmap private slots in __x86_set_memory_region" failed to apply to 4.2-stable tree

index 7bf8096f013d..3ac33f86c873 100644
@@ -7477,23 +7477,53 @@ void kvm_arch_sync_events(struct kvm *kvm)
 int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 {
 	int i, r;
+	u64 hva;
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	struct kvm_memory_slot *slot, old;
 
 	/* Called with kvm->slots_lock held.  */
 	if (WARN_ON(id >= KVM_MEM_SLOTS_NUM))
 		return -EINVAL;
 
+	slot = id_to_memslot(slots, id);
+	if (size) {
+		if (WARN_ON(slot->npages))
+			return -EEXIST;
+
+		/*
+		 * MAP_SHARED to prevent internal slot pages from being moved
+		 * by fork()/COW.
+		 */
+		hva = vm_mmap(NULL, 0, size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_ANONYMOUS, 0);
+		if (IS_ERR((void *)hva))
+			return PTR_ERR((void *)hva);
+	} else {
+		if (!slot->npages)
+			return 0;
+
+		hva = 0;
+	}
+
+	old = *slot;
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
 		struct kvm_userspace_memory_region m;
 
 		m.slot = id | (i << 16);
 		m.flags = 0;
 		m.guest_phys_addr = gpa;
+		m.userspace_addr = hva;
 		m.memory_size = size;
 		r = __kvm_set_memory_region(kvm, &m);
 		if (r < 0)
 			return r;
 	}
 
+	if (!size) {
+		r = vm_munmap(old.userspace_addr, old.npages * PAGE_SIZE);
+		WARN_ON(r < 0);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__x86_set_memory_region);

@@ -7623,27 +7653,6 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
-	/*
-	 * Only private memory slots need to be mapped here since
-	 * KVM_SET_MEMORY_REGION ioctl is no longer supported.
-	 */
-	if ((memslot->id >= KVM_USER_MEM_SLOTS) && (change == KVM_MR_CREATE)) {
-		unsigned long userspace_addr;
-
-		/*
-		 * MAP_SHARED to prevent internal slot pages from being moved
-		 * by fork()/COW.
-		 */
-		userspace_addr = vm_mmap(NULL, 0, memslot->npages * PAGE_SIZE,
-					 PROT_READ | PROT_WRITE,
-					 MAP_SHARED | MAP_ANONYMOUS, 0);
-
-		if (IS_ERR((void *)userspace_addr))
-			return PTR_ERR((void *)userspace_addr);
-
-		memslot->userspace_addr = userspace_addr;
-	}
-
 	return 0;
 }
 

@@ -7705,17 +7714,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 {
 	int nr_mmu_pages = 0;
 
-	if (change == KVM_MR_DELETE && old->id >= KVM_USER_MEM_SLOTS) {
-		int ret;
-
-		ret = vm_munmap(old->userspace_addr,
-				old->npages * PAGE_SIZE);
-		if (ret < 0)
-			printk(KERN_WARNING
-			       "kvm_vm_ioctl_set_memory_region: "
-			       "failed to munmap memory\n");
-	}
-
 	if (!kvm->arch.n_requested_mmu_pages)
 		nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);