KVM: s390: vsie: Fix refcount overflow for shadow gmaps

In most cases gmap_put() was not called when it should have.

Add the missing gmap_put() in vsie_run().

Fixes: e38c884 ("KVM: s390: Switch to new gmap")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/kvm/vsie.c

@@ -1328,7 +1328,7 @@ static void unregister_shadow_scb(struct kvm_vcpu *vcpu)
 static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 {
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
-	struct gmap *sg;
+	struct gmap *sg = NULL;
 	int rc = 0;
 
 	while (1) {
@@ -1368,6 +1368,8 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 			sg = gmap_put(sg);
 		cond_resched();
 	}
+	if (sg)
+		sg = gmap_put(sg);
 
 	if (rc == -EFAULT) {
 		/*