Index: sys/kern/subr_uio.c
===================================================================
--- sys/kern/subr_uio.c
+++ sys/kern/subr_uio.c
@@ -206,31 +206,32 @@
 static int
 uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
 {
-	struct thread *td;
 	struct iovec *iov;
 	size_t cnt;
 	int error, newflags, save;
 
-	td = curthread;
 	error = 0;
 
 	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
 	    ("uiomove: mode"));
-	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == td,
+	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove proc"));
-	if (!nofault)
-		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
-		    "Calling uiomove()");
-
-	/* XXX does it make a sense to set TDP_DEADLKTREAT for UIO_SYSSPACE ? */
-	newflags = TDP_DEADLKTREAT;
-	if (uio->uio_segflg == UIO_USERSPACE && nofault) {
-		/*
-		 * Fail if a non-spurious page fault occurs.
-		 */
-		newflags |= TDP_NOFAULTING | TDP_RESETSPUR;
+
+	if (uio->uio_segflg == UIO_USERSPACE) {
+		newflags = TDP_DEADLKTREAT;
+		if (nofault) {
+			/*
+			 * Fail if a non-spurious page fault occurs.
+			 */
+			newflags |= TDP_NOFAULTING | TDP_RESETSPUR;
+		} else {
+			WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
+			    "Calling uiomove()");
+		}
+		save = curthread_pflags_set(newflags);
+	} else {
+		KASSERT(nofault == 0, ("uiomove: nofault"));
 	}
-	save = curthread_pflags_set(newflags);
 
 	while (n > 0 && uio->uio_resid) {
 		iov = uio->uio_iov;
@@ -272,7 +273,8 @@
 		n -= cnt;
 	}
 out:
-	curthread_pflags_restore(save);
+	if (uio->uio_segflg == UIO_USERSPACE) 
+		curthread_pflags_restore(save);
 	return (error);
 }