diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -605,16 +605,6 @@
 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
     stack_t *stack)
 {
-
-	/*
-	 * Do any extra cleaning that needs to be done.
-	 * The thread may have optional components
-	 * that are not present in a fresh thread.
-	 * This may be a recycled thread so make it look
-	 * as though it's newly allocated.
-	 */
-	cpu_thread_clean(td);
-
 #ifdef COMPAT_FREEBSD32
 	if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
 		/*
diff --git a/sys/compat/linux/linux_fork.c b/sys/compat/linux/linux_fork.c
--- a/sys/compat/linux/linux_fork.c
+++ b/sys/compat/linux/linux_fork.c
@@ -301,8 +301,6 @@
 	else
 		em->child_clear_tid = NULL;
 
-	cpu_thread_clean(newtd);
-
 	linux_set_upcall(newtd, args->stack);
 
 	PROC_LOCK(p);
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -480,16 +480,6 @@
 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
     stack_t *stack)
 {
-
-	/* 
-	 * Do any extra cleaning that needs to be done.
-	 * The thread may have optional components
-	 * that are not present in a fresh thread.
-	 * This may be a recycled thread so make it look
-	 * as though it's newly allocated.
-	 */
-	cpu_thread_clean(td);
-
 	/*
 	 * Set the trap frame to point at the beginning of the entry
 	 * function.