Index: head/sys/kern/kern_thread.c
===================================================================
--- head/sys/kern/kern_thread.c
+++ head/sys/kern/kern_thread.c
@@ -346,6 +346,7 @@
 	td = (struct thread *)mem;
 	td->td_state = TDS_INACTIVE;
 	td->td_lastcpu = td->td_oncpu = NOCPU;
+	td->td_allocdomain = vm_phys_domain(vtophys(td));
 
 	/*
 	 * Note that td_critnest begins life as 1 because the thread is not
@@ -544,7 +545,7 @@
 	struct thread_domain_data *tdd;
 	struct thread *ztd;
 
-	tdd = &thread_domain_data[vm_phys_domain(vtophys(td))];
+	tdd = &thread_domain_data[td->td_allocdomain];
 	ztd = atomic_load_ptr(&tdd->tdd_zombies);
 	for (;;) {
 		td->td_zombie = ztd;
Index: head/sys/sys/proc.h
===================================================================
--- head/sys/sys/proc.h
+++ head/sys/sys/proc.h
@@ -246,6 +246,7 @@
 	sigqueue_t	td_sigqueue;	/* (c) Sigs arrived, not delivered. */
 #define	td_siglist	td_sigqueue.sq_signals
 	u_char		td_lend_user_pri; /* (t) Lend user pri. */
+	u_char		td_allocdomain;	/* (b) NUMA domain backing this struct thread. */
 
 /* Cleared during fork1() */
 #define	td_startzero td_flags