diff --git a/sys/arm/arm/mp_machdep.c b/sys/arm/arm/mp_machdep.c
--- a/sys/arm/arm/mp_machdep.c
+++ b/sys/arm/arm/mp_machdep.c
@@ -182,6 +182,7 @@
 	pc->pc_curthread = pc->pc_idlethread;
 	pc->pc_curpcb = pc->pc_idlethread->td_pcb;
 	set_curthread(pc->pc_idlethread);
+	schedinit_ap();
 #ifdef VFP
 	vfp_init();
 #endif
diff --git a/sys/arm64/arm64/mp_machdep.c b/sys/arm64/arm64/mp_machdep.c
--- a/sys/arm64/arm64/mp_machdep.c
+++ b/sys/arm64/arm64/mp_machdep.c
@@ -255,6 +255,7 @@
 	/* Initialize curthread */
 	KASSERT(PCPU_GET(idlethread) != NULL, ("no idle thread"));
 	pcpup->pc_curthread = pcpup->pc_idlethread;
+	schedinit_ap();
 
 	/* Initialize curpmap to match TTBR0's current setting. */
 	pmap0 = vmspace_pmap(&vmspace0);
diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -678,6 +678,13 @@
 	mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN);
 }
 
+void
+schedinit_ap(void)
+{
+
+	/* Nothing needed. */
+}
+
 int
 sched_runnable(void)
 {
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -1743,6 +1743,26 @@
 	ts0->ts_cpu = curcpu;	/* set valid CPU number */
 }
 
+/*
+ * schedinit_ap() is needed prior to calling sched_throw(NULL) to ensure that
+ * the pcpu requirements are met for any calls in the period between curthread
+ * initialization and sched_throw().  One can safely add threads to the queue
+ * before sched_throw(), for instance, as long as the thread lock is setup
+ * correctly.
+ *
+ * TDQ_SELF() relies on the below sched pcpu setting; it may be used only
+ * after schedinit_ap().
+ */
+void
+schedinit_ap(void)
+{
+
+#ifdef SMP
+	PCPU_SET(sched, DPCPU_PTR(tdq));
+#endif
+	PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(TDQ_SELF());
+}
+
 /*
  * This is only somewhat accurate since given many processes of the same
  * priority they will switch when their slices run out, which will be
@@ -2973,19 +2993,14 @@
 	struct thread *newtd;
 	struct tdq *tdq;
 
+	tdq = TDQ_SELF();
 	if (__predict_false(td == NULL)) {
-#ifdef SMP
-		PCPU_SET(sched, DPCPU_PTR(tdq));
-#endif
-		/* Correct spinlock nesting and acquire the correct lock. */
-		tdq = TDQ_SELF();
 		TDQ_LOCK(tdq);
+		/* Correct spinlock nesting. */
 		spinlock_exit();
 		PCPU_SET(switchtime, cpu_ticks());
 		PCPU_SET(switchticks, ticks);
-		PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(tdq);
 	} else {
-		tdq = TDQ_SELF();
 		THREAD_LOCK_ASSERT(td, MA_OWNED);
 		THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq));
 		tdq_load_rem(tdq, td);
diff --git a/sys/mips/mips/mp_machdep.c b/sys/mips/mips/mp_machdep.c
--- a/sys/mips/mips/mp_machdep.c
+++ b/sys/mips/mips/mp_machdep.c
@@ -311,6 +311,7 @@
 	/* Initialize curthread. */
 	KASSERT(PCPU_GET(idlethread) != NULL, ("no idle thread"));
 	PCPU_SET(curthread, PCPU_GET(idlethread));
+	schedinit_ap();
 
 	mtx_lock_spin(&ap_boot_mtx);
 
diff --git a/sys/powerpc/aim/mp_cpudep.c b/sys/powerpc/aim/mp_cpudep.c
--- a/sys/powerpc/aim/mp_cpudep.c
+++ b/sys/powerpc/aim/mp_cpudep.c
@@ -35,6 +35,7 @@
 #include <sys/bus.h>
 #include <sys/pcpu.h>
 #include <sys/proc.h>
+#include <sys/sched.h>
 #include <sys/smp.h>
 
 #include <machine/bus.h>
@@ -134,6 +135,7 @@
 #endif
 	pcpup->pc_curpcb = pcpup->pc_curthread->td_pcb;
 	sp = pcpup->pc_curpcb->pcb_sp;
+	schedinit_ap();
 
 	return (sp);
 }
diff --git a/sys/powerpc/booke/mp_cpudep.c b/sys/powerpc/booke/mp_cpudep.c
--- a/sys/powerpc/booke/mp_cpudep.c
+++ b/sys/powerpc/booke/mp_cpudep.c
@@ -35,6 +35,7 @@
 #include <sys/bus.h>
 #include <sys/pcpu.h>
 #include <sys/proc.h>
+#include <sys/sched.h>
 #include <sys/smp.h>
 
 #include <machine/pcb.h>
@@ -85,6 +86,7 @@
 #endif
 	pcpup->pc_curpcb = pcpup->pc_curthread->td_pcb;
 	sp = pcpup->pc_curpcb->pcb_sp;
+	schedinit_ap();
 
 	/* XXX shouldn't the pcb_sp be checked/forced for alignment here?? */
 
diff --git a/sys/riscv/riscv/mp_machdep.c b/sys/riscv/riscv/mp_machdep.c
--- a/sys/riscv/riscv/mp_machdep.c
+++ b/sys/riscv/riscv/mp_machdep.c
@@ -248,6 +248,7 @@
 	/* Initialize curthread */
 	KASSERT(PCPU_GET(idlethread) != NULL, ("no idle thread"));
 	pcpup->pc_curthread = pcpup->pc_idlethread;
+	schedinit_ap();
 
 	/*
 	 * Identify current CPU. This is necessary to setup
diff --git a/sys/sys/sched.h b/sys/sys/sched.h
--- a/sys/sys/sched.h
+++ b/sys/sys/sched.h
@@ -226,6 +226,11 @@
  * Fixup scheduler state for proc0 and thread0
  */
 void schedinit(void);
+
+/*
+ * Fixup scheduler state for secondary APs
+ */
+void schedinit_ap(void);
 #endif /* _KERNEL */
 
 /* POSIX 1003.1b Process Scheduling */
diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1040,6 +1040,7 @@
 	/* Initialize curthread. */
 	KASSERT(PCPU_GET(idlethread) != NULL, ("no idle thread"));
 	PCPU_SET(curthread, PCPU_GET(idlethread));
+	schedinit_ap();
 
 	mtx_lock_spin(&ap_boot_mtx);