diff --git a/sys/alpha/alpha/trap.c b/sys/alpha/alpha/trap.c
index eb9bc0677b5..0bc735454be 100644
--- a/sys/alpha/alpha/trap.c
+++ b/sys/alpha/alpha/trap.c
@@ -773,7 +773,7 @@ ast(framep)
 	 * acquiring and releasing mutexes in assembly is not fun.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (!(astpending() || resched_wanted())) {
+	if (!(astpending(p) || resched_wanted())) {
 		mtx_unlock_spin(&sched_lock);
 		return;
 	}
@@ -781,7 +781,7 @@ ast(framep)
 	sticks = p->p_sticks;
 	p->p_md.md_tf = framep;
 
-	astoff();
+	astoff(p);
 	cnt.v_soft++;
 	mtx_intr_enable(&sched_lock);
 	if (p->p_sflag & PS_OWEUPC) {
diff --git a/sys/alpha/include/cpu.h b/sys/alpha/include/cpu.h
index 3e0696f0265..798f8ddc59b 100644
--- a/sys/alpha/include/cpu.h
+++ b/sys/alpha/include/cpu.h
@@ -80,7 +80,7 @@ struct clockframe {
 #define	need_proftick(p) do {						\
 	mtx_lock_spin(&sched_lock);					\
 	(p)->p_sflag |= PS_OWEUPC;					\
-	aston();							\
+	aston(p);							\
 	mtx_unlock_spin(&sched_lock);					\
 } while (0)
 
diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c
index 4a89c399855..f778666aa07 100644
--- a/sys/amd64/amd64/trap.c
+++ b/sys/amd64/amd64/trap.c
@@ -1285,14 +1285,14 @@ ast(frame)
 	 * acquiring and releasing mutexes in assembly is not fun.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (!(astpending() || resched_wanted())) {
+	if (!(astpending(p) || resched_wanted())) {
 		mtx_unlock_spin(&sched_lock);
 		return;
 	}
 
 	sticks = p->p_sticks;
 
-	astoff();
+	astoff(p);
 	mtx_intr_enable(&sched_lock);
 	atomic_add_int(&cnt.v_soft, 1);
 	if (p->p_sflag & PS_OWEUPC) {
diff --git a/sys/amd64/include/cpu.h b/sys/amd64/include/cpu.h
index 9ecc87aa460..74f21b9debf 100644
--- a/sys/amd64/include/cpu.h
+++ b/sys/amd64/include/cpu.h
@@ -79,7 +79,7 @@
 #define	need_proftick(p) do {						\
 	mtx_lock_spin(&sched_lock);					\
 	(p)->p_sflag |= PS_OWEUPC;					\
-	aston();							\
+	aston(p);							\
 	mtx_unlock_spin(&sched_lock);					\
 } while (0)
 
diff --git a/sys/i386/i386/trap.c b/sys/i386/i386/trap.c
index 4a89c399855..f778666aa07 100644
--- a/sys/i386/i386/trap.c
+++ b/sys/i386/i386/trap.c
@@ -1285,14 +1285,14 @@ ast(frame)
 	 * acquiring and releasing mutexes in assembly is not fun.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (!(astpending() || resched_wanted())) {
+	if (!(astpending(p) || resched_wanted())) {
 		mtx_unlock_spin(&sched_lock);
 		return;
 	}
 
 	sticks = p->p_sticks;
 
-	astoff();
+	astoff(p);
 	mtx_intr_enable(&sched_lock);
 	atomic_add_int(&cnt.v_soft, 1);
 	if (p->p_sflag & PS_OWEUPC) {
diff --git a/sys/i386/include/cpu.h b/sys/i386/include/cpu.h
index 9ecc87aa460..74f21b9debf 100644
--- a/sys/i386/include/cpu.h
+++ b/sys/i386/include/cpu.h
@@ -79,7 +79,7 @@
 #define	need_proftick(p) do {						\
 	mtx_lock_spin(&sched_lock);					\
 	(p)->p_sflag |= PS_OWEUPC;					\
-	aston();							\
+	aston(p);							\
 	mtx_unlock_spin(&sched_lock);					\
 } while (0)
 
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
index fb4b4a6e3a0..6e99f24b093 100644
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -172,14 +172,14 @@ hardclock(frame)
 		    itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
 			mtx_lock_spin(&sched_lock);
 			p->p_sflag |= PS_ALRMPEND;
-			aston();
+			aston(p);
 			mtx_unlock_spin(&sched_lock);
 		}
 		if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
 		    itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
 			mtx_lock_spin(&sched_lock);
 			p->p_sflag |= PS_PROFPEND;
-			aston();
+			aston(p);
 			mtx_unlock_spin(&sched_lock);
 		}
 	}
diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c
index 4a89c399855..f778666aa07 100644
--- a/sys/kern/subr_trap.c
+++ b/sys/kern/subr_trap.c
@@ -1285,14 +1285,14 @@ ast(frame)
 	 * acquiring and releasing mutexes in assembly is not fun.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (!(astpending() || resched_wanted())) {
+	if (!(astpending(p) || resched_wanted())) {
 		mtx_unlock_spin(&sched_lock);
 		return;
 	}
 
 	sticks = p->p_sticks;
 
-	astoff();
+	astoff(p);
 	mtx_intr_enable(&sched_lock);
 	atomic_add_int(&cnt.v_soft, 1);
 	if (p->p_sflag & PS_OWEUPC) {
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 4beb0bcec23..224c5ace0ab 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -396,22 +396,26 @@ sigonstack(size_t sp)
 } while (0)
 
 /*
- * Notify the current process (p) that it has a signal pending,
- * process as soon as possible.
+ * Schedule an Asynchronous System Trap (AST) on return to user mode.
  */
-#define	aston()		signotify(CURPROC)
-#define	signotify(p) do {						\
+#define	aston(p) do {							\
 	mtx_assert(&sched_lock, MA_OWNED);				\
 	(p)->p_sflag |= PS_ASTPENDING;					\
 } while (0)
 
-#define	astpending()	(curproc->p_sflag & PS_ASTPENDING)
+#define	astpending(p)	((p)->p_sflag & PS_ASTPENDING)
 
-#define astoff() do {							\
+#define astoff(p) do {							\
 	mtx_assert(&sched_lock, MA_OWNED);				\
-	CURPROC->p_sflag &= ~PS_ASTPENDING;				\
+	(p)->p_sflag &= ~PS_ASTPENDING;					\
 } while (0)
 
+/*
+ * Notify the current process (p) that it has a signal pending,
+ * process as soon as possible.
+ */
+#define	signotify(p)	aston(p)
+
 /* Handy macro to determine if p1 can mangle p2. */
 #define	PRISON_CHECK(p1, p2) \
 	((p1)->p_prison == NULL || (p1)->p_prison == (p2)->p_prison)