Index: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
===================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
+++ head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
@@ -7257,6 +7257,44 @@
 }
 
 /*
+ * Disables interrupts and sets the per-thread inprobe flag. When DEBUG is
+ * defined, we also assert that we are not recursing unless the probe ID is an
+ * error probe.
+ */
+static dtrace_icookie_t
+dtrace_probe_enter(dtrace_id_t id)
+{
+	dtrace_icookie_t cookie;
+
+	cookie = dtrace_interrupt_disable();
+
+	/*
+	 * Unless this is an ERROR probe, we are not allowed to recurse in
+	 * dtrace_probe(). Recursing into DTrace probe usually means that a
+	 * function is instrumented that should not have been instrumented or
+	 * that the ordering guarantee of the records will be violated,
+	 * resulting in unexpected output. If there is an exception to this
+	 * assertion, a new case should be added.
+	 */
+	ASSERT(curthread->t_dtrace_inprobe == 0 ||
+	    id == dtrace_probeid_error);
+	curthread->t_dtrace_inprobe = 1;
+
+	return (cookie);
+}
+
+/*
+ * Disables interrupts and clears the per-thread inprobe flag.
+ */
+static void
+dtrace_probe_exit(dtrace_icookie_t cookie)
+{
+
+	curthread->t_dtrace_inprobe = 0;
+	dtrace_interrupt_enable(cookie);
+}
+
+/*
  * If you're looking for the epicenter of DTrace, you just found it.  This
  * is the function called by the provider to fire a probe -- from which all
  * subsequent probe-context DTrace activity emanates.
@@ -7290,7 +7328,7 @@
 		return;
 #endif
 
-	cookie = dtrace_interrupt_disable();
+	cookie = dtrace_probe_enter(id);
 	probe = dtrace_probes[id - 1];
 	cpuid = curcpu;
 	onintr = CPU_ON_INTR(CPU);
@@ -7301,7 +7339,7 @@
 		 * We have hit in the predicate cache; we know that
 		 * this predicate would evaluate to be false.
 		 */
-		dtrace_interrupt_enable(cookie);
+		dtrace_probe_exit(cookie);
 		return;
 	}
 
@@ -7313,7 +7351,7 @@
 		/*
 		 * We don't trace anything if we're panicking.
 		 */
-		dtrace_interrupt_enable(cookie);
+		dtrace_probe_exit(cookie);
 		return;
 	}
 
@@ -7939,7 +7977,7 @@
 	if (vtime)
 		curthread->t_dtrace_start = dtrace_gethrtime();
 
-	dtrace_interrupt_enable(cookie);
+	dtrace_probe_exit(cookie);
 }
 
 /*
Index: head/sys/cddl/dev/dtrace/dtrace_cddl.h
===================================================================
--- head/sys/cddl/dev/dtrace/dtrace_cddl.h
+++ head/sys/cddl/dev/dtrace/dtrace_cddl.h
@@ -46,6 +46,7 @@
 typedef struct kdtrace_thread {
 	u_int8_t	td_dtrace_stop;	/* Indicates a DTrace-desired stop */
 	u_int8_t	td_dtrace_sig;	/* Signal sent via DTrace's raise() */
+	u_int8_t	td_dtrace_inprobe; /* Are we in a probe? */
 	u_int		td_predcache;	/* DTrace predicate cache */
 	u_int64_t	td_dtrace_vtime; /* DTrace virtual time */
 	u_int64_t	td_dtrace_start; /* DTrace slice start time */
@@ -97,6 +98,7 @@
 #define	t_dtrace_start	td_dtrace->td_dtrace_start
 #define	t_dtrace_stop	td_dtrace->td_dtrace_stop
 #define	t_dtrace_sig	td_dtrace->td_dtrace_sig
+#define	t_dtrace_inprobe	td_dtrace->td_dtrace_inprobe
 #define	t_predcache	td_dtrace->td_predcache
 #define	t_dtrace_ft	td_dtrace->td_dtrace_ft
 #define	t_dtrace_on	td_dtrace->td_dtrace_on