--- sys/kern/subr_turnstile.c	2012-12-16 21:34:47.380655934 +0100
+++ sys/kern/subr_turnstile.c.new	2012-12-16 21:34:34.876655759 +0100
@@ -210,20 +210,19 @@
 
 		thread_lock_flags(td, MTX_DUPOK);
 		mtx_unlock_spin(&ts->ts_lock);
 		MPASS(td->td_proc != NULL);
 		MPASS(td->td_proc->p_magic == P_MAGIC);
 
 		/*
 		 * If the thread is asleep, then we are probably about
-		 * to deadlock.  To make debugging this easier, just
-		 * panic and tell the user which thread misbehaved so
-		 * they can hopefully get a stack trace from the truly
-		 * misbehaving thread.
+		 * to deadlock.  To make debugging this easier, show
+		 * backtrace of misbehaving thread and panic to not
+		 * leave the kernel deadlocked.
 		 */
 		if (TD_IS_SLEEPING(td)) {
 			printf(
 		"Sleeping thread (tid %d, pid %d) owns a non-sleepable lock\n",
 			    td->td_tid, td->td_proc->p_pid);
 			kdb_backtrace_thread(td);
 			panic("sleeping thread");
 		}