--- a/sys/src/9/port/proc.c	Thu Apr  5 20:21:39 2018
+++ b/sys/src/9/port/proc.c	Wed Feb  4 20:30:44 2026
@@ -894,7 +894,9 @@
 	lock(r);
 	p = r->p;
 
-	if(p != nil){
+	if(p == nil)
+		unlock(r);
+	else{
 		lock(&p->rlock);
 		if(p->state != Wakeme || p->r != r){
 			iprint("%p %p %d\n", p->r, r, p->state);
@@ -902,10 +904,10 @@
 		}
 		r->p = nil;
 		p->r = nil;
+		unlock(r);
 		ready(p);
 		unlock(&p->rlock);
 	}
-	unlock(r);
 
 	splx(s);
 
@@ -958,8 +960,13 @@
 				panic("postnote: state %d %d %d", r->p != p, p->r != r, p->state);
 			p->r = nil;
 			r->p = nil;
-			ready(p);
+			/*
+			 * The unlock must precede ready(p), in case the readied process
+			 * immediately deallocates the Rendez. This can happen with semacquire,
+			 * where the Rendez is on the stack.
+			 */
 			unlock(r);
+			ready(p);
 			break;
 		}