--- /n/sources/plan9/sys/src/9k/port/sysseg.c	Thu Jan 27 13:38:26 2022
+++ /sys/src/9k/port/sysseg.c	Fri Oct 30 00:00:00 2026
@@ -422,6 +422,8 @@
 			pteflush(pte, ps/pgsize, pe/pgsize);
 
 		chunk = pe-ps;
+		if(chunk > len)
+			chunk = len;
 		len -= chunk;
 		addr += chunk;