stress2: Added a regression test

tools/test/stress2/misc/pager_read_error.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+#
+# Copyright (c) 2025 Peter Holm <pho@FreeBSD.org>
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+# Hunt for "vm_fault: pager read error, pid 32939 (mmap)"
+
+# "panic: namei: unexpected flags: 0x10000000" seen:
+# https://people.freebsd.org/~pho/stress/log/log0585.txt
+# Fixed by: 58b2bd33aff7
+
+. ../default.cfg
+
+md=$mdstart
+mp=$mntpoint
+mdconfig -l | grep -q md$md && mdconfig -d -u $md
+mount | grep -q "on $mp " && umount -f $mp
+
+mdconfig -a -t swap -s 1g -u $md
+newfs -U /dev/md$md > /dev/null
+mount /dev/md$md $mp
+
+export RUNDIR=$mp/stressX
+../testcases/swap/swap -t 5m -i 20 -l 100 > /dev/null &
+sleep 5
+../testcases/mmap/mmap -t 5m -i 20 -l 100 > /dev/null 2>&1 &
+sleep 5
+umount -f $mp
+pkill swap mmap
+wait
+
+mdconfig -d -u $md
+exit 0