#!/bin/bash

sysctl -w kernel.hung_task_timeout_secs=15
umount /root/temp
mkfs.ext4 -F -b 4096 /dev/sda 100M
mount /dev/sda /root/temp
dd if=/dev/zero of=/root/temp/file bs=4K count=1
for i in {0..1100}
do
	touch /root/temp/f_$i
	dd if=/dev/zero of=/root/temp/f_$i bs=4K count=1
	dd if=/dev/zero of=/root/temp/f_$i bs=4K count=1 seek=2
	dd if=/dev/zero of=/root/temp/f_$i bs=4K count=1 seek=4
	dd if=/dev/zero of=/root/temp/f_$i bs=4K count=1 seek=6
done
dd if=/dev/zero of=/root/temp/consumer bs=1M count=68
umount /root/temp

mount -odiscard /dev/sda /root/temp
for i in {0..1100}
do
	dd if=/dev/zero of=/root/temp/f_$i bs=4K count=1 seek=8 &
done
sleep 1
dmesg -c > /dev/null
wait
sync &
sleep 1
while true
do
	res=`dmesg -c`
	if [[ "$res" =~ "wait free" ]]
	then
		echo "delete file"
		rm -f /root/temp/file
		break;
	elif [[ "$res" =~ "will hung" ]]
	then
		echo "will hung"
		break;
	fi
	sleep 1
done