Greetings,
I have an xfs umount hang caused by forcing the block device to return
i/o errors while copying files to the filesystem.
Detailed steps to reproduce the problem on virtualbox are below.
The linux version is a recent pull and reports as 3.15.0-rc3.
[ 2040.248096] INFO: task umount:10303 blocked for more than 120 seconds.
[ 2040.323947] Not tainted 3.15.0-rc3 #4
[ 2040.343423] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2040.352665] umount D ffffffff8180fe40 0 10303 8691 0x00000000
[ 2040.404918] ffff88001e33dd58 0000000000000086 ffff88001e33dd48 ffffffff81080f82
[ 2040.489901] ffff88001b311900 0000000000013180 ffff88001e33dfd8 0000000000013180
[ 2040.534772] ffff88003daa3200 ffff88001b311900 ffff88002421aec0 ffff88002421ae80
[ 2040.587450] Call Trace:
[ 2040.592176] [<ffffffff81080f82>] ? try_to_wake_up+0x232/0x2b0
[ 2040.620212] [<ffffffff816c54d9>] schedule+0x29/0x70
[ 2040.627685] [<ffffffffa04c4cd6>] xfs_ail_push_all_sync+0x96/0xd0 [xfs]
[ 2040.632236] [<ffffffff81092230>] ? __wake_up_sync+0x20/0x20
[ 2040.659105] [<ffffffffa04731a3>] xfs_unmountfs+0x63/0x160 [xfs]
[ 2040.691774] [<ffffffffa0478f65>] ? kmem_free+0x35/0x40 [xfs]
[ 2040.698610] [<ffffffffa0474cf5>] xfs_fs_put_super+0x25/0x60 [xfs]
[ 2040.706838] [<ffffffff8119561e>] generic_shutdown_super+0x7e/0x100
[ 2040.723958] [<ffffffff811956d0>] kill_block_super+0x30/0x80
[ 2040.734963] [<ffffffff8119591d>] deactivate_locked_super+0x4d/0x80
[ 2040.745485] [<ffffffff8119652e>] deactivate_super+0x4e/0x70
[ 2040.751274] [<ffffffff811b1d42>] mntput_no_expire+0xd2/0x160
[ 2040.755894] [<ffffffff811b2fff>] SyS_umount+0xaf/0x3b0
[ 2040.761032] [<ffffffff816d1592>] system_call_fastpath+0x16/0x1b
[ .060058] XFS (sdb): xfs_log_force: error 5 returned.
[ 268059] XFS (sdb): xfs_log_force: error 5 returned.
I took a look at xfs_ail_push_all_sync and it is pretty easy to see
the hang. But it is not obvious to me how to fix it.
Any ideas would be appreciated.
I am available to run additional tests or capture more logging
or whatever if that would help.
Thanks,
Bob
virtual box setup
-----------------
1 GB ram
8 GB disk
4 processors
Operating System: Linux
Version: Debian (64 bit)
Bridged networking
iso: debian-7.4.0-amd64-netinst.iso
Software selection
select SSH server
select Standard system utilities
deselect everything else
dhcp ip address: 172.17.5.129
upgrade linux to 3.15.0-rc3
---------------------------
ssh 172.17.5.129
su
cd /mnt/ksrc/linux
make modules_install
make install
reboot
install tools
-------------
ssh 172.17.5.129
su
apt-get install xfsprogs
apt-get install open-iscsi
apt-get install --no-install-recommends targetcli python-urwid
reboot
reproduce bug
-------------
ssh 172.17.5.129
su
targetcli
cd backstores
fileio/ create name=file_backend2 file_or_dev=my_disk2 size=1G
/iscsi create
portals/ create 172.17.5.129
cd <
luns/ create /backstores/fileio/file_backend2
cd <
set attribute authentication=0 demo_mode_write_protect=0 generate_node_acls=1 cache_dynamic_acls=1
exit
iscsiadm -m discovery -t sendtargets -p 172.17.5.129
iscsiadm -m node --login --target iqn.from_previous_iscsiadm_cmd_output
fdisk -l
mkfs -t xfs -f /dev/sdXX
mkdir /mnt/vola
put following lines in a shell script "foo.sh", fix up target and block device
set -x
iscsiadm -m node --target iqn.2003-01.org.linux-iscsi.debian.x8664:sn.51ab79ac3ce2 --login
sleep 1
mount -t xfs /dev/sdb /mnt/vola
sleep 10
iscsiadm -m node -U all
sleep 1
umount /mnt/vola
run the shell script in a loop like:
while true; do ./foo.sh; done
in another terminal run the following:
while true; do cp -r /usr/lib /mnt/vola; done
The hang seems to take from two to ten minutes to occur.
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