On Fri 09 Aug 2013 09:45:02 PM CST, David Caro Estevez wrote:
Sometimes we get this error when running the vdsm tests:

ERROR: testLoopMount (mountTests.MountTests)
Traceback (most recent call last):
   File "/ephemeral0/vdsm_unit_tests_gerrit_el/tests/mountTests.py", line 69, 
in testLoopMount
   File "/ephemeral0/vdsm_unit_tests_gerrit_el/vdsm/storage/mount.py", line 
222, in mount
     return self._runcmd(cmd, timeout)
   File "/ephemeral0/vdsm_unit_tests_gerrit_el/vdsm/storage/mount.py", line 
238, in _runcmd
     raise MountError(rc, ";".join((out, err)))
MountError: (2, ';mount: could not find any free loop device\n')
-------------------- >> begin captured logging << --------------------
Storage.Misc.excCmd: DEBUG: '/sbin/mkfs.ext2 -F /tmp/tmpq95svr' (cwd None)
Storage.Misc.excCmd: DEBUG: SUCCESS: <err> = 'mke2fs 1.41.12 (17-May-2010)\n'; 
<rc> = 0
Storage.Misc.excCmd: DEBUG: '/usr/bin/sudo -n /bin/mount -o loop /tmp/tmpq95svr 
/tmp/tmpcS29EU' (cwd None)

The problem is that it seems that the loop devices that are not being released 
(maybe when the test fails?) and the system runs out of devices eventually.
Can you take a look to see where the cleanup fails and fix it?

It seems the system run out of loop devices. You could use 'losetup -l' to check the usages of the loop devices. If there's some leaks, you could use losetup to fix it manually. Otherwise, that means you need increase the number of loop devices. How to do that depends on your distro:

On latest fedora, loop module is kernel built-in, so you have to change the boot kernel parameter: append to the end of each linux line in /boot/grub2/grub.cfg:

For distros which loop modules is loaded as a separate module:
enter following line in /etc/modprobe.conf
options loop max_loop=64

Hope it helps.


pd. To free a loop device you have to umount it and then losetup -d 
<loopdevice>, that way the device gets liberated. Also it might be a good 
solution to create a specific device per test, that way it will never run out of them 
no matter how many tests run in parallel, but that requires a little more 

David Caro

Red Hat Czech s.r.o.
Continuous Integration Engineer - EMEA ENG Virtualization R&D

Tel.: +420 532 294 605
Email: dc...@redhat.com
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purky┼łova 99/71, 612 45, Brno, Czech Republic
RHT Global #: 82-62605

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