Re: [PATCH vfs/for-next v2] cgroup: fix top cgroup refcnt leak

[David Howells <dhowells@redhat.com>]

I'm seeing something a bit weird, but I'm not sure why.  If I expand Andrei's
test script to:

	set -m
	d=$(mktemp -d /tmp/cg.XXXXXX)
	mkdir $d/a1
	mount -t cgroup -o none,name=xxxxy xxx $d/a1
	mkdir $d/a2
	mount -t cgroup -o none,name=xxxxy xxx $d/a2
	mkdir -p $d/a1/test
	umount $d/a1
	umount $d/a2

	d=$(mktemp -d /tmp/cg.XXXXXX)
	mkdir $d/a1
	mount -t cgroup -o none,name=xxxxy xxx $d/a1
	mkdir $d/a2
	mount -t cgroup -o none,name=xxxxy xxx $d/a2

	rmdir $d/a1/test
	umount $d/a1
	umount $d/a2

then a cgroup gets leaked at the end.  Just retaining the final:

	for i in `seq 2`; do 
		umount $d/a$i
	done

in place of the two final expanded umount commands fixes the issue.

The mounts are getting released, but not the cgroups as far as I can tell.

David