On 2013/4/18 19:37, alexey.kodanev@xxxxxxxxxx wrote: > Hi All > > I would like to report the NULL deref on umount. Tested it in linux kernel 3.7.10 and it's still in the 3.9.0-rc7. > / > Test-case description: > Mount cgroup filesystem with xattr option and create inside root cgroup another hierarchy. > Then set extended attribute to any files within root hierarchy or sub hierarchie. > Then remove (rmdir) sub hierarchy and call umount cgroup filesystem. Afterthat, umount crash the kernel. > > Also, if you don't remove sub hierarchy (steps 1.4 & 2.9 in examples below), calling umount will produce nothing except that cgroup filesystem will be unmounted (no cgroup files in the directory) but with error: cgroups continue working, while call mount again to get control access to running cgroups will produce error, such as filesystem is already mounted, but in /proc/mounts you don't have such mount point. And there is no way to get control access back to the running cgroups, except for reboot. > > Here are some manual methods which will reproduce Linux crash. > > 1. One way to reproduce this fault: > > 1.1% mount -t cgroup cgroot_test -o xattr /sys/fs/cgroup > 1.2% mkdir /sys/fs/cgroup/test_subsys > 1.3% setfattr -n trusted.value -v test_value /sys/fs/cgroup/tasks > 1.4% rmdir /sys/fs/cgroup/test_subsys > 1.5% umount cgroot_test > Thanks for the report! A fix will be followed soon. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
