Mount some filesystem, below that mountpoint as user mount some fuse fs (tried that with sshfs and fuseiso, both same error), fusermount -u the fuse fs, try to unmount the filesystem -> busy. ml@lara:~> id -u 500 ml@lara:~> grep test /etc/fstab /dev/vg1/test /mnt2 ext4acl,user_xattr,user,noauto 0 0 ml@lara:~> mount /mnt2 ml@lara:~> cd /mnt2 ml@lara:/mnt2> ls -l insgesamt 24 drwx------ 2 root root 16384 4. Mai 11:24 lost+found drwxr-xr-x 2 root root 4096 4. Mai 11:44 test drwxr-xr-x 2 ml users 4096 4. Mai 11:25 xenia ml@lara:/mnt2> sshfs xenia: xenia Password: ml@lara:/mnt2> ls xenia/bla xenia/bla ml@lara:/mnt2> fusermount -u xenia ml@lara:/mnt2> cd ml@lara:~> umount /mnt2 umount: /mnt2: target is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) ml@lara:~> fuser -m /mnt2 ml@lara:~> It does'nt matter if the mounting and unmounting of the /mnt2 filesystem is done as user or as root, same result. This works in 3.8(.x). Bisecting yields 57eccb830f1cc93d4b506ba306d8dfa685e0c88f is the first bad commit commit 57eccb830f1cc93d4b506ba306d8dfa685e0c88f Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Date: Fri Feb 22 22:49:10 2013 -0500 mount: consolidate permission checks ... and ask for global CAP_SYS_ADMIN only for superblock-level remounts Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> :040000 040000 4e926c083f6ede645158f02714d73cdd3b233a05 584611744bad96544578259a6fa176577df0ebbd M fs After reverting 57eccb830f1cc93d4b506ba306d8dfa685e0c88f from 3.9 that umount above works (not busy). I've seen that this patch also was identified as problem in relation with user ns and module loading, see lkml CAGXu5jLciqXcuhzDVPKPqA+mwv8e28zGAMScatzov3U07BuBaQ@xxxxxxxxxxxxxx After fixing this upstream the fix should be an stabile candidate. -- MfG, Michael Leun -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html