Comment 21 for bug 1516451

Ramon, thank you for the detailed test case, I was able to run through it exactly as you described, both as root user (see attached) and as nagios (with sudo setup). I suspect I'm unable to reproduce the issue you're seeing since under lxc the /sys/kernel/debug directory belongs to the host and thus is owned by nobody:nogroup, (although I should think that it would produce a permission denied error.)

From the host:
# mount | grep tracing
tracefs on /sys/kernel/debug/tracing type tracefs (rw,relatime)

In any case, regarding the bug itself, I am able to detect the permissions error:

# /usr/lib/nagios/plugins/check_disk -e
DISK CRITICAL - /sys/kernel/debug/tracing is not accessible: Permission denied

# ls -la /sys/kernel/debug/tracing
ls: cannot access '/sys/kernel/debug/tracing': Permission denied

# /usr/lib/nagios/plugins/check_disk -e -X tracefs
DISK OK| /=44420MB;;;0;3754403 /dev=0MB;;;0;0 /dev/full=0MB;;;0;16018 /dev/null=0MB;;;0;16018 /dev/random=0MB;;;0;16018 /dev/tty=0MB;;;0;16018 /dev/urandom=0MB;;;0;16018 /dev/zero=0MB;;;0;16018 /dev/fuse=0MB;;;0;16018 /dev/net/tun=0MB;;;0;16018 /dev/lxd=0MB;;;0;0 /dev/.lxd-mounts=0MB;;;0;0 /dev/shm=0MB;;;0;16041 /run=16MB;;;0;16041 /run/lock=0MB;;;0;5 /sys/fs/cgroup=0MB;;;0;16041 /var/lib/lxd/shmounts=0MB;;;0;0 /var/lib/lxd/devlxd=0MB;;;0;0 /run/user/1001=0MB;;;0;3208

The suggestion in comment #16 looks like the best approach for addressing the issue so far. Alternatively, I posted a patch to LP #1827159 for altering check_disk itself, however as mentioned in comment #9 on this bug, excluding all tmpfs would be too broad.

Ramon, if you can test out the approach outlined in comment #16 and let me know if it seems suitable for your use case, perhaps we should proceed with implementing an SRU for that.