What's /var/lib/ureadahead/debugfs ?

[zefew]

I'm on Karmic and my HDD is formatted in ext4. What's /var/lib/ureadahead/debugfs and why is it there? How do it get rid of it?

$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             448G  271G  173G  62% /
udev                  2.0G  300K  2.0G   1% /dev
none                  2.0G  100K  2.0G   1% /dev/shm
none                  2.0G  208K  2.0G   1% /var/run
none                  2.0G     0  2.0G   0% /var/lock
none                  2.0G     0  2.0G   0% /lib/init/rw
none                  448G  271G  173G  62% /var/lib/ureadahead/debugfs

[zefew]

No one knows what it is?

I couldn't find any documentation.

[missive@hotmail.com]

> What's /var/lib/ureadahead/debugfs ?

I started seeing this recently also.

I installed 9.10 fresh in virtualbox and I see it there also.

I asked on IRC #ubuntu and no one else would admit to seeing
this, but I asked if anyone was using encrypted home folders
and no one would admit to that either.

My guess is that it is something that is happening because of
using the encrypted home folders feature.

Are you using encrypted home folders?

One way I was able to get rid of the debugfs entry was:

chmod 0 /sbin/debugfs

The virtual system booted and logged in to my account normally.
I do not see any problems, but I have not used it extensively like
that.

Anyone know if that will cause any other problems?

[missive@hotmail.com]

> chmod 0 /sbin/debugfs

Strangely, this worked in the virtualbox install, but on my
actual install there is still a debugfs entry in the df output.

[cybermatthieu]

I had the same /var/lib/ureadahead/debugfs listed in df.

I'm running VmWare, and after deleting my only snapshot /var/lib/ureadahead/debugfs disappeared.

Could this really be related to snapshots?

[madmonkeyz]

I have the same problem on an "unvirtual" machine (if thats the word) - its actually at 97%.

[jfhopkin]

I'm seeing it too, no VMware, no encryption - it's not far off being an out-of-the-box installation.

df:

none                  142G   18G  117G  14% /var/lib/ureadahead/debugfs

mount:

none on /var/lib/ureadahead/debugfs type debugfs (rw)

Now if all that space were real ...!

[packs]

i can see the same /var/lib/ureadahead/debugfs on my ubuntu 9.10 server box
no encryptions,fresh install.

/dev/sda3 21G 1.9G 18G 10% /
udev 1006M 200K 1006M 1% /dev
none 1006M 0 1006M 0% /dev/shm
none 1006M 296K 1006M 1% /var/run
none 1006M 0 1006M 0% /var/lock
none 1006M 0 1006M 0% /lib/init/rw
none 21G 1.9G 18G 10% /var/lib/ureadahead/debugfs
/dev/sda1 204G 70G 124G 36% /home

[AncientPC]

FWIW, I see it to and it's mimic'ing my / partition. I've upgraded this laptop from 8.04 -> 8.10 -> 9.04 -> 9.10.

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             9.6G  5.9G  3.7G  62% /
udev                  1.5G  256K  1.5G   1% /dev
none                  1.5G  844K  1.5G   1% /dev/shm
none                  1.5G  368K  1.5G   1% /var/run
none                  1.5G     0  1.5G   0% /var/lock
none                  1.5G     0  1.5G   0% /lib/init/rw
none                  9.6G  5.9G  3.7G  62% /var/lib/ureadahead/debugfs
/dev/sda3              64G   42G   22G  66% /home


/dev/sda1 on / type jfs (rw,relatime,errors=remount-ro)
proc on /proc type proc (rw)
none on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
none on /dev/shm type tmpfs (rw,nosuid,nodev)
none on /var/run type tmpfs (rw,nosuid,mode=0755)
none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
none on /var/lib/ureadahead/debugfs type debugfs (rw)
/dev/sda3 on /home type jfs (rw,relatime)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/xxxx/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=xxxx)

[NHclimber]

The kernel filesystem tracers that ureadahead uses to 'profile' the boot process are expected to be at the debugfs mountpoint, /sys/kernel/debug. If a quick test reveals that the mountpoint isn't up yet, rather than wait for the mountpoint (and potentially missing more profiling it could do), ureadahead mounts a temporary debugfs at /var/lib/ureadhead/debugfs so that it can get to the filesystem tracers (do_sys_open, open_exec & uselib syscalls).

According to the dev in this bug report (https://bugs.launchpad.net/ubuntu/+s...ad/+bug/499773), a left-over temporary mountpoint indicates that ureadahead crashed out, leaving the mountpoint in /etc/mtab. A quick scan of the source seems to confirm this, but maybe something was overlooked.

Can you confirm if the mountpont is stale ('cat /proc/self/mountinfo')?