Comment 45 for bug 927636

I also get this error since long time ago, however is not always, it's just sometimes. When it happens i'm not able to login. After i input username+pw and click login it gets blocked and I can do nothing but rebooting the bad way.

In my error report generated by Ubuntu I have the following:
   "plymouth error destination "(%rdi)"... not located in a known VMA region (needed writable region)!"
   "writing unknown VMA"

<- i'm not sure if this helps. To me seems a problem of timing of loading something during the boot and login. However some users solve it by changing permissions, so maybe is related to the above message that I have read it happens when a process tries to access to RAM addresses is not allowed to. Some users said to give 775 others 777, if 775 works, maybe the key is the group writable permission.

The dependencies of plymouth seems long:
sudo apt-get remove --simulate plymouth
The following packages will be REMOVED:
  cryptsetup gdm lightdm mountall plymouth plymouth-label plymouth-theme-ubuntu-gnome-logo plymouth-theme-ubuntu-gnome-text plymouth-theme-ubuntu-logo plymouth-theme-ubuntu-text ubuntu-desktop ubuntu-gnome-desktop unity unity-greeter unity-tweak-tool upstart

Are any of this packages ran under a user account without permission to fire plymouth?, moreover, does that account belong to a group that actually has write permission on plymouth?. Why timing on logging matters? (I do sometimes login smoothly and sometimes not).

Sorry, but i can go further on this, and these are the questions that come to my head that might, might not, give a hint to someone else.