When a process will go to 'D' state?

Question

I'm using "Linux hostname 2.6.28-15-generic #49-Ubuntu SMP Tue Aug 18 18:40:08 UTC 2009 i686 GNU/Linux"

All the client machines will use Thin-client ,I will use my laptop for working and I will mount my home directory from server to my laptop.

If I open the firefox in my laptop the firefox window will not open because the process is in 'D' state, and all other users machines got hang up and the lockd process is in 'D' state,

ps ajx | grep firefox

1  6187  4313  4313 ?   -1 D<    1030   3:16 /usr/lib/firefox-3.5b4pre/firefox-3.5

   7610  7622  7621  7610 pts/3      7621 S+    1030   0:00 grep firefox

if I check the syslog

Jul 13 10:35:56 hostname kernel: [222583.872059] lockd: cannot monitor laptop

Jul 13 10:35:57 hostname kernel: [222583.872059] lockd: cannot monitor laptop

ps ajx | grep lockd

root 9178 0.0 0.0 0 0 ? D< 13:35 0:00 [lockd]

root 11039 0.0 0.0 3340 796 pts/3 S<+ 14:18 0:00 grep lockd

The same message for all the client machines.

When a process will goes to 'D' state?

When the lockd process will go to 'D' state?

What is the purpose of lockd process.

Solution 1

It means "uninterruptible sleep".

D    Uninterruptible sleep (usually IO)

In this state, a process doesn't wake up right away to process signals. When doing device I/O it's the only way to go (otherwise data corruption could result).

Solution 2

D state code means that process is in uninterruptible sleep.

• usually this is due to I/O.
• lockd is in-kernel daemon that manages NFS locking.

Probably, your problem has to do with NFS communication.

Comments

[Admin]

how to avoid this ? the lockd process should not go to 'D' state, what I need to do ?

[Admin]

@ungalnanban: It is impossible, processes always go in and out of 'D' if using I/O. So in your case process is trying to, for example, read or write some data, acquire a lock, cannot do that and keeps waiting. You have to debug what it is waiting for etc. I am not an NFS expert to tell that, sorry.