How to stop 'uninterruptible' process on Linux?

Solution 1:

Simple answer: you cannot.

Longer answer: the uninterruptable sleep means the process will not be woken up by signals. It can be only woken up by what it's waiting for. When I get such situations eg. with CD-ROM, I usually reset the computer by using suspend-to-disk and resuming.

Solution 2:

Killing an uninterruptible process succeeds, it just doesn't do so immediately. The process won't disappear until it actually receives the signal. So sending a signal alone is not enough to get rid of the process, you also have to wake it up from uninterruptible sleep.

Tanel Poder has written a great guide to analyse D state processes. It is very typical that this state is caused by incomplete I/O, e.g. network failure. slm has posted some very useful pointers on superuser how to unjam the network I/O, and also about the problem itself.

Personally, when dealing with Windows on VirtualBox, and even with wine, I often run into this problem because of a cdrom I/O that never completes (I guess its some sort of disc presence check). ATA devices can be reset, which likely will unjam the process. For instance, I'm using the following little script to reset both my optical drives, unjamming the processes they are blocking:

echo 1 > /sys/block/sr0/delete
echo 1 > /sys/block/sr1/delete
echo "- - -" > /sys/class/scsi_host/host7/scan

Solution 3:

The D state basically means that the process is waiting for disk I/O, or other block I/O that can't be interrupted. Sometimes this means the kernel or device is feverishly trying to read a bad block (especially from an optical disk). Sometimes it means there's something else.

The process cannot be killed until it gets out of the D state. Find out what it is waiting for and fix that. The easy way is to reboot. Sometimes removing the disk in question helps, but that can be rather dangerous: unfixable catastrophic hardware failure if you don't know what you're doing (read: smoke coming out).

Solution 4:

I recently encountered a process in D state on a remote server and would like to clarify that a hard reboot or power cycle is needed to remove the process.

Don't try a soft reboot until you have exhausted all other options. For example, you can try freeing up whatever resource the process is hanging on. A soft reboot might give you a system that is partially shut down and will no longer respond to ssh, but won't reboot because it is hung trying to terminate the uninterruptible process.