I have had this occur 2x in the last couple hours.
I have been clicking around checking out reporting and log files, when the webadmin becomes horribly slow.
Checking top, shows %wa to be in the high 90's.
Running ps aux | grep D shows prpc [webadmin] as being one of the culprits.
Only way to recover is by doing a reboot, which this last time took 5 minutes to even begin after issuing the command.
I have already ensured that DMA is enabled on my drive, and I know from checking that the noatime option is present for all partitions in the /etc/fstab file.
So this tells me that there has to be something in the code..it even brings my load everage up to over 7.