Another strange "hang"

[Paul Goyette <paul%whooppee.com@localhost>]

On a dual-core amd64 system running 4.99.53 (sources from 2/7/2008 at 
01:00 UTC) I issued at 'df' command.  Nothing else happening on the 
system.  The df command hung.  So I started up another window and tried 
another df command, and it also hung.

From a third window, ps shows that both df commands are waiting for 
'tstile'.  In previous hangs, the system has eventually recovered, but 
these two df commands have been hung for a hour.

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