proc_pid_status dereferences pointers in the task structure even if the
task is already dead.  This is probably the reason for the oops described
in

http://bugme.osdl.org/show_bug.cgi?id=3812

The attached patch removes the pointer dereferences by using pid_alive()
for testing that the task structure contents is still valid before
dereferencing them.  The task structure itself is guaranteed to be valid -
we hold a reference count.
Signed-Off-By: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>