In very few conditions it is possible that procfs subsystem may race with exit 
routine.

Panic string : Kernel memory fault

0 boot 
1 panic
2 trap 
3 _XentMM 
4 simple_lock 
5 task_deallocate 
6 procfs_ioctl 
7 vn_ioctl src/kernel/vfs/vfs_vnops.c : 1738

