Hi-

I have been experiencing various oopses in the procfs code when rapidly 
adding and removing /proc entries.  It seems that the main problem is 
lack of proper locking around code that traverses or modifies the 
proc_dir_entry tree.  There is also the matter of proc_kill_inodes() 
clearing the file pointer's f_op, which caused oopses in vfs_read() in 
my testing.

I have followed the example of proc_lookup() and used 
lock_kernel/unlock_kernel around critical sections.  I'm not much of a 
filesystem person, so I would appreciate a review of the patch from 
folks more knowledgeable.  I have been testing the code on a couple of 
dual processor machines (i386 and ppc64) without incident.

Please see http://bugme.osdl.org/show_bug.cgi?id=1552 for oops traces 
and a testcase.  Andrew posted a one-liner patch there which was 
included in mm4 which is also needed.

Patch is against 2.6.0-test9-mm4.

Thanks,
Nathan