Re: [patch 050/160] prctl: add PR_SET_PROCTITLE_AREA option for prctl()

On Fri, 5 Mar 2010, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org wrote:

This patch makes it possible for userspace to implement setproctitle()
cleanly.  It adds a new PR_SET_PROCTITLE_AREA option for prctl(), which
updates task's mm_struct->arg_start and arg_end to the given area.

This looks overly complicated. Why do you change the whole locking rules, 
instead of protecting _only_ the "arg_start/arg_end" case? 

The thing is, there's no reason to hold the mmap_sem over the whole thing, 
and I don't think this is important enough to be a valid reason for 
exposing a whole new "locked" access variant, when a simple "protect just 
the arg_start/end" would handle it.

			Linus