Commit b231cca4 ("message queues: increase range limits") changed
mqueue default value when attr parameter is specified NULL from hard
coded value to fs.mqueue.{msg,msgsize}_max sysctl value.

This made large side effect.  When user need to use two mqueue
applications 1) using !NULL attr parameter and it require big message
size and 2) using NULL attr parameter and only need small size message,
app (1) require to raise fs.mqueue.msgsize_max and app (2) consume large
memory size even though it doesn't need.

Doug Ledford propsed to switch back it to static hard coded value.
However it also has a compatibility problem.  Some applications might
started depend on the default value is tunable.

The solution is to separate default value from maximum value.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>
Acked-by: NDoug Ledford <dledford@redhat.com>
Acked-by: NJoe Korty <joe.korty@ccur.com>
Cc: Amerigo Wang <amwang@redhat.com>
Acked-by: NSerge E. Hallyn <serue@us.ibm.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>