2.4.9aa3

[Andrea Arcangeli]

Only in 2.4.9aa2: 00_silent-stack-overflow-5
Only in 2.4.9aa3: 00_silent-stack-overflow-6

	Updated to run expand_stack always with the mm write semaphore acquired
	to fix the race conditions. Upgrading the semaphore during
	map_user_kiobuf was quite painful so I just disallowed to do direct I/O
	on a growsdown VMA (you can still do that as far as it doesn't need to
	be live extended on the fly).

Only in 2.4.9aa3: 00_vm_raend-race-1

	Sanitize the vm_raend field before trusting it, such field is racy.

Only in 2.4.9aa2: 10_expand-stack-smp-1

	Dropped (it wasn't needed).

Only in 2.4.9aa2: 70_mmap-rb-4
Only in 2.4.9aa3: 70_mmap-rb-5

	Backed out a few unnecessary minor changes.

Andrea