vma_prio_tree_insert() relies on the fact, that vma was
vma_prio_tree_init()'ed.

Content of vma->shared should be considered undefined, until this vma is
inserted into i_mmap/i_mmap_nonlinear.  It's better to do proper
initialization in vma_prio_tree_add/insert.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Rajesh Venkatasubramanian <vrajesh@umich.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>