mm: handle write faults to RO pages under the VMA lock

I think this is a pretty rare occurrence, but for consistency handle
faults with the VMA lock held the same way that we handle other faults
with the VMA lock held.

Link: https://lkml.kernel.org/r/20231006195318.4087158-7-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>