BACKPORT: FROMGIT: mm: handle PUD faults under the VMA lock

Postpone checking the VMA_LOCK flag until we've attempted to handle faults
on PUDs.  There's a mild upside to this patch in that we'll allocate the
page tables while under the VMA lock rather than the mmap lock, reducing
the hold time on the mmap lock, since the retry will find the page tables
already populated.  The real purpose here is to make a commit that shows
we don't call ->huge_fault under the VMA lock.  We do now handle setting
the accessed bit on a PUD fault under the VMA lock, but that doesn't seem
likely to be a measurable difference.

Link: https://lkml.kernel.org/r/20230724185410.1124082-5-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 3c04dd18ba57c6753a7ddc6e6c902550a7ac54d9
https: //git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
[surenb: resolved merge conflicts in wp_huge_pud()]

Bug: 293665307
Change-Id: Ife20ed7de6444c0e424e12f9fdcdc8f8ecaed2aa
Signed-off-by: Suren Baghdasaryan <surenb@google.com>