mm: remove pointless struct in struct page definition

mm: remove pointless struct in struct page definition

This patchset implements per kmemcg accounting of page tables
(x86-only), pipe buffers, and unix socket buffers.

Patches 1-3 are just cleanups that are not supposed to introduce any
functional changes.  Patches 4 and 5 move charge/uncharge to generic
page allocator paths for the sake of accounting pipe and unix socket
buffers.  Patches 5-7 make x86 page tables, pipe buffers, and unix
socket buffers accountable.

This patch (of 8):

... to reduce indentation level thus leaving more space for comments.

Link: http://lkml.kernel.org/r/f34ffe70fce2b0b9220856437f77972d67c14275.1464079537.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>