Patch series "mm/page_reporting: Make page reporting work on arm64 with 64KB page size", v4.

The page reporting threshold is currently equal to @pageblock_order, which
is 13 and 512MB on arm64 with 64KB base page size selected.  The page
reporting won't be triggered if the freeing page can't come up with a free
area like that huge.  The condition is hard to be met, especially when the
system memory becomes fragmented.

This series intends to solve the issue by having page reporting threshold
as 5 (2MB) on arm64 with 64KB base page size.  The patches are organized
as:

   PATCH[1/4] Fix some coding style in __page_reporting_request().
   PATCH[2/4] Represents page reporting order with variable so that it can
              be exported as module parameter.
   PATCH[3/4] Allows the device driver (e.g. virtio_balloon) to specify
              the page reporting order when the device info is registered.
   PATCH[4/4] Specifies the page reporting order to 5, corresponding to
              2MB in size on ARM64 when 64KB base page size is used.

This patch (of 4):

The lines of comments would be starting with one, instead two space.  This
corrects the style.

Link: https://lkml.kernel.org/r/20210625014710.42954-1-gshan@redhat.com
Link: https://lkml.kernel.org/r/20210625014710.42954-2-gshan@redhat.comSigned-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>