mm: improve documentation of page_order
authorMel Gorman <mgorman@suse.de>
Thu, 23 Jan 2014 23:53:38 +0000 (15:53 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 24 Jan 2014 00:36:53 +0000 (16:36 -0800)
commit6c14466cc00ff13121ae782d33d9df0fde20b124
tree65cf09a45f47de60638fdd1fe3140f9b8bdc27b9
parent0eef615665ede1e0d603ea9ecca88c1da6f02234
mm: improve documentation of page_order

Developers occasionally try and optimise PFN scanners by using
page_order but miss that in general it requires zone->lock.  This has
happened twice for compaction.c and rejected both times.  This patch
clarifies the documentation of page_order and adds a note to
compaction.c why page_order is not used.

[akpm@linux-foundation.org: tweaks]
[lauraa@codeaurora.org: Corrected a page_zone(page)->lock reference]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/compaction.c
mm/internal.h