tree 65cf09a45f47de60638fdd1fe3140f9b8bdc27b9
parent 0eef615665ede1e0d603ea9ecca88c1da6f02234
author Mel Gorman <mgorman@suse.de> 1390521218 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1390523813 -0800

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>