mm/page_alloc: fix the page address of higher page's buddy calculation
authorLi Haifeng <omycle@gmail.com>
Mon, 17 Sep 2012 21:09:21 +0000 (14:09 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 2 Oct 2012 17:30:05 +0000 (10:30 -0700)
commitaa7994f281a5e705b5f9cb13b3219fc346263872
treebcb197b1091bfd854890418b2aebd92c077b9a2f
parenta4dd7e6c27a37237f09d437a515a3330093d4f70
mm/page_alloc: fix the page address of higher page's buddy calculation

commit 0ba8f2d59304dfe69b59c034de723ad80f7ab9ac upstream.

The heuristic method for buddy has been introduced since commit
43506fad21ca ("mm/page_alloc.c: simplify calculation of combined index
of adjacent buddy lists").  But the page address of higher page's buddy
was wrongly calculated, which will lead page_is_buddy to fail for ever.
IOW, the heuristic method would be disabled with the wrong page address
of higher page's buddy.

Calculating the page address of higher page's buddy should be based
higher_page with the offset between index of higher page and index of
higher page's buddy.

Signed-off-by: Haifeng Li <omycle@gmail.com>
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: KyongHo Cho <pullip.cho@samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm/page_alloc.c