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| author | Marcelo Roberto Jimenez <mroberto@cpti.cetuc.puc-rio.br> | 2010-05-24 14:32:47 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-25 08:07:01 -0700 |
| commit | 0faa56389c793cda7f967117415717bbab24fe4e (patch) | |
| tree | b0d5f12579a4448adff2b6e462488f3cc6d75326 /include | |
| parent | ff3d58c22b6827039983911d3460cf0c1657f8cc (diff) | |
| download | lwn-0faa56389c793cda7f967117415717bbab24fe4e.tar.gz lwn-0faa56389c793cda7f967117415717bbab24fe4e.zip | |
mm: fix NR_SECTION_ROOTS == 0 when using using sparsemem extreme.
Got this while compiling for ARM/SA1100:
mm/sparse.c: In function '__section_nr':
mm/sparse.c:135: warning: 'root' is used uninitialized in this function
This patch follows Russell King's suggestion for a new calculation for
NR_SECTION_ROOTS. Thanks also to Sergei Shtylyov for pointing out the
existence of the macro DIV_ROUND_UP.
Atsushi Nemoto observed:
: This fix doesn't just silence the warning - it fixes a real problem.
:
: Without this fix, mem_section[] might have 0 size so mem_section[0]
: will share other variable area. For example, I got:
:
: c030c700 b __warned.16478
: c030c700 B mem_section
: c030c701 b __warned.16483
:
: This might cause very strange behavior. Your patch actually fixes it.
Signed-off-by: Marcelo Roberto Jimenez <mroberto@cpti.cetuc.puc-rio.br>
Cc: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mmzone.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index fd55f725a09e..f6f2c505fa7e 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -981,7 +981,7 @@ struct mem_section { #endif #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT) -#define NR_SECTION_ROOTS (NR_MEM_SECTIONS / SECTIONS_PER_ROOT) +#define NR_SECTION_ROOTS DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT) #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1) #ifdef CONFIG_SPARSEMEM_EXTREME |