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authorMarcelo Roberto Jimenez <mroberto@cpti.cetuc.puc-rio.br>2010-05-24 14:32:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-25 08:07:01 -0700
commit0faa56389c793cda7f967117415717bbab24fe4e (patch)
treeb0d5f12579a4448adff2b6e462488f3cc6d75326
parentff3d58c22b6827039983911d3460cf0c1657f8cc (diff)
downloadop-kernel-dev-0faa56389c793cda7f967117415717bbab24fe4e.zip
op-kernel-dev-0faa56389c793cda7f967117415717bbab24fe4e.tar.gz
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>
-rw-r--r--include/linux/mmzone.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fd55f72..f6f2c50 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
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