From 12783b002db1f02c29353c8f698a85514420b9f4 Mon Sep 17 00:00:00 2001
From: Mike Kravetz <kravetz@us.ibm.com>
Date: Sat, 20 May 2006 15:00:05 -0700
Subject: [PATCH] [PATCH] SPARSEMEM incorrectly calculates section number
A bad calculation/loop in __section_nr() could result in incorrect section
information being put into sysfs memory entries. This primarily impacts
memory add operations as the sysfs information is used while onlining new
memory.
Fix suggested by Dave Hansen.
Note that the bug may not be obvious from the patch. It actually occurs in
the function's return statement:
return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
In the existing code, root_nr has already been multiplied by
SECTIONS_PER_ROOT.
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
mm/sparse.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/mm/sparse.c b/mm/sparse.c
index c5e89eb9ac8ff..100040c0dfb6c 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -87,11 +87,8 @@ int __section_nr(struct mem_section* ms)
unsigned long root_nr;
struct mem_section* root;
- for (root_nr = 0;
- root_nr < NR_MEM_SECTIONS;
- root_nr += SECTIONS_PER_ROOT) {
- root = __nr_to_section(root_nr);
-
+ for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
+ root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
if (!root)
continue;
--
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