Commit 12783b00 authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds
Browse files

[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: default avatarMike Kravetz <kravetz@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ad8f5797

mm/sparse.c

+2 −5
Original line number Diff line number Diff line
@@ -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;