[ 004/108] mm/ia64: fix a memory block size bug

Ben Hutchings
2012-10-07T23:22:24Z

From: Jianguo Wu <wujianguo@huawei.com>

commit 05cf96398e1b6502f9e191291b715c7463c9d5dd upstream.

I found following definition in include/linux/memory.h, in my IA64
platform, SECTION_SIZE_BITS is equal to 32, and MIN_MEMORY_BLOCK_SIZE
will be 0.

#define MIN_MEMORY_BLOCK_SIZE (1 << SECTION_SIZE_BITS)

Because MIN_MEMORY_BLOCK_SIZE is int type and length of 32bits,
so MIN_MEMORY_BLOCK_SIZE(1 << 32) will will equal to 0.
Actually when SECTION_SIZE_BITS >= 31, MIN_MEMORY_BLOCK_SIZE will be wrong.
This will cause wrong system memory infomation in sysfs.
I think it should be:

#define MIN_MEMORY_BLOCK_SIZE (1UL << SECTION_SIZE_BITS)

And "echo offline > memory0/state" will cause following call trace:

kernel BUG at mm/memory_hotplug.c:885!
sh[6455]: bugcheck! 0 [1]
Pid: 6455, CPU 0, comm: sh
psr : 0000101008526030 ifs : 8000000000000fa4 ip : [<a0000001008c40f0>] Not tainted (3.6.0-rc1)
ip is at offline_pages+0x210/0xee0
Call Trace:
show_stack+0x80/0xa0
show_regs+0x640/0x920
die+0x190/0x2c0
die_if_kernel+0x50/0x80
ia64_bad_break+0x3d0/0x6e0
ia64_native_leave_kernel+0x0/0x270
offline_pages+0x210/0xee0
alloc_pages_current+0x180/0x2a0

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/linux/memory.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/memory.h b/include/linux/memory.h
index 1ac7f6e..ff9a9f8 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -19,7 +19,7 @@
#include <linux/compiler.h>
#include <linux/mutex.h>

-#define MIN_MEMORY_BLOCK_SIZE (1 << SECTION_SIZE_BITS)
+#define MIN_MEMORY_BLOCK_SIZE (1UL << SECTION_SIZE_BITS)

struct memory_block {
unsigned long start_section_nr;