This is a note to let you know that I've just added the patch titled
sb_edac: Avoid overflow errors at memory size calculation
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sb_edac-avoid-overflow-errors-at-memory-size-calculation.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b39bfb4cc09a0663d13b537e69e8241e6cc8ce71 Mon Sep 17 00:00:00 2001
From: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Date: Thu, 20 Sep 2012 12:09:30 -0300
Subject: sb_edac: Avoid overflow errors at memory size calculation
From: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
commit deb09ddaff1435f72dd598d38f9b58354c68a5ec upstream.
Sandy bridge EDAC is calculating the memory size with overflow.
Basically, the size field and the integer calculation is using 32 bits.
More bits are needed, when the DIMM memories have high density.
The net result is that memories are improperly reported there, when
high-density DIMMs are used:
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 591: mc#0: channel 0, dimm 0, -16384 Mb (-4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 591: mc#0: channel 1, dimm 0, -16384 Mb (-4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
As the number of pages value is handled at the EDAC core as unsigned
ints, the driver shows the 16 GB memories at sysfs interface as 16760832
MB! The fix is simple: calculate the number of pages as unsigned 64-bits
integer.
After the patch, the memory size (16 GB) is properly detected:
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 592: mc#0: channel 0, dimm 0, 16384 Mb (4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 592: mc#0: channel 1, dimm 0, 16384 Mb (4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
[bwh: Backported to 3.2:
- Adjust context
- Debug log function is debugf0(), not edac_dbg()]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Qiang Huang <h.huangqiang@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/edac/sb_edac.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -555,7 +555,8 @@ static int get_dimm_config(const struct
{
struct sbridge_pvt *pvt = mci->pvt_info;
struct csrow_info *csr;
- int i, j, banks, ranks, rows, cols, size, npages;
+ unsigned i, j, banks, ranks, rows, cols, npages;
+ u64 size;
int csrow = 0;
unsigned long last_page = 0;
u32 reg;
@@ -627,10 +628,10 @@ static int get_dimm_config(const struct
cols = numcol(mtr);
/* DDR3 has 8 I/O banks */
- size = (rows * cols * banks * ranks) >> (20 - 3);
+ size = ((u64)rows * cols * banks * ranks) >> (20 - 3);
npages = MiB_TO_PAGES(size);
- debugf0("mc#%d: channel %d, dimm %d, %d Mb (%d pages) bank: %d, rank: %d, row: %#x, col: %#x\n",
+ debugf0("mc#%d: channel %d, dimm %d, %Ld Mb (%d pages) bank: %d, rank: %d, row: %#x, col: %#x\n",
pvt->sbridge_dev->mc, i, j,
size, npages,
banks, ranks, rows, cols);
Patches currently in stable-queue which might be from mchehab@xxxxxxxxxx are
queue-3.4/sb_edac-avoid-overflow-errors-at-memory-size-calculation.patch
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