6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Quanquan Cao <caoqq@xxxxxxxxxxx>
commit d76779dd3681c01a4c6c3cae4d0627c9083e0ee6 upstream.
Creating a region with 16 memory devices caused a problem. The div_u64_rem
function, used for dividing an unsigned 64-bit number by a 32-bit one,
faced an issue when SZ_256M * p->interleave_ways. The result surpassed
the maximum limit of the 32-bit divisor (4G), leading to an overflow
and a remainder of 0.
note: At this point, p->interleave_ways is 16, meaning 16 * 256M = 4G
To fix this issue, I replaced the div_u64_rem function with div64_u64_rem
and adjusted the type of the remainder.
Signed-off-by: Quanquan Cao <caoqq@xxxxxxxxxxx>
Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Fixes: 23a22cd1c98b ("cxl/region: Allocate HPA capacity to regions")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cxl/core/region.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -525,7 +525,7 @@ static int alloc_hpa(struct cxl_region *
struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
struct cxl_region_params *p = &cxlr->params;
struct resource *res;
- u32 remainder = 0;
+ u64 remainder = 0;
lockdep_assert_held_write(&cxl_region_rwsem);
@@ -545,7 +545,7 @@ static int alloc_hpa(struct cxl_region *
(cxlr->mode == CXL_DECODER_PMEM && uuid_is_null(&p->uuid)))
return -ENXIO;
- div_u64_rem(size, SZ_256M * p->interleave_ways, &remainder);
+ div64_u64_rem(size, (u64)SZ_256M * p->interleave_ways, &remainder);
if (remainder)
return -EINVAL;
