On 1/24/24 02:15, Quanquan Cao wrote:
> 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 <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
> ---
> drivers/cxl/core/region.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 0f05692bfec3..ce0e2d82bb2b 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -525,7 +525,7 @@ static int alloc_hpa(struct cxl_region *cxlr,
> resource_size_t size)
> 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,
> resource_size_t size)
> (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;
>
