6.6-stable review patch. If anyone has any objections, please let me know.
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From: Quanquan Cao caoqq@fujitsu.com
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@fujitsu.com Reviewed-by: Dave Jiang dave.jiang@intel.com Fixes: 23a22cd1c98b ("cxl/region: Allocate HPA capacity to regions") Cc: stable@vger.kernel.org Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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;