From: Quanquan Cao <caoqq@fujitsu.com>
To: dave.jiang@intel.com, vishal.l.verma@intel.com
Cc: linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev,
Quanquan Cao <caoqq@fujitsu.com>
Subject: [PATCH] cxl/region：Fix overflow issue in alloc_hpa()
Date: Wed, 24 Jan 2024 17:15:26 +0800 [thread overview]
Message-ID: <20240124091527.8469-1-caoqq@fujitsu.com> (raw)
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>
---
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;
--
2.43.0
next reply other threads:[~2024-01-24 9:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-24 9:15 Quanquan Cao [this message]
2024-01-24 23:59 ` [PATCH] cxl/region：Fix overflow issue in alloc_hpa() fan
2024-01-25 0:02 ` Dave Jiang
2024-01-26 17:42 ` Jonathan Cameron
2024-01-29 2:22 ` Cao, Quanquan/曹 全全
2024-01-26 21:47 ` Alison Schofield
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