[PATCH v3] RDMA/rtrs: client: Fix clt_path::max_pages_per_mr calculation

[PATCH v3] RDMA/rtrs: client: Fix clt_path::max_pages_per_mr calculation

[Honggang LI]

If device max_mr_size bits in the range [mr_page_shift+31:mr_page_shift]
are zero, the `min3` function will set clt_path::max_pages_per_mr to
zero.

`alloc_path_reqs` will pass zero, which is invalid, as the third parameter
to `ib_alloc_mr`.

Fixes: 6a98d71daea1 ("RDMA/rtrs: client: main functionality")
Signed-off-by: Honggang LI <honggangli@163.com>
---
v2 -> v3:
Use `min_not_zero`.
v1 -> v2:
Correct the commit message and set max_pages_per_mr to U32_MAX
as Michael Gur suggested.
 drivers/infiniband/ulp/rtrs/rtrs-clt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
index 71387811b281..2b397a544cb9 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
@@ -1464,6 +1464,7 @@ static void query_fast_reg_mode(struct rtrs_clt_path *clt_path)
 	mr_page_shift      = max(12, ffs(ib_dev->attrs.page_size_cap) - 1);
 	max_pages_per_mr   = ib_dev->attrs.max_mr_size;
 	do_div(max_pages_per_mr, (1ull << mr_page_shift));
+	max_pages_per_mr = min_not_zero((u32)max_pages_per_mr, U32_MAX);
 	clt_path->max_pages_per_mr =
 		min3(clt_path->max_pages_per_mr, (u32)max_pages_per_mr,
 		     ib_dev->attrs.max_fast_reg_page_list_len);
-- 
2.52.0

Re: [PATCH v3] RDMA/rtrs: client: Fix clt_path::max_pages_per_mr calculation

[Leon Romanovsky]

On Mon, 29 Dec 2025 10:56:17 +0800, Honggang LI wrote:
> If device max_mr_size bits in the range [mr_page_shift+31:mr_page_shift]
> are zero, the `min3` function will set clt_path::max_pages_per_mr to
> zero.
> 
> `alloc_path_reqs` will pass zero, which is invalid, as the third parameter
> to `ib_alloc_mr`.
> 
> [...]

Applied, thanks!

[1/1] RDMA/rtrs: client: Fix clt_path::max_pages_per_mr calculation
      https://git.kernel.org/rdma/rdma/c/43bd09d5b750f7

Best regards,
-- 
Leon Romanovsky <leon@kernel.org>