The MR memory allocation requests extra bytes to guarantee that there
is enough space to find the memory aligned to MLX5_UMR_ALIGN.
For power-of-two sizes, the alignment can be guaranteed by kmalloc()
according to commit 59bb47985c1d ("mm, sl[aou]b: guarantee natural
alignment for kmalloc(power-of-two)").
So if target alignment is power-of-two and adding the extra bytes
crosses a power-of-two boundary, use the next power-of-two as the
allocation size.
Signed-off-by: Yuanyuan Zhong <[email protected]>
---
drivers/infiniband/hw/mlx5/mr.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 2017ede100a6..92f35fafb2c0 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1766,6 +1766,11 @@ mlx5_alloc_priv_descs(struct ib_device *device,
int ret;
add_size = max_t(int, MLX5_UMR_ALIGN - ARCH_KMALLOC_MINALIGN, 0);
+ if (is_power_of_2(MLX5_UMR_ALIGN) && add_size) {
+ int end = max_t(int, MLX5_UMR_ALIGN, roundup_pow_of_two(size));
+
+ add_size = min_t(int, end - size, add_size);
+ }
mr->descs_alloc = kzalloc(size + add_size, GFP_KERNEL);
if (!mr->descs_alloc)
--
2.34.1