From fbc0d19393cbf49c28f538b7fdd94f92655f7870 Mon Sep 17 00:00:00 2001

From: Niklas Schnelle <schnelle@linux.ibm.com>

Date: Wed, 8 Sep 2021 10:18:48 +0200

Subject: [PATCH] RDMA/mlx5: Fix number of allocated XLT entries

Git-commit: 9660dcbe0d9186976917c94bce4e69dbd8d7a974

Patch-mainline: v5.15-rc1

References: stable-5.14.4

commit 9660dcbe0d9186976917c94bce4e69dbd8d7a974 upstream.

In commit 8010d74b9965b ("RDMA/mlx5: Split the WR setup out of

mlx5_ib_update_xlt()") the allocation logic was split out of

mlx5_ib_update_xlt() and the logic was changed to enable better OOM

handling. Sadly this change introduced a miscalculation of the number of

entries that were actually allocated when under memory pressure where it

can actually become 0 which on s390 lets dma_map_single() fail.

It can also lead to corruption of the free pages list when the wrong

number of entries is used in the calculation of sg->length which is used

as argument for free_pages().

Fix this by using the allocation size instead of misusing get_order(size).

Cc: stable@vger.kernel.org

Fixes: 8010d74b9965 ("RDMA/mlx5: Split the WR setup out of mlx5_ib_update_xlt()")

Link: https://lore.kernel.org/r/20210908081849.7948-1-schnelle@linux.ibm.com

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/infiniband/hw/mlx5/mr.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c

index 3f1c5a4f158b..19713cdd7b78 100644

--- a/drivers/infiniband/hw/mlx5/mr.c

+++ b/drivers/infiniband/hw/mlx5/mr.c

@@ -1024,7 +1024,7 @@ static void *mlx5_ib_alloc_xlt(size_t *nents, size_t ent_size, gfp_t gfp_mask)

 	if (size > MLX5_SPARE_UMR_CHUNK) {

 		size = MLX5_SPARE_UMR_CHUNK;

-		*nents = get_order(size) / ent_size;

+		*nents = size / ent_size;

 		res = (void *)__get_free_pages(gfp_mask | __GFP_NOWARN,

 					       get_order(size));

 		if (res)

-- 

2.26.2