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From: Niklas Schnelle <schnelle@linux.ibm.com>
To: Leon Romanovsky <leon@kernel.org>, Jason Gunthorpe <jgg@ziepe.ca>,
	Doug Ledford <dledford@redhat.com>
Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] RDMA/mlx5: Fix number of allocated XLT entries
Date: Wed,  1 Sep 2021 13:26:24 +0200	[thread overview]
Message-ID: <20210901112625.1638072-1-schnelle@linux.ibm.com> (raw)

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: 8010d74b9965b ("RDMA/mlx5: Split the WR setup out of mlx5_ib_update_xlt()")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 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)
-- 
2.25.1


             reply	other threads:[~2021-09-01 11:26 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 11:26 Niklas Schnelle [this message]
2021-09-01 11:26 ` [PATCH 2/2] RDMA/mlx5: Fix xlt_chunk_align calculation Niklas Schnelle

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