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Subject[PATCH 4.9 115/177] IB/rxe: Dont clamp residual length to mtu
4.9-stable review patch.  If anyone has any objections, please let me know.


From: Johannes Thumshirn <>

[ Upstream commit d52418502e288b5c7e9e2e6cf1de5f1d3d79d2e1 ]

When reading a RDMA WRITE FIRST packet we copy the DMA length from the RDMA
header into the qp->resp.resid variable for later use. Later in check_rkey()
we clamp it to the MTU if the packet is an RDMA WRITE packet and has a
residual length bigger than the MTU. Later in write_data_in() we subtract the
payload of the packet from the residual length. If the packet happens to have a
payload of exactly the MTU size we end up with a residual length of 0 despite
the packet not being the last in the conversation. When the next packet in the
conversation arrives, we don't have any residual length left and thus set the QP
into an error state.

This broke NVMe over Fabrics functionality over rdma_rxe.ko

The patch was verified using the following test.

# echo eth0 > /sys/module/rdma_rxe/parameters/add
# nvme connect -t rdma -a -s 1023 -n nvmf-test
# mkfs.xfs -fK /dev/nvme0n1
meta-data=/dev/nvme0n1 isize=256 agcount=4, agsize=65536 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=0 finobt=0, sparse=0
data = bsize=4096 blocks=262144, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount /dev/nvme0n1 /tmp/
[ 148.923263] XFS (nvme0n1): Mounting V4 Filesystem
[ 148.961196] XFS (nvme0n1): Ending clean mount
# dd if=/dev/urandom of=test.bin bs=1M count=128
128+0 records in
128+0 records out
134217728 bytes (134 MB, 128 MiB) copied, 0.437991 s, 306 MB/s
# sha256sum test.bin
cde42941f045efa8c4f0f157ab6f29741753cdd8d1cff93a6b03649d83c4129a test.bin
# cp test.bin /tmp/
sha256sum /tmp/test.bin
cde42941f045efa8c4f0f157ab6f29741753cdd8d1cff93a6b03649d83c4129a /tmp/test.bin

Signed-off-by: Johannes Thumshirn <>
Cc: Hannes Reinecke <>
Cc: Sagi Grimberg <>
Cc: Max Gurtovoy <>
Acked-by: Moni Shoua <>
Signed-off-by: Doug Ledford <>
Signed-off-by: Sasha Levin <>
Signed-off-by: Greg Kroah-Hartman <>
drivers/infiniband/sw/rxe/rxe_resp.c | 2 --
1 file changed, 2 deletions(-)

--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -471,8 +471,6 @@ static enum resp_states check_rkey(struc
goto err;
- qp->resp.resid = mtu;
} else {
if (pktlen != resid) {

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