My suggestion for 2.6.32.43-0.4.1.xs1.8.0.855.170800xen is to compile the driver without iser and srp :
./mlnx_add_kernel_support.sh -m /mnt/tmp/OFED --make-iso -t /mnt/tmp --without-srp --without-iser -t (output dir)
Then install the new ISO with mlnxofedinstall script.
Other options are :
1.Revert back to 2.6.32.43-0.4.1.xs1.8.0.847
2.Use MLNX_OFED 2.2