I have been kept digging, and here is what I have observed:
I just did a
[root@sc2u0n0 ~]# lsinitrd /boot/initramfs-3.10.0-327.28.2.el7.x86_64.img|less
[...]
drwxr-xr-x 5 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core
-rw-r--r-- 1 root root 21149 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_addr.ko
-rw-r--r-- 1 root root 82669 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_cm.ko
-rw-r--r-- 1 root root 159989 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_core.ko
-rw-r--r-- 1 root root 77565 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_mad.ko
-rw-r--r-- 1 root root 51765 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_sa.ko
-rw-r--r-- 1 root root 33549 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_ucm.ko
-rw-r--r-- 1 root root 35829 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_umad.ko
-rw-r--r-- 1 root root 87141 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/ib_uverbs.ko
-rw-r--r-- 1 root root 68989 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/iw_cm.ko
-rw-r--r-- 1 root root 75765 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/rdma_cm.ko
-rw-r--r-- 1 root root 37637 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/core/rdma_ucm.ko
drwxr-xr-x 12 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/cxgb3
-rw-r--r-- 1 root root 233861 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/cxgb3/iw_cxgb3.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/cxgb4
-rw-r--r-- 1 root root 286621 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/cxgb4/iw_cxgb4.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/ipath
-rw-r--r-- 1 root root 439149 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/ipath/ib_ipath.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mlx4
-rw-r--r-- 1 root root 250733 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mlx4/mlx4_ib.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mlx5
-rw-r--r-- 1 root root 192053 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mlx5/mlx5_ib.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mthca
-rw-r--r-- 1 root root 221773 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/mthca/ib_mthca.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/nes
-rw-r--r-- 1 root root 274037 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/nes/iw_nes.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/ocrdma
-rw-r--r-- 1 root root 131165 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/ocrdma/ocrdma.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/qib
-rw-r--r-- 1 root root 600661 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/qib/ib_qib.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/usnic
-rw-r--r-- 1 root root 135229 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/hw/usnic/usnic_verbs.ko
drwxr-xr-x 7 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/ipoib
-rw-r--r-- 1 root root 161509 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/ipoib/ib_ipoib.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/iser
-rw-r--r-- 1 root root 85917 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/iser/ib_iser.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/isert
-rw-r--r-- 1 root root 91245 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/isert/ib_isert.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/srp
-rw-r--r-- 1 root root 85757 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/srp/ib_srp.ko
drwxr-xr-x 2 root root 0 Aug 7 15:31 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/srpt
-rw-r--r-- 1 root root 92813 Aug 3 04:52 usr/lib/modules/3.10.0-327.28.2.el7.x86_64/kernel/drivers/infiniband/ulp/srpt/ib_srpt.ko
[...]
Yes. I am new to IB, but I am very sure the above is from the distro. The mlnxofedinstall perl script doesn't run dracut -f, as proved by the following:
[root@sc2u0n0 mlnx_ofed]#
Thus, even the Mellanox drivers/kernel modules are loaded with its openibd running, I suspect that both the inbox and Mellanox ones are loaded. The outcome under such a circumstance is not something I have much experience - since I am new to IB. But my experience with other drivers tells me that it's not going to be good. If this is indeed the case, then there is a bug in the mlnxofedinstall perl script (missing a critical step!) that should be fixed ASAP.
I have started thinking whether I should use the uninstall.sh that comes with MLNX_OFED to uninstall it, and then just use the inbox IB modules/drivers.