This is a note to let you know that I've just added the patch titled

xprtrdma: Fix BUG after a device removal

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: xprtrdma-fix-bug-after-a-device-removal.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From e89e8d8fcdc6751e86ccad794b052fe67e6ad619 Mon Sep 17 00:00:00 2001

From: Chuck Lever chuck.lever@oracle.com Date: Wed, 31 Jan 2018 12:34:13 -0500 Subject: xprtrdma: Fix BUG after a device removal

From: Chuck Lever chuck.lever@oracle.com

commit e89e8d8fcdc6751e86ccad794b052fe67e6ad619 upstream.

Michal Kalderon reports a BUG that occurs just after device removal:

[ 169.112490] rpcrdma: removing device qedr0 for 192.168.110.146:20049 [ 169.143909] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 [ 169.181837] IP: rpcrdma_dma_unmap_regbuf+0xa/0x60 [rpcrdma]

The RPC/RDMA client transport attempts to allocate some resources on demand. Registered buffers are one such resource. These are allocated (or re-allocated) by xprt_rdma_allocate to hold RPC Call and Reply messages. A hardware resource is associated with each of these buffers, as they can be used for a Send or Receive Work Request.

If a device is removed from under an NFS/RDMA mount, the transport layer is responsible for releasing all hardware resources before the device can be finally unplugged. A BUG results when the NFS mount hasn't yet seen much activity: the transport tries to release resources that haven't yet been allocated.

rpcrdma_free_regbuf() already checks for this case, so just move that check to cover the DEVICE_REMOVAL case as well.

Reported-by: Michal Kalderon Michal.Kalderon@cavium.com Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA ...") Signed-off-by: Chuck Lever chuck.lever@oracle.com Tested-by: Michal Kalderon Michal.Kalderon@cavium.com Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- net/sunrpc/xprtrdma/verbs.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -1476,6 +1476,9 @@ __rpcrdma_dma_map_regbuf(struct rpcrdma_ static void rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb) { + if (!rb) + return; + if (!rpcrdma_regbuf_is_mapped(rb)) return;

@@ -1491,9 +1494,6 @@ rpcrdma_dma_unmap_regbuf(struct rpcrdma_ void rpcrdma_free_regbuf(struct rpcrdma_regbuf *rb) { - if (!rb) - return; - rpcrdma_dma_unmap_regbuf(rb); kfree(rb); }

Patches currently in stable-queue which might be from chuck.lever@oracle.com are

queue-4.15/xprtrdma-fix-bug-after-a-device-removal.patch queue-4.15/xprtrdma-fix-calculation-of-ri_max_send_sges.patch