Patch "xprtrdma: Fix BUG after a device removal" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

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 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xprtrdma-fix-bug-after-a-device-removal.patch
and it can be found in the queue-4.14 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
@@ -1331,6 +1331,9 @@ __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;
 
@@ -1346,9 +1349,6 @@ 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-4.14/xprtrdma-fix-bug-after-a-device-removal.patch
queue-4.14/xprtrdma-fix-calculation-of-ri_max_send_sges.patch