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@xxxxxxxxxxxxxxx> know about it. >From e89e8d8fcdc6751e86ccad794b052fe67e6ad619 Mon Sep 17 00:00:00 2001 From: Chuck Lever <chuck.lever@xxxxxxxxxx> Date: Wed, 31 Jan 2018 12:34:13 -0500 Subject: xprtrdma: Fix BUG after a device removal From: Chuck Lever <chuck.lever@xxxxxxxxxx> 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@xxxxxxxxxx> Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA ...") Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Tested-by: Michal Kalderon <Michal.Kalderon@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v4.12+ Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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@xxxxxxxxxx are queue-4.14/xprtrdma-fix-bug-after-a-device-removal.patch queue-4.14/xprtrdma-fix-calculation-of-ri_max_send_sges.patch