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xprtrdma: Fix BUG after a device removal
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>
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@ -1502,6 +1502,9 @@ __rpcrdma_dma_map_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
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static void
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rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb)
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{
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if (!rb)
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return;
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if (!rpcrdma_regbuf_is_mapped(rb))
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return;
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@ -1517,9 +1520,6 @@ rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb)
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void
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rpcrdma_free_regbuf(struct rpcrdma_regbuf *rb)
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{
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if (!rb)
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return;
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rpcrdma_dma_unmap_regbuf(rb);
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kfree(rb);
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}
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