> From: Chuck Lever [mailto:chucklever@xxxxxxxxx] On Behalf Of Chuck Lever > Sent: Wednesday, January 31, 2018 6:04 PM > To: Kalderon, Michal <Michal.Kalderon@xxxxxxxxxx> > Cc: linux-rdma@xxxxxxxxxxxxxxx > Subject: [PATCH v1] 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@xxxxxxxxxx> > Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA ...") > Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> > --- > net/sunrpc/xprtrdma/verbs.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c > index bb56b9d..e6f84a6 100644 > --- a/net/sunrpc/xprtrdma/verbs.c > +++ b/net/sunrpc/xprtrdma/verbs.c > @@ -1502,6 +1502,9 @@ struct rpcrdma_regbuf * static void > rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb) { > + if (!rb) > + return; > + > if (!rpcrdma_regbuf_is_mapped(rb)) > return; > > @@ -1517,9 +1520,6 @@ struct rpcrdma_regbuf * void > rpcrdma_free_regbuf(struct rpcrdma_regbuf *rb) { > - if (!rb) > - return; > - > rpcrdma_dma_unmap_regbuf(rb); > kfree(rb); > } Thanks, Tested-by: Michal Kalderon <Michal.Kalderon@xxxxxxxxxx> ��.n��������+%������w��{.n�����{���fk��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
