4.20-stable review patch. If anyone has any objections, please let me know.
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From: Chuck Lever chuck.lever@oracle.com
commit e2f34e26710bfaa545a9d9cd0c70137406401467 upstream.
While chasing yet another set of DMAR fault reports, I noticed that the frwr recycler conflates whether or not an MR has been DMA unmapped with frwr->fr_state. Actually the two have only an indirect relationship. It's in fact impossible to guess reliably whether the MR has been DMA unmapped based on its fr_state field, especially as the surrounding code and its assumptions have changed over time.
A better approach is to track the DMA mapping status explicitly so that the recycler is less brittle to unexpected situations, and attempts to DMA-unmap a second time are prevented.
Signed-off-by: Chuck Lever chuck.lever@oracle.com Cc: stable@vger.kernel.org # v4.20 Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/sunrpc/xprtrdma/frwr_ops.c | 6 ++++-- net/sunrpc/xprtrdma/verbs.c | 9 ++++++--- 2 files changed, 10 insertions(+), 5 deletions(-)
--- a/net/sunrpc/xprtrdma/frwr_ops.c +++ b/net/sunrpc/xprtrdma/frwr_ops.c @@ -117,15 +117,15 @@ static void frwr_mr_recycle_worker(struct work_struct *work) { struct rpcrdma_mr *mr = container_of(work, struct rpcrdma_mr, mr_recycle); - enum rpcrdma_frwr_state state = mr->frwr.fr_state; struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
trace_xprtrdma_mr_recycle(mr);
- if (state != FRWR_FLUSHED_LI) { + if (mr->mr_dir != DMA_NONE) { trace_xprtrdma_mr_unmap(mr); ib_dma_unmap_sg(r_xprt->rx_ia.ri_device, mr->mr_sg, mr->mr_nents, mr->mr_dir); + mr->mr_dir = DMA_NONE; }
spin_lock(&r_xprt->rx_buf.rb_mrlock); @@ -150,6 +150,8 @@ frwr_op_init_mr(struct rpcrdma_ia *ia, s if (!mr->mr_sg) goto out_list_err;
+ frwr->fr_state = FRWR_IS_INVALID; + mr->mr_dir = DMA_NONE; INIT_LIST_HEAD(&mr->mr_list); INIT_WORK(&mr->mr_recycle, frwr_mr_recycle_worker); sg_init_table(mr->mr_sg, depth); --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -1329,9 +1329,12 @@ rpcrdma_mr_unmap_and_put(struct rpcrdma_ { struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
- trace_xprtrdma_mr_unmap(mr); - ib_dma_unmap_sg(r_xprt->rx_ia.ri_device, - mr->mr_sg, mr->mr_nents, mr->mr_dir); + if (mr->mr_dir != DMA_NONE) { + trace_xprtrdma_mr_unmap(mr); + ib_dma_unmap_sg(r_xprt->rx_ia.ri_device, + mr->mr_sg, mr->mr_nents, mr->mr_dir); + mr->mr_dir = DMA_NONE; + } __rpcrdma_mr_put(&r_xprt->rx_buf, mr); }