Hi Dan-
> On Aug 14, 2020, at 1:37 PM, Dan Aloni <dan@xxxxxxxxxxxx> wrote:
>
> It was observed that on disconnections, these unmaps don't occur. The
> relevant path is rpcrdma_mrs_destroy(), being called from
> rpcrdma_xprt_disconnect().
MRs are supposed to be unmapped right after they are used, so
during disconnect they should all be unmapped already. How often
do you see a DMA mapped MR in this code path? Do you have a
reproducer I can try?
> Signed-off-by: Dan Aloni <dan@xxxxxxxxxxxx>
> ---
> net/sunrpc/xprtrdma/frwr_ops.c | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index 7f94c9a19fd3..3899a5310214 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -49,6 +49,19 @@
> # define RPCDBG_FACILITY RPCDBG_TRANS
> #endif
>
> +static void frwr_mr_unmap(struct rpcrdma_mr *mr)
> +{
> + struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
> +
> + if (mr->mr_dir == DMA_NONE)
> + return;
> +
> + trace_xprtrdma_mr_unmap(mr);
> + ib_dma_unmap_sg(r_xprt->rx_ep->re_id->device,
> + mr->mr_sg, mr->mr_nents, mr->mr_dir);
> + mr->mr_dir = DMA_NONE;
> +}
> +
> /**
> * frwr_release_mr - Destroy one MR
> * @mr: MR allocated by frwr_mr_init
> @@ -58,6 +71,8 @@ void frwr_release_mr(struct rpcrdma_mr *mr)
> {
> int rc;
>
> + frwr_mr_unmap(mr);
> +
> rc = ib_dereg_mr(mr->frwr.fr_mr);
> if (rc)
> trace_xprtrdma_frwr_dereg(mr, rc);
> @@ -71,12 +86,7 @@ static void frwr_mr_recycle(struct rpcrdma_mr *mr)
>
> trace_xprtrdma_mr_recycle(mr);
>
> - if (mr->mr_dir != DMA_NONE) {
> - trace_xprtrdma_mr_unmap(mr);
> - ib_dma_unmap_sg(r_xprt->rx_ep->re_id->device,
> - mr->mr_sg, mr->mr_nents, mr->mr_dir);
> - mr->mr_dir = DMA_NONE;
> - }
> + frwr_mr_unmap(mr);
>
> spin_lock(&r_xprt->rx_buf.rb_lock);
> list_del(&mr->mr_all);
> --
> 2.25.4
>
--
Chuck Lever
