On Fri, 2018-01-12 at 09:32 -0700, Jason Gunthorpe wrote: > On Fri, Jan 12, 2018 at 11:42:22AM +0800, Jianchao Wang wrote: > > Customer reported memory corruption issue on previous mlx4_en driver > > version where the order-3 pages and multiple page reference counting > > were still used. > > > > Finally, find out one of the root causes is that the HW may see stale > > rx_descs due to prod db updating reaches HW before rx_desc. Especially > > when cross order-3 pages boundary and update a new one, HW may write > > on the pages which may has been freed and allocated again by others. > > > > To fix it, add a wmb between rx_desc and prod db updating to ensure > > the order. Even thougth order-0 and page recycling has been introduced, > > the disorder between rx_desc and prod db still could lead to corruption > > on different inbound packages. > > > > Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx> > > drivers/net/ethernet/mellanox/mlx4/en_rx.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > > index 85e28ef..eefa82c 100644 > > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c > > @@ -555,7 +555,7 @@ static void mlx4_en_refill_rx_buffers(struct mlx4_en_priv *priv, > > break; > > ring->prod++; > > } while (likely(--missing)); > > - > > + wmb(); /* ensure rx_desc updating reaches HW before prod db updating */ > > mlx4_en_update_rx_prod_db(ring); > > } > > > > Does this need to be dma_wmb(), and should it be in > mlx4_en_update_rx_prod_db ? > +1 on dma_wmb() On what architecture bug was observed ? In any case, the barrier should be moved in mlx4_en_update_rx_prod_db() I think. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
