1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 7d2ec9ee5097..77dca1e05bba 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -601,6 +601,23 @@ void mlx5_ib_free_implicit_mr(struct mlx5_ib_mr *imr)
 	 */
 	synchronize_srcu(&dev->odp_srcu);
 
+	/*
+	 * All work on the prefetch list must be completed, xa_erase() prevented
+	 * new work from being created.
+	 */
+	wait_event(imr->q_deferred_work, !atomic_read(&imr->num_deferred_work));
+
+	/*
+	 * At this point it is forbidden for any other thread to enter
+	 * pagefault_mr() on this imr. It is already forbidden to call
+	 * pagefault_mr() on an implicit child. Due to this additions to
+	 * implicit_children are prevented.
+	 */
+
+	/*
+	 * Block destroy_unused_implicit_child_mr() from incrementing
+	 * num_deferred_work.
+	 */
 	xa_lock(&imr->implicit_children);
 	xa_for_each (&imr->implicit_children, idx, mtt) {
 		__xa_erase(&imr->implicit_children, idx);
@@ -609,9 +626,8 @@ void mlx5_ib_free_implicit_mr(struct mlx5_ib_mr *imr)
 	xa_unlock(&imr->implicit_children);
 
 	/*
-	 * num_deferred_work can only be incremented inside the odp_srcu, or
-	 * under xa_lock while the child is in the xarray. Thus at this point
-	 * it is only decreasing, and all work holding it is now on the wq.
+	 * Wait for any concurrent destroy_unused_implicit_child_mr() to
+	 * complete.
 	 */
 	wait_event(imr->q_deferred_work, !atomic_read(&imr->num_deferred_work));
 
@@ -1781,9 +1797,7 @@ static bool init_prefetch_work(struct ib_pd *pd,
 		work->frags[i].mr =
 			get_prefetchable_mr(pd, advice, sg_list[i].lkey);
 		if (!work->frags[i].mr) {
-			work->num_sge = i - 1;
-			if (i)
-				destroy_prefetch_work(work);
+			work->num_sge = i;
 			return false;
 		}
 
@@ -1849,6 +1863,7 @@ int mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
 	srcu_key = srcu_read_lock(&dev->odp_srcu);
 	if (!init_prefetch_work(pd, advice, pf_flags, work, sg_list, num_sge)) {
 		srcu_read_unlock(&dev->odp_srcu, srcu_key);
+		destroy_prefetch_work(work);
 		return -EINVAL;
 	}
 	queue_work(system_unbound_wq, &work->work);