Merge branch 'odp_rework' into rdma.git for-next

Jason Gunthorpe says:

====================
In order to hoist the interval tree code out of the drivers and into the
mmu_notifiers it is necessary for the drivers to not use the interval tree
for other things.

This series replaces the interval tree with an xarray and along the way
re-aligns all the locking to use a sensible SRCU model where the 'update'
step is done by modifying an xarray.

The result is overall much simpler and with less locking in the critical
path. Many functions were reworked for clarity and small details like
using 'imr' to refer to the implicit MR make the entire code flow here
more readable.

This also squashes at least two race bugs on its own, and quite possibily
more that haven't been identified.
====================

Merge conflicts with the odp statistics patch resolved.

* branch 'odp_rework':
  RDMA/odp: Remove broken debugging call to invalidate_range
  RDMA/mlx5: Do not race with mlx5_ib_invalidate_range during create and destroy
  RDMA/mlx5: Do not store implicit children in the odp_mkeys xarray
  RDMA/mlx5: Rework implicit ODP destroy
  RDMA/mlx5: Avoid double lookups on the pagefault path
  RDMA/mlx5: Reduce locking in implicit_mr_get_data()
  RDMA/mlx5: Use an xarray for the children of an implicit ODP
  RDMA/mlx5: Split implicit handling from pagefault_mr
  RDMA/mlx5: Set the HW IOVA of the child MRs to their place in the tree
  RDMA/mlx5: Lift implicit_mr_alloc() into the two routines that call it
  RDMA/mlx5: Rework implicit_mr_get_data
  RDMA/mlx5: Delete struct mlx5_priv->mkey_table
  RDMA/mlx5: Use a dedicated mkey xarray for ODP
  RDMA/mlx5: Split sig_err MR data into its own xarray
  RDMA/mlx5: Use SRCU properly in ODP prefetch

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 19 insertions, 19 deletions

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 163ff7ba92b7..d7d5fadf0899 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -508,7 +508,6 @@ static int ib_umem_odp_map_dma_single_page(
 {
 	struct ib_device *dev = umem_odp->umem.ibdev;
 	dma_addr_t dma_addr;
-	int remove_existing_mapping = 0;
 	int ret = 0;
 
 	/*
@@ -534,28 +533,29 @@ static int ib_umem_odp_map_dma_single_page(
 	} else if (umem_odp->page_list[page_index] == page) {
 		umem_odp->dma_list[page_index] |= access_mask;
 	} else {
-		pr_err("error: got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n",
-		       umem_odp->page_list[page_index], page);
-		/* Better remove the mapping now, to prevent any further
-		 * damage. */
-		remove_existing_mapping = 1;
+		/*
+		 * This is a race here where we could have done:
+		 *
+		 *         CPU0                             CPU1
+		 *   get_user_pages()
+		 *                                       invalidate()
+		 *                                       page_fault()
+		 *   mutex_lock(umem_mutex)
+		 *    page from GUP != page in ODP
+		 *
+		 * It should be prevented by the retry test above as reading
+		 * the seq number should be reliable under the
+		 * umem_mutex. Thus something is really not working right if
+		 * things get here.
+		 */
+		WARN(true,
+		     "Got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n",
+		     umem_odp->page_list[page_index], page);
+		ret = -EAGAIN;
 	}
 
 out:
 	put_user_page(page);
-
-	if (remove_existing_mapping) {
-		ib_umem_notifier_start_account(umem_odp);
-		dev->ops.invalidate_range(
-			umem_odp,
-			ib_umem_start(umem_odp) +
-				(page_index << umem_odp->page_shift),
-			ib_umem_start(umem_odp) +
-				((page_index + 1) << umem_odp->page_shift));
-		ib_umem_notifier_end_account(umem_odp);
-		ret = -EAGAIN;
-	}
-
 	return ret;
 }