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>

9 files changed, 624 insertions, 641 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;
 }
 
diff --git a/drivers/infiniband/hw/mlx5/cq.c b/drivers/infiniband/hw/mlx5/cq.c
index 45f48cde6b9d..cc938d27f913 100644
--- a/drivers/infiniband/hw/mlx5/cq.c
+++ b/drivers/infiniband/hw/mlx5/cq.c
@@ -423,9 +423,6 @@ static int mlx5_poll_one(struct mlx5_ib_cq *cq,
 	struct mlx5_cqe64 *cqe64;
 	struct mlx5_core_qp *mqp;
 	struct mlx5_ib_wq *wq;
-	struct mlx5_sig_err_cqe *sig_err_cqe;
-	struct mlx5_core_mkey *mmkey;
-	struct mlx5_ib_mr *mr;
 	uint8_t opcode;
 	uint32_t qpn;
 	u16 wqe_ctr;
@@ -519,27 +516,29 @@ repoll:
 			}
 		}
 		break;
-	case MLX5_CQE_SIG_ERR:
-		sig_err_cqe = (struct mlx5_sig_err_cqe *)cqe64;
+	case MLX5_CQE_SIG_ERR: {
+		struct mlx5_sig_err_cqe *sig_err_cqe =
+			(struct mlx5_sig_err_cqe *)cqe64;
+		struct mlx5_core_sig_ctx *sig;
 
-		xa_lock(&dev->mdev->priv.mkey_table);
-		mmkey = xa_load(&dev->mdev->priv.mkey_table,
+		xa_lock(&dev->sig_mrs);
+		sig = xa_load(&dev->sig_mrs,
 				mlx5_base_mkey(be32_to_cpu(sig_err_cqe->mkey)));
-		mr = to_mibmr(mmkey);
-		get_sig_err_item(sig_err_cqe, &mr->sig->err_item);
-		mr->sig->sig_err_exists = true;
-		mr->sig->sigerr_count++;
+		get_sig_err_item(sig_err_cqe, &sig->err_item);
+		sig->sig_err_exists = true;
+		sig->sigerr_count++;
 
 		mlx5_ib_warn(dev, "CQN: 0x%x Got SIGERR on key: 0x%x err_type %x err_offset %llx expected %x actual %x\n",
-			     cq->mcq.cqn, mr->sig->err_item.key,
-			     mr->sig->err_item.err_type,
-			     mr->sig->err_item.sig_err_offset,
-			     mr->sig->err_item.expected,
-			     mr->sig->err_item.actual);
+			     cq->mcq.cqn, sig->err_item.key,
+			     sig->err_item.err_type,
+			     sig->err_item.sig_err_offset,
+			     sig->err_item.expected,
+			     sig->err_item.actual);
 
-		xa_unlock(&dev->mdev->priv.mkey_table);
+		xa_unlock(&dev->sig_mrs);
 		goto repoll;
 	}
+	}
 
 	return 0;
 }
diff --git a/drivers/infiniband/hw/mlx5/devx.c b/drivers/infiniband/hw/mlx5/devx.c
index d609f4659afb..6b1fca91d7d3 100644
--- a/drivers/infiniband/hw/mlx5/devx.c
+++ b/drivers/infiniband/hw/mlx5/devx.c
@@ -1265,8 +1265,8 @@ static int devx_handle_mkey_indirect(struct devx_obj *obj,
 	mkey->pd = MLX5_GET(mkc, mkc, pd);
 	devx_mr->ndescs = MLX5_GET(mkc, mkc, translations_octword_size);
 
-	return xa_err(xa_store(&dev->mdev->priv.mkey_table,
-			       mlx5_base_mkey(mkey->key), mkey, GFP_KERNEL));
+	return xa_err(xa_store(&dev->odp_mkeys, mlx5_base_mkey(mkey->key), mkey,
+			       GFP_KERNEL));
 }
 
 static int devx_handle_mkey_create(struct mlx5_ib_dev *dev,
@@ -1345,9 +1345,9 @@ static int devx_obj_cleanup(struct ib_uobject *uobject,
 		 * the mmkey, we must wait for that to stop before freeing the
 		 * mkey, as another allocation could get the same mkey #.
 		 */
-		xa_erase(&obj->ib_dev->mdev->priv.mkey_table,
+		xa_erase(&obj->ib_dev->odp_mkeys,
 			 mlx5_base_mkey(obj->devx_mr.mmkey.key));
-		synchronize_srcu(&dev->mr_srcu);
+		synchronize_srcu(&dev->odp_srcu);
 	}
 
 	if (obj->flags & DEVX_OBJ_FLAGS_DCT)
diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 20fabb368f61..0a8a1a129f17 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -6133,11 +6133,10 @@ static struct ib_counters *mlx5_ib_create_counters(struct ib_device *device,
 static void mlx5_ib_stage_init_cleanup(struct mlx5_ib_dev *dev)
 {
 	mlx5_ib_cleanup_multiport_master(dev);
-	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING)) {
-		srcu_barrier(&dev->mr_srcu);
-		cleanup_srcu_struct(&dev->mr_srcu);
-	}
+	WARN_ON(!xa_empty(&dev->odp_mkeys));
+	cleanup_srcu_struct(&dev->odp_srcu);
 
+	WARN_ON(!xa_empty(&dev->sig_mrs));
 	WARN_ON(!bitmap_empty(dev->dm.memic_alloc_pages, MLX5_MAX_MEMIC_PAGES));
 }
 
@@ -6189,15 +6188,15 @@ static int mlx5_ib_stage_init_init(struct mlx5_ib_dev *dev)
 	mutex_init(&dev->cap_mask_mutex);
 	INIT_LIST_HEAD(&dev->qp_list);
 	spin_lock_init(&dev->reset_flow_resource_lock);
+	xa_init(&dev->odp_mkeys);
+	xa_init(&dev->sig_mrs);
 
 	spin_lock_init(&dev->dm.lock);
 	dev->dm.dev = mdev;
 
-	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING)) {
-		err = init_srcu_struct(&dev->mr_srcu);
-		if (err)
-			goto err_mp;
-	}
+	err = init_srcu_struct(&dev->odp_srcu);
+	if (err)
+		goto err_mp;
 
 	return 0;
 
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 3a97c2da632a..5b4c5751a98f 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -604,7 +604,6 @@ struct mlx5_ib_mr {
 	struct mlx5_ib_dev     *dev;
 	u32 out[MLX5_ST_SZ_DW(create_mkey_out)];
 	struct mlx5_core_sig_ctx    *sig;
-	unsigned int		live;
 	void			*descs_alloc;
 	int			access_flags; /* Needed for rereg MR */
 
@@ -616,12 +615,18 @@ struct mlx5_ib_mr {
 	u64			data_iova;
 	u64			pi_iova;
 
-	atomic_t		num_leaf_free;
-	wait_queue_head_t       q_leaf_free;
-	struct mlx5_async_work  cb_work;
-	atomic_t		num_pending_prefetch;
+	/* For ODP and implicit */
+	atomic_t		num_deferred_work;
+	struct xarray		implicit_children;
+	union {
+		struct rcu_head rcu;
+		struct list_head elm;
+		struct work_struct work;
+	} odp_destroy;
 	struct ib_odp_counters	odp_stats;
 	bool			is_odp_implicit;
+
+	struct mlx5_async_work  cb_work;
 };
 
 static inline bool is_odp_mr(struct mlx5_ib_mr *mr)
@@ -977,7 +982,9 @@ struct mlx5_ib_dev {
 	 * Sleepable RCU that prevents destruction of MRs while they are still
 	 * being used by a page fault handler.
 	 */
-	struct srcu_struct      mr_srcu;
+	struct srcu_struct      odp_srcu;
+	struct xarray		odp_mkeys;
+
 	u32			null_mkey;
 	struct mlx5_ib_flow_db	*flow_db;
 	/* protect resources needed as part of reset flow */
@@ -999,6 +1006,8 @@ struct mlx5_ib_dev {
 	struct mlx5_srq_table   srq_table;
 	struct mlx5_async_ctx   async_ctx;
 	struct mlx5_devx_event_table devx_event_table;
+
+	struct xarray sig_mrs;
 };
 
 static inline struct mlx5_ib_cq *to_mibcq(struct mlx5_core_cq *mcq)
@@ -1162,6 +1171,7 @@ struct mlx5_ib_mr *mlx5_ib_alloc_implicit_mr(struct mlx5_ib_pd *pd,
 					     struct ib_udata *udata,
 					     int access_flags);
 void mlx5_ib_free_implicit_mr(struct mlx5_ib_mr *mr);
+void mlx5_ib_fence_odp_mr(struct mlx5_ib_mr *mr);
 int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
 			  u64 length, u64 virt_addr, int access_flags,
 			  struct ib_pd *pd, struct ib_udata *udata);
@@ -1223,6 +1233,8 @@ int mlx5_mr_cache_cleanup(struct mlx5_ib_dev *dev);
 
 struct mlx5_ib_mr *mlx5_mr_cache_alloc(struct mlx5_ib_dev *dev, int entry);
 void mlx5_mr_cache_free(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr);
+int mlx5_mr_cache_invalidate(struct mlx5_ib_mr *mr);
+
 int mlx5_ib_check_mr_status(struct ib_mr *ibmr, u32 check_mask,
 			    struct ib_mr_status *mr_status);
 struct ib_wq *mlx5_ib_create_wq(struct ib_pd *pd,
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 986a7722ab27..f583476f5c8b 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -50,7 +50,6 @@ enum {
 static void clean_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr);
 static void dereg_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr);
 static int mr_cache_max_order(struct mlx5_ib_dev *dev);
-static int unreg_umr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr);
 
 static bool umr_can_use_indirect_mkey(struct mlx5_ib_dev *dev)
 {
@@ -59,13 +58,9 @@ static bool umr_can_use_indirect_mkey(struct mlx5_ib_dev *dev)
 
 static int destroy_mkey(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 {
-	int err = mlx5_core_destroy_mkey(dev->mdev, &mr->mmkey);
+	WARN_ON(xa_load(&dev->odp_mkeys, mlx5_base_mkey(mr->mmkey.key)));
 
-	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING))
-		/* Wait until all page fault handlers using the mr complete. */
-		synchronize_srcu(&dev->mr_srcu);
-
-	return err;
+	return mlx5_core_destroy_mkey(dev->mdev, &mr->mmkey);
 }
 
 static int order2idx(struct mlx5_ib_dev *dev, int order)
@@ -94,8 +89,6 @@ static void reg_mr_callback(int status, struct mlx5_async_work *context)
 	struct mlx5_cache_ent *ent = &cache->ent[c];
 	u8 key;
 	unsigned long flags;
-	struct xarray *mkeys = &dev->mdev->priv.mkey_table;
-	int err;
 
 	spin_lock_irqsave(&ent->lock, flags);
 	ent->pending--;
@@ -122,13 +115,6 @@ static void reg_mr_callback(int status, struct mlx5_async_work *context)
 	ent->size++;
 	spin_unlock_irqrestore(&ent->lock, flags);
 
-	xa_lock_irqsave(mkeys, flags);
-	err = xa_err(__xa_store(mkeys, mlx5_base_mkey(mr->mmkey.key),
-				&mr->mmkey, GFP_ATOMIC));
-	xa_unlock_irqrestore(mkeys, flags);
-	if (err)
-		pr_err("Error inserting to mkey tree. 0x%x\n", -err);
-
 	if (!completion_done(&ent->compl))
 		complete(&ent->compl);
 }
@@ -218,9 +204,6 @@ static void remove_keys(struct mlx5_ib_dev *dev, int c, int num)
 		mlx5_core_destroy_mkey(dev->mdev, &mr->mmkey);
 	}
 
-	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING))
-		synchronize_srcu(&dev->mr_srcu);
-
 	list_for_each_entry_safe(mr, tmp_mr, &del_list, list) {
 		list_del(&mr->list);
 		kfree(mr);
@@ -511,7 +494,7 @@ void mlx5_mr_cache_free(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 	c = order2idx(dev, mr->order);
 	WARN_ON(c < 0 || c >= MAX_MR_CACHE_ENTRIES);
 
-	if (unreg_umr(dev, mr)) {
+	if (mlx5_mr_cache_invalidate(mr)) {
 		mr->allocated_from_cache = false;
 		destroy_mkey(dev, mr);
 		ent = &cache->ent[c];
@@ -555,10 +538,6 @@ static void clean_keys(struct mlx5_ib_dev *dev, int c)
 		mlx5_core_destroy_mkey(dev->mdev, &mr->mmkey);
 	}
 
-#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-	synchronize_srcu(&dev->mr_srcu);
-#endif
-
 	list_for_each_entry_safe(mr, tmp_mr, &del_list, list) {
 		list_del(&mr->list);
 		kfree(mr);
@@ -1335,10 +1314,15 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
 
 	if (is_odp_mr(mr)) {
 		to_ib_umem_odp(mr->umem)->private = mr;
-		atomic_set(&mr->num_pending_prefetch, 0);
+		atomic_set(&mr->num_deferred_work, 0);
+		err = xa_err(xa_store(&dev->odp_mkeys,
+				      mlx5_base_mkey(mr->mmkey.key), &mr->mmkey,
+				      GFP_KERNEL));
+		if (err) {
+			dereg_mr(dev, mr);
+			return ERR_PTR(err);
+		}
 	}
-	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING))
-		smp_store_release(&mr->live, 1);
 
 	return &mr->ibmr;
 error:
@@ -1346,22 +1330,29 @@ error:
 	return ERR_PTR(err);
 }
 
-static int unreg_umr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
+/**
+ * mlx5_mr_cache_invalidate - Fence all DMA on the MR
+ * @mr: The MR to fence
+ *
+ * Upon return the NIC will not be doing any DMA to the pages under the MR,
+ * and any DMA inprogress will be completed. Failure of this function
+ * indicates the HW has failed catastrophically.
+ */
+int mlx5_mr_cache_invalidate(struct mlx5_ib_mr *mr)
 {
-	struct mlx5_core_dev *mdev = dev->mdev;
 	struct mlx5_umr_wr umrwr = {};
 
-	if (mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)
+	if (mr->dev->mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR)
 		return 0;
 
 	umrwr.wr.send_flags = MLX5_IB_SEND_UMR_DISABLE_MR |
 			      MLX5_IB_SEND_UMR_UPDATE_PD_ACCESS;
 	umrwr.wr.opcode = MLX5_IB_WR_UMR;
-	umrwr.pd = dev->umrc.pd;
+	umrwr.pd = mr->dev->umrc.pd;
 	umrwr.mkey = mr->mmkey.key;
 	umrwr.ignore_free_state = 1;
 
-	return mlx5_ib_post_send_wait(dev, &umrwr);
+	return mlx5_ib_post_send_wait(mr->dev, &umrwr);
 }
 
 static int rereg_umr(struct ib_pd *pd, struct mlx5_ib_mr *mr,
@@ -1445,7 +1436,7 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
 		 * UMR can't be used - MKey needs to be replaced.
 		 */
 		if (mr->allocated_from_cache)
-			err = unreg_umr(dev, mr);
+			err = mlx5_mr_cache_invalidate(mr);
 		else
 			err = destroy_mkey(dev, mr);
 		if (err)
@@ -1558,6 +1549,7 @@ static void clean_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 					  mr->sig->psv_wire.psv_idx))
 			mlx5_ib_warn(dev, "failed to destroy wire psv %d\n",
 				     mr->sig->psv_wire.psv_idx);
+		xa_erase(&dev->sig_mrs, mlx5_base_mkey(mr->mmkey.key));
 		kfree(mr->sig);
 		mr->sig = NULL;
 	}
@@ -1573,54 +1565,20 @@ static void dereg_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr)
 	int npages = mr->npages;
 	struct ib_umem *umem = mr->umem;
 
-	if (is_odp_mr(mr)) {
-		struct ib_umem_odp *umem_odp = to_ib_umem_odp(umem);
-
-		/* Prevent new page faults and
-		 * prefetch requests from succeeding
-		 */
-		WRITE_ONCE(mr->live, 0);
-
-		/* Wait for all running page-fault handlers to finish. */
-		synchronize_srcu(&dev->mr_srcu);
-
-		/* dequeue pending prefetch requests for the mr */
-		if (atomic_read(&mr->num_pending_prefetch))
-			flush_workqueue(system_unbound_wq);
-		WARN_ON(atomic_read(&mr->num_pending_prefetch));
-
-		/* Destroy all page mappings */
-		if (!umem_odp->is_implicit_odp)
-			mlx5_ib_invalidate_range(umem_odp,
-						 ib_umem_start(umem_odp),
-						 ib_umem_end(umem_odp));
-		else
-			mlx5_ib_free_implicit_mr(mr);
-		/*
-		 * We kill the umem before the MR for ODP,
-		 * so that there will not be any invalidations in
-		 * flight, looking at the *mr struct.
-		 */
-		ib_umem_odp_release(umem_odp);
-		atomic_sub(npages, &dev->mdev->priv.reg_pages);
-
-		/* Avoid double-freeing the umem. */
-		umem = NULL;
-	}
+	/* Stop all DMA */
+	if (is_odp_mr(mr))
+		mlx5_ib_fence_odp_mr(mr);
+	else
+		clean_mr(dev, mr);
 
-	clean_mr(dev, mr);
+	if (mr->allocated_from_cache)
+		mlx5_mr_cache_free(dev, mr);
+	else
+		kfree(mr);
 
-	/*
-	 * We should unregister the DMA address from the HCA before
-	 * remove the DMA mapping.
-	 */
-	mlx5_mr_cache_free(dev, mr);
 	ib_umem_release(umem);
-	if (umem)
-		atomic_sub(npages, &dev->mdev->priv.reg_pages);
+	atomic_sub(npages, &dev->mdev->priv.reg_pages);
 
-	if (!mr->allocated_from_cache)
-		kfree(mr);
 }
 
 int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
@@ -1632,6 +1590,11 @@ int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
 		dereg_mr(to_mdev(mmr->klm_mr->ibmr.device), mmr->klm_mr);
 	}
 
+	if (is_odp_mr(mmr) && to_ib_umem_odp(mmr->umem)->is_implicit_odp) {
+		mlx5_ib_free_implicit_mr(mmr);
+		return 0;
+	}
+
 	dereg_mr(to_mdev(ibmr->device), mmr);
 
 	return 0;
@@ -1795,8 +1758,15 @@ static int mlx5_alloc_integrity_descs(struct ib_pd *pd, struct mlx5_ib_mr *mr,
 	if (err)
 		goto err_free_mtt_mr;
 
+	err = xa_err(xa_store(&dev->sig_mrs, mlx5_base_mkey(mr->mmkey.key),
+			      mr->sig, GFP_KERNEL));
+	if (err)
+		goto err_free_descs;
 	return 0;
 
+err_free_descs:
+	destroy_mkey(dev, mr);
+	mlx5_free_priv_descs(mr);
 err_free_mtt_mr:
 	dereg_mr(to_mdev(mr->mtt_mr->ibmr.device), mr->mtt_mr);
 	mr->mtt_mr = NULL;
@@ -1949,9 +1919,19 @@ struct ib_mw *mlx5_ib_alloc_mw(struct ib_pd *pd, enum ib_mw_type type,
 		}
 	}
 
+	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING)) {
+		err = xa_err(xa_store(&dev->odp_mkeys,
+				      mlx5_base_mkey(mw->mmkey.key), &mw->mmkey,
+				      GFP_KERNEL));
+		if (err)
+			goto free_mkey;
+	}
+
 	kfree(in);
 	return &mw->ibmw;
 
+free_mkey:
+	mlx5_core_destroy_mkey(dev->mdev, &mw->mmkey);
 free:
 	kfree(mw);
 	kfree(in);
@@ -1965,13 +1945,12 @@ int mlx5_ib_dealloc_mw(struct ib_mw *mw)
 	int err;
 
 	if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING)) {
-		xa_erase(&dev->mdev->priv.mkey_table,
-			 mlx5_base_mkey(mmw->mmkey.key));
+		xa_erase(&dev->odp_mkeys, mlx5_base_mkey(mmw->mmkey.key));
 		/*
 		 * pagefault_single_data_segment() may be accessing mmw under
 		 * SRCU if the user bound an ODP MR to this MW.
 		 */
-		synchronize_srcu(&dev->mr_srcu);
+		synchronize_srcu(&dev->odp_srcu);
 	}
 
 	err = mlx5_core_destroy_mkey(dev->mdev, &mmw->mmkey);
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index b332117bca97..45ee40c2f36e 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -93,158 +93,152 @@ struct mlx5_pagefault {
 
 static u64 mlx5_imr_ksm_entries;
 
-static int check_parent(struct ib_umem_odp *odp,
-			       struct mlx5_ib_mr *parent)
+void mlx5_odp_populate_klm(struct mlx5_klm *pklm, size_t idx, size_t nentries,
+			   struct mlx5_ib_mr *imr, int flags)
 {
-	struct mlx5_ib_mr *mr = odp->private;
-
-	return mr && mr->parent == parent && !odp->dying;
-}
-
-static struct ib_ucontext_per_mm *mr_to_per_mm(struct mlx5_ib_mr *mr)
-{
-	if (WARN_ON(!mr || !is_odp_mr(mr)))
-		return NULL;
-
-	return to_ib_umem_odp(mr->umem)->per_mm;
-}
-
-static struct ib_umem_odp *odp_next(struct ib_umem_odp *odp)
-{
-	struct mlx5_ib_mr *mr = odp->private, *parent = mr->parent;
-	struct ib_ucontext_per_mm *per_mm = odp->per_mm;
-	struct rb_node *rb;
-
-	down_read(&per_mm->umem_rwsem);
-	while (1) {
-		rb = rb_next(&odp->interval_tree.rb);
-		if (!rb)
-			goto not_found;
-		odp = rb_entry(rb, struct ib_umem_odp, interval_tree.rb);
-		if (check_parent(odp, parent))
-			goto end;
-	}
-not_found:
-	odp = NULL;
-end:
-	up_read(&per_mm->umem_rwsem);
-	return odp;
-}
-
-static struct ib_umem_odp *odp_lookup(u64 start, u64 length,
-				      struct mlx5_ib_mr *parent)
-{
-	struct ib_ucontext_per_mm *per_mm = mr_to_per_mm(parent);
-	struct ib_umem_odp *odp;
-	struct rb_node *rb;
-
-	down_read(&per_mm->umem_rwsem);
-	odp = rbt_ib_umem_lookup(&per_mm->umem_tree, start, length);
-	if (!odp)
-		goto end;
-
-	while (1) {
-		if (check_parent(odp, parent))
-			goto end;
-		rb = rb_next(&odp->interval_tree.rb);
-		if (!rb)
-			goto not_found;
-		odp = rb_entry(rb, struct ib_umem_odp, interval_tree.rb);
-		if (ib_umem_start(odp) > start + length)
-			goto not_found;
-	}
-not_found:
-	odp = NULL;
-end:
-	up_read(&per_mm->umem_rwsem);
-	return odp;
-}
-
-void mlx5_odp_populate_klm(struct mlx5_klm *pklm, size_t offset,
-			   size_t nentries, struct mlx5_ib_mr *mr, int flags)
-{
-	struct ib_pd *pd = mr->ibmr.pd;
-	struct mlx5_ib_dev *dev = to_mdev(pd->device);
-	struct ib_umem_odp *odp;
-	unsigned long va;
-	int i;
+	struct mlx5_klm *end = pklm + nentries;
 
 	if (flags & MLX5_IB_UPD_XLT_ZAP) {
-		for (i = 0; i < nentries; i++, pklm++) {
+		for (; pklm != end; pklm++, idx++) {
 			pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
-			pklm->key = cpu_to_be32(dev->null_mkey);
+			pklm->key = cpu_to_be32(imr->dev->null_mkey);
 			pklm->va = 0;
 		}
 		return;
 	}
 
 	/*
-	 * The locking here is pretty subtle. Ideally the implicit children
-	 * list would be protected by the umem_mutex, however that is not
+	 * The locking here is pretty subtle. Ideally the implicit_children
+	 * xarray would be protected by the umem_mutex, however that is not
 	 * possible. Instead this uses a weaker update-then-lock pattern:
 	 *
 	 *  srcu_read_lock()
-	 *    <change children list>
+	 *    xa_store()
 	 *    mutex_lock(umem_mutex)
 	 *     mlx5_ib_update_xlt()
 	 *    mutex_unlock(umem_mutex)
 	 *    destroy lkey
 	 *
-	 * ie any change the children list must be followed by the locked
-	 * update_xlt before destroying.
+	 * ie any change the xarray must be followed by the locked update_xlt
+	 * before destroying.
 	 *
 	 * The umem_mutex provides the acquire/release semantic needed to make
-	 * the children list visible to a racing thread. While SRCU is not
+	 * the xa_store() visible to a racing thread. While SRCU is not
 	 * technically required, using it gives consistent use of the SRCU
-	 * locking around the children list.
+	 * locking around the xarray.
 	 */
-	lockdep_assert_held(&to_ib_umem_odp(mr->umem)->umem_mutex);
-	lockdep_assert_held(&mr->dev->mr_srcu);
+	lockdep_assert_held(&to_ib_umem_odp(imr->umem)->umem_mutex);
+	lockdep_assert_held(&imr->dev->odp_srcu);
 
-	odp = odp_lookup(offset * MLX5_IMR_MTT_SIZE,
-			 nentries * MLX5_IMR_MTT_SIZE, mr);
+	for (; pklm != end; pklm++, idx++) {
+		struct mlx5_ib_mr *mtt = xa_load(&imr->implicit_children, idx);
 
-	for (i = 0; i < nentries; i++, pklm++) {
 		pklm->bcount = cpu_to_be32(MLX5_IMR_MTT_SIZE);
-		va = (offset + i) * MLX5_IMR_MTT_SIZE;
-		if (odp && ib_umem_start(odp) == va) {
-			struct mlx5_ib_mr *mtt = odp->private;
-
+		if (mtt) {
 			pklm->key = cpu_to_be32(mtt->ibmr.lkey);
-			odp = odp_next(odp);
+			pklm->va = cpu_to_be64(idx * MLX5_IMR_MTT_SIZE);
 		} else {
-			pklm->key = cpu_to_be32(dev->null_mkey);
+			pklm->key = cpu_to_be32(imr->dev->null_mkey);
+			pklm->va = 0;
 		}
-		mlx5_ib_dbg(dev, "[%d] va %lx key %x\n",
-			    i, va, be32_to_cpu(pklm->key));
 	}
 }
 
-static void mr_leaf_free_action(struct work_struct *work)
+static void dma_fence_odp_mr(struct mlx5_ib_mr *mr)
+{
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+
+	/* Ensure mlx5_ib_invalidate_range() will not touch the MR any more */
+	mutex_lock(&odp->umem_mutex);
+	if (odp->npages) {
+		mlx5_mr_cache_invalidate(mr);
+		ib_umem_odp_unmap_dma_pages(odp, ib_umem_start(odp),
+					    ib_umem_end(odp));
+		WARN_ON(odp->npages);
+	}
+	odp->private = NULL;
+	mutex_unlock(&odp->umem_mutex);
+
+	if (!mr->allocated_from_cache) {
+		mlx5_core_destroy_mkey(mr->dev->mdev, &mr->mmkey);
+		WARN_ON(mr->descs);
+	}
+}
+
+/*
+ * This must be called after the mr has been removed from implicit_children
+ * and the SRCU synchronized.  NOTE: The MR does not necessarily have to be
+ * empty here, parallel page faults could have raced with the free process and
+ * added pages to it.
+ */
+static void free_implicit_child_mr(struct mlx5_ib_mr *mr, bool need_imr_xlt)
 {
-	struct ib_umem_odp *odp = container_of(work, struct ib_umem_odp, work);
-	int idx = ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT;
-	struct mlx5_ib_mr *mr = odp->private, *imr = mr->parent;
+	struct mlx5_ib_mr *imr = mr->parent;
 	struct ib_umem_odp *odp_imr = to_ib_umem_odp(imr->umem);
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+	unsigned long idx = ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT;
 	int srcu_key;
 
-	mr->parent = NULL;
-	synchronize_srcu(&mr->dev->mr_srcu);
+	/* implicit_child_mr's are not allowed to have deferred work */
+	WARN_ON(atomic_read(&mr->num_deferred_work));
 
-	if (smp_load_acquire(&imr->live)) {
-		srcu_key = srcu_read_lock(&mr->dev->mr_srcu);
+	if (need_imr_xlt) {
+		srcu_key = srcu_read_lock(&mr->dev->odp_srcu);
 		mutex_lock(&odp_imr->umem_mutex);
-		mlx5_ib_update_xlt(imr, idx, 1, 0,
+		mlx5_ib_update_xlt(mr->parent, idx, 1, 0,
 				   MLX5_IB_UPD_XLT_INDIRECT |
 				   MLX5_IB_UPD_XLT_ATOMIC);
 		mutex_unlock(&odp_imr->umem_mutex);
-		srcu_read_unlock(&mr->dev->mr_srcu, srcu_key);
+		srcu_read_unlock(&mr->dev->odp_srcu, srcu_key);
 	}
-	ib_umem_odp_release(odp);
+
+	dma_fence_odp_mr(mr);
+
+	mr->parent = NULL;
 	mlx5_mr_cache_free(mr->dev, mr);
+	ib_umem_odp_release(odp);
+	atomic_dec(&imr->num_deferred_work);
+}
+
+static void free_implicit_child_mr_work(struct work_struct *work)
+{
+	struct mlx5_ib_mr *mr =
+		container_of(work, struct mlx5_ib_mr, odp_destroy.work);
+
+	free_implicit_child_mr(mr, true);
+}
+
+static void free_implicit_child_mr_rcu(struct rcu_head *head)
+{
+	struct mlx5_ib_mr *mr =
+		container_of(head, struct mlx5_ib_mr, odp_destroy.rcu);
 
-	if (atomic_dec_and_test(&imr->num_leaf_free))
-		wake_up(&imr->q_leaf_free);
+	/* Freeing a MR is a sleeping operation, so bounce to a work queue */
+	INIT_WORK(&mr->odp_destroy.work, free_implicit_child_mr_work);
+	queue_work(system_unbound_wq, &mr->odp_destroy.work);
+}
+
+static void destroy_unused_implicit_child_mr(struct mlx5_ib_mr *mr)
+{
+	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+	unsigned long idx = ib_umem_start(odp) >> MLX5_IMR_MTT_SHIFT;
+	struct mlx5_ib_mr *imr = mr->parent;
+
+	xa_lock(&imr->implicit_children);
+	/*
+	 * This can race with mlx5_ib_free_implicit_mr(), the first one to
+	 * reach the xa lock wins the race and destroys the MR.
+	 */
+	if (__xa_cmpxchg(&imr->implicit_children, idx, mr, NULL, GFP_ATOMIC) !=
+	    mr)
+		goto out_unlock;
+
+	atomic_inc(&imr->num_deferred_work);
+	call_srcu(&mr->dev->odp_srcu, &mr->odp_destroy.rcu,
+		  free_implicit_child_mr_rcu);
+
+out_unlock:
+	xa_unlock(&imr->implicit_children);
 }
 
 void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
@@ -258,16 +252,15 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 	int in_block = 0;
 	u64 addr;
 
-	if (!umem_odp) {
-		pr_err("invalidation called on NULL umem or non-ODP umem\n");
-		return;
-	}
-
+	mutex_lock(&umem_odp->umem_mutex);
+	/*
+	 * If npages is zero then umem_odp->private may not be setup yet. This
+	 * does not complete until after the first page is mapped for DMA.
+	 */
+	if (!umem_odp->npages)
+		goto out;
 	mr = umem_odp->private;
 
-	if (!mr || !mr->ibmr.pd)
-		return;
-
 	start = max_t(u64, ib_umem_start(umem_odp), start);
 	end = min_t(u64, ib_umem_end(umem_odp), end);
 
@@ -277,7 +270,6 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 	 * overwrite the same MTTs.  Concurent invalidations might race us,
 	 * but they will write 0s as well, so no difference in the end result.
 	 */
-	mutex_lock(&umem_odp->umem_mutex);
 	for (addr = start; addr < end; addr += BIT(umem_odp->page_shift)) {
 		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
 		/*
@@ -323,14 +315,9 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 
 	ib_umem_odp_unmap_dma_pages(umem_odp, start, end);
 
-
-	if (unlikely(!umem_odp->npages && mr->parent &&
-		     !umem_odp->dying)) {
-		WRITE_ONCE(mr->live, 0);
-		umem_odp->dying = 1;
-		atomic_inc(&mr->parent->num_leaf_free);
-		schedule_work(&umem_odp->work);
-	}
+	if (unlikely(!umem_odp->npages && mr->parent))
+		destroy_unused_implicit_child_mr(mr);
+out:
 	mutex_unlock(&umem_odp->umem_mutex);
 }
 
@@ -422,239 +409,213 @@ static void mlx5_ib_page_fault_resume(struct mlx5_ib_dev *dev,
 			    wq_num, err);
 }
 
-static struct mlx5_ib_mr *implicit_mr_alloc(struct ib_pd *pd,
-					    struct ib_umem_odp *umem_odp,
-					    bool ksm, int access_flags)
+static struct mlx5_ib_mr *implicit_get_child_mr(struct mlx5_ib_mr *imr,
+						unsigned long idx)
 {
-	struct mlx5_ib_dev *dev = to_mdev(pd->device);
+	struct ib_umem_odp *odp;
 	struct mlx5_ib_mr *mr;
+	struct mlx5_ib_mr *ret;
 	int err;
 
-	mr = mlx5_mr_cache_alloc(dev, ksm ? MLX5_IMR_KSM_CACHE_ENTRY :
-					    MLX5_IMR_MTT_CACHE_ENTRY);
+	odp = ib_umem_odp_alloc_child(to_ib_umem_odp(imr->umem),
+				      idx * MLX5_IMR_MTT_SIZE,
+				      MLX5_IMR_MTT_SIZE);
+	if (IS_ERR(odp))
+		return ERR_CAST(odp);
 
+	ret = mr = mlx5_mr_cache_alloc(imr->dev, MLX5_IMR_MTT_CACHE_ENTRY);
 	if (IS_ERR(mr))
-		return mr;
-
-	mr->ibmr.pd = pd;
-
-	mr->dev = dev;
-	mr->access_flags = access_flags;
-	mr->mmkey.iova = 0;
-	mr->umem = &umem_odp->umem;
-
-	if (ksm) {
-		err = mlx5_ib_update_xlt(mr, 0,
-					 mlx5_imr_ksm_entries,
-					 MLX5_KSM_PAGE_SHIFT,
-					 MLX5_IB_UPD_XLT_INDIRECT |
-					 MLX5_IB_UPD_XLT_ZAP |
-					 MLX5_IB_UPD_XLT_ENABLE);
-
-	} else {
-		err = mlx5_ib_update_xlt(mr, 0,
-					 MLX5_IMR_MTT_ENTRIES,
-					 PAGE_SHIFT,
-					 MLX5_IB_UPD_XLT_ZAP |
-					 MLX5_IB_UPD_XLT_ENABLE |
-					 MLX5_IB_UPD_XLT_ATOMIC);
-	}
-
-	if (err)
-		goto fail;
+		goto out_umem;
 
+	mr->ibmr.pd = imr->ibmr.pd;
+	mr->access_flags = imr->access_flags;
+	mr->umem = &odp->umem;
 	mr->ibmr.lkey = mr->mmkey.key;
 	mr->ibmr.rkey = mr->mmkey.key;
-
-	mlx5_ib_dbg(dev, "key %x dev %p mr %p\n",
-		    mr->mmkey.key, dev->mdev, mr);
-
-	return mr;
-
-fail:
-	mlx5_ib_err(dev, "Failed to register MKEY %d\n", err);
-	mlx5_mr_cache_free(dev, mr);
-
-	return ERR_PTR(err);
-}
-
-static struct ib_umem_odp *implicit_mr_get_data(struct mlx5_ib_mr *mr,
-						u64 io_virt, size_t bcnt)
-{
-	struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.pd->device);
-	struct ib_umem_odp *odp, *result = NULL;
-	struct ib_umem_odp *odp_mr = to_ib_umem_odp(mr->umem);
-	u64 addr = io_virt & MLX5_IMR_MTT_MASK;
-	int nentries = 0, start_idx = 0, ret;
-	struct mlx5_ib_mr *mtt;
-
-	mutex_lock(&odp_mr->umem_mutex);
-	odp = odp_lookup(addr, 1, mr);
-
-	mlx5_ib_dbg(dev, "io_virt:%llx bcnt:%zx addr:%llx odp:%p\n",
-		    io_virt, bcnt, addr, odp);
-
-next_mr:
-	if (likely(odp)) {
-		if (nentries)
-			nentries++;
-	} else {
-		odp = ib_umem_odp_alloc_child(odp_mr, addr, MLX5_IMR_MTT_SIZE);
-		if (IS_ERR(odp)) {
-			mutex_unlock(&odp_mr->umem_mutex);
-			return ERR_CAST(odp);
-		}
-
-		mtt = implicit_mr_alloc(mr->ibmr.pd, odp, 0,
-					mr->access_flags);
-		if (IS_ERR(mtt)) {
-			mutex_unlock(&odp_mr->umem_mutex);