RDMA/umem: Move all the ODP related stuff out of ucontext and into per_mm

This is the first step to make ODP use the owning_mm that is now part of
struct ib_umem.

Each ODP umem is linked to a single per_mm structure, which in turn, is
linked to a single mm, via the embedded mmu_notifier. This first patch
introduces the structure and reworks eveything to use it.

This also needs to introduce tgid into the ib_ucontext_per_mm, as
get_user_pages_remote() requires the originating task for statistics
tracking.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

2 files changed, 73 insertions, 63 deletions

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 42272b2bf595..6bf3fc0c12a1 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -115,34 +115,35 @@ static void ib_umem_notifier_end_account(struct ib_umem_odp *umem_odp)
 }
 
 /* Account for a new mmu notifier in an ib_ucontext. */
-static void ib_ucontext_notifier_start_account(struct ib_ucontext *context)
+static void
+ib_ucontext_notifier_start_account(struct ib_ucontext_per_mm *per_mm)
 {
-	atomic_inc(&context->notifier_count);
+	atomic_inc(&per_mm->notifier_count);
 }
 
 /* Account for a terminating mmu notifier in an ib_ucontext.
  *
  * Must be called with the ib_ucontext->umem_rwsem semaphore unlocked, since
  * the function takes the semaphore itself. */
-static void ib_ucontext_notifier_end_account(struct ib_ucontext *context)
+static void ib_ucontext_notifier_end_account(struct ib_ucontext_per_mm *per_mm)
 {
-	int zero_notifiers = atomic_dec_and_test(&context->notifier_count);
+	int zero_notifiers = atomic_dec_and_test(&per_mm->notifier_count);
 
 	if (zero_notifiers &&
-	    !list_empty(&context->no_private_counters)) {
+	    !list_empty(&per_mm->no_private_counters)) {
 		/* No currently running mmu notifiers. Now is the chance to
 		 * add private accounting to all previously added umems. */
 		struct ib_umem_odp *odp_data, *next;
 
 		/* Prevent concurrent mmu notifiers from working on the
 		 * no_private_counters list. */
-		down_write(&context->umem_rwsem);
+		down_write(&per_mm->umem_rwsem);
 
 		/* Read the notifier_count again, with the umem_rwsem
 		 * semaphore taken for write. */
-		if (!atomic_read(&context->notifier_count)) {
+		if (!atomic_read(&per_mm->notifier_count)) {
 			list_for_each_entry_safe(odp_data, next,
-						 &context->no_private_counters,
+						 &per_mm->no_private_counters,
 						 no_private_counters) {
 				mutex_lock(&odp_data->umem_mutex);
 				odp_data->mn_counters_active = true;
@@ -152,7 +153,7 @@ static void ib_ucontext_notifier_end_account(struct ib_ucontext *context)
 			}
 		}
 
-		up_write(&context->umem_rwsem);
+		up_write(&per_mm->umem_rwsem);
 	}
 }
 
@@ -179,19 +180,20 @@ static int ib_umem_notifier_release_trampoline(struct ib_umem_odp *umem_odp,
 static void ib_umem_notifier_release(struct mmu_notifier *mn,
 				     struct mm_struct *mm)
 {
-	struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+	struct ib_ucontext_per_mm *per_mm =
+		container_of(mn, struct ib_ucontext_per_mm, mn);
 
-	if (!context->invalidate_range)
+	if (!per_mm->context->invalidate_range)
 		return;
 
-	ib_ucontext_notifier_start_account(context);
-	down_read(&context->umem_rwsem);
-	rbt_ib_umem_for_each_in_range(&context->umem_tree, 0,
+	ib_ucontext_notifier_start_account(per_mm);
+	down_read(&per_mm->umem_rwsem);
+	rbt_ib_umem_for_each_in_range(&per_mm->umem_tree, 0,
 				      ULLONG_MAX,
 				      ib_umem_notifier_release_trampoline,
 				      true,
 				      NULL);
-	up_read(&context->umem_rwsem);
+	up_read(&per_mm->umem_rwsem);
 }
 
 static int invalidate_page_trampoline(struct ib_umem_odp *item, u64 start,
@@ -217,23 +219,24 @@ static int ib_umem_notifier_invalidate_range_start(struct mmu_notifier *mn,
 						    unsigned long end,
 						    bool blockable)
 {
-	struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+	struct ib_ucontext_per_mm *per_mm =
+		container_of(mn, struct ib_ucontext_per_mm, mn);
 	int ret;
 
-	if (!context->invalidate_range)
+	if (!per_mm->context->invalidate_range)
 		return 0;
 
 	if (blockable)
-		down_read(&context->umem_rwsem);
-	else if (!down_read_trylock(&context->umem_rwsem))
+		down_read(&per_mm->umem_rwsem);
+	else if (!down_read_trylock(&per_mm->umem_rwsem))
 		return -EAGAIN;
 
-	ib_ucontext_notifier_start_account(context);
-	ret = rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
+	ib_ucontext_notifier_start_account(per_mm);
+	ret = rbt_ib_umem_for_each_in_range(&per_mm->umem_tree, start,
 				      end,
 				      invalidate_range_start_trampoline,
 				      blockable, NULL);
-	up_read(&context->umem_rwsem);
+	up_read(&per_mm->umem_rwsem);
 
 	return ret;
 }
@@ -250,9 +253,10 @@ static void ib_umem_notifier_invalidate_range_end(struct mmu_notifier *mn,
 						  unsigned long start,
 						  unsigned long end)
 {
-	struct ib_ucontext *context = container_of(mn, struct ib_ucontext, mn);
+	struct ib_ucontext_per_mm *per_mm =
+		container_of(mn, struct ib_ucontext_per_mm, mn);
 
-	if (!context->invalidate_range)
+	if (!per_mm->context->invalidate_range)
 		return;
 
 	/*
@@ -260,12 +264,12 @@ static void ib_umem_notifier_invalidate_range_end(struct mmu_notifier *mn,
 	 * in ib_umem_notifier_invalidate_range_start so we shouldn't really block
 	 * here. But this is ugly and fragile.
 	 */
-	down_read(&context->umem_rwsem);
-	rbt_ib_umem_for_each_in_range(&context->umem_tree, start,
+	down_read(&per_mm->umem_rwsem);
+	rbt_ib_umem_for_each_in_range(&per_mm->umem_tree, start,
 				      end,
 				      invalidate_range_end_trampoline, true, NULL);
-	up_read(&context->umem_rwsem);
-	ib_ucontext_notifier_end_account(context);
+	up_read(&per_mm->umem_rwsem);
+	ib_ucontext_notifier_end_account(per_mm);
 }
 
 static const struct mmu_notifier_ops ib_umem_notifiers = {
@@ -277,6 +281,7 @@ static const struct mmu_notifier_ops ib_umem_notifiers = {
 struct ib_umem_odp *ib_alloc_odp_umem(struct ib_ucontext *context,
 				      unsigned long addr, size_t size)
 {
+	struct ib_ucontext_per_mm *per_mm;
 	struct ib_umem_odp *odp_data;
 	struct ib_umem *umem;
 	int pages = size >> PAGE_SHIFT;
@@ -292,6 +297,7 @@ struct ib_umem_odp *ib_alloc_odp_umem(struct ib_ucontext *context,
 	umem->page_shift = PAGE_SHIFT;
 	umem->writable   = 1;
 	umem->is_odp = 1;
+	odp_data->per_mm = per_mm = &context->per_mm;
 
 	mutex_init(&odp_data->umem_mutex);
 	init_completion(&odp_data->notifier_completion);
@@ -310,15 +316,15 @@ struct ib_umem_odp *ib_alloc_odp_umem(struct ib_ucontext *context,
 		goto out_page_list;
 	}
 
-	down_write(&context->umem_rwsem);
-	context->odp_mrs_count++;
-	rbt_ib_umem_insert(&odp_data->interval_tree, &context->umem_tree);
-	if (likely(!atomic_read(&context->notifier_count)))
+	down_write(&per_mm->umem_rwsem);
+	per_mm->odp_mrs_count++;
+	rbt_ib_umem_insert(&odp_data->interval_tree, &per_mm->umem_tree);
+	if (likely(!atomic_read(&per_mm->notifier_count)))
 		odp_data->mn_counters_active = true;
 	else
 		list_add(&odp_data->no_private_counters,
-			 &context->no_private_counters);
-	up_write(&context->umem_rwsem);
+			 &per_mm->no_private_counters);
+	up_write(&per_mm->umem_rwsem);
 
 	return odp_data;
 
@@ -334,6 +340,7 @@ int ib_umem_odp_get(struct ib_umem_odp *umem_odp, int access)
 {
 	struct ib_ucontext *context = umem_odp->umem.context;
 	struct ib_umem *umem = &umem_odp->umem;
+	struct ib_ucontext_per_mm *per_mm;
 	int ret_val;
 	struct pid *our_pid;
 	struct mm_struct *mm = get_task_mm(current);
@@ -396,28 +403,30 @@ int ib_umem_odp_get(struct ib_umem_odp *umem_odp, int access)
 	 * notification before the "current" task (and MM) is
 	 * destroyed. We use the umem_rwsem semaphore to synchronize.
 	 */
-	down_write(&context->umem_rwsem);
-	context->odp_mrs_count++;
+	umem_odp->per_mm = per_mm = &context->per_mm;
+
+	down_write(&per_mm->umem_rwsem);
+	per_mm->odp_mrs_count++;
 	if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
 		rbt_ib_umem_insert(&umem_odp->interval_tree,
-				   &context->umem_tree);
-	if (likely(!atomic_read(&context->notifier_count)) ||
-	    context->odp_mrs_count == 1)
+				   &per_mm->umem_tree);
+	if (likely(!atomic_read(&per_mm->notifier_count)) ||
+	    per_mm->odp_mrs_count == 1)
 		umem_odp->mn_counters_active = true;
 	else
 		list_add(&umem_odp->no_private_counters,
-			 &context->no_private_counters);
-	downgrade_write(&context->umem_rwsem);
+			 &per_mm->no_private_counters);
+	downgrade_write(&per_mm->umem_rwsem);
 
-	if (context->odp_mrs_count == 1) {
+	if (per_mm->odp_mrs_count == 1) {
 		/*
 		 * Note that at this point, no MMU notifier is running
-		 * for this context!
+		 * for this per_mm!
 		 */
-		atomic_set(&context->notifier_count, 0);
-		INIT_HLIST_NODE(&context->mn.hlist);
-		context->mn.ops = &ib_umem_notifiers;
-		ret_val = mmu_notifier_register(&context->mn, mm);
+		atomic_set(&per_mm->notifier_count, 0);
+		INIT_HLIST_NODE(&per_mm->mn.hlist);
+		per_mm->mn.ops = &ib_umem_notifiers;
+		ret_val = mmu_notifier_register(&per_mm->mn, mm);
 		if (ret_val) {
 			pr_err("Failed to register mmu_notifier %d\n", ret_val);
 			ret_val = -EBUSY;
@@ -425,7 +434,7 @@ int ib_umem_odp_get(struct ib_umem_odp *umem_odp, int access)
 		}
 	}
 
-	up_read(&context->umem_rwsem);
+	up_read(&per_mm->umem_rwsem);
 
 	/*
 	 * Note that doing an mmput can cause a notifier for the relevant mm.
@@ -437,7 +446,7 @@ int ib_umem_odp_get(struct ib_umem_odp *umem_odp, int access)
 	return 0;
 
 out_mutex:
-	up_read(&context->umem_rwsem);
+	up_read(&per_mm->umem_rwsem);
 	vfree(umem_odp->dma_list);
 out_page_list:
 	vfree(umem_odp->page_list);
@@ -449,7 +458,7 @@ out_mm:
 void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 {
 	struct ib_umem *umem = &umem_odp->umem;
-	struct ib_ucontext *context = umem->context;
+	struct ib_ucontext_per_mm *per_mm = umem_odp->per_mm;
 
 	/*
 	 * Ensure that no more pages are mapped in the umem.
@@ -460,11 +469,11 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 	ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem),
 				    ib_umem_end(umem));
 
-	down_write(&context->umem_rwsem);
+	down_write(&per_mm->umem_rwsem);
 	if (likely(ib_umem_start(umem) != ib_umem_end(umem)))
 		rbt_ib_umem_remove(&umem_odp->interval_tree,
-				   &context->umem_tree);
-	context->odp_mrs_count--;
+				   &per_mm->umem_tree);
+	per_mm->odp_mrs_count--;
 	if (!umem_odp->mn_counters_active) {
 		list_del(&umem_odp->no_private_counters);
 		complete_all(&umem_odp->notifier_completion);
@@ -477,13 +486,13 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 	 * that since we are doing it atomically, no other user could register
 	 * and unregister while we do the check.
 	 */
-	downgrade_write(&context->umem_rwsem);
-	if (!context->odp_mrs_count) {
+	downgrade_write(&per_mm->umem_rwsem);
+	if (!per_mm->odp_mrs_count) {
 		struct task_struct *owning_process = NULL;
 		struct mm_struct *owning_mm        = NULL;
 
-		owning_process = get_pid_task(context->tgid,
-					      PIDTYPE_PID);
+		owning_process =
+			get_pid_task(umem_odp->umem.context->tgid, PIDTYPE_PID);
 		if (owning_process == NULL)
 			/*
 			 * The process is already dead, notifier were removed
@@ -498,7 +507,7 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 			 * removed already.
 			 */
 			goto out_put_task;
-		mmu_notifier_unregister(&context->mn, owning_mm);
+		mmu_notifier_unregister(&per_mm->mn, owning_mm);
 
 		mmput(owning_mm);
 
@@ -506,7 +515,7 @@ out_put_task:
 		put_task_struct(owning_process);
 	}
 out:
-	up_read(&context->umem_rwsem);
+	up_read(&per_mm->umem_rwsem);
 
 	vfree(umem_odp->dma_list);
 	vfree(umem_odp->page_list);
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 9c87c98a0f19..ce678e1008a4 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -124,10 +124,11 @@ ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 	ucontext->cleanup_retryable = false;
 
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-	ucontext->umem_tree = RB_ROOT_CACHED;
-	init_rwsem(&ucontext->umem_rwsem);
-	ucontext->odp_mrs_count = 0;
-	INIT_LIST_HEAD(&ucontext->no_private_counters);
+	ucontext->per_mm.umem_tree = RB_ROOT_CACHED;
+	init_rwsem(&ucontext->per_mm.umem_rwsem);
+	ucontext->per_mm.odp_mrs_count = 0;
+	INIT_LIST_HEAD(&ucontext->per_mm.no_private_counters);
+	ucontext->per_mm.context = ucontext;
 
 	if (!(ib_dev->attrs.device_cap_flags & IB_DEVICE_ON_DEMAND_PAGING))
 		ucontext->invalidate_range = NULL;