RDMA/umem: Use umem->owning_mm inside ODP

Since ODP had a single struct mmu_notifier located in the ucontext it
could only handle a single MM at a time, and this prevented it from using
the new owning_mm system.

With the prior rework it is now simple to let ODP track multiple MMs per
ucontext, finish the job so that the per_mm is allocated on a mm by mm
basis, and freed when the last umem is dropped from the ucontext.

As a side effect the new saner locking removes the lockdep splat about
nesting the umem_rwsem between mmu_notifier_unregister and
ib_umem_odp_release.

It also makes ODP work with multiple processes, across, fork, etc.

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

1 files changed, 2 insertions, 20 deletions

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 2cf2cee5a753..6437e6af758d 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1488,25 +1488,6 @@ struct ib_rdmacg_object {
 #endif
 };
 
-#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
-struct ib_ucontext_per_mm {
-	struct ib_ucontext *context;
-
-	struct rb_root_cached umem_tree;
-	/*
-	 * Protects .umem_rbroot and tree, as well as odp_mrs_count and
-	 * mmu notifiers registration.
-	 */
-	struct rw_semaphore umem_rwsem;
-
-	struct mmu_notifier mn;
-	atomic_t notifier_count;
-	/* A list of umems that don't have private mmu notifier counters yet. */
-	struct list_head no_private_counters;
-	unsigned int odp_mrs_count;
-};
-#endif
-
 struct ib_ucontext {
 	struct ib_device       *device;
 	struct ib_uverbs_file  *ufile;
@@ -1523,7 +1504,8 @@ struct ib_ucontext {
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 	void (*invalidate_range)(struct ib_umem_odp *umem_odp,
 				 unsigned long start, unsigned long end);
-	struct ib_ucontext_per_mm per_mm;
+	struct mutex per_mm_list_lock;
+	struct list_head per_mm_list;
 #endif
 
 	struct ib_rdmacg_object	cg_obj;