selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/include/rdma/frmr_pools.h b/include/rdma/frmr_pools.h
new file mode 100644
index 000000000..aed4d69d3
--- /dev/null
+++ b/include/rdma/frmr_pools.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+ *
+ * Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ */
+
+#ifndef FRMR_POOLS_H
+#define FRMR_POOLS_H
+
+#include <linux/types.h>
+#include <asm/page.h>
+
+struct ib_device;
+struct ib_mr;
+
+struct ib_frmr_key {
+	u64 vendor_key;
+	/* A pool with non-zero kernel_vendor_key is a kernel-only pool. */
+	u64 kernel_vendor_key;
+	size_t num_dma_blocks;
+	int access_flags;
+	u8 ats:1;
+};
+
+struct ib_frmr_pool_ops {
+	int (*create_frmrs)(struct ib_device *device, struct ib_frmr_key *key,
+			    u32 *handles, u32 count);
+	void (*destroy_frmrs)(struct ib_device *device, u32 *handles,
+			      u32 count);
+	int (*build_key)(struct ib_device *device, const struct ib_frmr_key *in,
+			 struct ib_frmr_key *out);
+};
+
+int ib_frmr_pools_init(struct ib_device *device,
+		       const struct ib_frmr_pool_ops *pool_ops);
+void ib_frmr_pools_cleanup(struct ib_device *device);
+int ib_frmr_pool_pop(struct ib_device *device, struct ib_mr *mr);
+void ib_frmr_pool_push(struct ib_device *device, struct ib_mr *mr);
+void ib_frmr_pool_drop(struct ib_mr *mr);
+
+#endif /* FRMR_POOLS_H */