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, 22 insertions, 0 deletions

diff --git a/fs/gfs2/sys.h b/fs/gfs2/sys.h
new file mode 100644
index 000000000..f8dacf20e
--- /dev/null
+++ b/fs/gfs2/sys.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#ifndef __SYS_DOT_H__
+#define __SYS_DOT_H__
+
+#include <linux/spinlock.h>
+struct gfs2_sbd;
+
+int gfs2_sys_fs_add(struct gfs2_sbd *sdp);
+void gfs2_sys_fs_del(struct gfs2_sbd *sdp);
+
+int gfs2_sys_init(void);
+void gfs2_sys_uninit(void);
+
+int gfs2_recover_set(struct gfs2_sbd *sdp, unsigned jid);
+
+#endif /* __SYS_DOT_H__ */
+