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, 29 insertions, 0 deletions

diff --git a/Documentation/gpu/drivers.rst b/Documentation/gpu/drivers.rst
new file mode 100644
index 000000000..20d2c454a
--- /dev/null
+++ b/Documentation/gpu/drivers.rst
@@ -0,0 +1,29 @@
+========================
+GPU Driver Documentation
+========================
+
+.. toctree::
+   :maxdepth: 3
+
+   amdgpu/index
+   i915
+   imagination/index
+   intel-display/index
+   mcde
+   meson
+   nouveau
+   pl111
+   tegra
+   tve200
+   v3d
+   vc4
+   vkms
+   bridge/dw-hdmi
+   xen-front
+   xe/index
+   afbc
+   komeda-kms
+   panfrost
+   panthor
+   zynqmp
+   nova/index