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, 114 insertions, 0 deletions

diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst
new file mode 100644
index 000000000..aa7c959a5
--- /dev/null
+++ b/Documentation/process/index.rst
@@ -0,0 +1,114 @@
+.. raw:: latex
+
+	\renewcommand\thesection*
+	\renewcommand\thesubsection*
+
+.. _process_index:
+
+=============================================
+Working with the kernel development community
+=============================================
+
+So you want to be a Linux kernel developer?  Welcome!  While there is a lot
+to be learned about the kernel in a technical sense, it is also important
+to learn about how our community works.  Reading these documents will make
+it much easier for you to get your changes merged with a minimum of
+trouble.
+
+An introduction to how kernel development works
+-----------------------------------------------
+
+Read these documents first: an understanding of the material here will ease
+your entry into the kernel community.
+
+.. toctree::
+   :maxdepth: 1
+
+   howto
+   development-process
+   submitting-patches
+   submit-checklist
+
+Tools and technical guides for kernel developers
+------------------------------------------------
+
+This is a collection of material that kernel developers should be familiar
+with.
+
+.. toctree::
+   :maxdepth: 1
+
+   changes
+   programming-language
+   coding-style
+   maintainer-pgp-guide
+   email-clients
+   applying-patches
+   backporting
+   adding-syscalls
+   volatile-considered-harmful
+   botching-up-ioctls
+
+Policy guides and developer statements
+--------------------------------------
+
+These are the rules that we try to live by in the kernel community (and
+beyond).
+
+.. toctree::
+   :maxdepth: 1
+
+   license-rules
+   code-of-conduct
+   code-of-conduct-interpretation
+   contribution-maturity-model
+   kernel-enforcement-statement
+   kernel-driver-statement
+   stable-api-nonsense
+   stable-kernel-rules
+   management-style
+   researcher-guidelines
+   generated-content
+   coding-assistants
+   conclave
+
+Dealing with bugs
+-----------------
+
+Bugs are a fact of life; it is important that we handle them properly. The
+documents below provide general advice about debugging and describe our
+policies around the handling of a couple of special classes of bugs:
+regressions and security problems.
+
+.. toctree::
+   :maxdepth: 1
+
+   debugging/index
+   handling-regressions
+   security-bugs
+   threat-model
+   cve
+   embargoed-hardware-issues
+
+Maintainer information
+----------------------
+
+How to find the people who will accept your patches.
+
+.. toctree::
+   :maxdepth: 1
+
+   maintainer-handbooks
+   maintainers
+
+Other material
+--------------
+
+Here are some other guides to the community that are of interest to most
+developers:
+
+.. toctree::
+   :maxdepth: 1
+
+   kernel-docs
+   deprecated