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, 87 insertions, 0 deletions

diff --git a/Documentation/filesystems/hfs.rst b/Documentation/filesystems/hfs.rst
new file mode 100644
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+++ b/Documentation/filesystems/hfs.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+Macintosh HFS Filesystem for Linux
+==================================
+
+
+.. Note:: This filesystem doesn't have a maintainer.
+
+
+HFS stands for ``Hierarchical File System`` and is the filesystem used
+by the Mac Plus and all later Macintosh models.  Earlier Macintosh
+models used MFS (``Macintosh File System``), which is not supported,
+MacOS 8.1 and newer support a filesystem called HFS+ that's similar to
+HFS but is extended in various areas.  Use the hfsplus filesystem driver
+to access such filesystems from Linux.
+
+
+Mount options
+=============
+
+When mounting an HFS filesystem, the following options are accepted:
+
+  creator=cccc, type=cccc
+	Specifies the creator/type values as shown by the MacOS finder
+	used for creating new files.  Default values: '????'.
+
+  uid=n, gid=n
+  	Specifies the user/group that owns all files on the filesystems.
+	Default:  user/group id of the mounting process.
+
+  dir_umask=n, file_umask=n, umask=n
+	Specifies the umask used for all files , all directories or all
+	files and directories.  Defaults to the umask of the mounting process.
+
+  session=n
+  	Select the CDROM session to mount as HFS filesystem.  Defaults to
+	leaving that decision to the CDROM driver.  This option will fail
+	with anything but a CDROM as underlying devices.
+
+  part=n
+  	Select partition number n from the devices.  Does only makes
+	sense for CDROMS because they can't be partitioned under Linux.
+	For disk devices the generic partition parsing code does this
+	for us.  Defaults to not parsing the partition table at all.
+
+  quiet
+  	Ignore invalid mount options instead of complaining.
+
+
+Writing to HFS Filesystems
+==========================
+
+HFS is not a UNIX filesystem, thus it does not have the usual features you'd
+expect:
+
+ * You can't modify the set-uid, set-gid, sticky or executable bits or the uid
+   and gid of files.
+ * You can't create hard- or symlinks, device files, sockets or FIFOs.
+
+HFS does on the other have the concepts of multiple forks per file.  These
+non-standard forks are represented as hidden additional files in the normal
+filesystems namespace which is kind of a cludge and makes the semantics for
+the a little strange:
+
+ * You can't create, delete or rename resource forks of files or the
+   Finder's metadata.
+ * They are however created (with default values), deleted and renamed
+   along with the corresponding data fork or directory.
+ * Copying files to a different filesystem will loose those attributes
+   that are essential for MacOS to work.
+
+
+Creating HFS filesystems
+========================
+
+The hfsutils package from Robert Leslie contains a program called
+hformat that can be used to create HFS filesystem. See
+<https://www.mars.org/home/rob/proj/hfs/> for details.
+
+
+Credits
+=======
+
+The HFS drivers was written by Paul H. Hargrovea (hargrove@sccm.Stanford.EDU).
+Roman Zippel (roman@ardistech.com) rewrote large parts of the code and brought
+in btree routines derived from Brad Boyer's hfsplus driver.