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, 103 insertions, 0 deletions

diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c
new file mode 100644
index 000000000..ab6b916ad
--- /dev/null
+++ b/fs/netfs/stats.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Netfs support statistics
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+atomic_t netfs_n_rh_dio_read;
+atomic_t netfs_n_rh_readahead;
+atomic_t netfs_n_rh_read_folio;
+atomic_t netfs_n_rh_read_single;
+atomic_t netfs_n_rh_rreq;
+atomic_t netfs_n_rh_sreq;
+atomic_t netfs_n_rh_download;
+atomic_t netfs_n_rh_download_done;
+atomic_t netfs_n_rh_download_failed;
+atomic_t netfs_n_rh_download_instead;
+atomic_t netfs_n_rh_read;
+atomic_t netfs_n_rh_read_done;
+atomic_t netfs_n_rh_read_failed;
+atomic_t netfs_n_rh_zero;
+atomic_t netfs_n_rh_short_read;
+atomic_t netfs_n_rh_write;
+atomic_t netfs_n_rh_write_begin;
+atomic_t netfs_n_rh_write_done;
+atomic_t netfs_n_rh_write_failed;
+atomic_t netfs_n_rh_write_zskip;
+atomic_t netfs_n_rh_retry_read_req;
+atomic_t netfs_n_rh_retry_read_subreq;
+atomic_t netfs_n_wh_buffered_write;
+atomic_t netfs_n_wh_writethrough;
+atomic_t netfs_n_wh_dio_write;
+atomic_t netfs_n_wh_writepages;
+atomic_t netfs_n_wh_copy_to_cache;
+atomic_t netfs_n_wh_wstream_conflict;
+atomic_t netfs_n_wh_upload;
+atomic_t netfs_n_wh_upload_done;
+atomic_t netfs_n_wh_upload_failed;
+atomic_t netfs_n_wh_write;
+atomic_t netfs_n_wh_write_done;
+atomic_t netfs_n_wh_write_failed;
+atomic_t netfs_n_wh_retry_write_req;
+atomic_t netfs_n_wh_retry_write_subreq;
+atomic_t netfs_n_wb_lock_skip;
+atomic_t netfs_n_wb_lock_wait;
+atomic_t netfs_n_folioq;
+
+int netfs_stats_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "Reads  : DR=%u RA=%u RF=%u RS=%u WB=%u WBZ=%u\n",
+		   atomic_read(&netfs_n_rh_dio_read),
+		   atomic_read(&netfs_n_rh_readahead),
+		   atomic_read(&netfs_n_rh_read_folio),
+		   atomic_read(&netfs_n_rh_read_single),
+		   atomic_read(&netfs_n_rh_write_begin),
+		   atomic_read(&netfs_n_rh_write_zskip));
+	seq_printf(m, "Writes : BW=%u WT=%u DW=%u WP=%u 2C=%u\n",
+		   atomic_read(&netfs_n_wh_buffered_write),
+		   atomic_read(&netfs_n_wh_writethrough),
+		   atomic_read(&netfs_n_wh_dio_write),
+		   atomic_read(&netfs_n_wh_writepages),
+		   atomic_read(&netfs_n_wh_copy_to_cache));
+	seq_printf(m, "ZeroOps: ZR=%u sh=%u sk=%u\n",
+		   atomic_read(&netfs_n_rh_zero),
+		   atomic_read(&netfs_n_rh_short_read),
+		   atomic_read(&netfs_n_rh_write_zskip));
+	seq_printf(m, "DownOps: DL=%u ds=%u df=%u di=%u\n",
+		   atomic_read(&netfs_n_rh_download),
+		   atomic_read(&netfs_n_rh_download_done),
+		   atomic_read(&netfs_n_rh_download_failed),
+		   atomic_read(&netfs_n_rh_download_instead));
+	seq_printf(m, "CaRdOps: RD=%u rs=%u rf=%u\n",
+		   atomic_read(&netfs_n_rh_read),
+		   atomic_read(&netfs_n_rh_read_done),
+		   atomic_read(&netfs_n_rh_read_failed));
+	seq_printf(m, "UpldOps: UL=%u us=%u uf=%u\n",
+		   atomic_read(&netfs_n_wh_upload),
+		   atomic_read(&netfs_n_wh_upload_done),
+		   atomic_read(&netfs_n_wh_upload_failed));
+	seq_printf(m, "CaWrOps: WR=%u ws=%u wf=%u\n",
+		   atomic_read(&netfs_n_wh_write),
+		   atomic_read(&netfs_n_wh_write_done),
+		   atomic_read(&netfs_n_wh_write_failed));
+	seq_printf(m, "Retries: rq=%u rs=%u wq=%u ws=%u\n",
+		   atomic_read(&netfs_n_rh_retry_read_req),
+		   atomic_read(&netfs_n_rh_retry_read_subreq),
+		   atomic_read(&netfs_n_wh_retry_write_req),
+		   atomic_read(&netfs_n_wh_retry_write_subreq));
+	seq_printf(m, "Objs   : rr=%u sr=%u foq=%u wsc=%u\n",
+		   atomic_read(&netfs_n_rh_rreq),
+		   atomic_read(&netfs_n_rh_sreq),
+		   atomic_read(&netfs_n_folioq),
+		   atomic_read(&netfs_n_wh_wstream_conflict));
+	seq_printf(m, "WbLock : skip=%u wait=%u\n",
+		   atomic_read(&netfs_n_wb_lock_skip),
+		   atomic_read(&netfs_n_wb_lock_wait));
+	return fscache_stats_show(m);
+}
+EXPORT_SYMBOL(netfs_stats_show);