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, 132 insertions, 0 deletions

diff --git a/include/trace/events/readahead.h b/include/trace/events/readahead.h
new file mode 100644
index 000000000..087f171e2
--- /dev/null
+++ b/include/trace/events/readahead.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM readahead
+
+#if !defined(_TRACE_FILEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_READAHEAD_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+
+TRACE_EVENT(page_cache_ra_unbounded,
+	TP_PROTO(struct inode *inode, pgoff_t index, unsigned long nr_to_read,
+		 unsigned long lookahead_size),
+
+	TP_ARGS(inode, index, nr_to_read, lookahead_size),
+
+	TP_STRUCT__entry(
+		__field(u64, i_ino)
+		__field(dev_t, s_dev)
+		__field(pgoff_t, index)
+		__field(unsigned long, nr_to_read)
+		__field(unsigned long, lookahead_size)
+	),
+
+	TP_fast_assign(
+		__entry->i_ino = inode->i_ino;
+		__entry->s_dev = inode->i_sb->s_dev;
+		__entry->index = index;
+		__entry->nr_to_read = nr_to_read;
+		__entry->lookahead_size = lookahead_size;
+	),
+
+	TP_printk(
+		"dev=%d:%d ino=%llx index=%lu nr_to_read=%lu lookahead_size=%lu",
+		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
+		__entry->index, __entry->nr_to_read, __entry->lookahead_size
+	)
+);
+
+TRACE_EVENT(page_cache_ra_order,
+	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra),
+
+	TP_ARGS(inode, index, ra),
+
+	TP_STRUCT__entry(
+		__field(u64, i_ino)
+		__field(dev_t, s_dev)
+		__field(pgoff_t, index)
+		__field(unsigned int, order)
+		__field(unsigned int, size)
+		__field(unsigned int, async_size)
+		__field(unsigned int, ra_pages)
+	),
+
+	TP_fast_assign(
+		__entry->i_ino = inode->i_ino;
+		__entry->s_dev = inode->i_sb->s_dev;
+		__entry->index = index;
+		__entry->order = ra->order;
+		__entry->size = ra->size;
+		__entry->async_size = ra->async_size;
+		__entry->ra_pages = ra->ra_pages;
+	),
+
+	TP_printk(
+		"dev=%d:%d ino=%llx index=%lu order=%u size=%u async_size=%u ra_pages=%u",
+		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
+		__entry->index, __entry->order, __entry->size,
+		__entry->async_size, __entry->ra_pages
+	)
+);
+
+DECLARE_EVENT_CLASS(page_cache_ra_op,
+	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
+		 unsigned long req_count),
+
+	TP_ARGS(inode, index, ra, req_count),
+
+	TP_STRUCT__entry(
+		__field(u64, i_ino)
+		__field(loff_t, prev_pos)
+		__field(pgoff_t, index)
+		__field(unsigned long, req_count)
+		__field(dev_t, s_dev)
+		__field(unsigned int, order)
+		__field(unsigned int, size)
+		__field(unsigned int, async_size)
+		__field(unsigned int, ra_pages)
+		__field(unsigned int, mmap_miss)
+	),
+
+	TP_fast_assign(
+		__entry->i_ino = inode->i_ino;
+		__entry->s_dev = inode->i_sb->s_dev;
+		__entry->index = index;
+		__entry->order = ra->order;
+		__entry->size = ra->size;
+		__entry->async_size = ra->async_size;
+		__entry->ra_pages = ra->ra_pages;
+		__entry->mmap_miss = ra->mmap_miss;
+		__entry->prev_pos = ra->prev_pos;
+		__entry->req_count = req_count;
+	),
+
+	TP_printk(
+		"dev=%d:%d ino=%llx index=%lu req_count=%lu order=%u size=%u async_size=%u ra_pages=%u mmap_miss=%u prev_pos=%lld",
+		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
+		__entry->index, __entry->req_count, __entry->order,
+		__entry->size, __entry->async_size, __entry->ra_pages,
+		__entry->mmap_miss, __entry->prev_pos
+	)
+);
+
+DEFINE_EVENT(page_cache_ra_op, page_cache_sync_ra,
+	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
+		 unsigned long req_count),
+	TP_ARGS(inode, index, ra, req_count)
+);
+
+DEFINE_EVENT(page_cache_ra_op, page_cache_async_ra,
+	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
+		 unsigned long req_count),
+	TP_ARGS(inode, index, ra, req_count)
+);
+
+#endif /* _TRACE_FILEMAP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>