selftests/bpf: Add a test for objects stuck in free_by_rcu_ttracegrafted

Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first
free_bulk() starts RCU tasks trace GP and the rest of the elements are
freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear
in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and
waiting_for_gp_ttrace lists are empty.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/misc/lkdtm/rodata.c b/drivers/misc/lkdtm/rodata.c
new file mode 100644
index 000000000..baacb876d
--- /dev/null
+++ b/drivers/misc/lkdtm/rodata.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This includes functions that are meant to live entirely in .rodata
+ * (via objcopy tricks), to validate the non-executability of .rodata.
+ */
+#include "lkdtm.h"
+
+void noinstr lkdtm_rodata_do_nothing(void)
+{
+	/* Does nothing. We just want an architecture agnostic "return". */
+}