Since tracing_multi link does not set ftrace_managed, it would fail to release the tracing_multi link when attaching tracing_multi link and then attaching fentry link.
[ 3.714215] WARNING: kernel/bpf/trampoline.c:1727 at bpf_trampoline_multi_detach+0x20b/0x240, CPU#1: test_progs/97 ... [ 3.733170] bpf_tracing_multi_link_release+0x14/0x30 [ 3.733890] bpf_link_free+0x58/0x130 [ 3.734414] bpf_link_release+0x23/0x30 Fix it by setting 'ftrace_managed = true' in register_fentry_multi(). Note: the reason of targeting bpf-next tree is I'm planning to add tracing_multi link support for bpf progs, that would rely on the fix and have code conflict with the test. Leon Hwang (2): bpf: Mark tracing_multi trampolines as ftrace managed selftests/bpf: Test fentry link after tracing_multi link kernel/bpf/trampoline.c | 1 + .../selftests/bpf/prog_tests/tracing_multi.c | 69 +++++++++++++++++++ .../progs/tracing_multi_intersect_attach.c | 8 +++ 3 files changed, 78 insertions(+) -- 2.55.0
