bpf program should run under migration disabled, kprobe_multi_link_prog_run called the way from graph tracer, which disables preemption in function_graph_enter_regs, as Jiri and Yonghong suggested, there is no need to use migrate_disable. As a result, some overhead maybe will be reduced. Fixes: 0dcac2725406 ("bpf: Add multi kprobe link") Signed-off-by: Tao Chen --- kernel/trace/bpf_trace.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3ae52978cae..1993fc62539 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2734,14 +2734,19 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, goto out; } - migrate_disable(); + /* + * bpf program should run under migration disabled, kprobe_multi_link_prog_run + * called the way from graph tracer, which disables preemption in + * function_graph_enter_regs, so there is no need to use migrate_disable. + * Accessing the above percpu data bpf_prog_active is also safe for the same + * reason. + */ rcu_read_lock(); regs = ftrace_partial_regs(fregs, bpf_kprobe_multi_pt_regs_ptr()); old_run_ctx = bpf_set_run_ctx(&run_ctx.session_ctx.run_ctx); err = bpf_prog_run(link->link.prog, regs); bpf_reset_run_ctx(old_run_ctx); rcu_read_unlock(); - migrate_enable(); out: __this_cpu_dec(bpf_prog_active); -- 2.48.1