]> www.infradead.org Git - users/jedix/linux-maple.git/commit
bpf: Fix deadlock between rcu_tasks_trace and event_mutex.
authorAlexei Starovoitov <ast@kernel.org>
Mon, 24 Feb 2025 22:16:37 +0000 (14:16 -0800)
committerAndrii Nakryiko <andrii@kernel.org>
Wed, 26 Feb 2025 16:48:40 +0000 (08:48 -0800)
commit4580f4e0ebdf8dc8d506ae926b88510395a0c1d1
treeb211ddcd69bbd482b2ac339f186d84b0d94b703d
parentb123480eec64dd879785c28f2a2d582d111cfb59
bpf: Fix deadlock between rcu_tasks_trace and event_mutex.

Fix the following deadlock:
CPU A
_free_event()
  perf_kprobe_destroy()
    mutex_lock(&event_mutex)
      perf_trace_event_unreg()
        synchronize_rcu_tasks_trace()

There are several paths where _free_event() grabs event_mutex
and calls sync_rcu_tasks_trace. Above is one such case.

CPU B
bpf_prog_test_run_syscall()
  rcu_read_lock_trace()
    bpf_prog_run_pin_on_cpu()
      bpf_prog_load()
        bpf_tracing_func_proto()
          trace_set_clr_event()
            mutex_lock(&event_mutex)

Delegate trace_set_clr_event() to workqueue to avoid
such lock dependency.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250224221637.4780-1-alexei.starovoitov@gmail.com
kernel/trace/bpf_trace.c