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bpf: Fix deadlock between rcu_tasks_trace and event_mutex.

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[ Upstream commit 4580f4e0ebdf8dc8d506ae926b88510395a0c1d1 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexei Starovoitov
2025-02-24 14:16:37 -08:00
committed by Greg Kroah-Hartman
parent 7758e308ae
commit c5c833f637
1 changed files with 4 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/trace/bpf_trace.c
View File

@@ -403,7 +403,7 @@ static const struct bpf_func_proto bpf_trace_printk_proto = {
.arg2_type = ARG_CONST_SIZE,
};
static void __set_printk_clr_event(void)
static void __set_printk_clr_event(struct work_struct *work)
{
/*
* This program might be calling bpf_trace_printk,
@@ -416,10 +416,11 @@ static void __set_printk_clr_event(void)
if (trace_set_clr_event("bpf_trace", "bpf_trace_printk", 1))
pr_warn_ratelimited("could not enable bpf_trace_printk events");
}
static DECLARE_WORK(set_printk_work, __set_printk_clr_event);
const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
{
__set_printk_clr_event();
schedule_work(&set_printk_work);
return &bpf_trace_printk_proto;
}
@@ -462,7 +463,7 @@ static const struct bpf_func_proto bpf_trace_vprintk_proto = {
const struct bpf_func_proto *bpf_get_trace_vprintk_proto(void)
{
__set_printk_clr_event();
schedule_work(&set_printk_work);
return &bpf_trace_vprintk_proto;
}