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dea499781a
Warning happened in trace_buffered_event_disable() at
WARN_ON_ONCE(!trace_buffered_event_ref)
Call Trace:
? __warn+0xa5/0x1b0
? trace_buffered_event_disable+0x189/0x1b0
__ftrace_event_enable_disable+0x19e/0x3e0
free_probe_data+0x3b/0xa0
unregister_ftrace_function_probe_func+0x6b8/0x800
event_enable_func+0x2f0/0x3d0
ftrace_process_regex.isra.0+0x12d/0x1b0
ftrace_filter_write+0xe6/0x140
vfs_write+0x1c9/0x6f0
[...]
The cause of the warning is in __ftrace_event_enable_disable(),
trace_buffered_event_enable() was called once while
trace_buffered_event_disable() was called twice.
Reproduction script show as below, for analysis, see the comments:
```
#!/bin/bash
cd /sys/kernel/tracing/
# 1. Register a 'disable_event' command, then:
# 1) SOFT_DISABLED_BIT was set;
# 2) trace_buffered_event_enable() was called first time;
echo 'cmdline_proc_show:disable_event:initcall:initcall_finish' > \
set_ftrace_filter
# 2. Enable the event registered, then:
# 1) SOFT_DISABLED_BIT was cleared;
# 2) trace_buffered_event_disable() was called first time;
echo 1 > events/initcall/initcall_finish/enable
# 3. Try to call into cmdline_proc_show(), then SOFT_DISABLED_BIT was
# set again!!!
cat /proc/cmdline
# 4. Unregister the 'disable_event' command, then:
# 1) SOFT_DISABLED_BIT was cleared again;
# 2) trace_buffered_event_disable() was called second time!!!
echo '!cmdline_proc_show:disable_event:initcall:initcall_finish' > \
set_ftrace_filter
```
To fix it, IIUC, we can change to call trace_buffered_event_enable() at
fist time soft-mode enabled, and call trace_buffered_event_disable() at
last time soft-mode disabled.
Link: https://lore.kernel.org/linux-trace-kernel/20230726095804.920457-1-zhengyejian1@huawei.com
Cc: <mhiramat@kernel.org>
Fixes:
|
||
---|---|---|
.. | ||
rv | ||
blktrace.c | ||
bpf_trace.c | ||
bpf_trace.h | ||
error_report-traces.c | ||
fgraph.c | ||
fprobe.c | ||
ftrace_internal.h | ||
ftrace.c | ||
Kconfig | ||
kprobe_event_gen_test.c | ||
Makefile | ||
pid_list.c | ||
pid_list.h | ||
power-traces.c | ||
preemptirq_delay_test.c | ||
rethook.c | ||
ring_buffer_benchmark.c | ||
ring_buffer.c | ||
rpm-traces.c | ||
synth_event_gen_test.c | ||
trace_benchmark.c | ||
trace_benchmark.h | ||
trace_boot.c | ||
trace_branch.c | ||
trace_clock.c | ||
trace_dynevent.c | ||
trace_dynevent.h | ||
trace_entries.h | ||
trace_eprobe.c | ||
trace_event_perf.c | ||
trace_events_filter_test.h | ||
trace_events_filter.c | ||
trace_events_hist.c | ||
trace_events_inject.c | ||
trace_events_synth.c | ||
trace_events_trigger.c | ||
trace_events_user.c | ||
trace_events.c | ||
trace_export.c | ||
trace_fprobe.c | ||
trace_functions_graph.c | ||
trace_functions.c | ||
trace_hwlat.c | ||
trace_irqsoff.c | ||
trace_kdb.c | ||
trace_kprobe_selftest.c | ||
trace_kprobe_selftest.h | ||
trace_kprobe.c | ||
trace_mmiotrace.c | ||
trace_nop.c | ||
trace_osnoise.c | ||
trace_output.c | ||
trace_output.h | ||
trace_preemptirq.c | ||
trace_printk.c | ||
trace_probe_kernel.h | ||
trace_probe_tmpl.h | ||
trace_probe.c | ||
trace_probe.h | ||
trace_recursion_record.c | ||
trace_sched_switch.c | ||
trace_sched_wakeup.c | ||
trace_selftest_dynamic.c | ||
trace_selftest.c | ||
trace_seq.c | ||
trace_stack.c | ||
trace_stat.c | ||
trace_stat.h | ||
trace_synth.h | ||
trace_syscalls.c | ||
trace_uprobe.c | ||
trace.c | ||
trace.h | ||
tracing_map.c | ||
tracing_map.h |