[PATCH v5 6/8] selftests: tracing: Add a basic testcase for wprobe

[Masami Hiramatsu (Google)]

On Fri, 24 Oct 2025 22:31:06 +0100
Mark Brown <broonie at kernel.org> wrote:

> On Tue, Sep 23, 2025 at 10:17:47AM +0900, Masami Hiramatsu (Google) wrote:
> > From: Masami Hiramatsu (Google) <mhiramat at kernel.org>
> > 
> > Add 'add_remove_wprobe.tc' testcase for testing wprobe event that
> > tests adding and removing operations of the wprobe event.
> 
> Since this series has landed in -next we've been seeing hangs on a range
> of arm64 platforms running the ftrace tests, it looks like it's all of
> them.  Unfortunately the systems lock up with no output as soon as they
> start trying to do something with wprobes:
> 
> # ok 19 Generic dynamic event - add/remove kprobe events
> # ok 20 Generic dynamic event - add/remove synthetic events
> # ok 21 Generic dynamic event - add/remove tracepoint probe events
> # ok 22 Generic dynamic event - add/remove tracepoint probe events on module
> # ok 23 Generic dynamic event - add/remove/test uprobe events
> 
> the next test being add_remove_wprobe.tc, which doesn't seem to
> complete.  Full log (for what little it's worth):
> 
>    https://lava.sirena.org.uk/scheduler/job/2000440#L1860
> 
> I turned on -vvv logging and that generated the rather spectacularly
> more verbose:
> 
>    https://lava.sirena.org.uk/scheduler/job/2000676/log_file/plain
> 
> (in a somewhat processed format unfortunately.).  Looking at that log I
> do notice a bunch of "unexpected operators" reported by the shell, these
> systems are running dash not bash, though that doesn't seem related.  It
> looks like the script hangs in reset_trigger_file while grepping the
> trigger files rather than actually trying to do the test.
> 
> Sorry about the delay in reporting this.

OK, eventually, I confirmed it is stopped on enabling wprobe

+ . /mnt/ftrace/test.d/dynevent/add_remove_wprobe.tc
+ echo 0
+ echo
+ TARGET=jiffies
+ echo 'w:my_wprobe w at jiffies'
+ grep -q my_wprobe dynamic_events
+ '[' 0 -ne 0 ]
+ test -d events/wprobes/my_wprobe
+ '[' 0 -ne 0 ]
+ echo 1

I also confirmed:

~ # cd /sys/kernel/tracing/
/sys/kernel/tracing # echo 'w:my_wprobe w at jiffies' >> dynamic_events 
/sys/kernel/tracing # echo 1 > events/wprobes/my_wprobe/enable 

Freeze the machine.

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat at kernel.org>