> 2025年12月5日 23:08，Steven Rostedt <[email protected]> 写道：
>
> On Fri, 5 Dec 2025 17:29:33 +0800
> "qingwei.hu" <[email protected]> wrote:
>
>> From: Qingwei Hu <[email protected]>
>>
>> There is a possible configuration dependency:
>>
>> KPROBES_ON_FTRACE [=n]
>> ^----- KPROBES [=y]
>> |--- HAVE_KPROBES_ON_FTRACE [=n]
>> |--- DYNAMIC_FTRACE_WITH_REGS [=n]
>> ^----- FTRACE [=y]
>> |--- DYNAMIC_FTRACE [=y]
>> |--- HAVE_DYNAMIC_FTRACE_WITH_REGS [=n]
>>
>> With DYNAMIC_FTRACE=y, ftrace_location() is meaningful and may
>> return the same address as the probe target.
>>
>> However, when KPROBES_ON_FTRACE=n, the current implementation
>> returns -EINVAL after calling check_ftrace_location(), causing
>> the validation to fail.
>
> This is a feature not a bug.
>
> The reason is if you put a kprobe on a ftrace location, it can cause ftrace
> to trigger a bug, as kprobes will modify the location and ftrace will see
> something it doesn't expect and think the system is corrupted. We don't want
> that either.
>
> If you say "KPROBES_ON_FTRACE=n" and place a kprobe on a location that is
> controlled by ftrace, it had better fail!
>
> NAK
>
> -- Steve
Thanks for your clear explanation. I will look into other approaches
that work with this configuration.
