Re: [GIT PULL] probes: Update for v6.18

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Sun, 5 Oct 2025 09:20:29 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Thu, 2 Oct 2025 at 16:44, Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >
> > - wprobe: Introduce a watchpoint probe event based on hw_breakpoint.
> 
> This doesn't even build.
> 
>   kernel/trace/trace_wprobe.c: In function ‘__register_trace_wprobe’:
>   kernel/trace/trace_wprobe.c:176:20: error: cast to generic address
> space pointer from disjoint ‘__seg_gs’ address space pointer [-Werror]
> 
> and I see from the code that it has tried to brute-force it with an
> ugly cast, and it still is horribly horribly wrong.

Hmm, I applogise this error. I locally ran build tests and it passed.
But I might missed something.

> 
> The fix for compiler errors is basically never to just add a random
> cast. That will just make things worse, and in this case that
> 'IS_ERR()' function literally exists to find bad users like this.

OK.

> 
> I wondered why this hadn't been reported in linux-next, and the reason
> appears simple: none of this has BEEN in linux-next.
> 
> So no. I'm not pulling this. This violates all the regular rules for
> sending me new development, and then it doesn't even compile.
> 
> Since the pointer is a percpu pointer, the trivial fix is ato use the
> per-cpu specific functions (IS_ERR_PCPU(), PTR_ERR_PCPU(), etc).

OK.

> 
> However, since this wasn't in linux-next, that's not what I'm doing.
> 
> This is not getting pulled for 6.18 AT ALL, and for 6.19 it had better
> be in linux-next for a LOONG time.

Got it. Sorry about my mistake. Let me fix it on for-next, and
keep checking it is in linux-next and tested well.

Thank you,

> 
>            Linus


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