Re: [PATCH] scripts/decode_stacktrace.sh: fix build ID and PC source parsing

[Carlos Llamas <cmllamas@google.com>]

On Thu, Oct 30, 2025 at 08:57:58PM -0700, Andrew Morton wrote:
> On Thu, 30 Oct 2025 01:03:33 +0000 Carlos Llamas <cmllamas@google.com> wrote:
> 
> > Support for parsing PC source info in stacktraces (e.g. '(P)') was
> > added in commit 2bff77c665ed ("scripts/decode_stacktrace.sh: fix
> > decoding of lines with an additional info"). However, this logic was
> > placed after the build ID processing. This incorrect order fails to
> > parse lines containing both elements, e.g.:
> > 
> >   drm_gem_mmap_obj+0x114/0x200 [drm 03d0564e0529947d67bb2008c3548be77279fd27] (P)
> > 
> > This patch fixes the problem by extracting the PC source info first and
> > then processing the module build ID. With this change, the line above is
> > now properly parsed as such:
> > 
> >   drm_gem_mmap_obj (./include/linux/mmap_lock.h:212 ./include/linux/mm.h:811 drivers/gpu/drm/drm_gem.c:1177) drm (P)
> > 
> > While here, also add a brief explanation the build ID section.
> 
> Thanks for fixing this.  I'll queue it in mm.git's mm-hotfixes branch
> with a plan to upstream it into 6.18-rcX.

Thanks Andrew, and sorry for the late reply I completely missed this
email.

> 
> I'll add a cc:stable tag so this gets fixed in earlier kernel releases
> also.
> 
> But....
> 
> > Fixes: bdf8eafbf7f5 ("arm64: stacktrace: report source of unwind data")
> > Fixes: 2bff77c665ed ("scripts/decode_stacktrace.sh: fix decoding of lines with an additional info")
> 
> Which kernel releases?  We're fixing a commit from Oct 2024 and a
> commit from Jan 2025.  How are downstream people to understand what
> we're recommending here?
> 
> I view the Fixes: as a recommendation we make to -stable maintainers
> saying "I think this should be backported to <here> and later".  As
> such, giving them multiple backporting targets must make their little
> heads spin.

So I've heard conflicting arguments about backporting patches to stable
for these scripts. That's why I skipped the Cc: stable tag. IIRC, the
argument is that one should always run the ToT scripts? <shrug>

You are right about the multiple Fixes: though. I should have only used:

  Fixes: 2bff77c665ed ("scripts/decode_stacktrace.sh: fix decoding of lines with an additional info")

Thanks,
--
Carlos Llamas