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

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Message-ID: <aQvzC6HqCrCKd2uK@google.com>
Date: Thu, 6 Nov 2025 00:59:55 +0000
From: Carlos Llamas <cmllamas@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>,
	Breno Leitao <leitao@...ian.org>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Miroslav Benes <mbenes@...e.cz>, Mark Brown <broonie@...nel.org>,
	Puranjay Mohan <puranjay@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Catalin Marinas <catalin.marinas@....com>, kernel-team@...roid.com,
	linux-kernel@...r.kernel.org, Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] scripts/decode_stacktrace.sh: fix build ID and PC source
 parsing

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@...gle.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