linux-kernel - Re: [GIT PULL] objtool fixes and updates

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Message-ID: <Z+qLDGvkY+TXdCjK@rli9-mobl>
Date: Mon, 31 Mar 2025 20:31:08 +0800
From: Philip Li <philip.li@...el.com>
To: Ingo Molnar <mingo@...nel.org>
CC: Borislav Petkov <bp@...en8.de>, <lkp@...el.com>, Linus Torvalds
	<torvalds@...ux-foundation.org>, <linux-kernel@...r.kernel.org>, "Peter
 Zijlstra" <a.p.zijlstra@...llo.nl>, Josh Poimboeuf <jpoimboe@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, Andrew Morton
	<akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] objtool fixes and updates

On Mon, Mar 31, 2025 at 01:55:25PM +0200, Ingo Molnar wrote:
> 
> * Borislav Petkov <bp@...en8.de> wrote:
> 
> > On Fri, Mar 28, 2025 at 10:18:57PM +0100, Ingo Molnar wrote:
> > > Linus,
> > > 
> > > Please pull the latest objtool/urgent Git tree from:
> > > 
> > >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git objtool-urgent-2025-03-28
> > > 
> > >    # HEAD: ae958b12940bcd4ffa32c44684e4f2878bc5e140 objtool, drm/vmwgfx: Don't ignore vmw_send_msg() for ORC
> > > 
> > > [ Merge note: not all driver fixes below have maintainer acks. ]
> > 
> > Btw, test bot complains:
> > 
> > https://lore.kernel.org/r/202503292202.Sge7ZEUc-lkp@intel.com
> 
> AFAICS that particular report is not a new regression, but essentially 
> a test-bot false positive due to a reporting change, because the 
> objtool warning output changed.
> 
> This can be seen in the full report:
> 
>   https://lore.kernel.org/oe-kbuild-all/202503280703.OARM8SrY-lkp@intel.com/
> 
>   All warnings (new ones prefixed by >>):
> 
>      arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[22]=-1+0 reg2[22]=-2-160
>      arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[23]=-1+0 reg2[23]=-2-152
>   >> arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: skipping duplicate warning(s)
> 
> Note how '>>' is the new warning - the summary line added recently that 
> suggests that there's more warnings. It appears to me the test-bot 
> considers the other warnings old regressions, but I couldn't find any 
> trace of them being reported before. Maybe they weren't Cc:-ed to lkml.
> 
> Or maybe these *are* all new warnings. I've Cc:-ed the LKP folks.

Hi Ingo and all, sorry for confusion, here only the line with >> is considered
as new warning, due to the commit 0a7fb6f07e3a you mentioned.

>From the bot logic, the "stack state mismatch" are not regression (not new warnings),
which already exists in earlier commit.

> 
> To add confusion to confusion, the test bot also incorrectly attributed 
> ae958b1294 for that new warning line, and incorrectly categorized it as 
> a 'recent_error':
> 
>   recent_errors
>   `-- loongarch-randconfig-001-20250328
>       `-- arch-loongarch-kernel-traps.o:warning:objtool:show_stack:skipping-duplicate-warning(s)
> 
> While the commit that added this new reporting line is:
> 
>   0a7fb6f07e3a ("objtool: Increase per-function WARN_FUNC() rate limit")
> 
> ... which is a few weeks old and already upstream. We didn't get a 
> loongson related test-bot regression report for that commit or any 
> other commits, other than the weeks-late & self-contradictory report 
> against ae958b1294.

For 0a7fb6f07e3a, the bot only reported 2 times on x86 [1][2]. For this loongarch report,
the bisection is wrong and is a false positive, I will further check. Meanwhile, the bot
will ignore the bisection of this new objtool message as it is not really a new kernel issue.

[1] https://lore.kernel.org/oe-kbuild-all/202503191453.uFfxQy5R-lkp@intel.com/
[2] https://lore.kernel.org/oe-kbuild-all/202503181736.zkZUBv4N-lkp@intel.com/

> 
> So something's wonky with the test-bot reporting in this particular 
> case for loongson, or my parsing thereof.
> 
> Thanks,
> 
> 	Ingo
>