linux-kernel - Re: [4.14-rc1 x86] WARNING: kernel stack regs at f60bbb12 inswapper:1 has bad 'bp' value 0ba00000

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Message-ID: <20171003151539.ztjvgjjumqhwpfc4@treble>
Date:   Tue, 3 Oct 2017 10:15:39 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     bp@...en8.de, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org
Subject: Re: [4.14-rc1 x86] WARNING: kernel stack regs at f60bbb12
 inswapper:1 has bad 'bp' value 0ba00000

On Tue, Oct 03, 2017 at 09:35:18AM -0500, Josh Poimboeuf wrote:
> On Tue, Oct 03, 2017 at 10:44:13PM +0900, Tetsuo Handa wrote:
> > Josh Poimboeuf wrote:
> > 
> > > On Tue, Oct 03, 2017 at 12:37:44PM +0200, Borislav Petkov wrote:
> > > > On Tue, Oct 03, 2017 at 07:29:36PM +0900, Tetsuo Handa wrote:
> > > > > Tetsuo Handa wrote:
> > > > > > Tetsuo Handa wrote:
> > > > > > > Tetsuo Handa wrote:
> > > > > > > > I'm seeing below error between
> > > > > > > > 4898b99c261efe32 ("Merge tag 'acpi-4.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm") (git bisect good (presumably))
> > > > > > > > e6f3faa734a00c60 ("locking/lockdep: Fix workqueue crossrelease annotation") (git bisect bad) on linux.git .
> > > > > > > 
> > > > > > > F.Y.I. This error remains as of 46c1e79fee417f15 ("Merge branch 'perf-urgent-for-linus' of
> > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip") on linux.git .
> > > > > > > 
> > > > > > 
> > > > > > This error still remains as of 6e80ecdddf4ea6f3 ("Merge branch 'libnvdimm-fixes'
> > > > > > of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm") on linux.git .
> > > > > > 
> > > > > > I'm suspecting that this error is causing very unstable x86_32 kernel.
> > > > > > It seems that this error occurs (though rare frequency) even on x86_64 kernel.
> > > > > > 
> > > > > > Nobody cares?
> > > > > > 
> > > > > 4.14-rc3 still trivially panics due to this error. Is this problem known?
> > > 
> > > Can you try with the following patch?  It should hopefully give more
> > > useful information in the dump.
> > > 
> > I see. Here is the result.
> 
> Hm, that's not what I expected to happen...  I suspect this is stack
> corruption, with the result being slightly different every time.  Can
> you see if this patch fixes the panic?

On second thought, I don't think that's the right fix.  But I do think
what you're seeing is related to a lockdep issue:

  https://lkml.kernel.org/r/20171003140634.r2jzujgl62ox4uzh@wfg-t540p.sh.intel.com

I'm not sure yet why it's breaking the unwinder so badly though.

-- 
Josh