Re: Are jump labels broken on 6.11-rc1?

Darrick J. Wong
2024-09-16T16:08:02Z

On Thu, Sep 05, 2024 at 11:16:05AM +0200, Peter Zijlstra wrote:
> On Thu, Sep 05, 2024 at 10:12:41AM +0200, Peter Zijlstra wrote:
> > On Mon, Aug 26, 2024 at 08:35:06PM -0700, Darrick J. Wong wrote:
>
> > > [33965.988873] ------------[ cut here ]------------
> > > [33966.013870] WARNING: CPU: 1 PID: 8992 at kernel/jump_label.c:295 __static_key_slow_dec_cpuslocked.part.0+0xb0/0xc0
>
> > > [33966.040184] pc : __static_key_slow_dec_cpuslocked.part.0+0xb0/0xc0
> > > [33966.042845] lr : __static_key_slow_dec_cpuslocked.part.0+0x48/0xc0
>
> > > [33966.072840] Call trace:
> > > [33966.073838] __static_key_slow_dec_cpuslocked.part.0+0xb0/0xc0
> > > [33966.076105] static_key_slow_dec+0x48/0x88
>
> > > This corresponds to the:
> > >
> > > WARN_ON_ONCE(!static_key_slow_try_dec(key));
> >
> > But but but,... my patch killed that function. So are you sure it is
> > applied ?!
> >
> > Because this sounds like exactly that issue again.
> >
> > Anyway, it appears I had totally forgotten about this issue again due to
> > holidays, sorry. Let me stare hard at Thomas' patch and make a 'pretty'
> > one that does boot.
>
> I've taken tglx's version with a small change (added comment) and boot
> tested it and queued it here:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/urgent
>
> Could you please double check on both x86_64 and arm64?

Will send this out on the test farm tonight, thanks for the patch.

> If green by with the build robots and your own testing I'll push this
> into tip/locking/urgent to be sent to Linus on Sunday. Hopefully finally
> resolving this issue.

Sorry I didn't get to this earlier; I've been on vacation since the end
of August. Now to get to the ~1300 fsdevel emails... ;)

--D