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From: Chris Wilson <chris@chris-wilson.co.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
	tip-bot2 for Peter Zijlstra <tip-bot2@linutronix.de>,
	Qian Cai <cai@redhat.com>, x86 <x86@kernel.org>
Subject: Re: [tip: locking/core] lockdep: Fix usage_traceoverflow
Date: Tue, 27 Oct 2020 14:13:31 +0000	[thread overview]
Message-ID: <160380801190.10461.12497441495326131849@build.alporthouse.com> (raw)
In-Reply-To: <20201027124834.GL2628@hirez.programming.kicks-ass.net>

Quoting Peter Zijlstra (2020-10-27 12:48:34)
> On Tue, Oct 27, 2020 at 01:30:56PM +0100, Peter Zijlstra wrote:
> > This seems to make it happy. Not quite sure that's the best solution.
> > 
> > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> > index 3e99dfef8408..81295bc760fe 100644
> > --- a/kernel/locking/lockdep.c
> > +++ b/kernel/locking/lockdep.c
> > @@ -4411,7 +4405,9 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
> >               break;
> >  
> >       case LOCK_USED:
> > -             debug_atomic_dec(nr_unused_locks);
> > +     case LOCK_USED_READ:
> > +             if ((hlock_class(this)->usage_mask & (LOCKF_USED|LOCKF_USED_READ)) == new_mask)
> > +                     debug_atomic_dec(nr_unused_locks);
> >               break;
> >  
> >       default:
> 
> This also works, and I think I likes it better.. anyone?
> 
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 3e99dfef8408..e603e86c0227 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -4396,6 +4390,9 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
>         if (unlikely(hlock_class(this)->usage_mask & new_mask))
>                 goto unlock;
>  
> +       if (!hlock_class(this)->usage_mask)
> +               debug_atomic_dec(nr_unused_locks);
> +

From an outside perspective, this is much easier for me to match with
the assertion in lockdep_proc.

Our CI confirms this works, and we are just left with the new issue of

<4> [260.903453] hm#2, depth: 6 [6], eb18a85a2df37d3d != a6ee4649c0022599
<4> [260.903458] WARNING: CPU: 7 PID: 5515 at kernel/locking/lockdep.c:3679 check_chain_key+0x1a4/0x1f0

Thanks,
-Chris

  reply	other threads:[~2020-10-27 18:13 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-29 14:31 lockdep null-ptr-deref Qian Cai
2020-09-29 23:08 ` Boqun Feng
2020-09-30  9:16   ` Peter Zijlstra
2020-09-30  9:49     ` Peter Zijlstra
2020-09-30 12:18       ` Boqun Feng
2020-09-30 19:02         ` Peter Zijlstra
2020-10-02 12:36           ` Boqun Feng
2020-10-02 13:09             ` Peter Zijlstra
2020-10-02 13:35               ` Boqun Feng
2020-10-02 10:06       ` Peter Zijlstra
2020-10-02 13:40         ` Qian Cai
2020-10-07 16:20       ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra
2020-10-27 11:29         ` Chris Wilson
2020-10-27 11:59           ` Peter Zijlstra
2020-10-27 12:30             ` Peter Zijlstra
2020-10-27 12:48               ` Peter Zijlstra
2020-10-27 14:13                 ` Chris Wilson [this message]
2020-10-31 11:30                 ` [tip: locking/urgent] lockdep: Fix nr_unused_locks accounting tip-bot2 for Peter Zijlstra
2020-10-27 13:29               ` [tip: locking/core] lockdep: Fix usage_traceoverflow Chris Wilson
2020-10-27 15:45                 ` Peter Zijlstra
2020-10-27 16:34                   ` Chris Wilson
2020-10-28 17:40                     ` Chris Wilson
2020-10-28 18:06                       ` Chris Wilson
2020-10-28 19:42                       ` Peter Zijlstra
2020-10-28 19:59                         ` Peter Zijlstra
2020-10-30  3:51                           ` Boqun Feng
2020-10-30  9:38                             ` Peter Zijlstra
2020-10-30  9:55                               ` Peter Zijlstra
2020-11-02  5:37                               ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-02  5:37                                 ` [PATCH 2/2] lockdep/selftest: Add spin_nest_lock test Boqun Feng
2020-12-03 10:35                                   ` [tip: locking/core] " tip-bot2 for Boqun Feng
2020-11-05  6:25                                 ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-10 17:28                                 ` Peter Zijlstra
2020-11-11  8:23                                 ` [tip: locking/urgent] " tip-bot2 for Boqun Feng
2020-10-09  7:58       ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra

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