From: Peter Zijlstra <peterz@infradead.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
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 13:30:56 +0100 [thread overview]
Message-ID: <20201027123056.GE2651@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201027115955.GA2611@hirez.programming.kicks-ass.net>
On Tue, Oct 27, 2020 at 12:59:55PM +0100, Peter Zijlstra wrote:
> On Tue, Oct 27, 2020 at 11:29:35AM +0000, Chris Wilson wrote:
> > Quoting tip-bot2 for Peter Zijlstra (2020-10-07 17:20:13)
> > > The following commit has been merged into the locking/core branch of tip:
> > >
> > > Commit-ID: 24d5a3bffef117ed90685f285c6c9d2faa3a02b4
> > > Gitweb: https://git.kernel.org/tip/24d5a3bffef117ed90685f285c6c9d2faa3a02b4
> > > Author: Peter Zijlstra <peterz@infradead.org>
> > > AuthorDate: Wed, 30 Sep 2020 11:49:37 +02:00
> > > Committer: Peter Zijlstra <peterz@infradead.org>
> > > CommitterDate: Wed, 07 Oct 2020 18:14:17 +02:00
> > >
> > > lockdep: Fix usage_traceoverflow
> > >
> > > Basically print_lock_class_header()'s for loop is out of sync with the
> > > the size of of ->usage_traces[].
> >
> > We're hitting a problem,
> >
> > $ cat /proc/lockdep_stats
> >
> > upon boot generates:
> >
> > [ 29.465702] DEBUG_LOCKS_WARN_ON(debug_atomic_read(nr_unused_locks) != nr_unused)
> > [ 29.465716] WARNING: CPU: 0 PID: 488 at kernel/locking/lockdep_proc.c:256 lockdep_stats_show+0xa33/0xac0
> >
> > that bisected to this patch. Only just completed the bisection and
> > thought you would like a heads up.
>
> Oh hey, that's 'curious'... it does indeed trivially reproduce, let me
> have a poke.
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:
next prev parent reply other threads:[~2020-10-27 12:31 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 [this message]
2020-10-27 12:48 ` Peter Zijlstra
2020-10-27 14:13 ` Chris Wilson
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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