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Subject: Re: [tip: locking/core] lockdep: Fix usage_traceoverflow
From:   Chris Wilson <chris@chris-wilson.co.uk>
Cc:     Qian Cai <cai@redhat.com>,
        Peter Zijlstra (Intel) <peterz@infradead.org>,
        x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
To:     linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
        tip-bot2 for Peter Zijlstra <tip-bot2@linutronix.de>
Date:   Tue, 27 Oct 2020 11:29:35 +0000
Message-ID: <160379817513.29534.880306651053124370@build.alporthouse.com>
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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.
-Chris