Re: [tip: locking/core] lockdep: Fix usage_traceoverflow

Chris Wilson
2020-10-27T11:29:54Z

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