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@xxxxxxxxxxxxx> > > > AuthorDate: Wed, 30 Sep 2020 11:49:37 +02:00 > > > Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > > 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:
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