diff options
| author | Waiman Long <longman@redhat.com> | 2025-05-05 21:20:49 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-05-06 18:34:43 +0200 |
| commit | cdb7d2d68cde6145a06a56c9d5d5d917297501c6 (patch) | |
| tree | f09d0763743b8f715c727a1995e870ce66a4c043 | |
| parent | 6a1a219f535a437eb12a06d8cef2518e58654beb (diff) | |
locking/lockdep: Add number of dynamic keys to /proc/lockdep_stats
There have been recent reports about running out of lockdep keys:
MAX_LOCKDEP_KEYS too low!
One possible reason is that too many dynamic keys have been registered.
A possible culprit is the lockdep_register_key() call in qdisc_alloc()
of net/sched/sch_generic.c.
Currently, there is no way to find out how many dynamic keys have been
registered. Add such a stat to the /proc/lockdep_stats to get better
clarity.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20250506042049.50060-4-boqun.feng@gmail.com
| -rw-r--r-- | kernel/locking/lockdep.c | 3 | ||||
| -rw-r--r-- | kernel/locking/lockdep_internals.h | 1 | ||||
| -rw-r--r-- | kernel/locking/lockdep_proc.c | 2 |
3 files changed, 6 insertions, 0 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 050dbe9eec3c..dd2bbf73718b 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -219,6 +219,7 @@ static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); static struct hlist_head lock_keys_hash[KEYHASH_SIZE]; unsigned long nr_lock_classes; unsigned long nr_zapped_classes; +unsigned long nr_dynamic_keys; unsigned long max_lock_class_idx; struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); @@ -1238,6 +1239,7 @@ void lockdep_register_key(struct lock_class_key *key) goto out_unlock; } hlist_add_head_rcu(&key->hash_entry, hash_head); + nr_dynamic_keys++; out_unlock: graph_unlock(); restore_irqs: @@ -6609,6 +6611,7 @@ void lockdep_unregister_key(struct lock_class_key *key) pf = get_pending_free(); __lockdep_free_key_range(pf, key, 1); need_callback = prepare_call_rcu_zapped(pf); + nr_dynamic_keys--; } lockdep_unlock(); raw_local_irq_restore(flags); diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 20f9ef58d3d0..82156caf77d1 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -138,6 +138,7 @@ extern unsigned long nr_lock_classes; extern unsigned long nr_zapped_classes; extern unsigned long nr_zapped_lock_chains; extern unsigned long nr_list_entries; +extern unsigned long nr_dynamic_keys; long lockdep_next_lockchain(long i); unsigned long lock_chain_count(void); extern unsigned long nr_stack_trace_entries; diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 6db0f43fc4df..b52c07c4707c 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -286,6 +286,8 @@ static int lockdep_stats_show(struct seq_file *m, void *v) #endif seq_printf(m, " lock-classes: %11lu [max: %lu]\n", nr_lock_classes, MAX_LOCKDEP_KEYS); + seq_printf(m, " dynamic-keys: %11lu\n", + nr_dynamic_keys); seq_printf(m, " direct dependencies: %11lu [max: %lu]\n", nr_list_entries, MAX_LOCKDEP_ENTRIES); seq_printf(m, " indirect dependencies: %11lu\n", |