From: Jérôme Glisse <[email protected]> In __lock_release() we are removing one entry from the stack and rebuilding the hash chain by re-adding entry above the entry we just removed. If the entry removed was between 2 entry of same class then this 2 entry might be coalesced into one single entry which in turns means that the lockdep_depth value will not be incremented and thus the expected lockdep_depth value after this operation will be wrong triggering an unjustified WARN_ONCE() at the end of __lock_release().
This patch adjust the expect depth value by decrementing it if what was previously 2 entry inside the stack are coalesced into only one entry. Note that __lock_set_class() does not suffer from same issue as it adds a new class and thus can not lead to coalescing of stack entry. Signed-off-by: Jérôme Glisse <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sasha Levin <[email protected]> --- kernel/locking/lockdep.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 4e49cc4..cac5e21 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3428,6 +3428,8 @@ found_it: curr->curr_chain_key = hlock->prev_chain_key; for (i++; i < depth; i++) { + int tmp = curr->lockdep_depth; + hlock = curr->held_locks + i; if (!__lock_acquire(hlock->instance, hlock_class(hlock)->subclass, hlock->trylock, @@ -3435,6 +3437,13 @@ found_it: hlock->nest_lock, hlock->acquire_ip, hlock->references, hlock->pin_count)) return 0; + /* + * If nest_lock is true and the lock we just removed allow two + * lock of same class to be consolidated in only one held_lock + * then the lockdep_depth count will not increase as we expect + * it to. So adjust the expected depth value accordingly. + */ + depth -= (curr->lockdep_depth == tmp); } /* -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
