On Wed, Jul 03, 2019 at 11:21:26AM +0200, Sebastian Andrzej Siewior wrote: > An uninitialized/ zeroed mutex will go unnoticed because there is no > check for it. There is a magic check in the unlock's slowpath path which > might go unnoticed if the unlock happens in the fastpath. > > Add a ->magic check early in the mutex_lock() and mutex_trylock() path. > > Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> > --- > Nothing screamed during uninitialized usage of init_mm's context->lock > https://git.kernel.org/tip/32232b350d7cd93cdc65fe5a453e6a40b539e9f9 > > kernel/locking/mutex.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c > index 0c601ae072b3f..fb1f6f1e1cc61 100644 > --- a/kernel/locking/mutex.c > +++ b/kernel/locking/mutex.c > @@ -908,6 +908,10 @@ __mutex_lock_common(struct mutex *lock, long state, > unsigned int subclass, > > might_sleep(); > > +#ifdef CONFIG_DEBUG_MUTEXES > + DEBUG_LOCKS_WARN_ON(lock->magic != lock); > +#endif
Why do we need to check this so early, or could we move it into debug_mutex_lock_common() instead? Will
