On Tue, 2018-12-04 at 16:50 -0500, Waiman Long wrote: > On 12/04/2018 04:39 PM, Bart Van Assche wrote: > > On Tue, 2018-12-04 at 16:08 -0500, Waiman Long wrote: > > > On 12/03/2018 07:28 PM, Bart Van Assche wrote: > > > > Cc: Peter Zijlstra <[email protected]> > > > > Cc: Waiman Long <[email protected]> > > > > Cc: Johannes Berg <[email protected]> > > > > Signed-off-by: Bart Van Assche <[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 c936fce5b9d7..b4772e5fc176 100644 > > > > --- a/kernel/locking/lockdep.c > > > > +++ b/kernel/locking/lockdep.c > > > > @@ -727,6 +727,15 @@ static bool assign_lock_key(struct lockdep_map > > > > *lock) > > > > { > > > > unsigned long can_addr, addr = (unsigned long)lock; > > > > > > > > + /* > > > > + * lockdep_free_key_range() assumes that struct lock_class_key > > > > + * objects do not overlap. Since we use the address of lock > > > > + * objects as class key for static objects, check whether the > > > > + * size of lock_class_key objects does not exceed the size of > > > > + * the smallest lock object. > > > > + */ > > > > + BUILD_BUG_ON(sizeof(struct lock_class_key) > > > > > sizeof(raw_spinlock_t)); > > > > + > > > > if (__is_kernel_percpu_address(addr, &can_addr)) > > > > lock->key = (void *)can_addr; > > > > else if (__is_module_percpu_address(addr, &can_addr)) > > > > > > I don't understand what this check is for. lock_class_key and spinlock > > > are different objects. Their relative size shouldn't matter. > > > > Peter asked me to add this check. > > I haven't finished reviewing all your patches yet. Maybe one of the > subsequent patches requires this. If that is the case, you should move > this patch after that.
Hi Waiman, The existing (v4.20-rc5) code and the comment I added should be sufficient to understand this patch. Bart.
