Re: Crashes in next-20160915 (BUG at fs/notify/notification.c:66!)

[Michael Ellerman]

Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
> On Tue, 20 Sep 2016 11:10:35 +1000 Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
>> Jan Kara <jack@xxxxxxx> writes:
>> >
>> > Right, that was the problem. spin_is_locked() without CONFIG_SPINLOCK_DEBUG
>> > returns always 0.
>> 
>> Can we get this fixed soon please? It's breaking all my CI runs.
>
> It should be fixed in next -next.

Great thanks.

I did search LKML to see if Jan had sent a fix but I guess I missed it.

> diff -puN fs/notify/fanotify/fanotify_user.c~fsnotify-convert-notification_mutex-to-a-spinlock-fix fs/notify/fanotify/fanotify_user.c
> --- a/fs/notify/fanotify/fanotify_user.c~fsnotify-convert-notification_mutex-to-a-spinlock-fix
> +++ a/fs/notify/fanotify/fanotify_user.c
> @@ -54,7 +54,8 @@ struct kmem_cache *fanotify_perm_event_c
>  static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
>  					    size_t count)
>  {
> -	BUG_ON(!spin_is_locked(&group->notification_lock));
> +	BUG_ON(IS_ENABLED(CONFIG_SMP) &&
> +	       !spin_is_locked(&group->notification_lock));
  
I thought lockdep_assert_held() was preferred for checks like this that
are purely sanity checking, ie. not part of the algorithm.

cheers