Re: [for-next][PATCH 6/7] ring-buffer: Process commits whenever moving to a new page.

Steven Rostedt
2015-11-25T20:22:33Z

> diff --git a/kernel/module.c b/kernel/module.c
> index 8f051a106676..c0ae7c18c2fa 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -284,11 +284,25 @@ static void module_assert_mutex(void)
> static void module_assert_mutex_or_preempt(void)
> {
> #ifdef CONFIG_LOCKDEP
> + static int once;
> +
> if (unlikely(!debug_locks))
> return;
>
> - WARN_ON(!rcu_read_lock_sched_held() &&
> - !lockdep_is_held(&module_mutex));
> + /*
> + * Would be nice to use WARN_ON_ONCE(), but the warning
> + * that causes a stack trace may call __module_address()
> + * which may call here, and we trigger the warning again,
> + * before the WARN_ON_ONCE() updates its flag.
> + * To prevent the recursion, we need to open code the
> + * once logic.
> + */
> + if (!once &&
> + unlikely(!rcu_read_lock_sched_held() &&
> + !lockdep_is_held(&module_mutex))) {
> + once++;
> + WARN_ON(1);
> + }
> #endif
> }
>
>

Damn it. I added this via quilt to debug something (as this was causing
a crash), and forgot to pop it when doing my "git commit -a -s".

I'll have to nuke this part of the patch and rebase my tree :-(

-- Steve