Re: [PATCH 2/5] lockdep: check that no locks held at freeze time

From: Oleg Nesterov
Date: Fri Feb 15 2013 - 10:46:12 EST


On 02/14, Mandeep Singh Baines wrote:
>
> We shouldn't try_to_freeze if locks are held. Verified that
> I get no lockdep warnings after applying this patch and
> "vfork: don't freezer_count() for in-kernel users of CLONE_VFORK".

Ah. Now I understand why you did 1/5. Beacuse you call
debug_check_no_locks_held() right at the start of try_to_freeze(),
even if the caller can't be frozen.

> static inline bool try_to_freeze(void)
> {
> + debug_check_no_locks_held(current);
> might_sleep();
> if (likely(!freezing(current)))
> return false;

Up to maintainers, but perhaps you should check !PF_NOFREEZE at least?

Oleg.

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