Re: [PATCH v4] lockdep: check that no locks held at freeze time

From: Mandeep Singh Baines
Date: Wed Feb 20 2013 - 22:19:15 EST

On Wed, Feb 20, 2013 at 4:42 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 20 Feb 2013 16:28:07 -0800
> Mandeep Singh Baines <msb@xxxxxxxxxxxx> wrote:
>> > Backtraces aren't *that* bad. We'll easily be able to tell which of
>> > the two callsites triggered the trace.
>> >
>> Let's say there was a try_to_freeze() that got inlined indirectly
>> (multiple levels of inline) into do_exit. Wouldn't the backtraces for
>> the regular exit check and the try_to_freeze check be identical except
>> for the offset (do_exit+0x45 versus do_exit+0x88)? So unless you had
>> an object file you wouldn't know which check you hit.
> Mutter. Spose so. Vaguely possible. Yes, if we want to avoid a
> wont-happen, use __FILE__ and __LINE__. Or, probably more sanely,
> __func__.

Fair enough. I'll avoid using a macro unless/until its actually needed.


> Or uninline try_to_freeze(). If anything's calling that at high
> frequency, we have a problem. And given the number of callsites,
> getting it into icache might result in a faster kernel...
> (Someone needs to teach __might_sleep() about __ratelimit())
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