On Mon, Aug 10, 2020 at 10:41:54PM +0300, Dmitry Osipenko wrote: > 10.08.2020 22:25, Michał Mirosław пишет:
> >> The initialization cases that are the trigger are only done for coupled > >> regulators though AFAICT, otherwise we're not doing allocations with the > >> lock held and should be able to progress. > > I caught a few lockdep complaints that suggest otherwise, but I'm still > > looking into that. > The problem looks obvious to me. The regulator_init_coupling() is > protected with the list_mutex, the regulator_lock_dependent() also > protected with the list_mutex. Hence if offending reclaim happens from > init_coupling(), then there is a lockup. We may also have problems if I/O triggers allocations for some reason, though that's also going to be a limited set of cases. Might be what lockdep was showing though. > It should be enough just to keep the regulator_find_coupler() under > lock, or even completely remove the locking around init_coupling(). I > think it should be better to keep the find_coupler() protected. > Michał, does this fix yours problem? That was the sort of thing I was thinking about here - it should at least be an improvement if nothing else.
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