linux-kernel - Re: [PATCH 1/7] regulator: push allocation in regulator_init

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Message-ID: <20200811172015.GA21273@qmqm.qmqm.pl>
Date:   Tue, 11 Aug 2020 19:20:15 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
        Vladimir Zapolskiy <vz@...ia.com>
Subject: Re: [PATCH 1/7] regulator: push allocation in
 regulator_init_coupling() outside of lock

On Tue, Aug 11, 2020 at 07:27:43PM +0300, Dmitry Osipenko wrote:
> 11.08.2020 18:59, Dmitry Osipenko пишет:
> > 11.08.2020 04:07, Michał Mirosław пишет:
> >> Allocating memory with regulator_list_mutex held makes lockdep unhappy
> >> when memory pressure makes the system do fs_reclaim on eg. eMMC using
> >> a regulator. Push the lock inside regulator_init_coupling() after the
> >> allocation.
> > ...
> > 
> > Reviewed-by: Dmitry Osipenko <digetx@...il.com>
> On the other hand, couldn't it be better to just remove taking the
> list_mutex from the regulator_lock_dependent()?
> 
> I think the list_mutex is only needed to protect from supply/couple
> regulator being removed during of the locking process, but maybe this is
> not something we should worry about?

This is what I would like to see in the end, but it requires more
thought, at least around interaction with regulator_resolve_coupling()
and the regulator removal.

Best Regards,
Michał Mirosław