Messages in this thread | | | From | Rob Clark <> | Date | Mon, 13 Mar 2023 07:46:53 -0700 | Subject | Re: [PATCH 10/13] PM / QoS: Teach lockdep about dev_pm_qos_mtx locking order |
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On Mon, Mar 13, 2023 at 5:31 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Sun, Mar 12, 2023 at 9:42 PM Rob Clark <robdclark@gmail.com> wrote: > > > > From: Rob Clark <robdclark@chromium.org> > > > > Annotate dev_pm_qos_mtx to teach lockdep to scream about allocations > > that could trigger reclaim under dev_pm_qos_mtx. > > So why is this needed?
Because it allows lockdep to warn about problems even if it hasn't seen recursion into shrinker yet.
BR, -R
> > Signed-off-by: Rob Clark <robdclark@chromium.org> > > --- > > drivers/base/power/qos.c | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c > > index 9cba334b3729..d4addda3944a 100644 > > --- a/drivers/base/power/qos.c > > +++ b/drivers/base/power/qos.c > > @@ -1012,3 +1012,14 @@ void dev_pm_qos_hide_latency_tolerance(struct device *dev) > > pm_runtime_put(dev); > > } > > EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance); > > + > > +static int __init dev_pm_qos_init(void) > > +{ > > + /* Teach lockdep about lock ordering wrt. shrinker: */ > > + fs_reclaim_acquire(GFP_KERNEL); > > + might_lock(&dev_pm_qos_mtx); > > + fs_reclaim_release(GFP_KERNEL); > > + > > + return 0; > > +} > > +early_initcall(dev_pm_qos_init); > > -- > > 2.39.2 > >
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