From: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
To: Mike Galbraith <efault@gmx.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>
Cc: nando@ccrma.Stanford.EDU, LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [ANNOUNCE] v5.4.17-rt9
Date: Thu, 6 Feb 2020 22:13:46 -0800 [thread overview]
Message-ID: <a6a9ba66-4e63-8156-2e49-291087d9e847@ccrma.stanford.edu> (raw)
In-Reply-To: <1581055866.25780.7.camel@gmx.de>
On 2/6/20 10:11 PM, Mike Galbraith wrote:
> On Thu, 2020-02-06 at 15:59 -0800, Fernando Lopez-Lezcano wrote:
>> On 2/4/20 8:58 AM, Sebastian Andrzej Siewior wrote:
>>> Dear RT folks!
>>>
>>> I'm pleased to announce the v5.4.17-rt9 patch set.
>>
>> Thanks!
>> I see a continuous stream of these:
>
> (snips gripage)
>
> Yup, d67739268cf0 annoys RT locking if lockdep is enabled. The below
> shut it up for my i915 equipped lappy.
Wow, Mike, thanks!, will try it out and report...
(might take me a couple of days)
-- Fernando
> drm/i915/gt: use a LOCAL_IRQ_LOCK in __timeline_mark_lock()
>
> Quoting drm/i915/gt: Mark up the nested engine-pm timeline lock as irqsafe
>
> We use a fake timeline->mutex lock to reassure lockdep that the timeline
> is always locked when emitting requests. However, the use inside
> __engine_park() may be inside hardirq and so lockdep now complains about
> the mixed irq-state of the nested locked. Disable irqs around the
> lockdep tracking to keep it happy.
>
> This lockdep appeasement breaks RT because we take sleeping locks between
> __timeline_mark_lock()/unlock(). Use a LOCAL_IRQ_LOCK instead.
>
> Signed-off-by: Mike Galbraith <efaukt@gmx.de>
> ---
> drivers/gpu/drm/i915/gt/intel_engine_pm.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> @@ -38,12 +38,15 @@ static int __engine_unpark(struct intel_
> }
>
> #if IS_ENABLED(CONFIG_LOCKDEP)
> +#include <linux/locallock.h>
> +
> +static DEFINE_LOCAL_IRQ_LOCK(timeline_lock);
>
> static inline unsigned long __timeline_mark_lock(struct intel_context *ce)
> {
> unsigned long flags;
>
> - local_irq_save(flags);
> + local_lock_irqsave(timeline_lock, flags);
> mutex_acquire(&ce->timeline->mutex.dep_map, 2, 0, _THIS_IP_);
>
> return flags;
> @@ -53,7 +56,7 @@ static inline void __timeline_mark_unloc
> unsigned long flags)
> {
> mutex_release(&ce->timeline->mutex.dep_map, 0, _THIS_IP_);
> - local_irq_restore(flags);
> + local_unlock_irqrestore(timeline_lock, flags);
> }
>
> #else
>
>
next prev parent reply other threads:[~2020-02-07 6:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 16:58 [ANNOUNCE] v5.4.17-rt9 Sebastian Andrzej Siewior
2020-02-06 23:59 ` Fernando Lopez-Lezcano
2020-02-07 6:11 ` Mike Galbraith
2020-02-07 6:13 ` Fernando Lopez-Lezcano [this message]
2020-02-07 6:56 ` Mike Galbraith
2020-06-20 10:09 ` v5.4.17-rt10 does not boot on intel ycollette.nospam
2020-06-20 12:35 ` ycollette.nospam
2020-06-25 16:55 ` v5.6.17 (was v5.4.17-rt10) " Fernando Lopez-Lezcano
2020-02-12 10:20 ` [ANNOUNCE] v5.4.17-rt9 Sebastian Andrzej Siewior
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