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From:   Chris Wilson <chris@chris-wilson.co.uk>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Pavel Machek <pavel@ucw.cz>, airlied@redhat.com,
        intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com,
        joonas.lahtinen@linux.intel.com,
        kernel list <linux-kernel@vger.kernel.org>,
        matthew.auld@intel.com, rodrigo.vivi@intel.com
Subject: Re: Linus, please revert 7dc8f11437: regression in 5.7-rc0, hangs while attempting to run X
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com
Message-ID: <158624426770.4794.6070200474948860768@build.alporthouse.com>
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Date:   Tue, 07 Apr 2020 08:24:27 +0100
Sender: linux-kernel-owner@vger.kernel.org
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Quoting Pavel Machek (2020-04-07 08:20:47)
> 
> On Fri 2020-04-03 15:00:31, Pavel Machek wrote:
> > Hi!
> > 
> > 7dc8f1143778a35b190f9413f228b3cf28f67f8d
> > 
> >     drm/i915/gem: Drop relocation slowpath
> >     
> >     Since the relocations are no longer performed under a global
> >     struct_mutex, or any other lock, that is also held by pagefault handlers,
> >     we can relax and allow our fast path to take a fault. As we no longer
> >     need to abort the fast path for lock avoidance, we no longer need the
> >     slow path handling at all.
> > 
> > causes regression on thinkpad x220: instead of starting X, I'm looking
> > at blinking cursor.
> > 
> > Reverting the patch on too of 919dce24701f7b3 fixes things for me.
> 
> I have received no feedback from patch authors, and I believe we don't
> want to break boot in -rc1 on Intel hardware... so the commit should
> be simply reverted.

Beyond the fix already submitted?
-Chris