linux-kernel - Re: 3.5 regression on i915

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Message-Id: <b94cdc$6rvo8m@fmsmga001.fm.intel.com>
Date:	Sat, 06 Oct 2012 09:43:08 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Willy Tarreau <w@....eu>
Cc:	Daniel Vetter <daniel.vetter@...ll.ch>,
	linux-kernel@...r.kernel.org, Dave Airlie <airlied@...il.com>
Subject: Re: 3.5 regression on i915

On Sat, 6 Oct 2012 10:20:16 +0200, Willy Tarreau <w@....eu> wrote:
> Hi Chris,
> 
> On Sat, Oct 06, 2012 at 09:04:34AM +0100, Chris Wilson wrote:
> > > The crash happens here in i915_gem_entervt_ioctl() :
> > > 
> > >     3659          BUG_ON(!list_empty(&dev_priv->mm.active_list));
> > >     3660          BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
> > >  -> 3661          BUG_ON(!list_empty(&dev_priv->mm.inactive_list));
> > >     3662          mutex_unlock(&dev->struct_mutex);
> > 
> > That BUG_ON there is silly and can simply be removed. The check is to
> > verify that no batches were submitted to the kernel whilst the UMS/GEM
> > client was suspended - to which the BUG_ONs are a crude approximation.
> > Furthermore, the checks are too late, since it means we attempted to
> > program the hardware whilst it was in an invalid state, the BUG_ONs are
> > the least of your concerns at that point.
> 
> Excellent, that fixed it ! X still segfaults when KMS is used, but
> I expect more of a pure user-space issue here since there is nothing
> in dmesg.
> 
> Would some of you accept the following patch and tag it for -stable ?

Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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