linux-kernel - Re: PROBLEM: i915 causes complete desktop freezes in 4.15-rc5

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Date:   Fri, 5 Jan 2018 17:05:18 -0500
From:   Alexandru Chirvasitu <achirvasub@...il.com>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        intel-gfx@...ts.freedesktop.org,
        kernel list <linux-kernel@...r.kernel.org>
Subject: Re: PROBLEM: i915 causes complete desktop freezes in 4.15-rc5

Here we go.

I have

CONFIG_PAGE_POISONING not set
CONFIG_SLUB_STATS=y
CONFIG_SLUB_DEBUG not set
CONFIG_KASAN=y

.config attached along as well for verification, in case I missed
anything.

Again crashed by an attempt to open a terminal window.

---
Incidentally, Re: this:

> > > Ok, it looks like poisoning is only available if CONFIG_SLUB_DEBUG is
> > > set. Since it is not set, don't worry about it ;)

I actually still had PAGE_POISONING on after turning off SLUB_DEBUG,
so had to actively turn off both. And I never found a SLAB_POISON,
even after choosing SLAB over SLUB as an experiment.

That's an aside though; shouldn't matter much to the task at hand,
unless I misunderstood the instructions.

On Fri, Jan 05, 2018 at 08:02:48PM +0000, Chris Wilson wrote:
> Quoting Alexandru Chirvasitu (2018-01-05 19:58:42)
> > OK, I then plan to try with the previous config, plus these
> > modifications:
> > 
> > CONFIG_PAGE_POISONING not set
> > CONFIG_SLUB_STATS=y
> > 
> > I'm a little puzzled about this:
> 
> [snip]
> 
> > > It would be CONFIG_SLUB_STATS and then you would a
> > > /sys/kernel/slab/i915_dependency/ directory with all the details of the
> > > slab, and in particular a poison file showing the status (and allowing
> > > it to modified) of slab poisoning
> > > 
> > > Ok, it looks like poisoning is only available if CONFIG_SLUB_DEBUG is
> > > set. Since it is not set, don't worry about it ;)
> > 
> > I actually do have SLUB_DEBUG set to 'y' in the kernel whose dmesg I
> > last sent you.
> 
> Ah, ok. I was looking at the config attached the first mail. Turn off
> SLUB_DEBUG for now to give ourselves the best chance at getting
> something from kasan. I hope it's worth the effort...
> -Chris

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