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

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Message-ID: <151473569074.2051.18107105776550332791@mail.alporthouse.com>
Date:   Sun, 31 Dec 2017 15:54:50 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Alexandru Chirvasitu <achirvasub@...il.com>,
        "Jani Nikula" <jani.nikula@...ux.intel.com>,
        "Joonas Lahtinen" <joonas.lahtinen@...ux.intel.com>,
        "Rodrigo Vivi" <rodrigo.vivi@...el.com>
Cc:     intel-gfx@...ts.freedesktop.org,
        "kernel list" <linux-kernel@...r.kernel.org>
Subject: Re: PROBLEM: i915 causes complete desktop freezes in 4.15-rc5

Quoting Alexandru Chirvasitu (2017-12-30 17:31:32)
> Short description: I get freezes of my desktop completely eliminating
> mouse / keyboard functionality.
> 
> I’m on an UltraLap 5330, Processor: i7-7500U, Memory: 32 GB DDR4-2133
> Video Card: Intel HD (included). It's running Void linux 64 bit. That
> distro's latest kernel is 4.14.8, but I've been trying out the 4.15-rc
> kernels. This has happened with rc3, rc4 and currently rc5.
> 
> I can ssh into the frozen machine and roam around freely. Xorg shows
> as <defunct> when I do, and nothing I have tried on the command line
> has succeeded in restroing functionality (killing processes, changing
> runlevels, etc.; there's no visible response from the computer). Only
> reboots resolve the matter (button reboots or issued as commands
> through ssh).
> 
> While ssh-d in I can get the dmesg log, which is attached. The
> relevant portion is presumably the trace at the very end.

I can't find how this can happen, the lists here are serialized by
struct_mutex. (The poison would indicate that the elements p->dfs_link
points to are freed, not p itself.) If you could run with lockdep (to
verify that the locks are indeed held here) and kasan to find the
alloc/free of the struct being used-after-free, that would be extremely
valuable.
-Chris