Re: [git pull] drm for 3.19-rc1

From: Linus Torvalds
Date: Mon Dec 15 2014 - 19:35:36 EST

On Sun, Dec 14, 2014 at 11:17 PM, Dave Airlie <airlied@xxxxxxxx> wrote:
> i915:
> Initial Skylake (SKL) support
> gen3/4 reset work
> start of dri1/ums removal
> infoframe tracking
> fixes for lots of things.

So I'm not sure how happy I am about this. It seems to work, but on
the very first boot I get this:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 1292 at
eb_lookup_vmas.isra.18+0x333/0x3d0 [i915]()
GPU use of dumb buffer is illegal.
Modules linked in: ip6t_rpfilter bnep ip6t_REJECT nf_reject_ipv6
bluetooth nf_conntrack_ipv6 ...
CPU: 1 PID: 1292 Comm: Xorg Not tainted 3.18.0-09423-g988adfdffdd4 #1
Hardware name: /DH87RL, BIOS
RLH8710H.86A.0327.2014.0924.1645 09/24/2014
Call Trace:
? sg_kfree+0x30/0x30
eb_lookup_vmas.isra.18+0x333/0x3d0 [i915]
i915_gem_do_execbuffer.isra.25+0x50d/0xd80 [i915]
? unlock_page+0x6d/0x80
i915_gem_execbuffer2+0xb1/0x2c0 [i915]
drm_ioctl+0x19c/0x630 [drm]
? file_has_perm+0x87/0xa0
? __audit_syscall_entry+0xac/0x100
? do_page_fault+0xc/0x10
---[ end trace cb3c78163212ca1d ]---

apparently Introduced by commit 355a70183848 ("drm/gem: Warn on
illegal use of the dumb buffer interface v2")

The commit says "the next step is to fail".

And I want to make it painfully clear that if somebody breaks existing
working setups, they don't get to work on the kernel.

So get rid of the warning. And get rid of the notion that you can just
fail. You can try to fix Xorg, and then come back to this - in a
couple of years - when it no longer happens.

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