On Mon, Dec 15, 2014 at 7:48 PM, Dave Airlie <airlied@xxxxxxxxx> wrote:
> On 16 December 2014 at 10:35, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>> 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
>> drivers/gpu/drm/i915/i915_gem_execbuffer.c:125
>> 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 ...
>> video
>> 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:
>> dump_stack+0x45/0x57
>> warn_slowpath_common+0x80/0xc0
>> warn_slowpath_fmt+0x41/0x50
>> ? 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]
>> do_vfs_ioctl+0x2e0/0x4e0
>> ? file_has_perm+0x87/0xa0
>> ? __audit_syscall_entry+0xac/0x100
>> SyS_ioctl+0x81/0xa0
>> ? do_page_fault+0xc/0x10
>> system_call_fastpath+0x12/0x17
>> ---[ 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.
>>
>
> I'd be inclined to just revert this for now, it is annoying we let
> userspace away with this, but we probably need to find a better
> way to enforce it, since the cat is out of the bag.
Replace w/ DRM_ERROR? (perhaps ratelimited..)?
It's not a driver error, so much as a warning for userspace that it is
doing something that is not expected to work on all hw / generations,
and it appears to be finding more or less what it was intended to
find, although I'm not sure the stack trace serves much purpose.
BR,
-R
> Dave.
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