Re: 3.5 regression on i915

[Willy Tarreau <w@1wt.eu>]

On Sat, Oct 06, 2012 at 10:04:00AM +0100, Chris Wilson wrote:
> On Sat, 6 Oct 2012 10:42:58 +0200, Willy Tarreau <w@1wt.eu> wrote:
> > On Sat, Oct 06, 2012 at 09:24:35AM +0100, Chris Wilson wrote:
> > > More likely X is segfaulting for another reason altogether. Can you
> > > please attach the stacktrace (with symbols!) and see if another
> > > bisection is required?
> > 
> > Yes, here it is.
> > 
> > (EE) intel(0): Failed to initialize kernel memory manager
> > 
> > Backtrace:
> > 0: X(xf86SigHandler+0x7e) [0x80d8b5e]
> > 1: [0xffffe400]
> > 2: /usr/lib/xorg/modules/drivers//intel_drv.so(i830_allocator_init+0x332) [0xb73756e2]
> 
> Drat, that is:
> 
> commit 7bb6fb8dd958ae773ac205282e3c0b56c22e01ed
> Author: Daniel Vetter <daniel.vetter@ffwll.ch>
> Date:   Tue Apr 24 08:22:52 2012 +0200
> 
>     drm/i915: disallow gem ums init ioctl for kms
>     
>     This ioctl used in a kms driver is only useful to create massive
>     havoc.
> 
> Can't see just why -intel crashes, but I presume it is during the
> i830_free_memory along that path.
> 
> Anyway, looks like that patch needs to be reverted.

Good catch, but now it dies later after screen goes black :

Backtrace:
0: X(xf86SigHandler+0x7e) [0x80d8b5e]
1: [0xffffe400]
2: /usr/lib/xorg/modules/drivers//intel_drv.so(I830Sync+0x4e) [0xb732eefe]
3: /usr/lib/xorg/modules/drivers//intel_drv.so [0xb733d916]
4: X(AbortDDX+0x8d) [0x80a146d]
5: X(AbortServer+0x28) [0x81b3ae8]
6: X(FatalError+0x66) [0x81b4066]
7: /usr/lib/xorg/modules/drivers//intel_drv.so [0xb733e626]
8: /usr/lib/xorg/modules/drivers//intel_drv.so [0xb733f962]
9: X(AddScreen+0x1fc) [0x806d42c]
10: X(InitOutput+0x21e) [0x80a1b7e]
11: X(main+0x296) [0x806dbb6]
12: /lib/libc.so.6(__libc_start_main+0xe0) [0xb7552390]
13: X(FontFileCompleteXLFD+0x20d) [0x806d121]

FatalError re-entered, aborting
Caught signal 11.  Server aborting

I suspect the error handling in this version of intel_drv is incomplete,
resulting in segfaults instead of plain error reporting.

Willy