[REGRESSION] Linux 4.9-rc4: gfx glitches on Intel Sandybridge (was: Re: Linux 4.9-rc4)

From: Martin Steigerwald
Date: Sun Nov 06 2016 - 09:54:50 EST


Am Samstag, 5. November 2016, 16:46:33 CET schrieb Linus Torvalds:
> So it's once again a Saturday afternoon rather than Sunday, this time
> because I felt this rc was already big enough.

With kernel 4.9-rc4 I saw gfx corruptions like


in Konversation, Konsole, Akregator and other KDE/Qt related apps up to the
point of not being able to use these applications in a meaningful way.

I first thought this might be due to upgrading Qt from 5.6.1 to 5.7.1, yet
after rebooting into 4.8 Linux kernel as packaged in Debian I saw no gfx
glitches like that anymore.

Anything known about this?

Machine is ThinkPad T520 with Sandybridge graphics.

Kernel compiled with Debian distro GCC 6 but using no-pie makefile patch.

Next week and weekend will be pretty busy and this is a production machine, so
bisection or any other time-consuming work on this is out of question for me.
I can provide additional details in case they are easy and quick enough to

System information (now back on 4.8 kernel):

# phoronix-test-suite system-info

Phoronix Test Suite v5.2.1
System Information

Processor: Intel Core i5-2520M @ 3.20GHz (4 Cores), Motherboard: LENOVO
42433WG, Chipset: Intel 2nd Generation Core Family DRAM, Memory: 16384MB,
Disk: 300GB INTEL SSDSA2CW30 + 480GB Crucial_CT480M50, Graphics: Intel 2nd
Generation Core Family IGP, Audio: Conexant CX20590, Monitor: P24T-7 LED,
Network: Intel 82579LM Gigabit Connection + Intel Centrino Advanced-N 6205

OS: Debian unstable, Kernel: 4.8.0-1-amd64 (x86_64), Desktop: KDE Frameworks
5, Display Server: X Server 1.18.4, Display Driver: modesetting 1.18.4,
OpenGL: 3.3 Mesa 12.0.3, Compiler: GCC 6.2.0 20161103, File-System: btrfs,
Screen Resolution: 3840x1080

# apt-show-versions | egrep "(^libgl1-mesa-dri|^libdrm-intel1|xserver-xorg-
core)" | grep amd64
libdrm-intel1:amd64/sid 2.4.71-1 uptodate
libgl1-mesa-dri:amd64/sid 12.0.3-3 uptodate
xserver-xorg-core:amd64/sid 2:1.18.4-2 uptodate

Excerpt of glxinfo:

Extended renderer info (GLX_MESA_query_renderer):
Vendor: Intel Open Source Technology Center (0x8086)
Device: Mesa DRI Intel(R) Sandybridge Mobile (0x126)
Version: 12.0.3
Accelerated: yes
Video memory: 1536MB
Unified memory: yes
Preferred profile: core (0x1)
Max core profile version: 3.3
Max compat profile version: 3.0
Max GLES1 profile version: 1.1
Max GLES[23] profile version: 3.0

X.org runs with modesetting driver (default was changed in Debian Sid a while