linux/drivers/gpu/drm
Willy Tarreau c77d7162a7 drm/i915: remove useless BUG_ON which caused a regression in 3.5.
starting an old X server causes a kernel BUG since commit 1b50247a8d:

------------[ cut here ]------------
kernel BUG at drivers/gpu/drm/i915/i915_gem.c:3661!
invalid opcode: 0000 [#1] SMP
Modules linked in: snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss uvcvideo
+videobuf2_core videodev videobuf2_vmalloc videobuf2_memops uhci_hcd ath9k mac80211 snd_hda_codec_realtek ath9k_common microcode
+ath9k_hw psmouse serio_raw sg ath cfg80211 atl1c lpc_ich mfd_core ehci_hcd snd_hda_intel snd_hda_codec snd_hwdep snd_pcm rtc_cmos
+snd_timer snd evdev eeepc_laptop snd_page_alloc sparse_keymap

Pid: 2866, comm: X Not tainted 3.5.6-rc1-eeepc #1 ASUSTeK Computer INC. 1005HA/1005HA
EIP: 0060:[<c12dc291>] EFLAGS: 00013297 CPU: 0
EIP is at i915_gem_entervt_ioctl+0xf1/0x110
EAX: f5941df4 EBX: f5940000 ECX: 00000000 EDX: 00020000
ESI: f5835400 EDI: 00000000 EBP: f51d7e38 ESP: f51d7e20
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
CR0: 8005003b CR2: b760e0a0 CR3: 351b6000 CR4: 000007d0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400
Process X (pid: 2866, ti=f51d6000 task=f61af8d0 task.ti=f51d6000)
Stack:
 00000001 00000000 f5835414 f51d7e84 f5835400 f54f85c0 f51d7f10 c12b530b
 00000001 c151b139 c14751b6 c152e030 00000b32 00006459 00000059 0000e200
 00000001 00000000 00006459 c159ddd0 c12dc1a0 ffffffea 00000000 00000000
Call Trace:
 [<c12b530b>] drm_ioctl+0x2eb/0x440
 [<c12dc1a0>] ? i915_gem_init+0xe0/0xe0
 [<c1052b2b>] ? enqueue_hrtimer+0x1b/0x50
 [<c1053321>] ? __hrtimer_start_range_ns+0x161/0x330
 [<c10530b3>] ? lock_hrtimer_base+0x23/0x50
 [<c1053163>] ? hrtimer_try_to_cancel+0x33/0x70
 [<c12b5020>] ? drm_version+0x90/0x90
 [<c10ca171>] vfs_ioctl+0x31/0x50
 [<c10ca2e4>] do_vfs_ioctl+0x64/0x510
 [<c10535de>] ? hrtimer_nanosleep+0x8e/0x100
 [<c1052c20>] ? update_rmtp+0x80/0x80
 [<c10ca7c9>] sys_ioctl+0x39/0x60
 [<c1433949>] syscall_call+0x7/0xb
Code: 83 c4 0c 5b 5e 5f 5d c3 c7 44 24 04 2c 05 53 c1 c7 04 24 6f ef 47 c1 e8 6e e0 fd ff c7 83 38 1e 00 00 00 00 00 00 e9 3f ff ff
+ff <0f> 0b eb fe 0f 0b eb fe 8d b4 26 00 00 00 00 0f 0b eb fe 8d b6
EIP: [<c12dc291>] i915_gem_entervt_ioctl+0xf1/0x110 SS:ESP 0068:f51d7e20
---[ end trace dd332ec083cbd513 ]---

The crash happens here in i915_gem_entervt_ioctl() :

    3659          BUG_ON(!list_empty(&dev_priv->mm.active_list));
    3660          BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
 -> 3661          BUG_ON(!list_empty(&dev_priv->mm.inactive_list));
    3662          mutex_unlock(&dev->struct_mutex);

Quoting Chris :
  "That BUG_ON there is silly and can simply be removed. The check is to
   verify that no batches were submitted to the kernel whilst the UMS/GEM
   client was suspended - to which the BUG_ONs are a crude approximation.
   Furthermore, the checks are too late, since it means we attempted to
   program the hardware whilst it was in an invalid state, the BUG_ONs are
   the least of your concerns at that point."

Note that this regression has been introduced in

commit 1b50247a8d
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Apr 24 15:47:30 2012 +0100

    drm/i915: Remove the list of pinned inactive objects

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[danvet: Added note about the regressing commit and cc: stable.]
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2012-10-07 22:57:25 +02:00
..
ast Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
cirrus Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
exynos Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
gma500 Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
i2c drm/i2c/ch7006: Convert to dev_pm_ops 2012-08-24 09:56:08 +10:00
i810 drm: use drm_compat_ioctl for 32-bit apps 2012-09-06 06:55:02 +10:00
i915 drm/i915: remove useless BUG_ON which caused a regression in 3.5. 2012-10-07 22:57:25 +02:00
mga drm: kill reclaim_buffers callback 2012-07-19 22:50:28 -04:00
mgag200 Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
nouveau Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
r128 drm: kill reclaim_buffers callback 2012-07-19 22:50:28 -04:00
radeon Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
savage drm: use drm_compat_ioctl for 32-bit apps 2012-09-06 06:55:02 +10:00
shmobile drm: Renesas SH Mobile DRM driver 2012-09-18 12:28:22 +02:00
sis drm: use drm_compat_ioctl for 32-bit apps 2012-09-06 06:55:02 +10:00
tdfx drm: use drm_compat_ioctl for 32-bit apps 2012-09-06 06:55:02 +10:00
ttm drm: Handle io prot correctly for MIPS. 2012-08-24 09:41:05 +10:00
udl Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
via drm: use drm_compat_ioctl for 32-bit apps 2012-09-06 06:55:02 +10:00
vmwgfx Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
ati_pcigart.c
drm_agpsupport.c
drm_auth.c
drm_buffer.c
drm_bufs.c drm: kill dma queue support 2012-07-19 22:50:55 -04:00
drm_cache.c drm/i915: Replace the array of pages with a scatterlist 2012-09-20 14:22:57 +02:00
drm_context.c drm: Unify and fix idr error handling 2012-04-24 09:50:20 +01:00
drm_crtc_helper.c drm: Don't initialize local ret variable when not needed 2012-05-22 10:32:58 +01:00
drm_crtc.c Linux 3.6-rc7 2012-09-24 18:17:12 +02:00
drm_debugfs.c drm: kill dma queue support 2012-07-19 22:50:55 -04:00
drm_dma.c drm: kill dma queue support 2012-07-19 22:50:55 -04:00
drm_dp_i2c_helper.c
drm_drv.c drm: make buffer management work without DRM_MASTER 2012-09-13 11:19:44 +10:00
drm_edid_load.c drm/edid: limit printk when facing bad edid 2012-09-17 11:16:40 +10:00
drm_edid_modes.h drm: consistently name interlaced modes 2012-09-13 11:21:03 +10:00
drm_edid.c drm: Export drm_probe_ddc() 2012-10-02 18:06:05 +02:00
drm_encoder_slave.c
drm_fb_cma_helper.c DRM: Add DRM KMS/FB CMA helper 2012-09-18 12:28:21 +02:00
drm_fb_helper.c drm/fb helper: don't call drm_helper_connector_dpms directly 2012-09-08 00:51:15 +02:00
drm_fops.c drm: track dev_mapping in more robust and flexible way 2012-07-25 14:09:30 +10:00
drm_gem_cma_helper.c DRM: Add DRM GEM CMA helper 2012-09-18 12:28:21 +02:00
drm_gem.c drm: Add colouring to the range allocator 2012-07-16 05:59:37 +10:00
drm_global.c
drm_hashtab.c
drm_info.c drm: kill dma queue support 2012-07-19 22:50:55 -04:00
drm_ioc32.c
drm_ioctl.c drm/prime: expose capability flags for userspace. 2012-05-18 11:12:16 +01:00
drm_irq.c drm: Add missing static storage class specifier in drm_irq.c file 2012-08-24 10:00:56 +10:00
drm_lock.c drm: ditch strange DRIVER_DMA_QUEUE only error bail-out 2012-07-19 22:50:47 -04:00
drm_memory.c
drm_mm.c drm: Add colouring to the range allocator 2012-07-16 05:59:37 +10:00
drm_modes.c drm: Remove two unused fields from struct drm_display_mode 2012-08-22 09:27:27 +10:00
drm_pci.c drm/pci: add support for getting the supported link bw. 2012-07-19 22:29:25 -04:00
drm_platform.c
drm_prime.c drm/prime: add exported buffers to current fprivs imported buffer list (v2) 2012-05-23 10:46:03 +01:00
drm_proc.c drm: Add missing static storage class specifiers in drm_proc.c file 2012-08-22 09:30:00 +10:00
drm_scatter.c
drm_stub.c drm: Don't initialize local ret variable when not needed 2012-05-22 10:32:58 +01:00
drm_sysfs.c drm: fail gracefully when proc isn't setup. 2012-07-16 05:57:03 +10:00
drm_trace_points.c
drm_trace.h
drm_usb.c drm/usb: fix module license on drm/usb layer. 2012-04-19 09:33:32 +01:00
drm_vm.c drm: Remove unnecessary test for ARM. 2012-09-13 11:28:39 +10:00
Kconfig drm: Renesas SH Mobile DRM driver 2012-09-18 12:28:22 +02:00
Makefile drm: Renesas SH Mobile DRM driver 2012-09-18 12:28:22 +02:00
README.drm

************************************************************
* For the very latest on DRI development, please see:      *
*     http://dri.freedesktop.org/                          *
************************************************************

The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).

The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:

    1. The DRM provides synchronized access to the graphics hardware via
       the use of an optimized two-tiered lock.

    2. The DRM enforces the DRI security policy for access to the graphics
       hardware by only allowing authenticated X11 clients access to
       restricted regions of memory.

    3. The DRM provides a generic DMA engine, complete with multiple
       queues and the ability to detect the need for an OpenGL context
       switch.

    4. The DRM is extensible via the use of small device-specific modules
       that rely extensively on the API exported by the DRM module.


Documentation on the DRI is available from:
    http://dri.freedesktop.org/wiki/Documentation
    http://sourceforge.net/project/showfiles.php?group_id=387
    http://dri.sourceforge.net/doc/

For specific information about kernel-level support, see:

    The Direct Rendering Manager, Kernel Support for the Direct Rendering
    Infrastructure
    http://dri.sourceforge.net/doc/drm_low_level.html

    Hardware Locking for the Direct Rendering Infrastructure
    http://dri.sourceforge.net/doc/hardware_locking_low_level.html

    A Security Analysis of the Direct Rendering Infrastructure
    http://dri.sourceforge.net/doc/security_low_level.html