REGRESSION: [i915] kernel NULL pointer dereference

[Tony Fischetti]

I just tested the v5.9-rc7 release on two of my machines and on one of the
machines, I got a bug/oops that prevents the video driver from working
properly.

This regression must have occurred somewhere between v5.9-rc8 and v5.9-rc9.
I'm attempting to git bisect it, but I wanted to bring it to your attention
since I'm unfamiliar with this subsystem and it's unlikely that I'll be
able to fix it/offer a patch myself.

Below are the relevant journal log entries. Please let me know if there's
any more information I can provide.


BUG: kernel NULL pointer dereference, address: 0000000000000054
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP NOPTI
CPU: 1 PID: 480 Comm: kworker/u25:0 Not tainted 5.9.0-rc7-alice-glass+ #1
Hardware name: LENOVO 10ST001QUS/312A, BIOS M1UKT4BA 11/11/2019
Workqueue: i915-userptr-acquire __i915_gem_userptr_get_pages_worker [i915]
RIP: 0010:__get_user_pages_remote+0xa0/0x2d0
Code: 85 e7 01 00 00 83 3b 01 0f 85 e0 01 00 00 f7 c1 00 00 04 00 0f 84 12
01 00 00 65 48 8b 04 25 00 6d 01 00 48 8b 80 58 03 00 00 <c7> 40 54 01 00
00 00 c6 04 24 00 4d 8d 6f 68 48

RSP: 0018:ffffaa38005a3df0 EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffffaa38005a3e64 RCX: 0000000000040001
RDX: 00000000000007e9 RSI: 00007ff21f800000 RDI: ffff8afde99a0440
RBP: 00007ff21f800000 R08: ffff8afde221c000 R09: 0000000000000000
R10: 0000000000000006 R11: 0000000000000005 R12: ffff8afde221c000
R13: ffff8afde221c000 R14: 0000000000042003 R15: ffff8afde99a0440
FS:  0000000000000000(0000) GS:ffff8afdfe240000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000054 CR3: 000000048320a005 CR4: 00000000001706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __i915_gem_userptr_get_pages_worker+0xd1/0x2b0 [i915]
 process_one_work+0x1c7/0x310
 worker_thread+0x28/0x3c0
 ? set_worker_desc+0xb0/0xb0
 kthread+0x123/0x140
 ? kthread_use_mm+0xe0/0xe0
 ret_from_fork+0x1f/0x30
Modules linked in: snd_hda_codec_hdmi snd_hda_codec_realtek
snd_hda_codec_generic ledtrig_audio iwlmvm mac80211 libarc4
x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclm ul
crc32_pclmul crc32c_intel iwlwifi i915 ghash_clmulni_intel i2c_algo_bit
drm_kms_helper snd_hda_intel syscopyarea snd_intel_dspcfg sysfillrect
mei_hdcp sysimgblt tpm_crb fb_sys_fops snd_hda_codec aesni_intel cec
snd_hwdep crypto_simd snd_hda_core glue_helper drm wmi_bmof
intel_wmi_thunderbolt snd_pcm intel_cstate i2c_i801 snd_timer mei_me
cfg80211 mei i2c_smbus pcspkr i2c_core wmi thermal tpm_tis tpm_tis_core tpm
rng_core acpi_pad ppdev lp ip_tables x_tables
CR2: 0000000000000054
---[ end trace aa62f3a2cc9e91a3 ]---
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20200928/4f36ea5e/attachment-0001.htm>