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<head>
<base href="https://bugs.freedesktop.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - kernel NULL pointer dereference: gen4_render_ring_flush [i915]"
href="https://bugs.freedesktop.org/show_bug.cgi?id=108984">108984</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>kernel NULL pointer dereference: gen4_render_ring_flush [i915]
</td>
</tr>
<tr>
<th>Product</th>
<td>DRI
</td>
</tr>
<tr>
<th>Version</th>
<td>XOrg git
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux (All)
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>critical
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>DRM/Intel
</td>
</tr>
<tr>
<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>elektron@halo.nu
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>Originally reported here:
<a href="https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914495">https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914495</a>
elektron@x200:~$ ls -la /vmlinuz*
lrwxrwxrwx 1 root root 27 Dec 4 23:23 /vmlinuz -> boot/vmlinuz-4.18.0-3-amd64
lrwxrwxrwx 1 root root 27 Dec 4 23:23 /vmlinuz.old ->
boot/vmlinuz-4.18.0-2-amd64
elektron@x200:~$ dpkg -l | grep linux-image | grep 4\.18
ii linux-image-4.18.0-1-amd64 4.18.6-1
amd64 Linux 4.18 for 64-bit PCs
ii linux-image-4.18.0-2-amd64 4.18.10-2+b1
amd64 Linux 4.18 for 64-bit PCs
ii linux-image-4.18.0-3-amd64 4.18.20-2
amd64 Linux 4.18 for 64-bit PCs
ii linux-image-amd64 4.18+100
amd64 Linux for 64-bit PCs (meta-package)
elektron@x200:~$ lspci | grep -i vga
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset
Integrated Graphics Controller (rev 07)
elektron@x200:~$ sudo journalctl --boot -1 | less
<SNIP>
Dec 05 08:00:10 x200 kernel: BUG: unable to handle kernel NULL pointer
dereference at 0000000000000008
Dec 05 08:00:10 x200 kernel: PGD 0 P4D 0
Dec 05 08:00:10 x200 kernel: Oops: 0000 [#1] SMP PTI
Dec 05 08:00:10 x200 kernel: CPU: 1 PID: 385 Comm: systemd-udevd Tainted: G
I 4.18.0-3-amd64 #1 Debian 4.18.20-2
Dec 05 08:00:10 x200 kernel: Hardware name: LENOVO 7459PB1/7459PB1, BIOS
CBET4000 3774c98 09/07/2016
Dec 05 08:00:10 x200 kernel: RIP: 0010:gen4_render_ring_flush+0x55/0xf0 [i915]
Dec 05 08:00:10 x200 kernel: Code: 00 be 16 00 00 00 48 89 ef e8 87 fe ff ff 48
3d 00 f0 ff ff 77 69 89 18 c7 40 04 02 40 00 7a 48 8b 55 78 48 8b 92 10 02 00
00 <48> 8b 52 08 48 c7 40 0c 00 00 00 00 83 ca 04 89 50 08 48 8d 50 14
Dec 05 08:00:10 x200 kernel: RSP: 0018:ffffa814811b7a88 EFLAGS: 00010287
Dec 05 08:00:10 x200 kernel: RAX: ffffa814903ed000 RBX: 0000000002000022 RCX:
000000000001ff68
Dec 05 08:00:10 x200 kernel: RDX: 0000000000000000 RSI: 00000000000001a8 RDI:
0000000000000150
Dec 05 08:00:10 x200 kernel: RBP: ffff9b9ce3b57d40 R08: 0000000000000001 R09:
0000000000000002
Dec 05 08:00:10 x200 kernel: R10: ffffa814811b7a58 R11: 0000000000000000 R12:
ffff9b9ce2340000
Dec 05 08:00:10 x200 kernel: R13: ffff9b9ce44ea600 R14: 0000000000000000 R15:
ffff9b9ce3b57d40
Dec 05 08:00:10 x200 kernel: FS: 00007fa115f0a8c0(0000)
GS:ffff9b9cefd00000(0000) knlGS:0000000000000000
Dec 05 08:00:10 x200 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 05 08:00:10 x200 kernel: CR2: 0000000000000008 CR3: 0000000220f7c000 CR4:
00000000000406e0
Dec 05 08:00:10 x200 kernel: Call Trace:
Dec 05 08:00:10 x200 kernel: i915_request_alloc+0x243/0x360 [i915]
Dec 05 08:00:10 x200 kernel: i915_gem_init+0x284/0x480 [i915]
Dec 05 08:00:10 x200 kernel: i915_driver_load+0xb22/0xef0 [i915]
Dec 05 08:00:10 x200 kernel: ? mutex_lock+0xe/0x30
Dec 05 08:00:10 x200 kernel: ? acpi_dev_found+0x5f/0x70
Dec 05 08:00:10 x200 kernel: local_pci_probe+0x42/0xa0
Dec 05 08:00:10 x200 kernel: ? pci_assign_irq+0x27/0x130
Dec 05 08:00:10 x200 kernel: pci_device_probe+0x146/0x1b0
Dec 05 08:00:10 x200 kernel: driver_probe_device+0x2fa/0x470
Dec 05 08:00:10 x200 kernel: __driver_attach+0xdc/0x100
Dec 05 08:00:10 x200 kernel: ? driver_probe_device+0x470/0x470
Dec 05 08:00:10 x200 kernel: bus_for_each_dev+0x76/0xc0
Dec 05 08:00:10 x200 kernel: ? klist_add_tail+0x3b/0x70
Dec 05 08:00:10 x200 kernel: bus_add_driver+0x161/0x260
Dec 05 08:00:10 x200 kernel: ? 0xffffffffc0b83000
Dec 05 08:00:10 x200 kernel: driver_register+0x5b/0xe0
Dec 05 08:00:10 x200 kernel: ? 0xffffffffc0b83000
Dec 05 08:00:10 x200 kernel: do_one_initcall+0x46/0x1c8
Dec 05 08:00:10 x200 kernel: ? _cond_resched+0x15/0x40
Dec 05 08:00:10 x200 kernel: ? kmem_cache_alloc_trace+0x15d/0x1c0
Dec 05 08:00:10 x200 kernel: ? do_init_module+0x22/0x201
Dec 05 08:00:10 x200 kernel: do_init_module+0x5b/0x201
Dec 05 08:00:10 x200 kernel: load_module.constprop.56+0x1649/0x1d80
Dec 05 08:00:10 x200 kernel: ? vfs_read+0x113/0x130
Dec 05 08:00:10 x200 kernel: ? vfs_read+0x113/0x130
Dec 05 08:00:10 x200 kernel: ? __do_sys_finit_module+0xe9/0x110
Dec 05 08:00:10 x200 kernel: __do_sys_finit_module+0xe9/0x110
Dec 05 08:00:10 x200 kernel: do_syscall_64+0x55/0x110
Dec 05 08:00:10 x200 kernel: entry_SYSCALL_64_after_hwframe+0x44/0xa9
Dec 05 08:00:10 x200 kernel: RIP: 0033:0x7fa11696ea79
Dec 05 08:00:10 x200 kernel: Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f
40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f
05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d df 43 0c 00 f7 d8 64 89 01 48
Dec 05 08:00:10 x200 kernel: RSP: 002b:00007ffc86db6728 EFLAGS: 00000246
ORIG_RAX: 0000000000000139
Dec 05 08:00:10 x200 kernel: RAX: ffffffffffffffda RBX: 0000559ef1eefd00 RCX:
00007fa11696ea79
Dec 05 08:00:10 x200 kernel: RDX: 0000000000000000 RSI: 00007fa116874cad RDI:
0000000000000011
Dec 05 08:00:10 x200 kernel: RBP: 00007fa116874cad R08: 0000000000000000 R09:
0000000000000000
Dec 05 08:00:10 x200 kernel: R10: 0000000000000011 R11: 0000000000000246 R12:
0000000000000000
Dec 05 08:00:10 x200 kernel: R13: 0000559ef1ed6430 R14: 0000000000020000 R15:
0000559ef1eefd00
Dec 05 08:00:10 x200 kernel: Modules linked in: arc4 ath9k ath9k_common
ath9k_hw coretemp ath kvm_intel snd_hda_codec_conexant snd_hda_codec_generic
kvm irqbypass i915(+) mac80211 evdev snd_hda_intel sg drm_kms_helper
snd_hda_codec iTCO_wdt serio_raw iTCO_vendor_support thinkpad_acpi snd_hda_core
drm cfg80211 snd_hwdep snd_pcm i2c_algo_bit snd_timer nvram snd soundcore
rfkill ac battery video pcc_cpufreq acpi_cpufreq button parport_pc ppdev lp
parport ip_tables x_tables autofs4 btrfs xor zstd_decompress zstd_compress
xxhash raid6_pq libcrc32c crc32c_generic ecb crypto_simd cryptd glue_helper
aes_x86_64 xts algif_skcipher af_alg dm_crypt dm_mod sd_mod ahci psmouse
libahci libata i2c_i801 scsi_mod lpc_ich ehci_pci uhci_hcd ehci_hcd thermal
e1000e usbcore usb_common
Dec 05 08:00:10 x200 kernel: CR2: 0000000000000008
Dec 05 08:00:10 x200 kernel: ---[ end trace 12fb00c23be607b4 ]---
Dec 05 08:00:10 x200 kernel: RIP: 0010:gen4_render_ring_flush+0x55/0xf0 [i915]
Dec 05 08:00:10 x200 kernel: Code: 00 be 16 00 00 00 48 89 ef e8 87 fe ff ff 48
3d 00 f0 ff ff 77 69 89 18 c7 40 04 02 40 00 7a 48 8b 55 78 48 8b 92 10 02 00
00 <48> 8b 52 08 48 c7 40 0c 00 00 00 00 83 ca 04 89 50 08 48 8d 50 14
Dec 05 08:00:10 x200 kernel: RSP: 0018:ffffa814811b7a88 EFLAGS: 00010287
Dec 05 08:00:10 x200 kernel: RAX: ffffa814903ed000 RBX: 0000000002000022 RCX:
000000000001ff68
Dec 05 08:00:10 x200 kernel: RDX: 0000000000000000 RSI: 00000000000001a8 RDI:
0000000000000150
Dec 05 08:00:10 x200 kernel: RBP: ffff9b9ce3b57d40 R08: 0000000000000001 R09:
0000000000000002
Dec 05 08:00:10 x200 kernel: R10: ffffa814811b7a58 R11: 0000000000000000 R12:
ffff9b9ce2340000
Dec 05 08:00:10 x200 kernel: R13: ffff9b9ce44ea600 R14: 0000000000000000 R15:
ffff9b9ce3b57d40
Dec 05 08:00:10 x200 kernel: FS: 00007fa115f0a8c0(0000)
GS:ffff9b9cefd00000(0000) knlGS:0000000000000000
Dec 05 08:00:10 x200 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 05 08:00:10 x200 kernel: CR2: 0000000000000008 CR3: 0000000220f7c000 CR4:
00000000000406e0
<SNIP>
I'm running Debian Buster on a Taurinus X200 (Lenovo x200, with
libreboot.) Let me know if there's any more info I can provide.
I tested some upstream stable kernels and can report that the bug is
not present in v4.18.19 and is present in v4.18.20.
* a9da8725b7a7 (tag: v4.18.20) Linux 4.18.20
* 6559b2338d96 (tag: v4.18.19) Linux 4.18.19
Specifically This seems to fix v4.18.20 for me:
<span class="quote">> commit e0790ccfd489d46c0eeed32a8c4443b9b2119766 (HEAD -> test)
> Author: Philip J Freeman <<a href="mailto:elektron@halo.nu">elektron@halo.nu</a>>
> Date: Fri Dec 7 16:02:46 2018 -0800
>
> Revert "drm/i915/ringbuffer: Delay after EMIT_INVALIDATE for gen4/gen5"
>
> This reverts commit 06e562e7f515292ea7721475950f23554214adde.</span >
></pre>
</div>
</p>
<hr>
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<ul>
<li>You are the assignee for the bug.</li>
<li>You are on the CC list for the bug.</li>
<li>You are the QA Contact for the bug.</li>
</ul>
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