Bug 196399 - WARNING at net/sched/sch_generic.c:316 dev_watchdog[...] when suspending
Summary: WARNING at net/sched/sch_generic.c:316 dev_watchdog[...] when suspending
Status: NEEDINFO
Alias: None
Product: Networking
Classification: Unclassified
Component: Other (show other bugs)
Hardware: All Linux
: P1 low
Assignee: Stephen Hemminger
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-07-17 08:34 UTC by Martin Peres
Modified: 2019-05-22 14:43 UTC (History)
4 users (show)

See Also:
Kernel Version: 4.11+
Tree: Mainline
Regression: Yes


Attachments

Description Martin Peres 2017-07-17 08:34:16 UTC
Hello,

We have found out that since at least 4.11-rc1, some machines in the Intel GFX CI lab have been generating the following warning when suspending to s4 (suspend to disk):

[  287.212825] ------------[ cut here ]------------
[  287.212829] WARNING: CPU: 0 PID: 3165 at net/sched/sch_generic.c:316 dev_watchdog+0x218/0x220
[  287.212830] Modules linked in: mcs7830 usbnet mii snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic i915 x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul snd_hda_intel snd_hda_codec snd_hwdep ghash_clmulni_intel snd_hda_core snd_pcm i2c_designware_platform i2c_designware_core mei_me mei prime_numbers i2c_hid pinctrl_sunrisepoint pinctrl_intel
[  287.212864] CPU: 0 PID: 3165 Comm: gem_exec_suspen Tainted: G     U          4.12.0-CI-CI_DRM_2829+ #1
[  287.212865] Hardware name: Dell Inc. XPS 13 9360/093TW6, BIOS 1.3.2 01/18/2017
[  287.212867] task: ffff8801b4084f40 task.stack: ffffc900001d8000
[  287.212869] RIP: 0010:dev_watchdog+0x218/0x220
[  287.212870] RSP: 0018:ffff88027e403e38 EFLAGS: 00010292
[  287.212872] RAX: 000000000000005a RBX: 0000000000000000 RCX: 0000000000000000
[  287.212874] RDX: 0000000000000002 RSI: ffffffff81cbcf89 RDI: ffffffff81c9c627
[  287.212875] RBP: ffff88027e403e68 R08: 0000000000000000 R09: 0000000000000001
[  287.212876] R10: 0000000028e9c215 R11: 0000000000000000 R12: ffff88026e08a848
[  287.212877] R13: 0000000000000000 R14: ffff88026e050020 R15: 0000000000000001
[  287.212878] FS:  00007f345056a8c0(0000) GS:ffff88027e400000(0000) knlGS:0000000000000000
[  287.212880] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  287.212881] CR2: 00000000008d7008 CR3: 00000001b4314000 CR4: 00000000003406f0
[  287.212882] Call Trace:
[  287.212883]  <IRQ>
[  287.212886]  ? qdisc_rcu_free+0x40/0x40
[  287.212888]  ? qdisc_rcu_free+0x40/0x40
[  287.212891]  call_timer_fn+0x8e/0x370
[  287.212894]  ? qdisc_rcu_free+0x40/0x40
[  287.212896]  expire_timers+0x150/0x1f0
[  287.212899]  run_timer_softirq+0x7c/0x160
[  287.212903]  __do_softirq+0x116/0x4a0
[  287.212906]  irq_exit+0xa9/0xc0
[  287.212909]  smp_apic_timer_interrupt+0x38/0x50
[  287.212912]  apic_timer_interrupt+0x90/0xa0
[  287.212914] RIP: 0010:delay_tsc+0x33/0xc0
[  287.212916] RSP: 0018:ffffc900001dbcd8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
[  287.212918] RAX: 0000000080000000 RBX: 00000005964f23a0 RCX: 0000000000000001
[  287.212919] RDX: 0000000080000001 RSI: ffffffff81c8e23a RDI: 00000000ffffffff
[  287.212920] RBP: ffffc900001dbcf8 R08: 0000000000000000 R09: 0000000000000001
[  287.212921] R10: 0000000000000000 R11: 0000000000000000 R12: 000000059633478e
[  287.212922] R13: 0000000000249f13 R14: 0000000000000000 R15: ffff880272eac008
[  287.212924]  </IRQ>
[  287.212929]  ? delay_tsc+0x6b/0xc0
[  287.212932]  __delay+0xa/0x10
[  287.212934]  __const_udelay+0x31/0x40
[  287.212936]  hibernation_debug_sleep+0x20/0x30
[  287.212938]  hibernation_snapshot+0x2bc/0x5f0
[  287.212940]  hibernate+0x159/0x2f0
[  287.212943]  state_store+0xe0/0xf0
[  287.212947]  kobj_attr_store+0xf/0x20
[  287.212949]  sysfs_kf_write+0x40/0x50
[  287.212951]  kernfs_fop_write+0x130/0x1b0
[  287.212955]  __vfs_write+0x23/0x120
[  287.212957]  ? rcu_read_lock_sched_held+0x75/0x80
[  287.212959]  ? rcu_sync_lockdep_assert+0x2a/0x50
[  287.212961]  ? __sb_start_write+0xfa/0x1f0
[  287.212964]  vfs_write+0xc5/0x1d0
[  287.212966]  ? trace_hardirqs_on_caller+0xe7/0x1c0
[  287.212969]  SyS_write+0x44/0xb0
[  287.212972]  entry_SYSCALL_64_fastpath+0x1c/0xb1
[  287.212973] RIP: 0033:0x7f344ed4a4a0
[  287.212974] RSP: 002b:00007ffef50dfaa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  287.212977] RAX: ffffffffffffffda RBX: ffffffff81470683 RCX: 00007f344ed4a4a0
[  287.212978] RDX: 0000000000000004 RSI: 000000000041d211 RDI: 0000000000000006
[  287.212979] RBP: ffffc900001dbf88 R08: 00000000008d6a50 R09: 0000000000000000
[  287.212980] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000041d211
[  287.212981] R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
[  287.212984]  ? __this_cpu_preempt_check+0x13/0x20
[  287.212988] Code: 63 8e 18 04 00 00 eb 93 4c 89 f7 c6 05 77 5c 77 00 01 e8 dc 7f fd ff 89 d9 48 89 c2 4c 89 f6 48 c7 c7 18 f4 cf 81 e8 f1 c4 9d ff <0f> ff eb c3 0f 1f 40 00 48 c7 47 08 00 00 00 00 55 48 c7 07 00 
[  287.213051] ---[ end trace b6016dcc7544a681 ]---

This is caught while running the intel-gpu-tools test named 'igt@gem_exec_suspend@basic-s4-devices' on the following machines:

 - Intel Kaby Lake-R RVP: Failure rate 123/135 run(s) (91%), last occurence: https://intel-gfx-ci.01.org/CI/CI_DRM_2828/fi-kbl-r/igt@gem_exec_suspend@basic-s4-devices.html
 - Intel Kaby Lake i7-7560u: Failure rate 196/305 run(s) (64%), last occurence: https://intel-gfx-ci.01.org/CI/CI_DRM_2827/fi-kbl-7560u/igt@gem_exec_suspend@basic-s4-devices.html 
 - Intel Skylake i7-6600u: Failure rate 23/75 run(s) (30%), last occurence: https://intel-gfx-ci.01.org/CI/CI_DRM_2824/fi-skl-6600u/igt@gem_exec_suspend@basic-s4-devices.html
 - Intel Sandy Bridge i7-2600: Failure rate 10/293 run(s) (3%), last occurence: https://intel-gfx-ci.01.org/CI/CI_DRM_2816/fi-snb-2600/igt@gem_exec_suspend@basic-s4-devices.html 

We have plenty of other machines that do not trigger this warning at all.

The bug used to live in fd.o's bugzilla, but it had no business being there: https://bugs.freedesktop.org/show_bug.cgi?id=100125

Let me know if I can help in some ways.
Comment 1 Martin Peres 2017-10-05 09:10:55 UTC
It was fixed. Let's close this bug.
Comment 2 Martin Peres 2017-11-27 16:43:52 UTC
It was never fixed, I apparently just had forgotten about our CI system carrying this extra patch: https://cgit.freedesktop.org/drm/drm-intel/commit/?h=topic/core-for-CI&id=d576dd33ecc7238e4dee92baca89d9c5e3543a44

Sorry for the noise!
Comment 3 Stephen Hemminger 2017-11-27 16:59:47 UTC
That patch is just a "shoot the messenger"

The root cause is a driver bug for what every network device you are using.
That information is not present in this bug report.
Comment 4 Martin Peres 2017-11-28 02:10:28 UTC
(In reply to Stephen Hemminger from comment #3)
> That patch is just a "shoot the messenger"

It absolutely is. I wrote this bug report immediately, but development team could not wait for the fixes to come upstream, so a developer just proposed to land this patch while we were waiting for comments. Then we got bigger fishes to fry and the bug has just rotten to the point where I even thought it was not a problem anymore... Shame on us!

> 
> The root cause is a driver bug for what every network device you are using.
> That information is not present in this bug report.

Fair enough, and the links I provided are all dead because we ran out of space on the server providing test results... Who would have thought that we would generate TB of datas per month...

Anyway, here is the information about a couple of hosts that exhibit the issue:

 - https://intel-gfx-ci.01.org/hardware/fi-snb-2600/
 - https://intel-gfx-ci.01.org/hardware/fi-skl-6600u/
 - https://intel-gfx-ci.01.org/hardware/fi-kbl-7560u/

I will try to verify tomorrow that it is still a problem on newer kernels than 4.11-rc5 (4.15).

Thanks!
Comment 5 Martin Peres 2017-11-29 12:05:47 UTC
Sorry for the slight delay. I managed to get some more recent results on a 4.15.0-rc1 base, and got 2 out of our 30 machines to reproduce the problem:

 - Skylake: https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_1460/fi-skl-6600u/igt@gem_exec_suspend@basic-s4-devices.html

 - Kabylake: https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_1460/fi-kbl-r/igt@gem_exec_suspend@basic-s4-devices.html

Check out the boot0 link to get the boot kernel logs, and dmesg0 for the kernel logs that happened during the execution of our testsuite. Sorry about the i915 spamming in the logs, it hopefully is not too annoying for you.
Comment 6 Stephen Hemminger 2017-11-29 17:46:13 UTC
*** Bug 198027 has been marked as a duplicate of this bug. ***
Comment 7 Daniel Vetter 2018-06-26 08:07:57 UTC
Just wanted to throw this out from our pile of hacks, but we're still hitting this:

[  224.739686] ------------[ cut here ]------------
[  224.739712] WARNING: CPU: 3 PID: 2982 at net/sched/sch_generic.c:461 dev_watchdog+0x1fd/0x210
[  224.739714] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_pcm i915 asix usbnet mii mei_me mei prime_numbers i2c_hid pinctrl_sunrisepoint pinctrl_intel btusb btrtl btbcm btintel bluetooth ecdh_generic
[  224.739775] CPU: 3 PID: 2982 Comm: gem_exec_suspen Tainted: G     U  W         4.18.0-rc2-CI-Patchwork_9414+ #1
[  224.739777] Hardware name: Dell Inc. XPS 13 9350/, BIOS 1.4.12 11/30/2016
[  224.739780] RIP: 0010:dev_watchdog+0x1fd/0x210
[  224.739781] Code: 49 63 4c 24 f0 eb 92 4c 89 ef c6 05 21 46 ad 00 01 e8 77 ee fc ff 89 d9 48 89 c2 4c 89 ee 48 c7 c7 88 4c 14 82 e8 a3 fe 84 ff <0f> 0b eb be 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 c7 47
[  224.739866] RSP: 0018:ffff88027dd83e40 EFLAGS: 00010286
[  224.739869] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000102
[  224.739871] RDX: 0000000080000102 RSI: ffffffff820c8c6c RDI: 00000000ffffffff
[  224.739873] RBP: ffff8802644c1540 R08: 0000000071be9b33 R09: 0000000000000000
[  224.739874] R10: ffff88027dd83dc0 R11: 0000000000000000 R12: ffff8802644c1588
[  224.739876] R13: ffff8802644c1160 R14: 0000000000000001 R15: ffff88026a5dc728
[  224.739878] FS:  00007f18f4887980(0000) GS:ffff88027dd80000(0000) knlGS:0000000000000000
[  224.739880] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  224.739881] CR2: 00007f4c627ae548 CR3: 000000022ca1a002 CR4: 00000000003606e0
[  224.739883] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  224.739885] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  224.739886] Call Trace:
[  224.739888]  <IRQ>
[  224.739892]  ? qdisc_reset+0xe0/0xe0
[  224.739894]  ? qdisc_reset+0xe0/0xe0
[  224.739897]  call_timer_fn+0x93/0x360
[  224.739903]  expire_timers+0xc1/0x1d0
[  224.739908]  run_timer_softirq+0xc7/0x170
[  224.739916]  __do_softirq+0xd9/0x505
[  224.739923]  irq_exit+0xa9/0xc0
[  224.739926]  smp_apic_timer_interrupt+0x9c/0x2d0
[  224.739929]  apic_timer_interrupt+0xf/0x20
[  224.739931]  </IRQ>
[  224.739934] RIP: 0010:delay_tsc+0x2e/0xb0
[  224.739936] Code: 49 89 fc 55 53 bf 01 00 00 00 e8 6d 2c 78 ff e8 88 9d b6 ff 41 89 c5 0f ae e8 0f 31 48 c1 e2 20 48 09 c2 48 89 d5 eb 16 f3 90 <bf> 01 00 00 00 e8 48 2c 78 ff e8 63 9d b6 ff 44 39 e8 75 36 0f ae
[  224.740021] RSP: 0018:ffffc900002f7d48 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
[  224.740024] RAX: 0000000080000000 RBX: 0000000649565ca9 RCX: 0000000000000001
[  224.740026] RDX: 0000000080000001 RSI: ffffffff820c8c6c RDI: 00000000ffffffff
[  224.740027] RBP: 00000006493ea9ce R08: 000000005e81e2ee R09: 0000000000000000
[  224.740029] R10: 0000000000000120 R11: 0000000000000000 R12: 00000000002ad8d6
[  224.740030] R13: 0000000000000003 R14: 0000000000000004 R15: ffff88025caf5408
[  224.740040]  ? delay_tsc+0x66/0xb0
[  224.740045]  hibernation_debug_sleep+0x1c/0x30
[  224.740048]  hibernation_snapshot+0x2c1/0x690
[  224.740053]  hibernate+0x142/0x2a4
[  224.740057]  state_store+0xd0/0xe0
[  224.740063]  kernfs_fop_write+0x104/0x190
[  224.740068]  __vfs_write+0x31/0x180
[  224.740072]  ? rcu_read_lock_sched_held+0x6f/0x80
[  224.740075]  ? rcu_sync_lockdep_assert+0x29/0x50
[  224.740078]  ? __sb_start_write+0x152/0x1f0
[  224.740080]  ? __sb_start_write+0x168/0x1f0
[  224.740084]  vfs_write+0xbd/0x1a0
[  224.740088]  ksys_write+0x50/0xc0
[  224.740094]  do_syscall_64+0x55/0x190
[  224.740097]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  224.740099] RIP: 0033:0x7f18f400a281
[  224.740100] Code: c3 0f 1f 84 00 00 00 00 00 48 8b 05 59 8d 20 00 c3 0f 1f 84 00 00 00 00 00 8b 05 8a d1 20 00 85 c0 75 16 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 57 f3 c3 0f 1f 44 00 00 41 54 55 49 89 d4 53
[  224.740186] RSP: 002b:00007fffd1f4fec8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  224.740189] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f18f400a281
[  224.740190] RDX: 0000000000000004 RSI: 00007f18f448069a RDI: 0000000000000006
[  224.740192] RBP: 00007fffd1f4fef0 R08: 0000000000000000 R09: 0000000000000000
[  224.740194] R10: 0000000000000000 R11: 0000000000000246 R12: 000055e795d03400
[  224.740195] R13: 00007fffd1f50500 R14: 0000000000000000 R15: 0000000000000000
[  224.740205] irq event stamp: 1582591
[  224.740207] hardirqs last  enabled at (1582590): [<ffffffff810f9f9c>] vprintk_emit+0x4bc/0x4d0
[  224.740210] hardirqs last disabled at (1582591): [<ffffffff81a0111c>] error_entry+0x7c/0x100
[  224.740212] softirqs last  enabled at (1582568): [<ffffffff81c0034f>] __do_softirq+0x34f/0x505
[  224.740215] softirqs last disabled at (1582571): [<ffffffff8108c959>] irq_exit+0xa9/0xc0
[  224.740218] WARNING: CPU: 3 PID: 2982 at net/sched/sch_generic.c:461 dev_watchdog+0x1fd/0x210
[  224.740219] ---[ end trace 6e41d690e611c338 ]---
Comment 9 Lakshminarayana Vudum 2018-08-31 05:06:48 UTC
Stephen, Any updates on this bug.
Comment 10 Stephen Hemminger 2018-08-31 15:07:27 UTC
It is most likely a network device suspend/resume
bug.  Figure out what device it is, look in kernel MAINTAINERS file and
email them (and netdev@vger.kernel.org). Kernel Bugzilla is not really
used by network developers.
Comment 11 Lakshminarayana Vudum 2018-09-07 12:01:24 UTC
Email sent to Oliver Neukum, netdev@vger.kernel.org.
Device details:
0b95:7720 ASIX Electronics Corp. AX88772
USB network card
driver seems to be usbnet
Comment 12 Lakshminarayana Vudum 2019-02-14 09:29:43 UTC
Last seen this issue on our CI systems CI_DRM_4376 (7 months, 3 weeks / 4365 runs ago). Since this issue was seen 7 months ago, can we close this issue?
Comment 13 Martin Peres 2019-04-04 07:00:04 UTC
(In reply to Stephen Hemminger from comment #10)
> It is most likely a network device suspend/resume
> bug.  Figure out what device it is, look in kernel MAINTAINERS file and
> email them (and netdev@vger.kernel.org). Kernel Bugzilla is not really
> used by network developers.

Thanks, this is exactly what we should have been doing a while ago...

So, here is the plan of action for the developer that will take care of this issue:
 - Send a revert of https://cgit.freedesktop.org/drm/drm-intel/commit/?h=topic/core-for-CI&id=d576dd33ecc7238e4dee92baca89d9c5e3543a44
 - Follow Stephen's recommendation
 - Make sure a patch lands
 - Done!
Comment 14 Arek Hiler 2019-05-06 10:13:37 UTC
I have done a two round of revert and it seems fine:
https://lists.freedesktop.org/archives/intel-gfx-trybot/2019-April/thread.html#70131

Now we need someone that can push to drm-tip's topic/core-for-CI to remove the hax.

Daniel?
Comment 15 Martin Peres 2019-05-22 14:42:21 UTC
(In reply to Arek Hiler from comment #14)
> I have done a two round of revert and it seems fine:
> https://lists.freedesktop.org/archives/intel-gfx-trybot/2019-April/thread.
> html#70131
> 
> Now we need someone that can push to drm-tip's topic/core-for-CI to remove
> the hax.
> 
> Daniel?

The fun is still going on fi-icl-dsi: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_6118/fi-icl-dsi/dmesg0.log

<4>[  108.016259] ------------[ cut here ]------------
<6>[  108.016363] NETDEV WATCHDOG: enx000acd289764 (ax88179_178a): transmit queue 0 timed out
<4>[  108.016397] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:447 dev_watchdog+0x2b3/0x2f0
<4>[  108.016401] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic mei_hdcp i915 x86_pkg_temp_thermal coretemp crct10dif_pclmul snd_hda_intel crc32_pclmul snd_hda_codec snd_hwdep ghash_clmulni_intel e1000e snd_hda_core snd_pcm ptp ax88179_178a pps_core usbnet mii mei_me mei prime_numbers
<4>[  108.016444] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G     U            5.2.0-rc1-CI-CI_DRM_6118+ #1
<4>[  108.016449] Hardware name: Intel Corporation Ice Lake Client Platform/IceLake Y LPDDR4x T4 RVP TLC, BIOS ICLSFWR1.R00.3102.A00.1903052247 03/05/2019
<4>[  108.016455] RIP: 0010:dev_watchdog+0x2b3/0x2f0
<4>[  108.016461] Code: 77 ff e9 42 ff ff ff 4c 89 f7 c6 05 ca 3d a8 00 01 e8 e1 57 fc ff 89 d9 48 89 c2 4c 89 f6 48 c7 c7 c8 8a 14 82 e8 3d cf 81 ff <0f> 0b e9 25 ff ff ff e8 21 45 8a ff 85 c0 75 b6 48 c7 c2 28 5d 07
<4>[  108.016466] RSP: 0018:ffffc90000003e30 EFLAGS: 00010282
<4>[  108.016472] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
<4>[  108.016476] RDX: 0000000000000000 RSI: ffffffff822180a0 RDI: 00000000ffffffff
<4>[  108.016481] RBP: ffff88828f9237e0 R08: 0000000078796510 R09: 0000000000000000
<4>[  108.016485] R10: ffffc90000003db0 R11: 0000000000000000 R12: ffff88828f923830
<4>[  108.016489] R13: 0000000000000000 R14: ffff88828f923400 R15: ffff88828f832b98
<4>[  108.016494] FS:  0000000000000000(0000) GS:ffff88829be00000(0000) knlGS:0000000000000000
<4>[  108.016499] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[  108.016503] CR2: 0000559a66cd0af8 CR3: 0000000005210003 CR4: 0000000000760ef0
<4>[  108.016508] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
<4>[  108.016512] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
<4>[  108.016516] PKRU: 55555554
<4>[  108.016520] Call Trace:
<4>[  108.016525]  <IRQ>
<4>[  108.016533]  ? qdisc_destroy+0x110/0x110
<4>[  108.016541]  call_timer_fn+0x98/0x2f0
<4>[  108.016548]  ? qdisc_destroy+0x110/0x110
<4>[  108.016554]  expire_timers+0xdc/0x1b0
<4>[  108.016563]  run_timer_softirq+0xc7/0x170
<4>[  108.016576]  __do_softirq+0xd8/0x4b9
<4>[  108.016596]  irq_exit+0xa9/0xc0
<4>[  108.016603]  smp_apic_timer_interrupt+0x9c/0x250
<4>[  108.016611]  apic_timer_interrupt+0xf/0x20
<4>[  108.016616]  </IRQ>
<4>[  108.016623] RIP: 0010:cpuidle_enter_state+0xae/0x450
<4>[  108.016629] Code: 44 00 00 31 ff e8 d2 62 92 ff 45 84 f6 74 12 9c 58 f6 c4 02 0f 85 78 03 00 00 31 ff e8 3b 45 99 ff e8 66 46 9d ff fb 45 85 ed <0f> 88 c9 02 00 00 4c 2b 24 24 48 ba cf f7 53 e3 a5 9b c4 20 49 63
<4>[  108.016633] RSP: 0018:ffffffff82203e58 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
<4>[  108.016639] RAX: ffffffff82217800 RBX: ffffffff822a1e40 RCX: 0000000000000000
<4>[  108.016643] RDX: 0000000000000046 RSI: 0000000000000006 RDI: ffffffff8212d1b9
<4>[  108.016647] RBP: ffff8882977adfa8 R08: 0000000000000000 R09: 0000000000000000
<4>[  108.016650] R10: 0000000000000000 R11: 0000000000000000 R12: 0000001926403514
<4>[  108.016654] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000003
<4>[  108.016681]  ? cpuidle_enter_state+0xaa/0x450
<4>[  108.016694]  cpuidle_enter+0x24/0x40
<4>[  108.016704]  do_idle+0x1f3/0x260
<4>[  108.016718]  cpu_startup_entry+0x14/0x20
<4>[  108.016727]  start_kernel+0x4b6/0x4d8
<4>[  108.016738]  secondary_startup_64+0xa4/0xb0
<4>[  108.016755] irq event stamp: 1110527
<4>[  108.016763] hardirqs last  enabled at (1110526): [<ffffffff81128635>] vprintk_emit+0x315/0x340
<4>[  108.016769] hardirqs last disabled at (1110527): [<ffffffff810019e0>] trace_hardirqs_off_thunk+0x1a/0x1c
<4>[  108.016776] softirqs last  enabled at (1110502): [<ffffffff810b6268>] irq_enter+0x58/0x60
<4>[  108.016782] softirqs last disabled at (1110503): [<ffffffff810b6319>] irq_exit+0xa9/0xc0
<4>[  108.016788] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:447 dev_watchdog+0x2b3/0x2f0
<4>[  108.016792] ---[ end trace b815283152d81882 ]---
Comment 16 Martin Peres 2019-05-22 14:43:25 UTC
For context, the above backtrace happened immediately after removing the following patch: https://cgit.freedesktop.org/drm/drm-intel/commit/?h=topic/core-for-CI&id=d576dd33ecc7238e4dee92baca89d9c5e3543a44

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