Comment 0 for bug 1854156

When connecting bg-open wifi, the system will freeze.

Hardware: Dell Precision 5720 AIO (CID 201701-25364)
Kernel: 4.4.0-170-generic #199-Ubuntu SMP Thu Nov 14 01:45:04 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Image: pre-installed image (xenial 4.4 based)

[Steps to Reproduce]
1. install the target image
2. when the system is ready, connect to wifi(bg-open channel) over network-manager applet.

[Expected Result]
Connection established

[Actual Result]
System freezed

[Reproducing Rate]
100% (5 out of 5)

[Additional Info]
I was sometimes able to catch the following kernel oops

Nov 27 18:40:01 201701-25364 kernel: [ 600.497340] ------------[ cut here ]------------
Nov 27 18:40:01 201701-25364 kernel: [ 600.497345] WARNING: CPU: 0 PID: 30 at /build/linux-AweC5P/linux-4.4.0/block/blk-mq.c:794 __blk_mq_run_hw_queue+0x305/0x3a0()
Nov 27 18:40:01 201701-25364 kernel: [ 600.497346] Modules linked in: nvram msr rfcomm cmac bnep uvcvideo videobuf2_vmalloc videobuf2_memops btusb videobuf2_v4l2 videobuf2_core btrtl v4l2_common btbcm btintel videodev bluetooth m
edia ecdh_generic input_leds joydev hid_multitouch arc4 dell_led i2c_designware_platform i2c_designware_core dell_wmi snd_hda_codec_realtek(OE) sparse_keymap snd_hda_codec_generic(OE) i915_bpo dcdbas dell_smm_hwmon intel_ips drm_k
ms_helper intel_rapl x86_pkg_temp_thermal iwlmvm(OE) intel_powerclamp coretemp drm kvm_intel mac80211(OE) i2c_algo_bit fb_sys_fops syscopyarea kvm sysfillrect sysimgblt snd_hda_intel(OE) snd_hda_codec(OE) irqbypass snd_hda_core(OE
) crct10dif_pclmul crc32_pclmul snd_hwdep ghash_clmulni_intel aesni_intel aes_x86_64 lrw snd_pcm gf128mul iwlwifi(OE) glue_helper ablk_helper cryptd snd_seq_midi snd_seq_midi_event cfg80211(OE) snd_rawmidi snd_seq serio_raw snd_se
q_device snd_timer rtsx_pci_ms compat(OE) snd memstick idma64 soundcore virt_dma mei_me intel_lpss_pci mei shpchp intel_lpss 8250_fintek mac_hid acpi_pad parport_pc ppdev lp parport autofs4 btrfs xor raid6_pq dm_mirror dm_region_h
ash dm_log hid_generic usbhid hid mmc_block uas usb_storage rtsx_pci_sdmmc psmouse e1000e ptp pps_core rtsx_pci ahci nvme libahci wmi video fjes
Nov 27 18:40:01 201701-25364 kernel: [ 600.497418] CPU: 0 PID: 30 Comm: kworker/4:0H Tainted: G OE 4.4.0-170-generic #199-Ubuntu
Nov 27 18:40:01 201701-25364 kernel: [ 600.497419] Hardware name: Dell Inc. Precision 5720 AIO/, BIOS 2.3.6 01/31/2018
Nov 27 18:40:01 201701-25364 kernel: [ 600.497421] Workqueue: kblockd blk_mq_run_work_fn
Nov 27 18:40:01 201701-25364 kernel: [ 600.497422] 0000000000000286 3b6f2186023dc8e9 ffff8808394dbd30 ffffffff8140cde1
Nov 27 18:40:01 201701-25364 kernel: [ 600.497424] 0000000000000000 ffffffff81d07a88 ffff8808394dbd68 ffffffff81086492
Nov 27 18:40:01 201701-25364 kernel: [ 600.497425] ffff880831d52400 ffff8808394dbda0 ffff88085dd15f80 ffff88085dd1b400
Nov 27 18:40:01 201701-25364 kernel: [ 600.497427] Call Trace:
Nov 27 18:40:01 201701-25364 kernel: [ 600.497430] [<ffffffff8140cde1>] dump_stack+0x63/0x82
Nov 27 18:40:01 201701-25364 kernel: [ 600.497433] [<ffffffff81086492>] warn_slowpath_common+0x82/0xc0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497435] [<ffffffff810865da>] warn_slowpath_null+0x1a/0x20
Nov 27 18:40:01 201701-25364 kernel: [ 600.497436] [<ffffffff813e8305>] __blk_mq_run_hw_queue+0x305/0x3a0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497439] [<ffffffff81862441>] ? __schedule+0x301/0x810
Nov 27 18:40:01 201701-25364 kernel: [ 600.497440] [<ffffffff8186244d>] ? __schedule+0x30d/0x810
Nov 27 18:40:01 201701-25364 kernel: [ 600.497441] [<ffffffff81862441>] ? __schedule+0x301/0x810
Nov 27 18:40:01 201701-25364 kernel: [ 600.497443] [<ffffffff813e8742>] blk_mq_run_work_fn+0x12/0x20
Nov 27 18:40:01 201701-25364 kernel: [ 600.497445] [<ffffffff810a0c5b>] process_one_work+0x16b/0x4e0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497446] [<ffffffff810a101e>] worker_thread+0x4e/0x590
Nov 27 18:40:01 201701-25364 kernel: [ 600.497447] [<ffffffff810a0fd0>] ? process_one_work+0x4e0/0x4e0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497449] [<ffffffff810a76f7>] kthread+0xe7/0x100
Nov 27 18:40:01 201701-25364 kernel: [ 600.497450] [<ffffffff81862441>] ? __schedule+0x301/0x810
Nov 27 18:40:01 201701-25364 kernel: [ 600.497452] [<ffffffff810a7610>] ? kthread_create_on_node+0x1e0/0x1e0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497454] [<ffffffff818677a5>] ret_from_fork+0x55/0x80
Nov 27 18:40:01 201701-25364 kernel: [ 600.497456] [<ffffffff810a7610>] ? kthread_create_on_node+0x1e0/0x1e0
Nov 27 18:40:01 201701-25364 kernel: [ 600.497457] ---[ end trace 87c55fce1375aae8 ]---

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-170-generic 4.4.0-170.199
ProcVersionSignature: Ubuntu 4.4.0-170.199-generic 4.4.200
Uname: Linux 4.4.0-170-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.21
Architecture: amd64
Date: Wed Nov 27 20:34:01 2019
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-xenial-amd64-20160624-2
InstallationDate: Installed on 2019-11-27 (0 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
SourcePackage: linux-signed
UpgradeStatus: No upgrade log present (probably fresh install)