Warning message and call trace in kernel log with kernel 4.8

[Donuts]

Host: VirtualBox 5.1.6, Lubuntu 16.04 x86-64 with kernel 4.8 from ​http://kernel.ubuntu.com/~kernel-ppa/mainline/

There is a warning and call trace in dmesg output when I boot the system with Linux kernel 4.8. Doesn't happen with kernel 4.7.6.

VirtualBox still seems to work fine when I run it, and it's not clear exactly what the warning is about. But maybe this is something that could/should be fixed?

Part of dmesg output:

[    5.340716] ------------[ cut here ]------------
[    5.340757] WARNING: CPU: 0 PID: 873 at ./include/linux/cpumask.h:121 VBoxHost_RTMpGetSet+0x85/0x90 [vboxdrv]
[    5.340758] Modules linked in: vboxdrv(OE+) nvidia_uvm(POE) joydev snd_hda_codec_hdmi snd_hda_codec_idt gpio_ich snd_hda_codec_generic snd_hda_intel snd_hda_codec dell_wmi sparse_keymap snd_hda_core snd_hwdep dell_rbtn dell_laptop dell_smbios snd_pcm dcdbas snd_seq_midi coretemp snd_seq_midi_event arc4 dell_smm_hwmon nvidia(POE) snd_rawmidi pcmcia kvm_intel kvm irqbypass iwl3945 iwlegacy snd_seq serio_raw mac80211 snd_seq_device snd_timer sg cfg80211 lpc_ich yenta_socket pcmcia_rsrc pcmcia_core rfkill drm snd soundcore shpchp evdev wmi battery ac acpi_cpufreq parport_pc ppdev lp parport autofs4 ext4 crc16 jbd2 fscrypto mbcache hid_generic usbhid hid psmouse ata_generic ahci libahci pata_acpi firewire_ohci firewire_core tg3 crc_itu_t ptp pps_core thermal video button
[    5.340807] CPU: 0 PID: 873 Comm: modprobe Tainted: P           OE   4.8.0-040800-generic #201610022031
[    5.340808] Hardware name: Dell Inc. Latitude D830                   /0HN338, BIOS A17 06/19/2013
[    5.340810]  0000000000000286 000000003ab118e1 ffffffffa135aec4 0000000000000000
[    5.340813]  0000000000000000 ffffffffa107f8ae 0000000000001fff ffff8e1697307b88
[    5.340815]  ffff8e1697307b98 00000000000007c8 ffff8e1697307ec0 ffffffffc1207f40
[    5.340817] Call Trace:
[    5.340823]  [<ffffffffa135aec4>] ? dump_stack+0x5c/0x78
[    5.340827]  [<ffffffffa107f8ae>] ? __warn+0xbe/0xe0
[    5.340845]  [<ffffffffc11db265>] ? VBoxHost_RTMpGetSet+0x85/0x90 [vboxdrv]
[    5.340862]  [<ffffffffc11ed666>] ? VBoxHost_RTMpGetArraySize+0x46/0xa0 [vboxdrv]
[    5.340880]  [<ffffffffc11d163d>] ? supdrvGipCreate+0x2d/0xb80 [vboxdrv]
[    5.340897]  [<ffffffffc11d7067>] ? VBoxHost_RTMemAllocTag+0x27/0x60 [vboxdrv]
[    5.340914]  [<ffffffffc11c8d30>] ? supdrvInitDevExt+0x170/0x310 [vboxdrv]
[    5.340926]  [<ffffffffc127f092>] ? VBoxDrvLinuxInit+0x92/0x1000 [vboxdrv]
[    5.340928]  [<ffffffffc127f000>] ? 0xffffffffc127f000
[    5.340930]  [<ffffffffa100218b>] ? do_one_initcall+0x4b/0x180
[    5.340933]  [<ffffffffa11f1a20>] ? kmem_cache_alloc_trace+0x150/0x1d0
[    5.340936]  [<ffffffffa118858c>] ? do_init_module+0x5b/0x1ed
[    5.340938]  [<ffffffffa110b7e8>] ? load_module+0x1938/0x1ca0
[    5.340940]  [<ffffffffa1107990>] ? m_show+0x1b0/0x1b0
[    5.340942]  [<ffffffffa110bd96>] ? SYSC_finit_module+0xc6/0xf0
[    5.340945]  [<ffffffffa17401f6>] ? entry_SYSCALL_64_fastpath+0x1e/0xa8
[    5.340946] ---[ end trace c392808305ee1d9b ]---

[Frank Mehnert]

Thanks. Happens only if CONFIG_DEBUG_PER_CPU_MAPS and CONFIG_CPUMASK_OFFSTACK is defined. Not very common configuration. r64153 contains a fix which will be part of the next 5.1 maintenance release.

[Donuts]

Thanks. I guess such configurations could become a lot more common. Presumably the kernel-ppa packages use the same kernel config as planned for when 4.8.x ships with the next Ubuntu release?

[Frank Mehnert]

Fix is part of VBox 5.1.8.