kernel bug when hotplugging a CPU

[Benjamin Drung]

When I hot-plug a CPU to an Ubuntu 14.10 VM running on KVM, I get following kernel bug. Ubuntu 14.04 is not affected by this bug.

# uname -a
Linux ubuntu 3.16.0-28-generic #38-Ubuntu SMP Fri Dec 12 17:37:40 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
# dmesg
[ 109.469094] CPU1 has been hot-added
[ 109.477005] SMP alternatives: switching to SMP code
[ 109.490583] x86: Booting SMP configuration:
[ 109.490586] smpboot: Booting Node 0 Processor 1 APIC 0x1
[ 109.476344] kvm-clock: cpu 1, msr 0:3ffe6041, secondary cpu clock
[ 109.586704] kvm: enabling virtualization on CPU1
[ 109.596330] KVM setup async PF for cpu 1
[ 109.596330] kvm-stealtime: cpu 1, msr 3de2d100
[ 109.596645] microcode: CPU1: patch_level=0x01000065
[ 109.596910] Will online and init hotplugged CPU: 1
[ 109.598469] kobject '(null)' (ffff88003de3b5d8): tried to add an uninitialized object, something is seriously wrong.
[ 109.599255] CPU: 0 PID: 1424 Comm: systemd-udevd Not tainted 3.16.0-28-generic #38-Ubuntu
[ 109.599257] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 109.599259] ffff880036465250 ffff88003af77c88 ffffffff81781eaa ffff88003de3b5d8
[ 109.599263] ffff88003af77cf8 ffffffff8139e896 ffff880000000020 ffff88003af77d08
[ 109.599266] ffff88003af77cb0 ffff88003af77cc8 ffffffff8137967b 0000000000000001
[ 109.599269] Call Trace:
[ 109.599276] [<ffffffff81781eaa>] dump_stack+0x45/0x56
[ 109.599280] [<ffffffff8139e896>] kobject_add+0xa6/0xb0
[ 109.599283] [<ffffffff8137967b>] ? get_first_sibling+0x2b/0x40
[ 109.599287] [<ffffffff8139d08d>] ? ida_get_new_above+0x1dd/0x210
[ 109.599291] [<ffffffff81378b66>] blk_mq_register_hctx+0xa6/0xc0
[ 109.599293] [<ffffffff813794c1>] blk_mq_sysfs_register+0x41/0x60
[ 109.599297] [<ffffffff81376fc2>] blk_mq_queue_reinit_notify+0x72/0xb0
[ 109.599300] [<ffffffff8109972d>] notifier_call_chain+0x4d/0x70
[ 109.599303] [<ffffffff8109983e>] __raw_notifier_call_chain+0xe/0x10
[ 109.599306] [<ffffffff81070133>] cpu_notify+0x23/0x50
[ 109.599309] [<ffffffff81070348>] _cpu_up+0x168/0x180
[ 109.599312] [<ffffffff810703ea>] cpu_up+0x8a/0xb0
[ 109.599315] [<ffffffff81778ee0>] cpu_subsys_online+0x40/0xa0
[ 109.599319] [<ffffffff814cf225>] device_online+0x65/0x90
[ 109.599322] [<ffffffff814cf2cd>] online_store+0x7d/0x90
[ 109.599325] [<ffffffff814cc658>] dev_attr_store+0x18/0x30
[ 109.599328] [<ffffffff8125950a>] sysfs_kf_write+0x3a/0x50
[ 109.599331] [<ffffffff812586ae>] kernfs_fop_write+0xee/0x180
[ 109.599335] [<ffffffff811e10b7>] vfs_write+0xb7/0x1f0
[ 109.599338] [<ffffffff811e1c66>] SyS_write+0x46/0xb0
[ 109.599342] [<ffffffff81789eed>] system_call_fastpath+0x1a/0x1f

I initially reported this bug in openSUSE and it was fixed in the Linus tree: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=06a41a9
---
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access /dev/snd/: No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
CRDA: Error: [Errno 2] No such file or directory
DistroRelease: Ubuntu 14.10
IwConfig:
 eth0 no wireless extensions.

 lo no wireless extensions.
Lsusb:
 Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
 Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: Bochs Bochs
Package: linux (not installed)
PciMultimedia:

ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-28-generic root=UUID=6c1dd17e-4ffe-45f6-a99d-6b2530505d72 ro consoleblank=0
ProcVersionSignature: Ubuntu 3.16.0-28.38-generic 3.16.7-ckt1
RelatedPackageVersions:
 linux-restricted-modules-3.16.0-28-generic N/A
 linux-backports-modules-3.16.0-28-generic N/A
 linux-firmware 1.138
RfKill: Error: [Errno 2] No such file or directory
Tags: utopic utopic
Uname: Linux 3.16.0-28-generic x86_64
UnreportableReason: The report belongs to a package that is not installed.
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

_MarkForUpload: True
dmi.bios.date: 01/01/2011
dmi.bios.vendor: Bochs
dmi.bios.version: Bochs
dmi.chassis.type: 1
dmi.chassis.vendor: Bochs
dmi.modalias: dmi:bvnBochs:bvrBochs:bd01/01/2011:svnBochs:pnBochs:pvr:cvnBochs:ct1:cvr:
dmi.product.name: Bochs
dmi.sys.vendor: Bochs

[Benjamin Drung (benjamin-drung)]

When I hot-plug a CPU to an openSUSE VM running on KVM, I get following kernel oops:

# uname -a
Linux opensuse 3.16.6-2-default #1 SMP Mon Oct 20 13:47:22 UTC 2014 (feb42ea) x86_64 x86_64 x86_64 GNU/Linux
# dmesg
[ 54.927758] CPU2 has been hot-added
[ 54.928610] smpboot: Booting Node 0 Processor 2 APIC 0x2
[ 0.004000] kvm-clock: cpu 2, msr 2:403de081, secondary cpu clock
[ 54.940001] TSC synchronization [CPU#1 -> CPU#2]:
[ 54.940001] Measured 195274448514 cycles TSC warp between CPUs, turning off TSC clock.
[ 54.940001] tsc: Marking TSC unstable due to check_tsc_sync_source failed
[ 54.960222] KVM setup async PF for cpu 2
[ 54.960265] kvm-stealtime: cpu 2, msr 24008d240
[ 54.960342] microcode: CPU2 sig=0x306c1, pf=0x1, revision=0x1
[ 55.012464] Will online and init hotplugged CPU: 2
[ 55.012574] kobject '(null)' (ffff88024009a3d8): tried to add an uninitialized object, something is seriously wrong.
[ 55.012615] CPU: 1 PID: 892 Comm: systemd-udevd Not tainted 3.16.6-2-default #1
[ 55.012649] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_171129-lamiak 04/01/2014
[ 55.012688] ffff8802347cbd98 ffffffff815ca482 ffff88024009a3d8 ffffffff8130e153
[ 55.012729] ffffffff00000020 ffff8802347cbda8 ffff8802347cbd50 00000001334da7a8
[ 55.012766] 000000000000b0a0 0000000001ca6930 0000000000000002 ffff8802334da298
[ 55.012804] Call Trace:
[ 55.012845] [<ffffffff81005096>] dump_trace+0x86/0x330
[ 55.012881] [<ffffffff810053d4>] show_stack_log_lvl+0x94/0x170
[ 55.012919] [<ffffffff81006a31>] show_stack+0x21/0x50
[ 55.012955] [<ffffffff815ca482>] dump_stack+0x41/0x51
[ 55.012990] [<ffffffff8130e153>] kobject_add+0xa3/0xb0
[ 55.013027] [<ffffffff812ed4a1>] blk_mq_register_hctx+0x91/0xb0
[ 55.013062] [<ffffffff812edd5e>] blk_mq_sysfs_register+0x3e/0x50
[ 55.013095] [<ffffffff812eb9c2>] blk_mq_queue_reinit_notify+0x72/0xb0
[ 55.013129] [<ffffffff810806bc>] notifier_call_chain+0x4c/0x70
[ 55.013162] [<ffffffff8105beef>] cpu_notify+0x1f/0x40
[ 55.013195] [<ffffffff8105c0d7>] _cpu_up+0x157/0x170
[ 55.013226] [<ffffffff8105c169>] cpu_up+0x79/0xa0
[ 55.013260] [<ffffffff815bf555>] cpu_subsys_online+0x35/0x80
[ 55.013294] [<ffffffff8140c64d>] device_online+0x5d/0xa0
[ 55.013328] [<ffffffff8140c705>] online_store+0x75/0x80
[ 55.013360] [<ffffffff8122127a>] kernfs_fop_write+0xda/0x150
[ 55.013394] [<ffffffff811b1aa2>] vfs_write+0xb2/0x1f0
[ 55.013426] [<ffffffff811b25e2>] SyS_write+0x42/0xa0
[ 55.013462] [<ffffffff815d0c2d>] system_call_fastpath+0x1a/0x1f
[ 55.013517] [<00007f9fbf3804e0>] 0x7f9fbf3804df

I can reproduce it on a Ubuntu 14.10 host with stock KVM and on Debian host with a custom KVM. The oops sometimes causes the virtual machine to freeze.

[Tiwai-r (tiwai-r)]

Could you check whether the issue is reproduced on 3.17 and 3.18 kernels available at OBS Kernel:stable and Kernel:HEAD repos?

[Benjamin Drung (benjamin-drung)]

(In reply to Takashi Iwai from comment #1)
> Could you check whether the issue is reproduced on 3.17 and 3.18 kernels
> available at OBS Kernel:stable and Kernel:HEAD repos?

Same result with linux 3.17 from OBS Kernel:stable:

# uname -a
Linux opensuse 3.17.4-4.g8622a2e-default #1 SMP Sat Dec 6 20:43:41 UTC 2014 (8622a2e) x86_64 x86_64 x86_64 GNU/Linux
# dmesg
[ 117.297802] CPU1 has been hot-added
[ 117.298543] SMP alternatives: switching to SMP code
[ 117.306886] x86: Booting SMP configuration:
[ 117.306922] smpboot: Booting Node 0 Processor 1 APIC 0x1
[ 0.008000] kvm-clock: cpu 1, msr 2:403de041, secondary cpu clock
[ 117.320007] TSC synchronization [CPU#0 -> CPU#1]:
[ 117.320007] Measured 407089711478 cycles TSC warp between CPUs, turning off TSC clock.
[ 117.320007] tsc: Marking TSC unstable due to check_tsc_sync_source failed
[ 117.338582] KVM setup async PF for cpu 1
[ 117.338626] kvm-stealtime: cpu 1, msr 24004d240
[ 117.338727] kobject '(null)' (ffff88024005a558): tried to add an uninitialized object, something is seriously wrong.
[ 117.338728] CPU: 0 PID: 841 Comm: systemd-udevd Not tainted 3.17.4-4.g8622a2e-default #1
[ 117.338729] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_171129-lamiak 04/01/2014
[ 117.338730] ffff8800bbaf3d98 ffffffff815dc842 ffff88024005a558 ffffffff813181c3
[ 117.338731] ffffffff00000020 ffff8800bbaf3da8 ffff8800bbaf3d50 0000000133a94f28
[ 117.338732] 000000000000b0a0 0000000001e779d0 0000000000000001 ffff880233a94a18
[ 117.338732] Call Trace:
[ 117.338740] [<ffffffff81005246>] dump_trace+0x86/0x330
[ 117.338742] [<ffffffff81005584>] show_stack_log_lvl+0x94/0x170
[ 117.338744] [<ffffffff81006be1>] show_stack+0x21/0x50
[ 117.338746] [<ffffffff815dc842>] dump_stack+0x41/0x51
[ 117.338749] [<ffffffff813181c3>] kobject_add+0xa3/0xb0
[ 117.338753] [<ffffffff812f74a1>] blk_mq_register_hctx+0x91/0xb0
[ 117.338755] [<ffffffff812f7d5e>] blk_mq_sysfs_register+0x3e/0x50
[ 117.338756] [<ffffffff812f5962>] blk_mq_queue_reinit_notify+0x72/0xb0
[ 117.338759] [<ffffffff8107985c>] notifier_call_chain+0x4c/0x70
[ 117.338761] [<ffffffff8105d6cf>] cpu_notify+0x1f/0x40
[ 117.338763] [<ffffffff8105d8b7>] _cpu_up+0x157/0x170
[ 117.338765] [<ffffffff8105d949>] cpu_up+0x79/0xa0
[ 117.338768] [<ffffffff815d1625>] cpu_subsys_online+0x35/0x80
[ 117.338776] [<ffffffff814150ed>] device_online+0x5d/0xa0
[ 117.338779] [<ffffffff814151a5>] online_store+0x75/0x80
[ 117.338782] [<ffffffff81227c4a>] kernfs_fop_write+0xda/0x150
[ 117.338785] [<ffffffff811b7d62>] vfs_write+0xb2/0x1f0
[ 117.338787] [<ffffffff811b88a2>] SyS_write+0x42/0xa0
[ 117.338788] [<ffffffff815e2f6d>] system_call_fastpath+0x1a/0x1f
[ 117.338800] [<00007f5728fbd4e0>] 0x7f5728fbd4e0
[ 117.338826] microcode: CPU1 sig=0x306c1, pf=0x1, revision=0x1
[ 117.393791] Will online and init hotplugged CPU: 1

[Benjamin Drung (benjamin-drung)]

Same result with linux 3.18 from OBS Kernel:HEAD:

# uname -a
Linux opensuse 3.18.0-rc7-2.g088d59b-default #1 SMP Fri Dec 5 00:03:54 UTC 2014 (088d59b) x86_64 x86_64 x86_64 GNU/Linux
# dmesg
[ 150.252464] CPU2 has been hot-added
[ 150.253350] smpboot: Booting Node 0 Processor 2 APIC 0x2
[ 0.004000] kvm-clock: cpu 2, msr 2:403de081, secondary cpu clock
[ 150.268003] TSC synchronization [CPU#1 -> CPU#2]:
[ 150.268003] Measured 518729842258 cycles TSC warp between CPUs, turning off TSC clock.
[ 150.268003] tsc: Marking TSC unstable due to check_tsc_sync_source failed
[ 150.285117] KVM setup async PF for cpu 2
[ 150.285201] kvm-stealtime: cpu 2, msr 24008c280
[ 150.296118] kobject '(null)' (ffffe8ffffc8b5d8): tried to add an uninitialized object, something is seriously wrong.
[ 150.296197] CPU: 1 PID: 1386 Comm: systemd-udevd Not tainted 3.18.0-rc7-2.g088d59b-default #1
[ 150.296243] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_171129-lamiak 04/01/2014
[ 150.296285] 0000000000000000 0000000000000002 ffffffff81605f07 ffffe8ffffc8b5d8
[ 150.296332] ffffffff8132c7a0 ffff88023341d370 0000000000000020 ffff8800bb05bd58
[ 150.296382] ffff8800bb05bd08 000000000000a0a0 000000003f441940 0000000000000007
[ 150.296427] Call Trace:
[ 150.296479] [<ffffffff81005306>] dump_trace+0x86/0x330
[ 150.296541] [<ffffffff81005644>] show_stack_log_lvl+0x94/0x170
[ 150.296596] [<ffffffff81006d21>] show_stack+0x21/0x50
[ 150.296673] [<ffffffff81605f07>] dump_stack+0x41/0x51
[ 150.296721] [<ffffffff8132c7a0>] kobject_add+0xa0/0xb0
[ 150.296767] [<ffffffff8130aee1>] blk_mq_register_hctx+0x91/0xb0
[ 150.296809] [<ffffffff8130b82e>] blk_mq_sysfs_register+0x3e/0x60
[ 150.296857] [<ffffffff81309298>] blk_mq_queue_reinit_notify+0xf8/0x190
[ 150.296900] [<ffffffff8107cfdc>] notifier_call_chain+0x4c/0x70
[ 150.296947] [<ffffffff8105fd23>] cpu_notify+0x23/0x50
[ 150.296988] [<ffffffff81060037>] _cpu_up+0x157/0x170
[ 150.297033] [<ffffffff810600d9>] cpu_up+0x89/0xb0
[ 150.297079] [<ffffffff815fa5b5>] cpu_subsys_online+0x35/0x80
[ 150.297127] [<ffffffff814323cd>] device_online+0x5d/0xa0
[ 150.297185] [<ffffffff81432485>] online_store+0x75/0x80
[ 150.297238] [<ffffffff81236a5a>] kernfs_fop_write+0xda/0x150
[ 150.297309] [<ffffffff811c5532>] vfs_write+0xb2/0x1f0
[ 150.297367] [<ffffffff811c5f42>] SyS_write+0x42/0xb0
[ 150.297442] [<ffffffff8160c4ed>] system_call_fastpath+0x16/0x1b
[ 150.297493] [<00007f0132fb24e0>] 0x7f0132fb24e0
[ 150.297583] microcode: CPU2 sig=0x306c1, pf=0x1, revision=0x1
[ 150.297727] Will online and init hotplugged CPU: 2

[Tiwai-r (tiwai-r)]

Thanks. So the bug still remains in the upstream, so we need to report it.

[Tiwai-r (tiwai-r)]

OK, I could reproduce this easily, too, and spotted the culprit.
The fix patch is below. I'm going to send the fix to upstream.

[Tiwai-r (tiwai-r)]

Created attachment 616585
Fix patch

[Tiwai-r (tiwai-r)]

The patch was merged to Linus tree, and backported to openSUSE 13.2 and stable branches now. SLE12 doesn't need this.

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1403459

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Benjamin (benjamin-redhat-bugs)]

When I hot-plug a CPU to a Fedora 21 VM running on KVM, I get following kernel bug:

$ uname -a
Linux fedora 3.17.6-300.fc21.x86_64 #1 SMP Mon Dec 8 22:29:32 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ journalctl
Dez 17 10:40:21 fedora kernel: CPU1 has been hot-added
Dez 17 10:40:21 fedora kernel: SMP alternatives: switching to SMP code
Dez 17 10:40:21 fedora kernel: x86: Booting SMP configuration:
Dez 17 10:40:21 fedora kernel: smpboot: Booting Node 0 Processor 1 APIC 0x1
Dez 17 10:40:21 fedora kernel: kvm-clock: cpu 1, msr 0:3ffca041, secondary cpu clock
Dez 17 10:40:21 fedora kernel: kvm: enabling virtualization on CPU1
Dez 17 10:40:21 fedora kernel: KVM setup async PF for cpu 1
Dez 17 10:40:21 fedora kernel: kvm-stealtime: cpu 1, msr 3de2d100
Dez 17 10:40:21 fedora kernel: kobject '(null)' (ffff88003de3b4d8): tried to add an uninitialized object, something is seriously wrong.
Dez 17 10:40:21 fedora kernel: CPU: 1 PID: 1056 Comm: systemd-udevd Not tainted 3.17.6-300.fc21.x86_64 #1
Dez 17 10:40:21 fedora kernel: Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Dez 17 10:40:21 fedora kernel: 0000000000000000 00000000ffd31f20 ffff88003b593c68 ffffffff8173f8aa
Dez 17 10:40:21 fedora kernel: ffff88003de3b4d8 ffff88003b593ce0 ffffffff813850e6 ffffffff00000020
Dez 17 10:40:21 fedora kernel: ffff88003b593cf0 ffff88003b593c98 00000000ffd31f20 0000000000000002
Dez 17 10:40:21 fedora kernel: Call Trace:
Dez 17 10:40:21 fedora kernel: [<ffffffff8173f8aa>] dump_stack+0x45/0x56
Dez 17 10:40:21 fedora kernel: [<ffffffff813850e6>] kobject_add+0xc6/0xd0
Dez 17 10:40:21 fedora kernel: [<ffffffff81383bd5>] ? ida_get_new_above+0x1f5/0x220
Dez 17 10:40:21 fedora kernel: [<ffffffff81362376>] blk_mq_register_hctx+0xa6/0xc0
Dez 17 10:40:21 fedora kernel: [<ffffffff81362cb1>] blk_mq_sysfs_register+0x41/0x60
Dez 17 10:40:21 fedora kernel: [<ffffffff813606b2>] blk_mq_queue_reinit_notify+0x72/0xb0
Dez 17 10:40:21 fedora kernel: [<ffffffff810b62dd>] notifier_call_chain+0x4d/0x70
Dez 17 10:40:21 fedora kernel: [<ffffffff810b63ee>] __raw_notifier_call_chain+0xe/0x10
Dez 17 10:40:21 fedora kernel: [<ffffffff81097363>] cpu_notify+0x23/0x50
Dez 17 10:40:21 fedora kernel: [<ffffffff81097598>] _cpu_up+0x188/0x1a0
Dez 17 10:40:21 fedora kernel: [<ffffffff8109763a>] cpu_up+0x8a/0xb0
Dez 17 10:40:21 fedora kernel: [<ffffffff81738fa0>] cpu_subsys_online+0x40/0xa0
Dez 17 10:40:21 fedora kernel: [<ffffffff814975b5>] device_online+0x65/0x90
Dez 17 10:40:21 fedora kernel: [<ffffffff81497675>] online_store+0x95/0xa0
Dez 17 10:40:21 fedora kernel: [<ffffffff81494708>] dev_attr_store+0x18/0x30
Dez 17 10:40:21 fedora kernel: [<ffffffff812895fa>] sysfs_kf_write+0x3a/0x50
Dez 17 10:40:21 fedora kernel: [<ffffffff812889de>] kernfs_fop_write+0xee/0x180
Dez 17 10:40:21 fedora kernel: [<ffffffff8120c597>] vfs_write+0xb7/0x1f0
Dez 17 10:40:21 fedora kernel: [<ffffffff81060e21>] ? trace_do_page_fault+0x41/0x100
Dez 17 10:40:21 fedora kernel: [<ffffffff8120d1c5>] SyS_write+0x55/0xd0
Dez 17 10:40:21 fedora kernel: [<ffffffff81746a69>] system_call_fastpath+0x16/0x1b
Dez 17 10:40:21 fedora kernel: microcode: CPU1: patch_level=0x01000065
Dez 17 10:40:21 fedora kernel: Will onl...

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Benjamin Drung (bdrung)]

apport information

[Joseph Salisbury (jsalisbury)]

Commit 06a41a9 was also cc'd to stable, so I should make it's way into the upstream stable kernels.

I built a Utopic test kernel with a cherry-pick of commit 06a41a9. The test kernel can be downloaded from:
http://kernel.ubuntu.com/~jsalisbury/lp1403459/

Can you test this kernel and see if it fixes this bug. Note, you will have to install both the linux-image and linux-image-extra .deb packages.

Thanks in advance!

[Josh (josh-redhat-bugs)]

Thanks for the report and the pointer to the patch. I've updated Fedora git to have this and it will be in the next build of each release.

[Benjamin Drung (bdrung)]

Hi Jospeh,

I installed the kernel from http://kernel.ubuntu.com/~jsalisbury/lp1403459/ and can confirm that this kernel version fixes the bug.

[Joseph Salisbury (jsalisbury)]

The patch has made its way into the linux-3.16.y-queue upstream branch, so it should be in Utopic shortly.

c3c75b2 blk-mq: Fix uninitialized kobject at CPU hotplugging

[Fedora (fedora-redhat-bugs)]

kernel-3.17.8-300.fc21 has been submitted as an update for Fedora 21.
https://admin.fedoraproject.org/updates/kernel-3.17.8-300.fc21

[Fedora (fedora-redhat-bugs)]

kernel-3.17.8-200.fc20 has been submitted as an update for Fedora 20.
https://admin.fedoraproject.org/updates/kernel-3.17.8-200.fc20

[Fedora (fedora-redhat-bugs)]

Package kernel-3.17.8-200.fc20:
* should fix your issue,
* was pushed to the Fedora 20 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing kernel-3.17.8-200.fc20'
as soon as you are able to, then reboot.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2015-0515/kernel-3.17.8-200.fc20
then log in and leave karma (feedback).

[Fedora (fedora-redhat-bugs)]

kernel-3.17.8-300.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.

[Fedora (fedora-redhat-bugs)]

kernel-3.17.8-200.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.

[Rolf Leggewie (r0lf)]

utopic has seen the end of its life and is no longer receiving any updates. Marking the utopic task for this ticket as "Won't Fix".