lts-utopic kernel needs boot-up race condition fix.

[Mike Waychison]

The underlying kernel bug was originally reported and fixed here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1508609

The bug was fixed confirmed not present in the original trusty kernel and has been fixed in vivid and wily, but was not addressed in utopic as it has EOL.

If my understanding is correct, while Utopic has EOL, the lts-utopic hwe kernel is expected to be supported until the final Trusty release (14.04.05) next summer. Can we have the original kernel issue also addressed in lts-utopic (assuming it hasn't been already?). We are seeing users running this kernel on trusty systems and they still appear to be affected.

Thanks!

[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 1527748

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.

[Joseph Salisbury (jsalisbury)]

That commit is in the lts-utopic kernel as of version: Ubuntu-lts-3.16.0-52.70. The commit is in the lts-utopic kernel as commit:

commit 360167ee41c46b271680cff869d48ed981691be9
Author: Jan H. Schönherr <email address hidden>
Date: Wed Aug 12 21:35:56 2015 +0200

    sched: Fix cpu_active_mask/cpu_online_mask race

Can you ask the users that are still affected by the bug to apply the latest updates and see if the bug still exists? If it does, just change the bug status back to 'Confirmed'.

Thanks in advance

[Leann Ogasawara (leannogasawara)]

Hi,

I believe this fix was picked up via bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1508133 ("Trusty update to 3.16.7-ckt18 stable release"). Upon examination of the lts-backport-utopic branch in Trusty, I see the following:

https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/trusty/commit/?h=lts-backport-utopic&id=360167ee41c46b271680cff869d48ed981691be9

~/ubuntu-trusty$ git describe --contains 360167ee41c46b271680cff869d48ed981691be9
Ubuntu-lts-3.16.0-52.70_14.04.1~78

commit 360167ee41c46b271680cff869d48ed981691be9
Author: Jan H. Schönherr <email address hidden>
Date: Wed Aug 12 21:35:56 2015 +0200

    sched: Fix cpu_active_mask/cpu_online_mask race

    BugLink: http://bugs.launchpad.net/bugs/1508133

    commit dd9d3843755da95f63dd3a376f62b3e45c011210 upstream.

Can you confirm that users still experiencing an issue have updated to at least a linux-lts-utopic-3.16.0-52.70~14.04.1 or newer kernel?

https://launchpad.net/ubuntu/+source/linux-lts-utopic/3.16.0-52.70~14.04.1

Thanks in advance.

[Mike Waychison (mikew-6)]

Here's the fragment of Oops I have demonstrating the crash. If I'm understanding the versioning here, it looks like the issue may now have been fully addressed by that patch alone? :(

[ 0.104000] CR2: ffff8807bffff000 CR3: 0000000001c13000 CR4: 00000000001406f0
[ 0.104000] Stack:
[ 0.104000] 0000000000000000 ffff880796773ea0 ffffffff8176bc39 ffff8807965d3140
[ 0.104000] ffff8807a1001b00 ffffffff81098810 0000000000000000 0000000000000000
[ 0.104000] ffff880796773f48 ffffffff810915f2 0000000000000001 0000000000000001
[ 0.104000] Call Trace:
[ 0.104000] [<ffffffff8176bc39>] ? schedule+0x29/0x70
[ 0.104000] [<ffffffff81098810>] ? SyS_setgroups+0x180/0x180
[ 0.104000] [<ffffffff810915f2>] kthread+0xd2/0xf0
[ 0.104000] [<ffffffff81091520>] ? kthread_create_on_node+0x1c0/0x1c0
[ 0.104000] [<ffffffff8176fbd8>] ret_from_fork+0x58/0x90
[ 0.104000] [<ffffffff81091520>] ? kthread_create_on_node+0x1c0/0x1c0
[ 0.104000] Code: 89 fa 48 0f a3 11 19 d2 31 f6 85 d2 40 0f 95 c6 ff d0 4c 89 e7 e8 62 de 11 00 48 83 c4 18 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b 0f 0b 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00
[ 0.104000] RIP [<ffffffff810989af>] smpboot_thread_fn+0x19f/0x1b0
[ 0.104000] RSP <ffff880796773e88>
[ 0.104028] ---[ end trace b59b90c026f24b92 ]---
[ 0.104734] ------------[ cut here ]------------
[ 0.105486] kernel BUG at /build/linux-lts-utopic-p81gRk/linux-lts-utopic-3.16.0/kernel/smpboot.c:134!
[ 0.106799] invalid opcode: 0000 [#2] SMP
[ 0.107528] Modules linked in:
[ 0.108000] CPU: 0 PID: 29 Comm: ksoftirqd/1 Tainted: G D 3.16.0-55-generic #74~14.04.1-Ubuntu
[ 0.108000] Hardware name: Google Google, BIOS Google 01/01/2011
[ 0.108000] task: ffff8807966f7010 ti: ffff880796778000 task.ti: ffff880796778000
[ 0.108000] RIP: 0010:[<ffffffff810989af>] [<ffffffff810989af>] smpboot_thread_fn+0x19f/0x1b0
[ 0.108000] RSP: 0000:ffff88079677be88 EFLAGS: 00010202
[ 0.108000] RAX: 0000000000000000 RBX: ffff8807966f7010 RCX: 0000000000000000
[ 0.108000] RDX: ffff88079677bfd8 RSI: ffff8807966f7010 RDI: 0000000000000001
[ 0.108000] RBP: ffff88079677bec8 R08: ffff880796778000 R09: 0000000000000246
[ 0.108000] R10: ffffffff8106b17c R11: ffffea001e59d800 R12: ffff8807a1001b20
[ 0.108000] R13: ffffffff81c40d20 R14: ffff8807966f7010 R15: ffff8807966f7010
[ 0.108000] FS: 0000000000000000(0000) GS:ffff8807bfc00000(0000) knlGS:0000000000000000
[ 0.108000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.108000] CR2: ffff8807bffff000 CR3: 0000000001c13000 CR4: 00000000001406f0
[ 0.108000] Stack:
[ 0.108000] 0000000000000000 ffff88079677bea0 ffffffff8176bc39 ffff8807965d3140
[ 0.108000] ffff8807a1001b20 ffffffff81098810 0000000000000000 0000000000000000
[ 0.108000] ffff88079677bf48 ffffffff810915f2 0000000000000001 0000000000000001
[ 0.108000] Call Trace:
[ 0.108000] [<ffffffff8176bc39>] ? schedule+0x29/0x70
[ 0.108000] [<ffffffff81098810>] ? SyS_setgroups+0x180/0x180
[ 0.108000] [<ffffffff810915f2>] kthread+0xd2/0xf0
[ 0.108000] [<ffffffff81091520>] ? kthread_create_on_node+0x1c0/0x1c0

[Mike Waychison (mikew-6)]

*not have

[Owen Hofmann (osh-c)]

It looks like the patch backported for https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1508609 is not quite enough to fix this issue on pre-4.1 kernels. Those kernels also need https://github.com/torvalds/linux/commit/00df35f991914db6b8bde8cf09808e19a9cffc3d (or in general, must call cpu_notify before smpboot_unpark_threads).