Re: [BUG v4.14-rt] kernel BUG at /work/rt/stable-rt.git/kernel/sched/core.c:1639!

[Mike Galbraith]

On Fri, 2018-08-17 at 16:23 -0400, Steven Rostedt wrote:
> Pulling in stable releases into v4.14-rt I triggered this with my CPU
> hotplug test:
> 
> ------------[ cut here ]------------
> kernel BUG at /work/rt/stable-rt.git/kernel/sched/core.c:1639!
> invalid opcode: 0000 [#1] PREEMPT SMP PTI
> Modules linked in: sunrpc ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables uinput snd_hda_codec_idt snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer snd shpchp i2c_i801 soundcore floppy i915 drm_kms_helper drm fb_sys_fops sysimgblt sysfillrect syscopyarea i2c_algo_bit iosf_mbi video [last unloaded: speedstep_lib]
> CPU: 1 PID: 2944 Comm: mkdumprd Not tainted 4.14.63-test-rt40+ #782
> Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
> task: ffff880037888d80 task.stack: ffffc90000538000
> RIP: 0010:select_fallback_rq+0xc3/0x122

I noticed this upstream, and had started hunting for the origin, but
had thought that 4.14-rt was OK.  Clearly not the case, but it's not
4.14.60.. stable changes interacting badly either, virgin 4.14.59-rt37
just reproduced in a vm clone of my workstation.

	-Mike