On 17/07/14 18:36, Bruno Wolff III wrote:
I did a few quick boots this morning while taking a bunch of pictures. I have
gone through some of them this morning and found one that shows bug on
was triggered at 5850 which is from:
BUG_ON(!cpumask_empty(sched_group_cpus(sg)));
You can see the JPEG at:
https://bugzilla.kernel.org/attachment.cgi?id=143331
Many thanks for testing this, Bruno!
So the memory of the cpumask of some sched_group(s) in your system has
been altered between __visit_domain_allocation_hell()->__sdt_alloc() and
build_sched_groups().
In the meantime, PeterZ has posted a patch which barfs when this happens
but also prints out the sched groups with the related cpus but also
includes the cpumask_clear so your machine would boot still fine.
If you could apply the patch:
https://lkml.org/lkml/2014/7/17/288
and then run it on your machine, that would give us more details, i.e.
the information on which sched_group(s) and in which sched domain level
(SMT and/or DIE) this issue occurs.
Another thing which you could do is to boot with an extra
'earlyprintk=keep sched_debug' in your command line options with a build
containing the cpumask_clear() in build_sched_groups() and extract the
dmesg output of the scheduler-setup code:
Example:
[ 0.119737] CPU0 attaching sched-domain:
[ 0.119740] domain 0: span 0-1 level SIBLING
[ 0.119742] groups: 0 (cpu_power = 588) 1 (cpu_power = 588)
[ 0.119745] domain 1: span 0-3 level MC
[ 0.119747] groups: 0-1 (cpu_power = 1176) 2-3 (cpu_power = 1176)
[ 0.119751] CPU1 attaching sched-domain:
[ 0.119752] domain 0: span 0-1 level SIBLING
[ 0.119753] groups: 1 (cpu_power = 588) 0 (cpu_power = 588)
[ 0.119756] domain 1: span 0-3 level MC
[ 0.119757] groups: 0-1 (cpu_power = 1176) 2-3 (cpu_power = 1176)
[ 0.119759] CPU2 attaching sched-domain:
[ 0.119760] domain 0: span 2-3 level SIBLING
[ 0.119761] groups: 2 (cpu_power = 588) 3 (cpu_power = 588)
[ 0.119764] domain 1: span 0-3 level MC
[ 0.119765] groups: 2-3 (cpu_power = 1176) 0-1 (cpu_power = 1176)
[ 0.119767] CPU3 attaching sched-domain:
[ 0.119768] domain 0: span 2-3 level SIBLING
[ 0.119769] groups: 3 (cpu_power = 588) 2 (cpu_power = 588)
[ 0.119772] domain 1: span 0-3 level MC
[ 0.119773] groups: 2-3 (cpu_power = 1176) 0-1 (cpu_power = 1176)
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