Re: [PATCH v2] cpuset: restore sanity to cpuset_cpus_allowed_fallback()

On Tue, Apr 09, 2019 at 04:40:03PM -0400, Joel Savitz [off-list ref] wrote:

	$ grep Cpus /proc/$$/status
	Cpus_allowed:	ff
	Cpus_allowed_list:	0-7

(a)
 

	$ taskset -p 4 $$
	pid 19202's current affinity mask: f
	pid 19202's new affinity mask: 4

	$ grep Cpus /proc/self/status
	Cpus_allowed:	04
	Cpus_allowed_list:	2

	# echo off > /sys/devices/system/cpu/cpu2/online
	$ grep Cpus /proc/$$/status
	Cpus_allowed:	0b
	Cpus_allowed_list:	0-1,3

I'm confused where this value comes from, I must be missing something.

Joel, is the task in question put into a cpuset with 0xf CPUs only (at
point (a))? Or are the CPUs 4-7 offlined as well?

Thanks,
Michal