On 2018/5/31 16:26, Peter Zijlstra wrote: > On Thu, May 31, 2018 at 04:12:34PM +0800, Zefan Li wrote: >> On 2018/5/31 9:25, Zefan Li wrote: >>> Hi Waiman, >>> >>> On 2018/5/30 21:46, Waiman Long wrote: >>>> It was found that the cpuset.cpus could contain CPUs that are not listed >>>> in their parent's cpu list as shown by the command sequence below: >>>> >>>> # echo "+cpuset" >cgroup.subtree_control >>>> # mkdir g1 >>>> # echo 0-5 >g1/cpuset.cpus >>>> # mkdir g1/g11 >>>> # echo "+cpuset" > g1/cgroup.subtree_control >>>> # echo 6-11 >g1/g11/cpuset.cpus >>>> # grep -R . g1 | grep "\.cpus" >>>> g1/cpuset.cpus:0-5 >>>> g1/cpuset.cpus.effective:0-5 >>>> g1/g11/cpuset.cpus:6-11 >>>> g1/g11/cpuset.cpus.effective:0-5 >>>> >>>> As the intersection of g11's cpus and that of g1 is empty, the effective >>>> cpus of g11 is just that of g1. The check in update_cpumask() is now >>>> corrected to make sure that cpus in a child cpus must be a subset of >>>> its parent's cpus. The error "write error: Invalid argument" will now >>>> be reported in the above case. >>>> >>> >>> We made the distinction between user-configured CPUs and effective CPUs >>> in commit 7e88291beefbb758, so actually it's not a bug. >>> >> >> I remember the original reason is to support restoration of the original >> cpu after cpu offline->online. We use user-configured CPUs to remember >> if the cpu should be restored in the cpuset after it's onlined. > > AFAICT you can do that and still have the child a subset of the parent, > no? > . Sure. IIRC this was suggested by Tejun as he had done something similar to devcgroup. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
