Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed nodemask

[Mel Gorman]

On Tue, Jan 31, 2017 at 07:52:37PM +0530, Anshuman Khandual wrote:
> At present, top_cpuset.mems_allowed is same as node_states[N_MEMORY] and it
> cannot be changed at the runtime. Maximum possible node_states[N_MEMORY]
> also gets reflected in top_cpuset.effective_mems interface. It prevents some
> one from removing or restricting memory placement which will be applicable
> system wide on a given memory node through cpuset mechanism which might be
> limiting. This solves the problem by enabling update_nodemask() function to
> accept changes to top_cpuset.mems_allowed as well. Once changed, it also
> updates the value of top_cpuset.effective_mems. Updates all it's task's
> mems_allowed nodemask as well. It calls cpuset_inc() to make sure cpuset
> is accounted for in the buddy allocator through cpusets_enabled() check.
> 

What's the point of allowing the root cpuset to be restricted?

-- 
Mel Gorman
SUSE Labs