Re: [PATCH 00/10] [v6] Migrate Pages in lieu of discard

[Dave Hansen]

...
>> == Open Issues ==
>>
>>  * For cpusets and memory policies that restrict allocations
>>    to PMEM, is it OK to demote to PMEM?  Do we need a cgroup-
>>    level API to opt-in or opt-out of these migrations?
> 
> I'm wondering if such usecases, which don't want to have memory
> allocate on pmem, will allow memory swapped out or reclaimed? If swap
> is allowed then I failed to see why migrating to pmem should be
> disallowed. If swap is not allowed, they should call mlock, then the
> memory won't be migrated to pmem as well.

Agreed.  I have a hard time imagining there are a lot of folks that can
tolerate the massive overhead from swapping, but can't tolerate the much
smaller overhead of going to pmem instead of DRAM.