On Tue, Jul 26, 2016 at 08:46:50AM +0100, Mel Gorman wrote:

On Tue, Jul 26, 2016 at 10:21:57AM +0900, Minchan Kim wrote:

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I believe proper fix is to modify get_scan_count. IOW, I think
we should introduce lruvec_reclaimable_lru_size with proper
classzone_idx but I don't know how we can fix it with memcg
which doesn't have zone stat now. should introduce zone stat
back to memcg? Or, it's okay to ignore memcg?

I think it's ok to ignore memcg in this case as a memcg shrink is often
going to be for pages that can use highmem anyway.

So, you mean it's okay to ignore kmemcg case?
If memcg guys agree it, I want to make get_scan_count consider
reclaimable lru size under the reclaim constraint, instead.

For now, I believe yet. My understanding is that the primary use cases
for kmemcg is systems running large numbers of containers. It consider
it extremely unlikely that large 32-bit systems are being used for large
numbers of containers and require usage of kmemcg.

Okay, Then how about this?
I didn't test it but I guess it should work.