Re: [PATCH v18 00/32] per memcg lru_lock

[Matthew Wilcox]

On Tue, Aug 25, 2020 at 11:26:58AM +0800, Alex Shi wrote:
> I tried reusing page->prviate to store lruvec pointer, that could remove some 
> regression on this, since private is generally unused on a lru page. But the patch
> is too buggy now. 

page->private is for the use of the filesystem.  You can grep for
attach_page_private() to see how most filesystems use it.
Some still use set_page_private() for various reasons.