Re: [v3 PATCH 2/4] mm: move mem_cgroup_uncharge out of __page_cache_release()

[Kirill A. Shutemov]

On Thu, Jun 13, 2019 at 05:56:47AM +0800, Yang Shi wrote:
> The later patch would make THP deferred split shrinker memcg aware, but
> it needs page->mem_cgroup information in THP destructor, which is called
> after mem_cgroup_uncharge() now.
> 
> So, move mem_cgroup_uncharge() from __page_cache_release() to compound
> page destructor, which is called by both THP and other compound pages
> except HugeTLB.  And call it in __put_single_page() for single order
> page.


If I read the patch correctly, it will change behaviour for pages with
NULL_COMPOUND_DTOR. Have you considered it? Are you sure it will not break
anything?

-- 
 Kirill A. Shutemov