On 21 Jul 2021, at 2:39, Huang Ying wrote:

> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> Anonymous pages are kept on their own LRU(s).  These lists could
> theoretically always be scanned and maintained.  But, without swap, there
> is currently nothing the kernel can *do* with the results of a scanned,
> sorted LRU for anonymous pages.
>
> A check for '!total_swap_pages' currently serves as a valid check as to
> whether anonymous LRUs should be maintained.  However, another method will
> be added shortly: page demotion.
>
> Abstract out the 'total_swap_pages' checks into a helper, give it a
> logically significant name, and check for the possibility of page
> demotion.
>
> Link: https://lkml.kernel.org/r/20210715055145.195411-7-ying.huang@intel.com
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Reviewed-by: Yang Shi <shy828301@gmail.com>
> Reviewed-by: Greg Thelen <gthelen@google.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Wei Xu <weixugc@google.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Keith Busch <kbusch@kernel.org>
> Cc: Yang Shi <yang.shi@linux.alibaba.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>  mm/vmscan.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
>

LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>

—
Best Regards,
Yan, Zi