Re: [PATCH v10] mm: vmscan: try to reclaim swapcache pages if no swap space

[Liu Shixin <liushixin2@huawei.com>]

On 2023/11/21 21:00, Michal Hocko wrote:
> On Tue 21-11-23 17:06:24, Liu Shixin wrote:
>
> However, in swapcache_only mode, the scan count still increased when scan
> non-swapcache pages because there are large number of non-swapcache pages
> and rare swapcache pages in swapcache_only mode, and if the non-swapcache
> is skipped and do not count, the scan of pages in isolate_lru_folios() can
> eventually lead to hung task, just as Sachin reported [2].
> I find this paragraph really confusing! I guess what you meant to say is
> that a real swapcache_only is problematic because it can end up not
> making any progress, correct? 
This paragraph is going to explain why checking swapcache_only after scan += nr_pages;
>
> AFAIU you have addressed that problem by making swapcache_only anon LRU
> specific, right? That would be certainly more robust as you can still
> reclaim from file LRUs. I cannot say I like that because swapcache_only
> is a bit confusing and I do not think we want to grow more special
> purpose reclaim types. Would it be possible/reasonable to instead put
> swapcache pages on the file LRU instead?
It looks like a good idea, but I'm not sure if it's possible. I can try it, is there anything to
pay attention to?

Thanks,