On Tue, Nov 21, 2023 at 5:00 AM Michal Hocko <mhocko@xxxxxxxx> 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? > > 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 That is my feeling as well. I don't like to have too many special purposes modes either. It makes the whole process much harder to reason. The comment seems to suggest it is not effective in some situations. I am wondering if we can address that situation more directly without the special mode. At the same time I am not very familiar with the reclaim code path yet. I need to learn more about this problem space to articulate my thoughts better . I can dig in more, I might ask a lot of silly questions. Chris > purpose reclaim types. Would it be possible/reasonable to instead put > swapcache pages on the file LRU instead? > -- > Michal Hocko > SUSE Labs >
