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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <878r6q9sx7.fsf@yhuang6-desk2.ccr.corp.intel.com> X-Rspamd-Queue-Id: E54CCC0006 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: sim1pdh43wpmwo6q1x5fd7k3jusx4p9t X-HE-Tag: 1700643308-498305 X-HE-Meta: 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 FEoYYFYx t/aiLIoqjjpqoDwpsumxACclXC8M1AQtuSnKGS2oa35A3Jdv9m3XJRlqQSSS3BL1b12eoXL/3WUGk0mrb3yc0Sgo+7maEfPAD5QPw19/YMTGy7hshpH59BS7i861wsMgrnSpzrremJ+qOKgaNibq+eZ2sMdq0SApuUblmAoSp6fW8OobSfMlkUPYInPQYjITn3RU+DoxwzFFIu1PrhlFVYSw/wZ60AGNBJ3G7jWLF/GCDVxo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed 22-11-23 14:57:24, Huang, Ying wrote: > Yosry Ahmed writes: > > > On Tue, Nov 21, 2023 at 10:41 PM Liu Shixin wrote: > >> > >> > >> 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? > > > > I think this might be more intrusive than we think. Every time a page > > is added to or removed from the swap cache, we will need to move it > > between LRUs. All pages on the anon LRU will need to go through the > > file LRU before being reclaimed. I think this might be too big of a > > change to achieve this patch's goal. > > We need to identify swap cache pages on file LRU firstly. It appears > hard from the current definition of page flags. > > /* Filesystems */ > PG_checked = PG_owner_priv_1, > > /* SwapBacked */ > PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ Checking along with folio_test_swapbacked would do the trick, right? -- Michal Hocko SUSE Labs