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b=Qz7mod4/HwaHJK0JAB3ytD3MH8bBSYf8iVVbxyfCL1i/Zs6EaxhyzZ0+HRfgGgLRE 7KYF+Vw44ia7HO0mtZe6yNWu2wGG5dX7LTzWtPvh5MEXCxFa2Opa4yGNWXBwiqumzT OQoZP7jTRMTNAN9wgg0KoDA+vKwqyQPTwQy/IXCqlURybqriy7jxNCQRmvtEEdhBEp 9Xj0bqmhY869YhySGf3rjhIWMZSOwhzaFPKHnbgQXjg1zVoB8XolM9ff6mKYt0gLHq xg18bmw/eeDCgNR1WtWJ8g7EWNw/CAxaofPrCUhSgPJqL78JV0q0plchZ5E05HZRz6 e2oH4RK5uPd8w== Received: by mail-pj1-f47.google.com with SMTP id 98e67ed59e1d1-2854757f0f8so920226a91.1 for ; Thu, 23 Nov 2023 09:30:35 -0800 (PST) X-Gm-Message-State: AOJu0YxSi1xgMsfXnO609bGoVh0DWH71jrjOKzh3yNSPixpUAyaPTYIY 622RKCgVk+gJ6k+Pws8+qt1J2H5ZEEFkJu7MoCQ0IQ== X-Google-Smtp-Source: AGHT+IHytp+/fh45uHnBzItufzEx7eCFYQ74dyRHbptCqeFGDEMvkjRENl6X2MFJeG5mhjUejhBp+JsLaOU1M3fpJ2s= X-Received: by 2002:a17:90b:1001:b0:285:6f1a:4a71 with SMTP id gm1-20020a17090b100100b002856f1a4a71mr149425pjb.32.1700760634650; Thu, 23 Nov 2023 09:30:34 -0800 (PST) MIME-Version: 1.0 References: <20231121090624.1814733-1-liushixin2@huawei.com> In-Reply-To: From: Chris Li Date: Thu, 23 Nov 2023 09:30:23 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v10] mm: vmscan: try to reclaim swapcache pages if no swap space To: Michal Hocko Cc: Liu Shixin , Yu Zhao , Andrew Morton , Yosry Ahmed , Huang Ying , Sachin Sant , Johannes Weiner , Kefeng Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 84EEE140025 X-Rspam-User: X-Stat-Signature: r76jwtp8wa9d89r6rxdgrqf479o3aa3i X-Rspamd-Server: rspam01 X-HE-Tag: 1700760636-464736 X-HE-Meta: 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 +4jYu2yP OxbF2GvErpztgVZADAK4km56dif6BAgGpLlNtQpnF3WnnVLZkokwEXuq1gVSOILPx48GbQXvAmQLWJEupXnNRKGk9gYbPlZw5i5cYEfW5u0cDW70R5S4z65r9VgZ/XWgJ8oxx2RN3hCKL3kb8C8DtMvC5Dh9eAnd+XA3FKhQQR/RKdfvfJq5JeIcJ9grbPL3Fa8zngBdCk4V1UEvzOSq6PepcA1ymDbwb/RpQzXgja9Yvb/VumcLEsXrKapSsyM7BIwqSfUu5bQeEi+FZO0Gg6rcn5w== 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 Tue, Nov 21, 2023 at 5:00=E2=80=AFAM Michal Hocko wrot= e: > > However, in swapcache_only mode, the scan count still increased when sc= an > > non-swapcache pages because there are large number of non-swapcache pag= es > > and rare swapcache pages in swapcache_only mode, and if the non-swapcac= he > > 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 >