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Wed, 8 Apr 2026 02:49:17 +0000 (UTC) Received: from localhost (unknown [10.72.112.14]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5A6CE300019F; Wed, 8 Apr 2026 02:49:15 +0000 (UTC) Date: Wed, 8 Apr 2026 10:49:12 +0800 From: Baoquan He To: Barry Song Cc: Johannes Weiner , Jianyue Wu , linux-mm@kvack.org, akpm@linux-foundation.org, david@kernel.org, mhocko@suse.com, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: move folio LRU helpers out of swap Message-ID: References: <20260407110002.204755-1-wujianyue000@gmail.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: fSIIbYGmPJhknmXOzE6gxViUQfBrB0XB0Nbls4MFKGI_1775616559 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: AEFCC1C0005 X-Stat-Signature: xs8xwutujuaxtpqk1cggfp1xazyosi3g X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775616565-251654 X-HE-Meta: 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 b0JO/VWg 1f3RF2XLR+9oZFyf3YXnPSWGwJUPOqW//HbbfDGEiTolmE20DlCYh8FwCbF/Gm8a/NPDl2JqnXc8dO7T5CoCw0Qe2ZwnJ1ar7WktqOB/8wUz9v9dco2zwxzsgctcouB1CmL97PWLZp3uKc45YR6qOq0pwcUgfiopfJX8Dj8zluxaJie03HyTdotcZ5VXEdSoURVpQndkg3kkmjhBRU8QJDiW9wrZzseSwstG6Hk6nRFMk/avCd1yr0pIbjZMxgsMlSh7fkgLAHxtBKyvb0WX6A0ZEG/sXVnqxQN+Q+S55Al+GxAbltDX78vdxDWNaRBwdOqfprvCLq/TEdFteaZcj+UAtD53xcc5iRFd+/Kr1cqO0oVzKovd4E5WM6IGeJvPHk3zHJqXJGElP5rKRP/SENyZ4dJtiZiXZG4KEzezq6QWJwgtWERBNGmxsuaU79WmpW9vaIJ7WPcvS2gs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/08/26 at 10:20am, Barry Song wrote: > On Wed, Apr 8, 2026 at 9:39 AM Baoquan He wrote: > > > > On 04/07/26 at 10:22am, Johannes Weiner wrote: > > > On Tue, Apr 07, 2026 at 07:00:02PM +0800, Jianyue Wu wrote: > > > > All allocated folios are added into lru lists for later reclaim whether > > > > they are file or anonymous folios. However those folio lru operation codes > > > > are put in mm/swap.c which is not so appropriate. Because swap code is > > > > only for anonymous folios. > > > > > > Ironically, the only thing that doesn't fit in this file is the swap > > > stuff. The page_cluster & sysctl should be static in swap_state.c. > > > > > > The rest seems thematically relatively clean - infrastructure for > > > managing folio lifetime. swap.c is not the best name for it, but short > > > of finding a very clear improvement I'd just leave it alone. > > > > Can't agree more. We should move page_cluster & sysctl and swap_setup() > > to mm/swap_state.c, and rename mm/swap.c to mm/folio_lru.c or something > > like that. > > Another issue is that many MM-internal items are placed in the > top-level include/linux/swap.h, which is supposed to be used by > code outside the MM subsystem as well. > > For example, the following are actually MM-internal: > > extern int vm_swappiness; > swap_setup(); > workingset_*(); > try_to_free_pages(); > zone_reclaimable_pages(); > lruvec_lru_size(); > try_to_free_mem_cgroup_pages(); > ... Ah, indeed. Seems we have been putting generic code related to reclaim into swap.h|.c due to historic reason. From discussion, I think the below three things are doable. 1) move page_cluster & sysctl and swap_setup() into mm/swap_state.c because page_cluster is only used in mm/swap_state.c as Johannes suggestd. And swap_setup() may need be renamed too? 2) rename mm/swap.c to mm/folio_lru.c or something like that to reflect its real content; 3) Just Barry pointed out, move generic code related to reclaim out of include/linux/swap.h e.g move into mm/internal.h if they are only called inside mm/ folder, Thanks Baoquan