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[109.81.88.253]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48897fd7e2bsm178382765e9.2.2026.04.07.05.46.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2026 05:46:56 -0700 (PDT) Date: Tue, 7 Apr 2026 14:46:54 +0200 From: Michal Hocko To: Jianyue Wu Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, david@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baohua@kernel.org, bhe@redhat.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 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 56FAD100002 X-Stat-Signature: kr6qks35x854pwffc6qnc8jpje3krrf8 X-Rspamd-Server: rspam06 X-HE-Tag: 1775566018-870258 X-HE-Meta: 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 PAm1o9py RuRPDHIo/oQag270pgwU0/MZav2LHAM1u1ixHveVAPv3cWK2Blm/tVEMIMK1/bodXcsMwloFsK80DSwGJyTajjU10CLGimcGgh6Fxn3rgUhMn0eh5sj+ZcZpYl/f3sS/woHHSo5ARVqxWCdI7OCYjQFW/j3/IfIwiw2vOVVlwYYzLOO5um+W3KZE5ms4vgZRiCGinZknIogb0kewOSZLpsBGmcPygvgZMPhPEpCC6uM6Tq0KrI3ydgb6YyRfBgVdPj4WT4mrHnUn7Q1k7xd4waflWm3wkNsJcGYWlH1ydozcyCh62td4iWY+I4wHc+7El/JSvj1OkvTOVTIVuIEkDU0Nf55jOOcQZ0NFdV7DInppF1PVLoR/IlM+74fLN0Trb11s81ewHPKFXd/y2nlK7FNwxwNfBrgE2zgYXrgP4QwrK7+p0NCrN4a/xveIa4O/BoFGfNymw8odsZfK1YfBezgd0xA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue 07-04-26 20:31:40, Jianyue Wu wrote: > On 4/7/2026 7:20 PM, Michal Hocko wrote: > > > > All that big churn is really worth it? Are there any other reasons than > > "not so appropriate"? > > > > Really if this is not a part of a much bigger plan then NAK. > > Hi Michal, > > The intent here is to keep generic LRU/reclaim helpers separate from > swap-specific code paths. OK, but why do we want this and cause a lot of code churn to achiev that? > The LRU helpers are shared by both file and anonymous memory, whereas > swap.c is meant to host logic tied to swap devices and swap entries. > Placing LRU code there would blur the boundary between general reclaim > and swap, and make the code harder to follow. The code is harder to follow than it could be, no questions about that. But that alone is a rather weak argument to justify a lot of code move that cause a lot of conflicts. > Separately, I’ve been looking at routing zram’s swap-slot handling > through swap-owned hooks (e.g., swap_ops / swapon probing), which would > involve swapfile.c and swap.h. That’s likely orthogonal to this LRU > move, but it’s driven by the same goal of clarifying the swap boundary. Does that work benefits huge by this work? -- Michal Hocko SUSE Labs