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b=bzPvRblRAgWfGDJ7LfEC5oGo+p7osBdjVsD922f2zO24o5OYJDcAOIrb3XQ5injHS 9CqvY3b/kT5zTdbtGnRxCHTXl0jDn1JUs2jg6wnEmA/9ZMTuTo7eQRX2ThUdvYBaM3 ihPGn6zGGppfoN/+n3cK06na1M6QE5loNKzNr5lw= Date: Fri, 24 Apr 2026 07:10:54 -0700 From: Andrew Morton To: "Barry Song (Xiaomi)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lance Yang , Xueyuan Chen , Kairui Song , Qi Zheng , Shakeel Butt , wangzicheng , Suren Baghdasaryan , Lei Liu , Matthew Wilcox , Axel Rasmussen , Yuanchu Xie , Wei Xu , Will Deacon Subject: Re: [PATCH] mm/mglru: Use folio_mark_accessed to replace folio_set_active in PF Message-Id: <20260424071054.3a4a09c61007e0c24d9223a1@linux-foundation.org> In-Reply-To: <20260418120233.7162-1-baohua@kernel.org> References: <20260418120233.7162-1-baohua@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: u1nr56cagtxmgb86fgyu8p51hi4jc11t X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9176B180003 X-Rspam-User: X-HE-Tag: 1777039856-346726 X-HE-Meta: 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 qtdj6gNP RR5IvfL+8oKD8SP/7q9RPAF0Blh0mYzYMj3o6FLtfQe0qJBbOCD7zFldRA9O8UFCwv+3oIPYtI8l5O60CYQTOEsdQ8YrzJAPAY+Y6smBO0G3E9zqnZYdtZR/V2NkGcgf0KLE7s0HF/JVQVO66jefj32SuVB7OeJ5wwFPfVd1rmbs/GxengIUIiSEmPmh1SDw7qFB73lmygiFkYCOU1qTc1esjI6g4vjSeA2HwlgBxyCniMgg6M0Zkag6AKBGjzDzuVng4UfzCZitbwfdkrUn5+E6rR839nY2Veby8eQ4PdnhPTNQ0tugMT1h/BrLWaHq37DdXs4BuqAoo+30Oj1oXa82Pd3uqyXA6V7R+uVQ3LF+Eh0GLRPRzRyMgL4Z8HhrQwv5gBbQVXIPijg1DZHOHovn2caRDCwFvMpUa09ZMwUw7Wb5sUj40j7Hfc2Z9IQHfylHvn48E2ycIJkY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 18 Apr 2026 20:02:33 +0800 "Barry Song (Xiaomi)" wrote: > MGLRU gives high priority to folios mapped in page tables. > As a result, folio_set_active() is invoked for all folios > read during page faults. In practice, however, readahead > can bring in many folios that are never accessed via page > tables. > > A previous attempt by Lei Liu proposed introducing a separate > LRU for readahead[1] to make readahead pages easier to reclaim, > but that approach is likely over-engineered. > > Before commit 4d5d14a01e2c ("mm/mglru: rework workingset > protection"), folios with PG_active were always placed in > the youngest generation, leading to over-protection and > increased refaults. After that commit, PG_active folios > are placed in the second youngest generation, which is > still too optimistic given the presence of readahead. In > contrast, the classic active/inactive scheme is more > conservative. > > This patch switches to folio_mark_accessed(). If > folio_check_references() later detects referenced PTEs, > the folio will be promoted based on the reference flag > set by folio_mark_accessed(). Sashiko: https://sashiko.dev/#/patchset/20260418120233.7162-1-baohua@kernel.org