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[84.247.152.65]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d75988cb5dsm2170415ad.64.2026.08.27.22.30.05 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 27 Aug 2026 22:30:15 -0700 (PDT) From: Lian Wang To: Kairui Song via B4 Relay Cc: linux-mm@kvack.org, Andrew Morton , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Shakeel Butt , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Chris Li , Baolin Wang , Ridong Chen , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Yu Zhao , Zi Yan , Qi Zheng , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Kairui Song , Kairui Song Subject: Re: [PATCH v3 5/6] mm/mglru: use explicit tier range in read_ctrl_pos() Date: Fri, 28 Aug 2026 13:29:28 +0800 Message-ID: <20260828052949.52874-1-lianux.mm@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260826-mglru-flags-cleanup-v3-5-d9f1c75549c8@tencent.com> References: <20260826-mglru-flags-cleanup-v3-0-d9f1c75549c8@tencent.com> <20260826-mglru-flags-cleanup-v3-5-d9f1c75549c8@tencent.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Kairui, > Replace it with explicit (tier_min, tier_max) parameters using a > closed [tier_min, tier_max] interval While touching read_ctrl_pos(), would it make sense to add: lockdep_assert_held(&lruvec->lru_lock); All current callers run under the lruvec lock. read_ctrl_pos() derives the history slot from min_seq and combines avg_refaulted/avg_total and protected with the atomic counters, while reset_ctrl_pos() rotates and clears that state under the same lock and already has this assertion. Adding the assertion here would document the snapshot contract and catch a future lockless caller before it can observe fields from different history epochs. If I missed an existing lockless caller, or if this is intentionally a best-effort snapshot, please ignore this suggestion. Thanks, Lian