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Thu, 19 Mar 2026 22:37:33 -0700 (PDT) From: Liew Rui Yan To: sj@kernel.org Cc: aethernet65535@gmail.com, damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] Docs/mm/damon: document min_nr_regions constraint and rationale Date: Fri, 20 Mar 2026 13:37:28 +0800 Message-ID: <20260320053728.213664-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260320052428.213230-1-aethernet65535@gmail.com> References: <20260320052428.213230-1-aethernet65535@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: C39E8180007 X-Stat-Signature: wo1e5tg8tzx5cbsurzx41611xnetnn5g X-HE-Tag: 1773985054-31931 X-HE-Meta: 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 l3CLL2VM 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The current DAMON implementation requires 'min_nr_regions' to be at least 3. However, this constraint is not explicitly documented in the admin-guide documents, nor is its design rationale explained in the design document. Add a section in design.rst to explain the rationale: the virtual address space monitoring design needs to handle at least three regions to accommodate two large unmapped areas. While this is specific to 'vaddr', DAMON currently enforces it across all operation sets for consistency. Also update reclaim.rst and lru_sort.rst by adding cross-references to this constraint at the end of their respective parameter description or usage sections, ensuring users are aware of the lower bound. This change is motivated from a recent discussion [1]. [1] https://lore.kernel.org/damon/20260319151528.86490-1-sj@kernel.org/T/#t