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Wed, 30 Sep 2026 10:02:36 +0000 X-Mizu-Trace-ID: 702ad52dc12a4244 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: songmuchun@bytedance.com Cc: maddy@linux.ibm.com, rppt@kernel.org, akpm@linux-foundation.org, david@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, muchun.song@linux.dev, Lance Yang Subject: Re: [PATCH v3 2/6] mm/sparse-vmemmap: support device DAX in common vmemmap path Date: Wed, 30 Sep 2026 18:02:26 +0800 Message-ID: <20260930100226.23688-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20260929053231.66085-3-songmuchun@bytedance.com> References: <20260929053231.66085-3-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 0668040009 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: frmdqmnsabaznkb9ncadf4wy1kujocm1 X-HE-Tag: 1790762568-440736 X-HE-Meta: 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 T7RUvH/r ts0PSlbVm96PagKY2LCD+5Mio8i/u0g/tNxWdEegWdYRT07JFOzesKZ8lzSRQopHlVAhhqD/GYFHscD8NeJl1z+9OajxftUZcrvFwsisavX1mCiBL7kTiJ5X9Pt9pYRczS0Chm6w/TpHmBctfSDhA7s/CrRT8zzu/BNA7ffP/EmBfuC+yDXcZ87jPkEnletzfZzWns4zrbYscXAxbgRKA2s8Qn4fCVkXNYVFSXj63+l2BStFZQe50RCDIAPROdcRe+k4ewPGxLziW26WTMQipq7LZrvPk6Z8N+gWAYoh9iUaj3MdDsFDgP6Gfwfe5qq+nJi9qNv9sdW53Thc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 29, 2026 at 01:32:27PM +0800, Muchun Song wrote: >The common vmemmap population path cannot yet handle optimized Device DAX >mappings on its own. It uses pfn_to_zone() to find the shared tail page, >but Device DAX populates its vmemmap at runtime before the ZONE_DEVICE span >is initialized. > >Teach the common path to use device_zone() for runtime optimized vmemmap >population while retaining pfn_to_zone() for early boot. This allows the >same path to support both early boot mappings and Device DAX. > >The backing PFN supplied by the Device DAX-specific population path is no >longer used, allowing the redundant lookup and population code to be >removed later. > >Signed-off-by: Muchun Song >Acked-by: Qi Zheng >--- Nothing jumped out at me, feel free to add: Reviewed-by: Lance Yang