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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID:AQAAfwBXruuntmhpi9oTAA--.20716S2 X-CM-SenderInfo: pfxlux1drrlkut6sx5pwlxzhxfrphubq/1tbiAQAQAGln+JMEtAAAsE X-Coremail-Antispam: 1Uk129KBjvJXoW7CF1Duw1DCr4DKw45GF1DAwb_yoW8AF47pF 4SqFWvgF4kJF1xGFs2vw1kX3WIqF409a17JrW7CFnrur4F9w18Jr4ayr1F9Fs7t34kGF1r XF4Dta4jqw1DXaUanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUj1kv1TuYvTs0mT0YCTnIWj DUYxn0WfASr-VFAU7a7-sFnT9fnUUIcSsGvfJ3UbIYCTnIWIevJa73UjIFyTuYvj4RJUUU UUUUU X-Rspam-User: X-Stat-Signature: ujg6qzcyqhm5o758cfmkjasifxxnp5fj X-Rspamd-Queue-Id: 6E1EC40003 X-Rspamd-Server: rspam04 X-HE-Tag: 1768470193-413680 X-HE-Meta: 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 q1cTEaT+ dREFezz+8j0x//sHkRTyrMly5N36CU0THG066dS5UR36Z3uUzIo3waqRgoAB6N2eK63V3rZqswWOOcIHdHd9NGteh9lI5ePyWYPrwTeUQbLYGLCK0yiN9x9dW3ASxWDSTy6L8uviFSHRkIN4KBVfYUkbD7Ud8JCuvkhpe9cfthpG0MoA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When a CXL RAM region is created in userspace, the memory capacity of the newly created region is not added to the CFMW-dedicated NUMA node. Instead, it is accumulated into an existing NUMA node (e.g., NUMA0 containing RAM). This makes it impossible to clearly distinguish between the two types of memory, which may affect memory-tiering applications. On 1/9/2026 1:48 AM, Andrew Morton wrote: > On Tue, 6 Jan 2026 11:10:42 +0800 Cui Chao wrote: > >> In some physical memory layout designs, the address space of CFMW >> resides between multiple segments of system memory belonging to >> the same NUMA node. In numa_cleanup_meminfo, these multiple segments >> of system memory are merged into a larger numa_memblk. When >> identifying which NUMA node the CFMW belongs to, it may be incorrectly >> assigned to the NUMA node of the merged system memory. >> >> Example memory layout: >> >> Physical address space: >> 0x00000000 - 0x1FFFFFFF System RAM (node0) >> 0x20000000 - 0x2FFFFFFF CXL CFMW (node2) >> 0x40000000 - 0x5FFFFFFF System RAM (node0) >> 0x60000000 - 0x7FFFFFFF System RAM (node1) >> >> After numa_cleanup_meminfo, the two node0 segments are merged into one: >> 0x00000000 - 0x5FFFFFFF System RAM (node0) // CFMW is inside the range >> 0x60000000 - 0x7FFFFFFF System RAM (node1) >> >> So the CFMW (0x20000000-0x2FFFFFFF) will be incorrectly assigned to node0. >> >> To address this scenario, accurately identifying the correct NUMA node >> can be achieved by checking whether the region belongs to both >> numa_meminfo and numa_reserved_meminfo. > Thanks. > > Can you please help us understand the userspace-visible runtime effects > of this incorrect assignment? -- Best regards, Cui Chao.