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b=e814AiMP04MGQQdvcF/eHiGR3mf/DMRLiaDPWrPEkG74cX3rRLhEga06ol//9OChC vkULXBUpl0DbaS8P8n8lV4PmH+yaM1LyzgRYvkc1THr/VqmymRuJ47mo/jn4h8uQVB 1kwCMTpAMOChF+x4dKZrsq1Dv3Akpd17X8oldoso= Date: Thu, 15 Jan 2026 10:18:58 -0800 From: Andrew Morton To: Cui Chao Cc: Jonathan Cameron , Mike Rapoport , Wang Yinfeng , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 1/1] mm: numa_memblks: Identify the accurate NUMA ID of CFMW Message-Id: <20260115101858.85fd7b8e837c1c92a4fdc5f0@linux-foundation.org> In-Reply-To: <9132054c-3017-4af0-84e0-e4359b0794a6@phytium.com.cn> References: <20260106031042.1606729-1-cuichao1753@phytium.com.cn> <20260106031042.1606729-2-cuichao1753@phytium.com.cn> <20260108094812.8757ce3ad8370668eaafb29c@linux-foundation.org> <9132054c-3017-4af0-84e0-e4359b0794a6@phytium.com.cn> 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-Rspam-User: X-Stat-Signature: i1wje8pu1z9eojxiz1ky561bp1nkhaw5 X-Rspamd-Queue-Id: 07183100007 X-Rspamd-Server: rspam04 X-HE-Tag: 1768501139-98902 X-HE-Meta: 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 BXovH9aL Se3vd/LLIn/avqGAkqbYoMdLhX+6tqBbZ8TVnHrE9SgXDymEBD1kCTj1cMwoR+SBPVD2FpJpRcH/TXiqAvkZ6Hz7ns25UDQjffSGK4bYJdhMvPxFqmiPKKbt1u53c0a3KnZqOqYIOC1pZJ0pW8uFOTzNoPCYhHLtnXkZhtfKatfWaOgOBS1FoCWEXrPdYXVRAMB/xjN2FaiLSEh0L4f9q3AaeEO5xSq5Q1o40tVuqD+kF3xkmveD+/YRomQnJfXrPNLCI0mREbOHLfC2Dm11EhS0vBOqDnVBsYOxCzJTdrCnP2+ng9EsGYfBiVEYdf3rFln5XvmYRsaxkzhtztgAb8XPyUKaSVLSOvXp2 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: On Thu, 15 Jan 2026 17:43:02 +0800 Cui Chao wrote: > 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. > OK, thanks, I added this to the changelog. Please retain it when sending v3. What I'm actually looking for here are answers to the questions Should we backport this into -stable kernels and if so, why? And if not, why not? So a very complete description of the runtime effects really helps myself and others to decide which kernels to patch. And it helps people to understand *why* we made that decision. And sorry, but "may affect memory-tiering applications" isn't very complete! So please, tell us how much our users are hurting from this and please make a recommendation on the backporting decision.