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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Muchun Song , Oscar Salvador , Alexander Graf , David Matlack , David Rientjes , Jason Gunthorpe , Samiullah Khawaja , Vipin Sharma , Zhu Yanjun , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [RFC PATCH 08/10] mm: hugetlb: disable CMA if liveupdate is enabled In-Reply-To: (Pasha Tatashin's message of "Tue, 23 Dec 2025 13:16:57 -0500") References: <20251206230222.853493-1-pratyush@kernel.org> <20251206230222.853493-9-pratyush@kernel.org> Date: Mon, 29 Dec 2025 22:14:50 +0100 Message-ID: <86v7hp7zxx.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 23FE61C0010 X-Rspamd-Server: rspam10 X-Stat-Signature: yprag96wwmhnpzppufdgphjeyuj1nbb6 X-HE-Tag: 1767042902-769858 X-HE-Meta: U2FsdGVkX1/fJ0NTxPGg1pUsYKUjDu+omTr2fRTjICEKesGoPhOTeuChXPzsoE1esA4ilbTcd4ndVN5DfLirisFdEEIMc9r2YVmcnOso8aqOWn4mOfkYh6QsBS1GJYjRjvUpUaTgmjjyswhrdujrYv1MvOv3Pkm0yDJbpTTfHwpV2NVk6NiOHFTHr+6RqpHOPh6BHU7eRrISWe/iqTAf86pA9pgZqQ4gj/xWsaKWj3vzMhjLmDrMAXLEuBvsIo3oOfMFxdm4K37qp0QNcg9G6cGnTSjyQjzdDH75M6DHymFEpiaJZgCYjuFtV+5bQS8wk84AdyXfZNpPQ/+HrZLEMKhZ5BwfnaZegAIi59XIJNRnya17vuA6QZ0/z9Adu/IzVVe21JSFcv8z/V5A1tpzDWdA2C/asJJdqln/ptEmmtcXgYSWB8r+xKHQBMr74HATfOhaMdpEAyCv+G4i0BK67M8T4bBnW/rJkmOeN5jYmGCNWeEoenTGOZkebtc9iURQ47tCyyyDx+YDoC2R5R1c4JW4Nssx/fkTgpX6Ry2JfLSMraMOyAmCyxzqfEcS3vvOdZDujgXAj3QlhtJvPnMBp4L0ULL8KDtD71p01BOEhDfjbYyT6AFcLq6kSB6FdlA9qAqStY91kjByCvTANAN8wnwG9Iaqs+RzqyRedGwAtzNEXD53sX3AxITU2PzikYSmFlRdPYtyq+zJyzUe15Tyu3g60PTnZ75Gb0ZCYlcHkdOJrcPNBTSZKzIxY5eerdqiwBB4VvGthQgO3raK5czrKMXbRTVj6nOMLUW0RAobrM9t/wiq8hUf3mIOzpruPkmDkbCAXpXBdUD4FFXo9/R6mWSpqKVoXEo9vOK6WiMWjvjI3C+5KM9ni9sS7W7dhte+VrDmumMp74tlu+Tp+A0a6aXoIuE7o1KJprffpcSp6WyRYMDBeYUWGeEOjAdQgOEq2aG1oSpZbf2K3fQcoyH ZK6cFqJg sxpF7v3djnK/h2QlSkYes+s7AJVzvvtP2fFGLPt9PxyobHK5oAP8C9mtXiWGsbe5Cj0n5n6OQdfjwSWeSwo8i5QRGHRtTY+7UYLanaC/dXGN6vE9Jstf7FvzGz9qx9OaSyGdM8zG8j12I/qNxlAzN+GLSRIkomnpytxbUxFnwKgMyWi9mDLbChMSqP5uZiXApJD/nomdIEQsQ6IA8c/GiT87z9+OXaVldUBrgvq5pVQtGTgirTSS5zIxTiw== 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 Tue, Dec 23 2025, Pasha Tatashin wrote: > On Sat, Dec 6, 2025 at 6:03=E2=80=AFPM Pratyush Yadav wrote: >> >> Hugetlb live update support does not yet work with CMA. Print a warning >> and disable CMA if the config for live updating hugetlb is enabled, and >> liveupdate is enabled at runtime. > > Could you please elaborate this commit to explain why it is not > supported, and what it would take to support CMA. The main reason is that when HugeTLB CMA is enabled, the huge pages come from CMA. If we have preserved pages, we would need to "insert" those pages into the CMA when they are restored. CMA does support multiple ranges, so I suppose it can be done, but it needs some plumbing to work properly. Will add this in the next revision. --=20 Regards, Pratyush Yadav