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Mon, 20 Apr 2026 23:56:12 -0700 (PDT) MIME-Version: 1.0 References: <20260417135805.1758378-1-ekffu200098@gmail.com> In-Reply-To: From: Sang-Heon Jeon Date: Tue, 21 Apr 2026 15:56:01 +0900 X-Gm-Features: AQROBzAdg2gdS3KDjvk2aGpa-rV7JJ-7DXvwsEhWWWwN200E8Uy85JIqLoWfXtU Message-ID: Subject: Re: [PATCH v2] mm/fake-numa: fix under-allocation detection in uniform split To: Mike Rapoport Cc: akpm@linux-foundation.org, djbw@kernel.org, mingo@kernel.org, linux-mm@kvack.org, Donghyeon Lee , Munhui Chae Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 4A0B5A0002 X-Stat-Signature: 3x4knhndd4a8y4fbt5daiq5kkkaff7x1 X-Rspam-User: X-HE-Tag: 1776754573-424962 X-HE-Meta: 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 ZsdmiMSI 23MM76+602ppixhz2pngsZ+7xqWyZRgFgo05EEdEVzuUAH/BM3NzXiihthq6DJqtWMOsftnm0vPWhTqIJW0Sr9zMZLSXKDlO+Eh5EPnNCulonWZCvdcOXVISi1VMDtmiCHl1JGOJlrATyG42N7jHeCS5FOq4Iv1DSRdn6sg5JQcRO9rcHPWVxV/FxQHJMqQ0XNDkDaRA7RGax62KWnaEXxsrEUHxeKJlYKAJisnsqe2bf7NiBpJOh/iQjuSg3qzm/v7tVMcW9DCvcvgLi6fTC2fkL7TPzDtO9jBk6vWp+ZLCk9jAXvjhw4viE3hPxsXBDHHZ6gGaBFOrmbStepKEQQQ85rlXzXP90MkLdaIMkDUnXztEqmkhSQzQgW0uzuievH4LZx99QUfNB4KKRrJynnM4ZpKIyDT/XDNGRFChATOV/K6c= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi On Tue, Apr 21, 2026 at 3:29=E2=80=AFPM Mike Rapoport wro= te: > > On Mon, Apr 20, 2026 at 11:26:13PM +0900, Sang-Heon Jeon wrote: > > On Mon, Apr 20, 2026 at 3:31=E2=80=AFPM Mike Rapoport = wrote: > > > On Fri, Apr 17, 2026 at 10:58:05PM +0900, Sang-Heon Jeon wrote: > > > > When split NUMA node uniformly, split_nodes_size_interleave_uniform= () > > > > returns the next absolute node ID, not the number of nodes created. > > > > > > > > The existing under-allocation detection logic compares next absolut= e node > > > > ID (ret) and request count (n), which only works when nid starts at= 0. > > > > > > > > For example, on a system with 2 physical NUMA nodes (node 0: 2GB, n= ode > > > > 1: 128MB) and numa=3Dfake=3D8U, 8 fake nodes are successfully creat= ed from > > > > node 0 and split_nodes_size_interleave_uniform() returns 8. For nod= e 1, > > > > fake node nid starts at 8, but only 4 fake nodes are created due to > > > > current FAKE_NODE_MIN_SIZE being 32MB, and > > > > split_nodes_size_interleave_uniform() returns 12. By existing > > > > under-allocation detection logic, "ret < n" (12 < 8) is false, so t= he > > > > > > In this example it would be 11, won't it? > > > I'll update when applying. > > > > Oops, my previous reply is not the main point of this review. (Please i= gnore it) > > But 12 is still correct, because split_nodes_size_interleave_uniform() > > returns next available node ID. > > > > IMHO, it would be clearer if both the commit message and the function > > comment change into "next available node ID". > > If you're okay with it, I'll create v3 patch soon, including minor fix = below > > No need for v3, I updated the comment and the whitespace: > https://git.kernel.org/rppt/memblock/c/a34436ac05e76bd6634a89fc0a399ab3a4= 8f509a Thanks for your help, Mike. However, it seems like '12' was changed to '11' in the commit message. I think this change should be rolled back. Could you check? > > Best Regards, > > Sang-Heon Jeon > > -- > Sincerely yours, > Mike. Best Regards, Sang-Heon Jeon