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Wed, 30 Sep 2026 02:11:30 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F ([2620:10d:c092:500::6:13b8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a0174d5191sm41627435e9.3.2026.09.30.02.11.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 02:11:30 -0700 (PDT) Date: Wed, 30 Sep 2026 05:11:28 -0400 From: Gregory Price To: Li Zhe Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, ziy@nvidia.com, joshua.hahnjy@gmail.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/numa_balancing: allow migrate on protnone reference with MPOL_WEIGHTED_INTERLEAVE policy Message-ID: References: <20260930072617.64665-1-lizhe.67@bytedance.com> <7df34f77-2c52-47a3-a495-d782009ab543@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7df34f77-2c52-47a3-a495-d782009ab543@bytedance.com> X-Rspam-User: X-Stat-Signature: gqifgebahcyemxj1crikcajca63ioo5y X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7F1768000C X-HE-Tag: 1790759492-349318 X-HE-Meta: U2FsdGVkX1+mxaKIJCDHMwiuQv64wNWMQ6Xn2Oay2jM3yHqHFXLv9KEfI/nItTZL38UWH9Ao3w6V1aDhE9MvGq7pr8x2vHoTetF1Ow/GgWgKFk8cmcUpU7SS2YYoa32nIc3dhr171Lndxcfr7e/Xqn91+0Jd0zpdwE0L+B555C0jQBQgB7AFNb4DtSK3BoXJs+kCuIGMOGeW/10KKr1cojFJOxfR8FeIwy1W34tjKb1F1o65B3QfJ0UVFl8Kfycxds8SIlalcPfXJnval/1QGApJO69dbZOE9RaRN62RhJUnlleIaCsM8OkkgBlS4SqhAIpqAa9+35jYO32+HdmqQRSgBqL5GC0+ZIHH5qQoDH4B2MbTE90Eeg0/kODxyrr8S7qprMukBvJ4QncnVGLRKYC7sLv13sR91Ekd+ZkEkKn8WTTBn1WzHK6M/u/sspvNbXzg4C40TPHKFvU+fq2kKQPn/z6VaFW9KCTEt/N4LHPpHQCEYfjY5ghldx6h8+UU6pwjgKNnVnJmNZ20znw0HIXVhPaRGx+ik2og2qBMTBQHBjGCU0rNVU+LqnL799Rewz9jNfDfwZy2+Xsd4H2khNY9vGbTRbIXc9T6c8g/HnKW/XNDj0G6nymFTh1q6lQQpATQWfVJPRTYScMAxKWJGofj3gS0d5Ty5C6yboFHtVCMQVvQKjfs/BxivVvgAu6KmuilVbcG0wXOnqoy6VrclcAVHDllIxpN174E2NArQO7nEwGqKr93jvofxMLnL/gbQhq0MK4hVHyHmhOBN10xgoYD4Z17hE9f8cacvN1gN0cImn9Isd952g5v6Qs+DcL59c/2eTzvZgMqJCJDi1FNzVphfIPOCYuhPc9mTZ4gENPNPRP0WnebKKGScOXWNhR7Hsu+4/KAHtE/O6WakLjEB2XxiSME3mmXqPwQpALWqxU5/BZ3vz8MzDiZCoRbozRuuCSiyHkqYruoULf/7oN THyql2hh 9jI5T2BJzU6BTXYJdOVTBAz7+lcYMFzbsINZw8GixHHsJJUwUKZ9F7Fd6stpRdvkhomBbFGP4LCUUvUiuI+G3sBAcqX1mWcgA+ptgNQCPeNi4T5uQxXfR34PKnmlSSSQzHfSF285KzzcHoM2/D0bxHIM6WA19GbmA2zEnxYMoYeeIeOlXWNp0MrZuT9mIMoo+zzUnpjWGElpYpR1jl5rxm70sTDqPXh5zgnCmsIa+R7U/t+45MGq9ScXQ7fU8tELkOuTQywSmONHouetGb7AwxtWv9wjTkW71dTvH9IlL6Rr4Kcoil74Kr7T/+1ajY5UzuJTlEwVMhlFXO97EvezNBEyakrDRDTFfe2Lu9OkuRsGfRbY7XD1RQx7k26zwo1IlyjM32ieTwpKMHsgwE14NTSNeSgoUxKYlTAukQNr0zyYu/kwZJWiXBX3UWOBY92DFIEF0za0LWwLGIRaFWtKjwLO1gZwYFW0D3mQv0DhuZZYT/FA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 30, 2026 at 04:59:50PM +0800, Li Zhe wrote: > On 9/30/26 4:43 PM, Gregory Price wrote: > > On Wed, Sep 30, 2026 at 03:26:17PM +0800, Li Zhe wrote: > >> Allow MPOL_F_NUMA_BALANCING for MPOL_WEIGHTED_INTERLEAVE. As with > >> MPOL_BIND and MPOL_PREFERRED_MANY, keep migration constrained by the > >> policy nodemask: if the CPU's node is outside the nodemask, do not > >> migrate the folio there. > >> > > Why for WEIGHTED_INTERLEAVE and not INTERLEAVE as well? > > > Thanks for pointing this out. > > I focused on MPOL_WEIGHTED_INTERLEAVE in v1 because the motivating use > case is to seed memory across tiers with a configurable ratio at > allocation time, and then let NUMA balancing/memory tiering adjust the > placement based on access patterns. With equal weights, > MPOL_WEIGHTED_INTERLEAVE can also cover the regular interleave > allocation pattern. > > That said, I agree that MPOL_INTERLEAVE can be handled consistently as > well. Since this is still an explicit opt-in via MPOL_F_NUMA_BALANCING, > unless others see a reason to keep MPOL_INTERLEAVE out, I will extend > this in v2 to cover both MPOL_INTERLEAVE and MPOL_WEIGHTED_INTERLEAVE > with the same nodemask constraint. > Looking at it, is there an actual reason to limit F_MORON at all? Or should we just lift if (pol->flags & MPOL_F_MORON) { /* * Optimize placement among multiple nodes * via NUMA balancing */ if (node_isset(thisnid, pol->nodes)) break; goto out; } Out ahead of everything? ~Gregory