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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-931062c4ea8sm34465885a.28.2026.07.22.20.25.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jul 2026 20:25:21 -0700 (PDT) Date: Wed, 22 Jul 2026 23:25:15 -0400 From: Gregory Price To: SJ Park Cc: arun.george@samsung.com, balbirs@nvidia.com, brendan.jackman@linux.dev, yuzenghui@huawei.com, apopple@nvidia.com, alucerop@amd.com, matthew.brost@intel.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, alison.schofield@intel.com, osandov@osandov.com, jannh@google.com, pfalcato@suse.de, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, pbonzini@redhat.com, osalvador@suse.de, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, mkoutny@suse.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, usama.arif@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, driver-core@lists.linux.dev, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-debuggers@vger.kernel.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v5 14/36] mm/damon: skip private node memory in DAMON migration and pageout Message-ID: References: <20260723001943.95854-1-sj@kernel.org> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260723001943.95854-1-sj@kernel.org> On Wed, Jul 22, 2026 at 05:19:42PM -0700, SJ Park wrote: > On Wed, 22 Jul 2026 08:16:56 -0400 Gregory Price wrote: > > > > "by default". Does that mean it could be reclaimable in some situations? If > > > so, could we check if it is reclaimable? > > > > > > > See the damon changes in: > > > > https://lore.kernel.org/linux-mm/al-pkvmgIxGu3LzM@gourry-fedora-PF4VCD3F/T/#mfb99303c85dd9d4c3f58832dc28fc55583a7217a > > Summarizing what you want to say, quoting something from the patch, or at least > calling it "26th patch of this series" would have made reviewing much easier. > Cc-ing damon@ for only patches that toucing DAMON source files and the cover > letter of the series could also be helpful. Please consider doing some of > these for future replies. > I have been very much discouraged from this kind of trimming because it removes the context of the series from the individual patches - making it even more confusing. But I understand, I will try to remember to do this for you. > So, I understand later patches will make it optionally reclaimable and update > this restriction by the 26th patch? That sounds fair. But, could we drop "by > default" from the above comment for reducing the confusion? Yes, but you bring up a good point - I think this two-step process is actually poor form and that I need to redo it. Maybe this can be redone as node states (features?) such as: N_MEMORY_RECLAIMABLE N_MEMORY_DEMOTABLE N_MEMORY_TIERABLE so these damon changes will forego this confusing intermediate step of: if (folio_is_private_node(folio)) and go straight to if (node_is_reclaimable(folio_nid(folio))) In the first patch - without ever having to revisit damon again. > > > > Technically there is nothing in migration core to prevent migration > > operations, it's done on a service basis - hotunplug, reclaim/demotion, > > user numa (mbind, migrate/move_pages) etc. > > > > Operations on private nodes/private node folioes are refused if the > > capability bit is not set. > > I haven't had a chance to read the entire series, sorry about that. So, do you > mean the above blocking is not really needed, or that will conditionally be > allowed by another later patch? > I will reduce this all to a single patch in v6, I see where things can be improved now based on a few pieces of feedback. Thanks SJ! ~Gregory