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[100.36.248.188]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-516d8cb9f11sm88159681cf.23.2026.05.24.18.50.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 24 May 2026 18:50:09 -0700 (PDT) Date: Sun, 24 May 2026 21:50:06 -0400 From: Gregory Price To: Balbir Singh Cc: lsf-pc@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, damon@lists.linux.dev, kernel-team@meta.com, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, longman@redhat.com, akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, osalvador@suse.de, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, jackmanb@google.com, sj@kernel.org, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, muchun.song@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, jannh@google.com, linmiaohe@huawei.com, nao.horiguchi@gmail.com, pfalcato@suse.de, rientjes@google.com, shakeel.butt@linux.dev, riel@surriel.com, harry.yoo@oracle.com, cl@gentwo.org, roman.gushchin@linux.dev, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, zhengqi.arch@bytedance.com, terry.bowman@amd.com Subject: Re: [LSF/MM/BPF TOPIC][RFC PATCH v4 00/27] Private Memory Nodes (w/ Compressed RAM) Message-ID: References: <20260222084842.1824063-1-gourry@gourry.net> 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: On Thu, May 21, 2026 at 04:23:28PM +1000, Balbir Singh wrote: > On Sun, Feb 22, 2026 at 03:48:15AM -0500, Gregory Price wrote: > > Topic type: MM > > > > Presenter: Gregory Price > > > > This series introduces N_MEMORY_PRIVATE, a NUMA node state for memory > > managed by the buddy allocator but excluded from normal allocations. > > > > I present it with an end-to-end Compressed RAM service (mm/cram.c) > > that would otherwise not be possible (or would be considerably more > > difficult, be device-specific, and add to the ZONE_DEVICE boondoggle). > > > > Do we have updates/notes from the meeting? > I have been on leave since LSF, but I do have some notes posted: https://lore.kernel.org/linux-mm/af9i7dkNvGGxPHzu@gourry-fedora-PF4VCD3F/ https://lore.kernel.org/linux-mm/agYJcRgOHho8upVv@gourry-fedora-PF4VCD3F/ I will be trying to post an updated set stripped down without the GFP flag as a first pass w/o RFC tags and no UAPI implications so that device folks can play with this upstream. I'm debating on whether to include OPS_MEMPOLICY in the initial version if only because it's not intuitive how it interacts with pagecache. That needs more time to bake. > > > > page = alloc_pages_node(nid, __GFP_PRIVATE, 0); > > Do we want to provide kernel level control over allocation of private > pages, I assumed that only user space applications? I would assume > node affinity would be the way to do so, unless we have multiple > alloc_pages_node() is the kernel interface > > > > /* Ok but I want to do something useful with it */ > > static const struct node_private_ops ops = { > > .migrate_to = my_migrate_to, > > .folio_migrate = my_folio_migrate, > > .flags = NP_OPS_MIGRATION | NP_OPS_MEMPOLICY, > > }; > > node_private_set_ops(nid, &ops); > > > > Could you explain this further? Why does OPS_MIGRATION > and OPS_MEMPOLICY needs to be set explictly? > Both of these have been removed from the upcoming version, but in this RFC version i was testing OPS_MIGRATION as an explicit flag that meant "migrate.c can touch the folios" while OPS_MEMPOLICY meant "mempolicy.c can touch the folios". As it turns out, OPS_MIGRATION is not a useful filter, as it doesn't actually filter anything (anything using OPS_MIGRATION would also need its own filter flag, so better to just drop it and do per-server opt-ins). ~Gregory