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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8cecd06e4d6sm231860136d6.36.2026.06.10.03.41.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 03:41:59 -0700 (PDT) Date: Wed, 10 Jun 2026 06:41:57 -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: linux-kernel@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 Wed, Jun 03, 2026 at 03:00:01PM +1000, Balbir Singh wrote: > > > > __GFP_THISNODE cannot be overloaded to do anything useful here. > > Let me clarify, I meant to say, let's use a nodemask for allocation > and __GFP_THISNODE gets us to the node we desire, if that is the only > node. My earlier comment might not have been clear. > I've been tested an stripped back patch set where I drop all FALLBACK entries for private nodes (including for itself) and only keep the NOFALLBACK entry for private nodes. This effectively isolates the nodes for any allocation without __GFP_THISNODE. This also precludes these nodes from ever using non-mbind mempolicies, which I think is a completely reasonable compromise and something I was already expecting we would do. Notably: slub.c injects __GFP_THISNODE internally on behalf of kmalloc, which causes spillage into private nodes because slub allows private nodes in its mask. I think this is fixable. I have to inspect some other __GFP_THISNODE users (hugetlb, some arch code, etc), but it seems like fully dropping the FALLBACK entries and requiring __GFP_THISNODE might be sufficient. ~Gregory