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b=lHjoTr7sIlcC9HNescoIpEPVQhPYNXrrn8kuYOlfh41Cd/1Outqp9FnHfcUeTMY0W iEkxlDCU3g121k8qL8QB4vVFyvlUqmahDpoM0wbD8edNTZvDyu4kC9L/+4efEQZRg9 9ug6ej2V7Wp/wLNPpr+vhhwio/AUSHk/cMZ3X0VOJN7l2YevgVwJt4HvwPKD5azCJG 3SsQehi0gO+JbVNmV9/lYMQEJp8KkZYPn1kJg0aUkJmJdAkjrHcgY+pbbeBIYzyBH6 dVPiOO+/ZBtF/BOxpPF09c9LCbWa+wijIvDfgmdiu0fzJngBcN+9tIejaPyPefGGlK 1ZJJoJQDTfZsg== Message-ID: Date: Wed, 10 Jun 2026 17:00:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC][RFC PATCH v4 00/27] Private Memory Nodes (w/ Compressed RAM) To: Gregory Price , 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, 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 References: <20260222084842.1824063-1-gourry@gourry.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 36FE7A0011 X-Rspam-User: X-Stat-Signature: d6xkypht8dmz4mshhymer49rxdimk86w X-Rspamd-Server: rspam08 X-HE-Tag: 1781103655-849845 X-HE-Meta: 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 uJxvI4TT 1f/m6Yyp/Sc/ENudAIRj7sz2jetiRlE5uTb/a+2Y5lUXV6JVUb+WkqaO2ATk7fzPZ03mQv262uq/6zy0Wa2U4OCPqfAx+oln6It4RIYVyryv/0YwHaruHDgLhXCC8glXZH7VVeCiw0k+Txm+ey5VlY9YzwHsMbQ5lKr24kfOEw2+nIhO7i91lQZrLv6SecnHGjQ65Ze8ggttsbcZb41O0D5dphhPgsUr2Lj7cee3OZ/303qIQRZSND7i8WtE8nfyugFF1ruv4E8ADRPKhFqgrXY8c4RYkgngCRosqXrdNx0h/G45LdIBzOg7f2CbVQMHDPVvgdC2OYYl6Nbo= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/10/26 12:41, Gregory Price wrote: > 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. Sorry, I haven't been able to follow up so far, and not sure if that's what you are discussing here ... After the LSF/MM session, I was wondering, whether if we focus on allowing only folios allocations to end up on private memory nodes for now: could the __GFP_THISNODE approach work there? Essentially, disallow any allocations on non-folio paths, and allow folio allocation only with __GFP_THISNODE set. I have to find time to read the other mails in this thread, on my todo list. So sorry if that is precisely what is being discussed here. -- Cheers, David