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[34.125.132.248]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a2f3d5dea1sm411421835ad.81.2026.01.04.01.04.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 01:04:22 -0800 (PST) Date: Sun, 4 Jan 2026 09:04:16 +0000 From: Bing Jiao To: Waiman Long Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, gourry@gourry.net, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, tj@kernel.org, mkoutny@suse.com, david@kernel.org, zhengqi.arch@bytedance.com, lorenzo.stoakes@oracle.com, axelrasmussen@google.com, chenridong@huaweicloud.com, yuanchu@google.com, weixugc@google.com, cgroups@vger.kernel.org Subject: Re: [PATCH v3] mm/vmscan: fix demotion targets checks in reclaim/demotion Message-ID: References: <20251221233635.3761887-1-bingjiao@google.com> <20251223212032.665731-1-bingjiao@google.com> <84ed9b5d-41d5-44a1-a1ad-2b3de8b50a50@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <84ed9b5d-41d5-44a1-a1ad-2b3de8b50a50@redhat.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3E41E40009 X-Stat-Signature: 9b34womk41hent5bsumzd7bq36gcctsw X-Rspam-User: X-HE-Tag: 1767517464-961342 X-HE-Meta: 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 4HiJIXP2 ssPMyXcjbzX+msyleIJ93g9i2zGrYi0V7mqNP3YTC7wTruIFAXf2othsBor1xoYEc5qyBRb+mBu9JWGTXFzr/TlmEYmimPIHRKMGExVkUjXdI2pi+xtWZShqsmT1Ze5X2SXVegEsu9W2jVW+KBxDaTzV1wlz2czQxfely8yO+PgysXijUUa3HBJc5qBPplkWXStjXT+B/3nOWfxwSle85uaF9/LjVfuBCz8t88ln8qHgJa8wdimwZAdL1gvHj/i1MAjJ8HMi1jJpBlk2FNHboRupTgrMyHYV3TWqKH6w7ULUhVJjD9AUEpkRW/1ZY0r2jxamFWuu6bc+u6k2Yym8IBrEERZR0/0cT8H78an88iqGZ9Ek= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Dec 26, 2025 at 03:24:29PM -0500, Waiman Long wrote: > The nodemask_t type can be large depending on the setting of > CONFIG_NODES_SHIFT. Passing a large data structure on stack may not be a > good idea. You can return a pointer to nodemask_t instead. In that case, you > will have a add a "const" qualifier to the return type to make sure that the > node mask won't get accidentally modified. Alternatively, you can pass a > nodemask_t pointer as an output parameter and copy out the nodemask_t data. > > The name "cpuset_node_get_allowed" doesn't fit the cpuset naming convention. > There is a "cpuset_mems_allowed(struct task_struct *)" to return > "mems_allowed" of a task. This new helper is for returning the mems_allowed > defined in the cpuset. Perhaps we could just use > "cpuset_nodes_allowed(struct cgroup *)". > > Cheers, > Longman Thank you for the explanation and suggestion. I have updated v4, which updates the functions to filter out nodes rather than returning mems_allowed. In v3, the caller need to declare a temp nodemask_t to store mems_allowed and then intersect with lower-tier nodemask, which is unnecessarily increase the stack size. The function name is updated as "cpuset_nodes_filter_allowed". Do you think it is still better to use "cpuset_nodes_allowed" when doing the filtering thing? Thanks, Bing