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Wysocki" , Danilo Krummrich , linux-mm@kvack.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arch_numa: remove redundant nodemask clears in numa_init() Message-Id: <20260624204030.3c8baa67713b6ca1d537baba@linux-foundation.org> In-Reply-To: <20260617163919.2544899-1-ekffu200098@gmail.com> References: <20260617163919.2544899-1-ekffu200098@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9147B40007 X-Stat-Signature: cae813bdiwn5gx797wnfbscyb5n8ruxm X-HE-Tag: 1782358831-602107 X-HE-Meta: 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 i13i6ioD ExOy+W6SbtVoHBiA2+jkMSAl12g+yrUch7v3vxXk1zSMe0hgT434XorQTZdc2ku9CtbwSMStc8pGpvc7ylPSCN32DUifB0Nii4j6jvNMVQq3/WdpBAPssrFmC0A/u3P+aJvrczNcJN6k4IV64uJk+dtjNFWt9cqkYL+pv7WT/+hNRsdVqGeyL5oshwdBmjyZKC5C7SKzk8VIu0afknQi5y1BtjLIcEV4TUFw2p3i6o0bRFDki3yzp9RNGwNjAneBKa9flI8OVCTc8b7hRAR30cRa1Gotb0wT6jeVM1cjXUkvJONwdDGwIIMlMO+ohMVhTEWIb Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 18 Jun 2026 01:39:19 +0900 Sang-Heon Jeon wrote: > numa_init() clears numa_nodes_parsed, node_possible_map and > node_online_map, then calls numa_memblks_init(), which clears the same > nodemasks. Nothing uses them in between. > > These clears have been redundant since commit 767507654c22 ("arch_numa: > switch over to numa_memblks") made numa_init() use numa_memblks_init(). > > No functional change. > > ... > > --- a/drivers/base/arch_numa.c > +++ b/drivers/base/arch_numa.c > @@ -231,10 +231,6 @@ static int __init numa_init(int (*init_func)(void)) > { > int ret; > > - nodes_clear(numa_nodes_parsed); > - nodes_clear(node_possible_map); > - nodes_clear(node_online_map); > - > ret = numa_memblks_init(init_func, /* memblock_force_top_down */ false); > if (ret < 0) > goto out_free_distance; hm, OK, thanks. A couple of driveby questions: Are the other nodes_clear() calls are needed - aren't these things zeroed when the kernel is loaded? Also, #define node_possible_map node_states[N_POSSIBLE] ... nodemask_t node_states[NR_NODE_STATES] __read_mostly = { [N_POSSIBLE] = NODE_MASK_ALL, why do we carefully initialize node_possible_map at compile-time then zero it within __init code?