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[2003:cb:c707:4f00:a44a:5ad6:765a:635]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39c3020d66csm14985167f8f.63.2025.04.08.03.17.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Apr 2025 03:17:53 -0700 (PDT) Message-ID: <92ff4f7f-90d2-48ab-8f7d-7fc3485276b5@redhat.com> Date: Tue, 8 Apr 2025 12:17:52 +0200 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] mm,slub: Do not special case N_NORMAL nodes for slab_nodes To: Oscar Salvador , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Harry Yoo , Jonathan Cameron , linux-cxl@vger.kernel.org References: <20250408084153.255762-1-osalvador@suse.de> <20250408084153.255762-2-osalvador@suse.de> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250408084153.255762-2-osalvador@suse.de> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: DJXKq0XPFzNsV-8TlGivtFnTkNVJtybBdJXNFhEOkoY_1744107474 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 08.04.25 10:41, Oscar Salvador wrote: > Currently, slab_mem_going_going_callback() checks whether the node has > N_NORMAL memory in order to be set in slab_nodes. > While it is true that gettind rid of that enforcing would mean > ending up with movables nodes in slab_nodes, the memory waste that comes > with that is negligible. > > So stop checking for status_change_nid_normal and just use status_change_nid > instead which works for both types of memory. > > Also, once we allocate the kmem_cache_node cache for the node in > slab_mem_online_callback(), we never deallocate it in > slab_mem_off_callback() when the node goes memoryless, so we can just > get rid of it. > > The only side effect is that we will stop clearing the node from slab_nodes. > Feel free to add a Suggested-by: if you think it applies. Do we have to take care of the N_NORMAL_MEMORY check in kmem_cache_init() ? Likely it would have to be a N_MEMORY check. But, I was wondering if we could get rid of the "slab_nodes" thingy as a first step? From 518a2b83a9c5bd85d74ddabbc36ce5d181a88ed6 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 8 Apr 2025 12:16:13 +0200 Subject: [PATCH] tmp Signed-off-by: David Hildenbrand --- mm/slub.c | 56 ++++--------------------------------------------------- 1 file changed, 4 insertions(+), 52 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index b46f87662e71d..afe31149e7f4e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -445,14 +445,6 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node) for (__node = 0; __node < nr_node_ids; __node++) \ if ((__n = get_node(__s, __node))) -/* - * Tracks for which NUMA nodes we have kmem_cache_nodes allocated. - * Corresponds to node_state[N_NORMAL_MEMORY], but can temporarily - * differ during memory hotplug/hotremove operations. - * Protected by slab_mutex. - */ -static nodemask_t slab_nodes; - #ifndef CONFIG_SLUB_TINY /* * Workqueue used for flush_cpu_slab(). @@ -3706,10 +3698,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (!slab) { /* * if the node is not online or has no normal memory, just - * ignore the node constraint + * ignore the node constraint. */ - if (unlikely(node != NUMA_NO_NODE && - !node_isset(node, slab_nodes))) + if (unlikely(node != NUMA_NO_NODE && !node_state(node, N_NORMAL_MEMORY))) node = NUMA_NO_NODE; goto new_slab; } @@ -3719,7 +3710,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, * same as above but node_match() being false already * implies node != NUMA_NO_NODE */ - if (!node_isset(node, slab_nodes)) { + if (!node_state(node, N_NORMAL_MEMORY)) { node = NUMA_NO_NODE; } else { stat(s, ALLOC_NODE_MISMATCH); @@ -5623,7 +5614,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) { int node; - for_each_node_mask(node, slab_nodes) { + for_each_node_state(node, N_NORMAL_MEMORY) { struct kmem_cache_node *n; if (slab_state == DOWN) { @@ -6164,30 +6155,6 @@ static int slab_mem_going_offline_callback(void *arg) return 0; } -static void slab_mem_offline_callback(void *arg) -{ - struct memory_notify *marg = arg; - int offline_node; - - offline_node = marg->status_change_nid_normal; - - /* - * If the node still has available memory. we need kmem_cache_node - * for it yet. - */ - if (offline_node < 0) - return; - - mutex_lock(&slab_mutex); - node_clear(offline_node, slab_nodes); - /* - * We no longer free kmem_cache_node structures here, as it would be - * racy with all get_node() users, and infeasible to protect them with - * slab_mutex. - */ - mutex_unlock(&slab_mutex); -} - static int slab_mem_going_online_callback(void *arg) { struct kmem_cache_node *n; @@ -6229,11 +6196,6 @@ static int slab_mem_going_online_callback(void *arg) init_kmem_cache_node(n); s->node[nid] = n; } - /* - * Any cache created after this point will also have kmem_cache_node - * initialized for the new node. - */ - node_set(nid, slab_nodes); out: mutex_unlock(&slab_mutex); return ret; @@ -6253,8 +6215,6 @@ static int slab_memory_callback(struct notifier_block *self, break; case MEM_OFFLINE: case MEM_CANCEL_ONLINE: - slab_mem_offline_callback(arg); - break; case MEM_ONLINE: case MEM_CANCEL_OFFLINE: break; @@ -6309,7 +6269,6 @@ void __init kmem_cache_init(void) { static __initdata struct kmem_cache boot_kmem_cache, boot_kmem_cache_node; - int node; if (debug_guardpage_minorder()) slub_max_order = 0; @@ -6321,13 +6280,6 @@ void __init kmem_cache_init(void) kmem_cache_node = &boot_kmem_cache_node; kmem_cache = &boot_kmem_cache; - /* - * Initialize the nodemask for which we will allocate per node - * structures. Here we don't need taking slab_mutex yet. - */ - for_each_node_state(node, N_NORMAL_MEMORY) - node_set(node, slab_nodes); - create_boot_cache(kmem_cache_node, "kmem_cache_node", sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN | SLAB_NO_OBJ_EXT, 0, 0); -- 2.48.1 Not sure if there are any races to consider ... just an idea. -- Cheers, David / dhildenb