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[79.242.61.201]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ec34bbd9csm54659795e9.20.2025.04.04.13.45.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Apr 2025 13:45:03 -0700 (PDT) Message-ID: <198f2cbe-b1cb-4239-833e-9aac33d978fa@redhat.com> Date: Fri, 4 Apr 2025 22:45:00 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 3/3] mm/mempolicy: Support memory hotplug in weighted interleave To: Rakie Kim , akpm@linux-foundation.org Cc: gourry@gourry.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, joshua.hahnjy@gmail.com, dan.j.williams@intel.com, ying.huang@linux.alibaba.com, Jonathan.Cameron@huawei.com, osalvador@suse.de, kernel_team@skhynix.com, honggyu.kim@sk.com, yunjeong.mun@sk.com References: <20250404074623.1179-1-rakie.kim@sk.com> <20250404074623.1179-4-rakie.kim@sk.com> From: David Hildenbrand Content-Language: en-US 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: <20250404074623.1179-4-rakie.kim@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.04.25 09:46, Rakie Kim wrote: > The weighted interleave policy distributes page allocations across multiple > NUMA nodes based on their performance weight, thereby improving memory > bandwidth utilization. The weight values for each node are configured > through sysfs. > > Previously, sysfs entries for configuring weighted interleave were created > for all possible nodes (N_POSSIBLE) at initialization, including nodes that > might not have memory. However, not all nodes in N_POSSIBLE are usable at > runtime, as some may remain memoryless or offline. > This led to sysfs entries being created for unusable nodes, causing > potential misconfiguration issues. > > To address this issue, this patch modifies the sysfs creation logic to: > 1) Limit sysfs entries to nodes that are online and have memory, avoiding > the creation of sysfs entries for nodes that cannot be used. > 2) Support memory hotplug by dynamically adding and removing sysfs entries > based on whether a node transitions into or out of the N_MEMORY state. > > Additionally, the patch ensures that sysfs attributes are properly managed > when nodes go offline, preventing stale or redundant entries from persisting > in the system. > > By making these changes, the weighted interleave policy now manages its > sysfs entries more efficiently, ensuring that only relevant nodes are > considered for interleaving, and dynamically adapting to memory hotplug > events. > > Signed-off-by: Rakie Kim > Signed-off-by: Honggyu Kim > Signed-off-by: Yunjeong Mun > --- > mm/mempolicy.c | 109 ++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 86 insertions(+), 23 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 73a9405ff352..f25c2c7f8fcf 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -113,6 +113,7 @@ > #include > #include > #include > +#include > > #include "internal.h" > > @@ -3390,6 +3391,7 @@ struct iw_node_attr { > > struct sysfs_wi_group { > struct kobject wi_kobj; > + struct mutex kobj_lock; > struct iw_node_attr *nattrs[]; > }; > > @@ -3439,13 +3441,24 @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr, > > static void sysfs_wi_node_delete(int nid) > { > - if (!wi_group->nattrs[nid]) > + struct iw_node_attr *attr; > + > + if (nid < 0 || nid >= nr_node_ids) > + return; > + > + mutex_lock(&wi_group->kobj_lock); > + attr = wi_group->nattrs[nid]; > + if (!attr) { > + mutex_unlock(&wi_group->kobj_lock); > return; > + } > + > + wi_group->nattrs[nid] = NULL; > + mutex_unlock(&wi_group->kobj_lock); > > - sysfs_remove_file(&wi_group->wi_kobj, > - &wi_group->nattrs[nid]->kobj_attr.attr); > - kfree(wi_group->nattrs[nid]->kobj_attr.attr.name); > - kfree(wi_group->nattrs[nid]); > + sysfs_remove_file(&wi_group->wi_kobj, &attr->kobj_attr.attr); > + kfree(attr->kobj_attr.attr.name); > + kfree(attr); > } > > static void sysfs_wi_release(struct kobject *wi_kobj) > @@ -3464,35 +3477,80 @@ static const struct kobj_type wi_ktype = { > > static int sysfs_wi_node_add(int nid) > { > - struct iw_node_attr *node_attr; > + int ret = 0; > char *name; > + struct iw_node_attr *new_attr = NULL; > > - node_attr = kzalloc(sizeof(*node_attr), GFP_KERNEL); > - if (!node_attr) > + if (nid < 0 || nid >= nr_node_ids) { > + pr_err("Invalid node id: %d\n", nid); > + return -EINVAL; > + } > + > + new_attr = kzalloc(sizeof(struct iw_node_attr), GFP_KERNEL); > + if (!new_attr) > return -ENOMEM; > > name = kasprintf(GFP_KERNEL, "node%d", nid); > if (!name) { > - kfree(node_attr); > + kfree(new_attr); > return -ENOMEM; > } > > - sysfs_attr_init(&node_attr->kobj_attr.attr); > - node_attr->kobj_attr.attr.name = name; > - node_attr->kobj_attr.attr.mode = 0644; > - node_attr->kobj_attr.show = node_show; > - node_attr->kobj_attr.store = node_store; > - node_attr->nid = nid; > + mutex_lock(&wi_group->kobj_lock); > + if (wi_group->nattrs[nid]) { > + mutex_unlock(&wi_group->kobj_lock); > + pr_info("Node [%d] already exists\n", nid); > + kfree(new_attr); > + kfree(name); > + return 0; > + } > + wi_group->nattrs[nid] = new_attr; > > - if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) { > - kfree(node_attr->kobj_attr.attr.name); > - kfree(node_attr); > - pr_err("failed to add attribute to weighted_interleave\n"); > - return -ENOMEM; > + sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr); > + wi_group->nattrs[nid]->kobj_attr.attr.name = name; > + wi_group->nattrs[nid]->kobj_attr.attr.mode = 0644; > + wi_group->nattrs[nid]->kobj_attr.show = node_show; > + wi_group->nattrs[nid]->kobj_attr.store = node_store; > + wi_group->nattrs[nid]->nid = nid; > + > + ret = sysfs_create_file(&wi_group->wi_kobj, > + &wi_group->nattrs[nid]->kobj_attr.attr); > + if (ret) { > + kfree(wi_group->nattrs[nid]->kobj_attr.attr.name); > + kfree(wi_group->nattrs[nid]); > + wi_group->nattrs[nid] = NULL; > + pr_err("Failed to add attribute to weighted_interleave: %d\n", ret); > } > + mutex_unlock(&wi_group->kobj_lock); > > - wi_group->nattrs[nid] = node_attr; > - return 0; > + return ret; > +} > + > +static int wi_node_notifier(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + int err; > + struct memory_notify *arg = data; > + int nid = arg->status_change_nid; > + > + if (nid < 0) > + goto notifier_end; > + > + switch(action) { > + case MEM_ONLINE: MEM_ONLINE is too late, we cannot fail hotplug at that point. Would MEM_GOING_ONLINE / MEM_CANCEL_ONLINE be better? > + err = sysfs_wi_node_add(nid); > + if (err) { > + pr_err("failed to add sysfs [node%d]\n", nid); > + return NOTIFY_BAD; Note that NOTIFY_BAD includes NOTIFY_STOP_MASK. So you wouldn't call other notifiers, but the overall memory onlining would succeed, which is bad. If we don't care about the error (not prevent hotplug) we could only pr_warn() and continue. Maybe this (unlikely) case is not a good reason to stop memory from getting onlined. OTOH, it will barely ever trigger in practice ... -- Cheers, David / dhildenb