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(p200300d82f022900f54fbad7c5f49404.dip0.t-ipconnect.de. [2003:d8:2f02:2900:f54f:bad7:c5f4:9404]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eaf445708sm17297552f8f.96.2025.04.16.06.02.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Apr 2025 06:02:09 -0700 (PDT) Message-ID: <2595106e-aa4a-4140-8f6a-05348497e2ee@redhat.com> Date: Wed, 16 Apr 2025 15:02:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/rmap: Move anon_vma initialization to anon_vma_ctor() To: Lorenzo Stoakes , Ye Liu Cc: Harry Yoo , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ye Liu , "Liam R. Howlett" , Vlastimil Babka References: <20250415092548.271718-1-ye.liu@linux.dev> <0696eaac-943f-4116-b682-f9b15de6aeaf@linux.dev> 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: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: M5bp_Wb1L-I3BPkAx9u5qgEwxU6Fnil-N2CFNaxXSwo_1744808531 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 6636A1A0012 X-Stat-Signature: iymrg9dzzuuxhdee5mb3e93a5w8gjqfi X-HE-Tag: 1744808535-27914 X-HE-Meta: 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 ekZGen9G 0ASXs2lIXmc8yRqzMJ8ItTTg9TvYyGKG+8tZ3NEpQny7gjwM8cvoMVuw6ClSwjmDI0np77guSa9/JbByJ/Sg1DPZ2ptnAIoxBWjQKf6rMu/Kq8Yha38OqQET+yYNlh4bBL8Qj6q67/9LHrh/sJTgPnAHuqMQZBWRr48HnvJOs+ZZnWyMo5o8w5CKgGkgZk2MM+UkT0/aLZPBFG3K/8dn8MSOZdOwrGJDxbwKJn6MYw3SZSUnek5yDWeHchraQsE1078Q50LQmV4a5YQqGdsUC0+Sw2vBWtxnwfaTgc/aOaWQevaHpN7rJZdQ3xVCR5YDGWOMh+/XDgpMwNAuSjOQbli8LLuEkHn+5bgMfrBveX1/hKBNfUvmM5YonofNohA26jJXkN0ZkB4Gb7YhASQ6HyLbnlnu53DC+gx9WxpppPGb9+qeg40Zlykh/zDVLdqkCiWHI4egNSP9EVPXYO93VNYMkZO0Liop+97/q 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 16.04.25 14:59, Lorenzo Stoakes wrote: > +cc David, Liam > > On Wed, Apr 16, 2025 at 09:34:30AM +0800, Ye Liu wrote: >> >> 在 2025/4/15 19:28, Harry Yoo 写道: >>> On Tue, Apr 15, 2025 at 05:25:48PM +0800, Ye Liu wrote: >>>> From: Ye Liu >>>> >>>> Currently, some initialization of anon_vma is performed in >>>> anon_vma_alloc(). Move the initialization to anon_vma_ctor() >>>> so that all object setup is handled in one place. >>>> >>>> Signed-off-by: Ye Liu >>>> --- >>> NACK unless the patch explains how the object's initial state >>> ('constructed state') is preserved between uses. >>> >>> anon_vma_ctor() is a slab constructor. That means it is called only once >>> when a slab (folio) is allocated, and not called again when an anon_vma >>> is allocated from an existing slab (folio). In other words it is not called >>> everytime an object allocated via kmem_cache_alloc() interface. >> Thank you for the feedback. You're absolutely right — I misunderstood >> how the slab constructor (ctor) works. I had assumed it would be called >> every time an object is allocated via kmem_cache_alloc(), but I now >> realize it is only called once when a new slab is initialized, not on >> every object allocation. >>> This patch looks very dangerous to me and makes me question whether you >>> tested it before submission. >>> >> Appreciate you catching this — and yes, I'll test it more thoroughly >> before submitting other patches. >> >> Drop it. >> >> Thanks, >> Ye >> > > I agree with Harry's assessment, also this is something that needs to be cc'd to > other developers - I am more generally working on anon_vma at the moment and > this is vma-adjacent even if slab-ish :) I stumbled over this patch on linux-mm and agreed with Harry's assessment as well. :) -- Cheers, David / dhildenb