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[91.12.111.102]) by smtp.gmail.com with ESMTPSA id f20-20020a05600c155400b0041665d968f1sm14949544wmg.47.2024.04.15.00.37.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Apr 2024 00:37:57 -0700 (PDT) Message-ID: Date: Mon, 15 Apr 2024 09:37:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] userfaultfd: remove WRITE_ONCE when setting folio->index during UFFDIO_MOVE To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: willy@infradead.org, peterx@redhat.com, lokeshgidra@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20240415020821.1152951-1-surenb@google.com> 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: <20240415020821.1152951-1-surenb@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: A67B640009 X-Rspam-User: X-Stat-Signature: ms1g9owg4caegn9roah9mqheidqx589o X-Rspamd-Server: rspam03 X-HE-Tag: 1713166686-823855 X-HE-Meta: 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 Ket7LPhH 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 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 15.04.24 04:08, Suren Baghdasaryan wrote: > When folio is moved with UFFDIO_MOVE it gets locked before the rmap and > index are modified. Due to the folio lock being already held, WRITE_ONCE() > is not needed when setting the folio index. Remove it. > > Reported-by: Matthew Wilcox > Signed-off-by: Suren Baghdasaryan > Cc: David Hildenbrand > Cc: Peter Xu > Cc: Lokesh Gidra > --- > mm/huge_memory.c | 2 +- > mm/userfaultfd.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 58f2c4745d80..ee12726291f1 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2200,7 +2200,7 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm > } > > folio_move_anon_rmap(src_folio, dst_vma); > - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); > + src_folio->index = linear_page_index(dst_vma, dst_addr); > > _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); > /* Follow mremap() behavior and treat the entry dirty after the move */ > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index b70618e8dcd2..575ccf90325a 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -1026,7 +1026,7 @@ static int move_present_pte(struct mm_struct *mm, > } > > folio_move_anon_rmap(src_folio, dst_vma); > - WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr)); > + src_folio->index = linear_page_index(dst_vma, dst_addr); > > orig_dst_pte = mk_pte(&src_folio->page, dst_vma->vm_page_prot); > /* Follow mremap() behavior and treat the entry dirty after the move */ > > base-commit: 3aec6b2b34e219898883d1e9ea7e911b4d3762a9 Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb