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[2003:cb:c70b:e100:38d6:8aa1:11b0:a20a]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-434d52b66ecsm33099575e9.39.2024.12.04.11.01.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Dec 2024 11:01:49 -0800 (PST) Message-ID: <0dc516ab-b2b0-414d-868e-880bd13b5cdd@redhat.com> Date: Wed, 4 Dec 2024 20:01:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] hugetlb: support FOLL_FORCE|FOLL_WRITE To: Guillaume Morin , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Muchun Song , Andrew Morton , Peter Xu , Eric Hagberg References: 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: 8Lj5FIMa9M2bqetiz5Iz06s4wZliDwAdhjM_yuK70uY_1733338912 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 510BCC0018 X-Stat-Signature: wp6raw45fyfwe5roi4uncif5zih1nxhh X-HE-Tag: 1733338901-547401 X-HE-Meta: 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 BpF5MCl5 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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 04.12.24 19:26, Guillaume Morin wrote: Patch prefix should likely be "mm/hugetlb: ..." > FOLL_FORCE|FOLL_WRITE has never been properly supported for hugetlb > mappings. Since 1d8d14641fd94, we explicitly reject it. However "Since commit 1d8d14641fd9 ("mm/hugetlb: support write-faults in shared mappings") ..." > running software on hugetlb mappings is a useful optimization. > Multiple tools allow to use that such as Intel iodlr or > libhugetlbfs. It would be better to link to the actual request where people ran into that when using PTRACE_POKETEXT That hugetlb is getting used is rather obvious :) > > Cc: Muchun Song > Cc: Andrew Morton > Cc: Peter Xu > Cc: David Hildenbrand > Cc: Eric Hagberg > Signed-off-by: Guillaume Morin > --- [...] > delayacct_wpcopy_end(); > return 0; > @@ -5943,7 +5944,8 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, > spin_lock(vmf->ptl); > vmf->pte = hugetlb_walk(vma, vmf->address, huge_page_size(h)); > if (likely(vmf->pte && pte_same(huge_ptep_get(mm, vmf->address, vmf->pte), pte))) { > - pte_t newpte = make_huge_pte(vma, &new_folio->page, !unshare); > + const bool writable = !unshare && (vma->vm_flags & VM_WRITE); > + pte_t newpte = make_huge_pte(vma, &new_folio->page, writable); > > /* Break COW or unshare */ > huge_ptep_clear_flush(vma, vmf->address, vmf->pte); After rebasing to [1] this hunk here can likely be dropped. make_huge_pte() will perform the VM_WRITE check. [1] https://lkml.kernel.org/r/20241204153100.1967364-1-david@redhat.com -- Cheers, David / dhildenb