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[2003:cb:c707:4f00:a44a:5ad6:765a:635]) by smtp.gmail.com with ESMTPSA id q14-20020a05600c46ce00b00412b4dca795sm12560584wmo.7.2024.03.12.07.34.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Mar 2024 07:34:14 -0700 (PDT) Message-ID: Date: Tue, 12 Mar 2024 15:34:13 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: Always initialise folio->_deferred_list To: Matthew Wilcox Cc: Andrew Morton , linux-mm@kvack.org References: <20240312035017.516865-1-willy@infradead.org> <78d1e235-b055-48ce-a987-e8719163caf7@redhat.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: 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: D244940022 X-Rspam-User: X-Stat-Signature: tdns3fjnt91en6ijksssh1uzui8wsjdb X-Rspamd-Server: rspam03 X-HE-Tag: 1710254058-757249 X-HE-Meta: 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 P5V2KF4R yEru1HpMGaP7gbZpze3naESCi+1044ViUmhATLyVPbTHZHEZHIziWrXmlFnpXjG7P7v2g3lMS/RsS8iUUgorF9U7nmi1jGwpOspJ+ggl2ObmVPIkQua4uvzqeHWd2IDNmA1lF7MTPEvx41aYglNtAa/WIXSZ1MCNEEqy3s9eA07gaVd4fFOplhoLJbeogRnIqGLyPLvlNrQmqEVSe6WyMM98J4WzYi26URc4jxM63It+rnv6BenZvHyjZ8qJDMIdaVKchEt9G582UKQuuQ55dDoV2ozMxq6K8z9oz90fNWOtPc++UcqnuosH882qTl0gQrwvyU/CJe5Sr4G+i4FUGeD09X6IK6sA8DFKrXQVp9bezmvtRg8vYH9X/tPBuqLKJClG1N3hbWkrPVdv24PJIpbMj4byvdkjuuzBvfpUI9J94N804pEzqJy/MKRjqMlEr9nQta/p9+p+7z9oMsSMmx7PFlQ== 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 12.03.24 15:01, Matthew Wilcox wrote: > On Tue, Mar 12, 2024 at 02:17:01PM +0100, David Hildenbrand wrote: >> On 12.03.24 04:50, Matthew Wilcox (Oracle) wrote: >>> +++ b/mm/page_alloc.c >>> @@ -1006,10 +1006,11 @@ static int free_tail_page_prepare(struct page *head_page, struct page *page) >>> } >>> break; >>> case 2: >>> - /* >>> - * the second tail page: ->mapping is >>> - * deferred_list.next -- ignore value. >>> - */ >>> + /* the second tail page: deferred_list overlaps ->mapping */ >>> + if (unlikely(!list_empty(&folio->_deferred_list))) { >>> + bad_page(page, "on deferred list"); >>> + goto out; >>> + } >> >> IIRC, hugetlb might overwrite this with _hugetlb_subpool? Isn't that a >> problem we have to handle? > > Ah yes, you're right. I think this should do the trick? > > +++ b/mm/hugetlb.c > @@ -1796,6 +1796,7 @@ static void __update_and_free_hugetlb_folio(struct hstate *h, > destroy_compound_gigantic_folio(folio, huge_page_order(h)); > free_gigantic_folio(folio, huge_page_order(h)); > } else { > + INIT_LIST_HEAD(&folio->_deferred_list); > __free_pages(&folio->page, huge_page_order(h)); Heh, __free_pages() says: "This function can free multi-page allocations that are not compound pages". I suspect that means "can also free compound pages", but it's confusing. Especially, I thought we recently learned that free hugetlb folios do have a refcount of 0? Confusing. Anyhow, I suspect your change does the trick and agree that __free_pages() might need a replacement. ... but it's confusing. -- Cheers, David / dhildenb