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[2003:cb:c73c:8100:600:a1e5:da94:a13a]) by smtp.gmail.com with ESMTPSA id b10-20020a05600c4e0a00b00412e445a6e4sm5139280wmq.25.2024.03.05.00.39.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Mar 2024 00:39:20 -0800 (PST) Message-ID: <24a7f4e5-9d30-494e-b19d-2e010a4c4b7e@redhat.com> Date: Tue, 5 Mar 2024 09:39:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] hugetlb: Make folio_test_hugetlb safer to call To: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org Cc: Oscar Salvador References: <20240301214712.2853147-1-willy@infradead.org> <20240301214712.2853147-2-willy@infradead.org> 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: <20240301214712.2853147-2-willy@infradead.org> 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: CB8A08000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: n519jpqnegccfq8phao4tinw3kys5p85 X-HE-Tag: 1709627964-125167 X-HE-Meta: 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 WlkFt8eW 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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 01.03.24 22:47, Matthew Wilcox (Oracle) wrote: > At least two places (memory failure and page migration) need to call > folio_test_hugetlb() without a reference on the folio. This can currently > result in false positives (returning true when the folio doesn't belong > to hugetlb) and more commonly in VM_BUG_ON() when a folio is split. > > The new way to distinguish a hugetlb folio is to see if (1) the page > is compound (or the folio is large) and (2) page[1].mapping is set to > the address of hugetlb_lock. If the folio is (or has been) large then > page[1] is guaranteed to exist. If the folio is split between the two > tests, page[1].mapping will be set to something which definitely isn't > the address of hugetlb_lock. > > Because we shift around the layout of struct folio a bit, we now use > page[1].private, which means we need to adjust __split_huge_page_tail() > a little. We also need to annoy the vmcore_info people again. Sorry. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > include/linux/mm_types.h | 4 +++- > include/linux/page-flags.h | 25 ++++--------------------- > kernel/vmcore_info.c | 3 ++- > mm/huge_memory.c | 10 ++-------- > mm/hugetlb.c | 24 ++++++++++++++++++++++++ > 5 files changed, 35 insertions(+), 31 deletions(-) > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index a7223ba3ea1e..fd80bf8b5d8a 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -289,6 +289,7 @@ typedef struct { > * @virtual: Virtual address in the kernel direct map. > * @_last_cpupid: IDs of last CPU and last process that accessed the folio. > * @_entire_mapcount: Do not use directly, call folio_entire_mapcount(). > + * @large_id: May identify the type of a large folio. > * @_nr_pages_mapped: Do not use directly, call folio_mapcount(). > * @_pincount: Do not use directly, call folio_maybe_dma_pinned(). > * @_folio_nr_pages: Do not use directly, call folio_nr_pages(). > @@ -348,9 +349,9 @@ struct folio { > struct { > unsigned long _flags_1; > unsigned long _head_1; > - unsigned long _folio_avail; > /* public: */ > atomic_t _entire_mapcount; > + void *large_id; > atomic_t _nr_pages_mapped; > atomic_t _pincount; Hm, I wanted that for the total mapcount. :( Great that hugetlb makes things once again worse for everybody ... gah. -- Cheers, David / dhildenb