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Mon, 19 Aug 2024 02:40:42 -0700 (PDT) Received: from [100.81.188.195] ([178.24.249.8]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5bebbe7ed31sm5569279a12.67.2024.08.19.02.40.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2024 02:40:42 -0700 (PDT) Message-ID: <966bfe10-6123-48db-95b7-ade2f794700d@redhat.com> Date: Mon, 19 Aug 2024 11:40:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] mm: khugepaged: use the number of pages in the folio to check the reference count To: Baolin Wang , akpm@linux-foundation.org Cc: hughd@google.com, willy@infradead.org, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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-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: rspam04 X-Rspamd-Queue-Id: DFC5B20004 X-Stat-Signature: fd3atk5i8u89o8ida9ggzrhmf6wdikh8 X-HE-Tag: 1724060446-710265 X-HE-Meta: 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 qMNn5oUr cMXJRQjNp4liZNP1UiaPP0C2ADMlnr97tcE/LW7IGEdA2zfMCGZA7h/C9ZYLPLQbbdzfvR/zPzNQshyd5jg96QSDi6vyDZ5jPbKcKV9fgaARMsH5bKa0Yg88frFWOExobz9Oa/7YBS6AkENt4KCJbTK1OGbNG3+d0h15fLA+rfCVvsN3ted8MFR33BSdH6n4fRo1U7DlwHH/90KkLJzVwPPwGQp3BJfnUfUIa4bWGdadPNUpIGIWdK9ZJpV3t21lc/X9k4S8oJcVvLRs9WFgzkhuO6JCUP1xeblcMlsq2WL4QdaLVIDCBf1EwGyHneXKOjaWO5aqJg66+M6w/YmeTnM2XiOshy6GKLewFz6j4L8/0YRLLgCe5LN9HZnfEOGB4FLmuoLZJ1YYCSngnwIHFA9h/iDKiuwNKlyp0IJpmwNCLDe4Uvjw+JZwv8afEDI/f87FeJ0r4tCXYnAd/VpVjfX0rIQ== 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 19.08.24 10:14, Baolin Wang wrote: > Use the number of pages in the folio to check the reference count as > preparation for supporting shmem mTHP collapse. > > Signed-off-by: Baolin Wang > --- > mm/khugepaged.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index f11b4f172e61..60d95f08610c 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1994,7 +1994,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > /* > * We control three references to the folio: ^ "three" is wrong now. > * - we hold a pin on it; > - * - one reference from page cache; > + * - nr_pages reference from page cache; > * - one from lru_isolate_folio; > * If those are the only references, then any new usage > * of the folio will have to fetch it from the page > @@ -2002,7 +2002,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > * truncate, so any new usage will be blocked until we > * unlock folio after collapse/during rollback. > */ > - if (folio_ref_count(folio) != 3) { > + if (folio_ref_count(folio) != 2 + folio_nr_pages(folio)) { > result = SCAN_PAGE_COUNT; > xas_unlock_irq(&xas); > folio_putback_lru(folio); > @@ -2185,7 +2185,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > folio_clear_active(folio); > folio_clear_unevictable(folio); > folio_unlock(folio); > - folio_put_refs(folio, 3); > + folio_put_refs(folio, 2 + folio_nr_pages(folio)); > } > > goto out; Acked-by: David Hildenbrand -- Cheers, David / dhildenb