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[2003:cb:c736:1000:9e30:2a8a:cd3d:419c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43b7370372dsm188399395e9.11.2025.03.04.02.15.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Mar 2025 02:15:57 -0800 (PST) Message-ID: Date: Tue, 4 Mar 2025 11:15:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/hugetlb: fix surplus pages in dissolve_free_huge_page() To: Jinjiang Tu , akpm@linux-foundation.org, muchun.song@linux.dev, osalvador@suse.de Cc: linux-mm@kvack.org, wangkefeng.wang@huawei.com, sunnanyong@huawei.com References: <20250303060920.2886263-1-tujinjiang@huawei.com> <7e3e8f34-cb61-4702-87c2-486803c5957e@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-MFC-PROC-ID: 3RhMR5ViJjBigM9pN4jC_Cw4NDICCQs7IY5jDwXea4A_1741083358 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: o3zsxazp3mqzjs37pc3kie61ai8cus6t X-Rspamd-Queue-Id: 564C58000B X-Rspamd-Server: rspam07 X-HE-Tag: 1741083361-376311 X-HE-Meta: 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 VfE+q47E MV7fmj6qSWxzRwIRygnclNYMkldOraSNW6pDOY6JNGE9KY2yVKsoFuoOyakFE3uW2wxmngC0BfSF/OGe76Delcbz0spTAcC5LCZIdCIRHJniD+Xl2/Qzb0ayQLM4v4yX0eHsAxJ1xscqJgnTBjXGUkid3pcQsrxUfKWVxc9PHBGoNdeVqkzk5II/OoAl8yBdzyCJYbu/rc1QJA3OAfPigA0rN7pIsw1X644NFiSYpQVHi3tGJKA/QLqQa993+jK9LI8zbOhIWVHBIU6PU7JuXWAt1AjAeaXC1RHaGsTTJOiemH7+NlDXR1cNSCMiIwqIS+fChx5/wJd01gzU5/jLqfFZEBaYxUMOHV9XK6KPcTLBfA/Urk9ng4yEM19e0NU6gAdETxP418hU28S7p3b19aqll0vYL+FZUuocqDMDfX8eAxfdOfMl0FEQyuUowQECpYr/IhtzgrgCGucyS30LTV7IrLlKXvaMRnBUkPpZYtJPBnD0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000240, 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 04.03.25 04:50, Jinjiang Tu wrote: > > 在 2025/3/3 21:45, David Hildenbrand 写道: >>> --- a/mm/hugetlb.c >>> +++ b/mm/hugetlb.c >>> @@ -2135,6 +2135,8 @@ int dissolve_free_hugetlb_folio(struct folio >>> *folio) >>>         if (!folio_ref_count(folio)) { >>>           struct hstate *h = folio_hstate(folio); >>> +        bool adjust_surplus = false; >>> + >>>           if (!available_huge_pages(h)) >>>               goto out; >>>   @@ -2157,7 +2159,9 @@ int dissolve_free_hugetlb_folio(struct folio >>> *folio) >>>               goto retry; >>>           } >>>   -        remove_hugetlb_folio(h, folio, false); >>> +        if (h->surplus_huge_pages_node[folio_nid(folio)]) >>> +            adjust_surplus = true; >> >> This change looks good to me >> >>> +        remove_hugetlb_folio(h, folio, adjust_surplus); >>>           h->max_huge_pages--; >>>           spin_unlock_irq(&hugetlb_lock); >>>   @@ -2177,7 +2181,7 @@ int dissolve_free_hugetlb_folio(struct folio >>> *folio) >>>               rc = hugetlb_vmemmap_restore_folio(h, folio); >>>               if (rc) { >>>                   spin_lock_irq(&hugetlb_lock); >>> -                add_hugetlb_folio(h, folio, false); >>> +                add_hugetlb_folio(h, folio, adjust_surplus); >> >> I'm not quite sure here, though. We dropped the hugetlb_lock, can't >> some weird concurrent action result in us not having to adjust surplus >> page anymore? > In this case, we will get a free surplus folio without reserved. > > The existing code has similar logic. In free_huge_folio()，when > h->surplus_huge_pages_node[nid] != 0, > update_and_free_hugetlb_folio->__update_and_free_hugetlb_folio > may fail due tohugetlb_vmemmap_restore_folio() too, and will treat it as > surplus folio. Right, in that scenario we'll even unconditionally treat it as a surplus page. So I guess it's fine (and it's a corner case either way ...) So with an improved patch description: Acked-by: David Hildenbrand -- Cheers, David / dhildenb