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[2003:cb:c707:4d00:6ac5:30d:1611:918f]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39c0b66d0dbsm13577415f8f.58.2025.04.01.01.19.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Apr 2025 01:19:25 -0700 (PDT) Message-ID: Date: Tue, 1 Apr 2025 10:19:24 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/7] mm/gup: remove gup_fast_pgd_leaf() and clean up the relevant codes To: Baoquan He , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, yanjun.zhu@linux.dev References: <20250331081327.256412-1-bhe@redhat.com> <20250331081327.256412-5-bhe@redhat.com> From: David Hildenbrand Content-Language: en-US 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: <20250331081327.256412-5-bhe@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 31.03.25 10:13, Baoquan He wrote: > In the current kernel, only pud huge page is supported in some > architectures. P4d and pgd huge pages haven't been supported yet. > And in mm/gup.c, there's no pgd huge page handling in the > follow_page_mask() code path. Hence it doesn't make sense to have > gup_fast_pgd_leaf() in gup_fast code path. I wonder if that was in place to handle (prepare for) very large hugetlb folios. Until a while ago, follow_page_mask() did not have to handle these hugetlb folios. But I assume it never got used. Acked-by: David Hildenbrand > > Here remove gup_fast_pgd_leaf() and clean up the relevant codes. > > Signed-off-by: Baoquan He > --- > mm/gup.c | 49 +++---------------------------------------------- > 1 file changed, 3 insertions(+), 46 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index a15317cf6641..58cdc5605a4a 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -3168,46 +3168,6 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, > return 1; > } > > -static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr, > - unsigned long end, unsigned int flags, struct page **pages, > - int *nr) > -{ > - int refs; > - struct page *page; > - struct folio *folio; > - > - if (!pgd_access_permitted(orig, flags & FOLL_WRITE)) > - return 0; > - > - BUILD_BUG_ON(pgd_devmap(orig)); > - > - page = pgd_page(orig); > - refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr); > - > - folio = try_grab_folio_fast(page, refs, flags); > - if (!folio) > - return 0; > - > - if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - if (!gup_fast_folio_allowed(folio, flags)) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - *nr += refs; > - folio_set_referenced(folio); > - return 1; > -} > - > static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, > unsigned long end, unsigned int flags, struct page **pages, > int *nr) > @@ -3302,12 +3262,9 @@ static void gup_fast_pgd_range(unsigned long addr, unsigned long end, > next = pgd_addr_end(addr, end); > if (pgd_none(pgd)) > return; > - if (unlikely(pgd_leaf(pgd))) { > - if (!gup_fast_pgd_leaf(pgd, pgdp, addr, next, flags, > - pages, nr)) > - return; > - } else if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, > - pages, nr)) > + BUILD_BUG_ON(pgd_leaf(pgd)); > + if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, > + pages, nr)) > return; > } while (pgdp++, addr = next, addr != end); > } -- Cheers, David / dhildenb