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[2003:cb:c70d:8400:ed9b:a3a:88e5:c6a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39d89361165sm1041910f8f.19.2025.04.09.02.03.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Apr 2025 02:03:27 -0700 (PDT) Message-ID: <5f0fe985-7512-4a94-aa5b-ddae176838a1@redhat.com> Date: Wed, 9 Apr 2025 11:03:26 +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] mm/hugetlb: Convert &folio->page to folio_page(folio, 0) To: Matthew Wilcox , nifan.cxl@gmail.com Cc: muchun.song@linux.dev, mcgrof@kernel.org, a.manzanares@samsung.com, dave@stgolabs.net, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Fan Ni References: <20250409004937.634713-1-nifan.cxl@gmail.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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 09.04.25 05:15, Matthew Wilcox wrote: > On Tue, Apr 08, 2025 at 05:49:10PM -0700, nifan.cxl@gmail.com wrote: >> From: Fan Ni >> >> Convert the use of &folio->page to folio_page(folio, 0) where struct >> filio fits in. This is part of the efforts to move some fields out of >> struct page to reduce its size. > > Thanks for sending the patch. You've mixed together quite a few things; > I'd suggest focusing on one API at a time. Agreed. > >> folio_get(folio); >> - folio_add_file_rmap_pmd(folio, &folio->page, vma); >> + folio_add_file_rmap_pmd(folio, folio_page(folio, 0), vma); >> add_mm_counter(mm, mm_counter_file(folio), HPAGE_PMD_NR); > > I think this is fine, but would defer to David Hildenbrand. For now this should be fine. We want a pointer at the actual first page. In some future (with folios spanning multiple PMDs), this will not be correct. But the THP changes should *absolutely* not be included in this hugetlb patch. I was severly confused staring at the usage of folio_add_file_rmap_pmd() in hugetlb context/ Actually, having to go back to my comments below to fix them up now that I see that this is mm/huge_memory.c | 30 +++++++++++++++++------------- mm/hugetlb.c | 20 +++++++++++--------- mm/hugetlb_vmemmap.c | 12 ++++++------ Makes me angry. > >> folio_get(folio); >> - folio_add_file_rmap_pud(folio, &folio->page, vma); >> + folio_add_file_rmap_pud(folio, folio_page(folio, 0), vma); >> add_mm_counter(mm, mm_counter_file(folio), HPAGE_PUD_NR); > > If that is fine, then so is this (put them in the same patchset). > >> spin_unlock(ptl); >> - if (flush_needed) >> - tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); >> + if (flush_needed) { >> + tlb_remove_page_size(tlb, folio_page(folio, 0), >> + HPAGE_PMD_SIZE); >> + } > > You don't need to add the extra braces here. I haven't looked into this > family of APIs; not sure if we should be passing the folio here or > if it should be taking a folio argument. > >> if (folio_maybe_dma_pinned(src_folio) || >> - !PageAnonExclusive(&src_folio->page)) { >> + !PageAnonExclusive(folio_page(src_folio, 0))) { >> err = -EBUSY; > > mmm. Another David question. For now this should be correct. (first page mapped by the PMD stores the flag) > >> for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) { >> - struct page *new_head = &folio->page + i; >> + struct page *new_head = folio_page(folio, i); >> > > This is definitely the right thing to do. > >> @@ -3403,7 +3405,7 @@ static void __split_folio_to_order(struct folio *folio, int old_order, >> if (new_order) >> folio_set_order(folio, new_order); >> else >> - ClearPageCompound(&folio->page); >> + ClearPageCompound(folio_page(folio, 0)); >> } > > I might be inclined to leave this one alone; this whole function needs > to be rewritten as part of the folio split. > >> folio_split_memcg_refs(folio, old_order, split_order); >> - split_page_owner(&folio->page, old_order, split_order); >> + split_page_owner(folio_page(folio, 0), old_order, split_order); >> pgalloc_tag_split(folio, old_order, split_order); > > Not sure if split_folio_owner is something that should exist. Haven't > looked into it. > >> */ >> - free_page_and_swap_cache(&new_folio->page); >> + free_page_and_swap_cache(folio_page(new_folio, 0)); >> } > > free_page_and_swap_cache() should be converted to be > free_folio_and_swap_cache(). > >> >> - return __folio_split(folio, new_order, &folio->page, page, list, true); >> + return __folio_split(folio, new_order, folio_page(folio, 0), page, >> + list, true); >> } > > Probably right. > >> { >> - return __folio_split(folio, new_order, split_at, &folio->page, list, >> - false); >> + return __folio_split(folio, new_order, split_at, folio_page(folio, 0), >> + list, false); >> } > > Ditto. > >> >> - return split_huge_page_to_list_to_order(&folio->page, list, ret); >> + return split_huge_page_to_list_to_order(folio_page(folio, 0), list, >> + ret); >> } > > Ditto. > >> >> - if (is_migrate_isolate_page(&folio->page)) >> + if (is_migrate_isolate_page(folio_page(folio, 0))) >> continue; > > I think we need an is_migrate_isolate_folio() instead of this. > >> if (folio_test_anon(folio)) >> - __ClearPageAnonExclusive(&folio->page); >> + __ClearPageAnonExclusive(folio_page(folio, 0)); >> folio->mapping = NULL; > > ... David. See above. > >> >> - split_page_owner(&folio->page, huge_page_order(src), huge_page_order(dst)); >> + split_page_owner(folio_page(folio, 0), huge_page_order(src), >> + huge_page_order(dst)); > > See earlier. > >> if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) { >> - if (!PageAnonExclusive(&old_folio->page)) { >> + if (!PageAnonExclusive(folio_page(old_folio, 0))) { >> folio_move_anon_rmap(old_folio, vma); >> - SetPageAnonExclusive(&old_folio->page); >> + SetPageAnonExclusive(folio_page(old_folio, 0)); >> } > > David. See above. > >> } >> VM_BUG_ON_PAGE(folio_test_anon(old_folio) && >> - PageAnonExclusive(&old_folio->page), &old_folio->page); >> + PageAnonExclusive(folio_page(old_folio, 0)), >> + folio_page(old_folio, 0)); > > The PageAnonExclusive() part of this change is for David to comment on, > but this should be a VM_BUG_ON_FOLIO() instead of calling folio_page() > to keep this a VM_BUG_ON_PAGE(). Agreed. -- Cheers, David / dhildenb