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([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38058b479a4sm9474406f8f.55.2024.10.28.06.46.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Oct 2024 06:46:25 -0700 (PDT) Message-ID: Date: Mon, 28 Oct 2024 14:46:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm: use aligned address in clear_gigantic_page() To: Kefeng Wang , Andrew Morton Cc: Matthew Wilcox , Muchun Song , "Huang, Ying" , linux-mm@kvack.org References: <20241026054307.3896926-1-wangkefeng.wang@huawei.com> <54f5f3ee-8442-4c49-ab4e-c46e8db73576@huawei.com> <4219a788-52ad-4d80-82e6-35a64c980d50@redhat.com> <127d4a00-29cc-4b45-aa96-eea4e0adaed2@huawei.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: <127d4a00-29cc-4b45-aa96-eea4e0adaed2@huawei.com> 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: 8bit X-Rspamd-Queue-Id: 5B7C610002B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: h559u8nr46poe31c159rfkiygfxiu3dd X-HE-Tag: 1730123148-239383 X-HE-Meta: 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 t4f/BUbQ 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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 28.10.24 14:33, Kefeng Wang wrote: > > > On 2024/10/28 21:14, David Hildenbrand wrote: >> On 28.10.24 13:52, Kefeng Wang wrote: >>> >>> >>> On 2024/10/28 18:00, David Hildenbrand wrote: >>>> On 26.10.24 07:43, Kefeng Wang wrote: >>>>> When clearing gigantic page, it zeros page from the first page to the >>>>> last page, if directly passing addr_hint which maybe not the address >>>>> of the first page of folio, then some archs could flush the wrong cache >>>>> if it does use the addr_hint as a hint. For non-gigantic page, it >>>>> calculates the base address inside, even passed the wrong addr_hint, it >>>>> only has performance impact as the process_huge_page() wants to process >>>>> target page last to keep its cache lines hot), no functional impact. >>>>> >>>>> Let's pass the real accessed address to folio_zero_user() and use the >>>>> aligned address in clear_gigantic_page() to fix it. >>>>> >>>>> Fixes: 78fefd04c123 ("mm: memory: convert clear_huge_page() to >>>>> folio_zero_user()") >>>>> Signed-off-by: Kefeng Wang >>>>> --- >>>>> v2: >>>>> - update changelog to clarify the impact, per Andrew >>>>> >>>>>    fs/hugetlbfs/inode.c | 2 +- >>>>>    mm/memory.c          | 1 + >>>>>    2 files changed, 2 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c >>>>> index a4441fb77f7c..a5ea006f403e 100644 >>>>> --- a/fs/hugetlbfs/inode.c >>>>> +++ b/fs/hugetlbfs/inode.c >>>>> @@ -825,7 +825,7 @@ static long hugetlbfs_fallocate(struct file *file, >>>>> int mode, loff_t offset, >>>>>                error = PTR_ERR(folio); >>>>>                goto out; >>>>>            } >>>>> -        folio_zero_user(folio, ALIGN_DOWN(addr, hpage_size)); >>>>> +        folio_zero_user(folio, addr); >>>>>            __folio_mark_uptodate(folio); >>>>>            error = hugetlb_add_to_page_cache(folio, mapping, index); >>>>>            if (unlikely(error)) { >>>>> diff --git a/mm/memory.c b/mm/memory.c >>>>> index 75c2dfd04f72..ef47b7ea5ddd 100644 >>>>> --- a/mm/memory.c >>>>> +++ b/mm/memory.c >>>>> @@ -6821,6 +6821,7 @@ static void clear_gigantic_page(struct folio >>>>> *folio, unsigned long addr, >>>>>        int i; >>>>>        might_sleep(); >>>>> +    addr = ALIGN_DOWN(addr, folio_size(folio)); >>>> >>>> Right, that's what's effectively done in a very bad way in >>>> process_huge_page() >>>> >>>> unsigned long addr = addr_hint & >>>>                ~(((unsigned long)nr_pages << PAGE_SHIFT) - 1); >>>> >>>> >>>> That should all be cleaned up ... process_huge_page() likely shouldn't >>> >>> Yes, let's fix the bug firstly, >>> >>>> be even consuming "nr_pages". >>> >>> No sure about this part, it uses nr_pages as the end and calculate the >>> 'base'. >> >> It should be using folio_nr_pages(). > > But process_huge_page() without an explicit folio argument, I'd like to > move the aligned address calculate into the folio_zero_user and > copy_user_large_folio(will rename it to folio_copy_user()) in the > following cleanup patches, or do it in the fix patches? First, why does folio_zero_user() call process_huge_page() for *a small folio*? Because we like or code to be extra complicated to understand? Or am I missing something important? Second, we should be passing the folio to "process_huge_page" and likely rename it to "folio_process_pages()" or sth like that. The function even documents "of the specified huge page", but there is none specified. The copy case might require a rework. I think this code needs a serious cleanup ... -- Cheers, David / dhildenb