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[2003:cb:c725:8700:77c7:bde:9446:8d34]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42f86b4aa15sm87301855e9.45.2024.10.07.02.43.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Oct 2024 02:43:24 -0700 (PDT) Message-ID: <4c497ac9-f8ed-466b-b253-d3bcc855f57e@redhat.com> Date: Mon, 7 Oct 2024 11:43:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] ksm: Use a folio in try_to_merge_one_page() To: "Matthew Wilcox (Oracle)" , Andrew Morton Cc: linux-mm@kvack.org, Alex Shi References: <20241002152533.1350629-1-willy@infradead.org> <20241002152533.1350629-2-willy@infradead.org> 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: <20241002152533.1350629-2-willy@infradead.org> 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-Stat-Signature: c5sbmr8inj9kxeusijid3qc64s9p9ji3 X-Rspamd-Queue-Id: 868C21C0013 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1728294208-572362 X-HE-Meta: U2FsdGVkX18FL9C6MBYgsCPXz2BSnJapfTZW6K9DFkPjyb23JqYorrb44hRH83IM5aWnJ3X2xN7UGoeq89HwF6lYjQ5DiprnaI2e7sqXtPzOSvMh9HG1nGRr0ek0mvCfpEYw7m3t276MRljETy8NtMkf62lj1Aw0bwBSBPngVM+Kw7rrm1ecY2uy3EDaYooKk8XsLqGyDERBw7xVovkPhenLN9gDSiTY9+trug2Fy1iB3VjzAM9VyeX3in6d6sSgBlQuOMO5wOB0pj69b2A8Ym/9GVw+sLA9I22lOHh9azq+pamCezHTuYzpcqHsmh2sil1n+fB6rcDFLrOi3cxHol4Wo4+YcxHfSf15QQ7MWHi6D7ktPX7d8QJG4hEKm0k67uvhxEII0ISvj4KYkKGjAQjuw8jtHrmdXaUqCkliKk4dsagkU0ilBeSgF/Z5M+CrkvjEf6IR4Pw7KaV/aZUXiYHZ6OuF533/lWuFMuqeWxZVasQHo87RiqpbvPceSbZd8gpzLiAsNxOV3nui6My1b2aSdLkb08EhQe43FX0GHbE4P2YeA2FtbN2A8bZTlynK7AX3342Zt4UEBOF5tXxWu+l5PDrSROUFdvSrLZ07cuA7ySLlU2TxTVp1yFOr8/0YNE3WkBZLe2qoYmry/D6yXVl9EUxyendpBas3uBkudKMdAeK86jhtGHBW6Uq1bMaIp/Y9onIbKfeWZjocgUpMYNxQNkEeg88bVbgT12KO/Go3d3nyUrW2osS7A9PBaXL2pTlYobrCHTDhI+80NrKXJaml32EQ8YgE4+T4vzcTkjPhy71uaCaNKG2GjTnZ7K8vv+J1soZKLV8xdPELH0XC/lyBgFDTbo3skFk2eMORexvIOblWtVmlaFvflkLTxsYpKOMic0NE/k4yDx+d2GBZ56omRM6LNi+MEUbQq2S3UzSOgYWtEZmSYQlO2t4x1PTtGqCLKCfdbmlZ5yInnxV p97Xy/Oj 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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 02.10.24 17:25, Matthew Wilcox (Oracle) wrote: > It is safe to use a folio here because all callers took a refcount on > this page. The one wrinkle is that we have to recalculate the value > of folio after splitting the page, since it has probably changed. > Replaces nine calls to compound_head() with one. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > mm/ksm.c | 33 +++++++++++++++++---------------- > 1 file changed, 17 insertions(+), 16 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index a2e2a521df0a..57f998b172e6 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -1443,28 +1443,29 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, > static int try_to_merge_one_page(struct vm_area_struct *vma, > struct page *page, struct page *kpage) > { > + struct folio *folio = page_folio(page); > pte_t orig_pte = __pte(0); > int err = -EFAULT; > > if (page == kpage) /* ksm page forked */ > return 0; > > - if (!PageAnon(page)) > + if (!folio_test_anon(folio)) > goto out; > > /* > * We need the folio lock to read a stable swapcache flag in > - * write_protect_page(). We use trylock_page() instead of > - * lock_page() because we don't want to wait here - we > - * prefer to continue scanning and merging different pages, > - * then come back to this page when it is unlocked. > + * write_protect_page(). We trylock because we don't want to wait > + * here - we prefer to continue scanning and merging different > + * pages, then come back to this page when it is unlocked. > */ > - if (!trylock_page(page)) > + if (!folio_trylock(folio)) > goto out; > > - if (PageTransCompound(page)) { > + if (folio_test_large(folio)) { > if (split_huge_page(page)) > goto out_unlock; > + folio = page_folio(page); > } > > /* > @@ -1473,28 +1474,28 @@ static int try_to_merge_one_page(struct vm_area_struct *vma, > * ptes are necessarily already write-protected. But in either > * case, we need to lock and check page_count is not raised. > */ > - if (write_protect_page(vma, page_folio(page), &orig_pte) == 0) { > + if (write_protect_page(vma, folio, &orig_pte) == 0) { > if (!kpage) { > /* > - * While we hold page lock, upgrade page from > - * PageAnon+anon_vma to PageKsm+NULL stable_node: > + * While we hold folio lock, upgrade folio from > + * anon to a NULL stable_node with the KSM flag set: > * stable_tree_insert() will update stable_node. > */ > - folio_set_stable_node(page_folio(page), NULL); > - mark_page_accessed(page); > + folio_set_stable_node(folio, NULL); > + folio_mark_accessed(folio); > /* > - * Page reclaim just frees a clean page with no dirty > + * Page reclaim just frees a clean folio with no dirty > * ptes: make sure that the ksm page would be swapped. > */ > - if (!PageDirty(page)) > - SetPageDirty(page); > + if (!folio_test_dirty(folio)) > + folio_mark_dirty(folio); Wouldn't the direct translation be folio_set_dirty()? I guess folio_mark_dirty() will work as well, as we'll usually end up in noop_dirty_folio() where we do a folio_test_set_dirty(). -- Cheers, David / dhildenb