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[2003:cb:c717:5f00:c949:6700:cce1:e60b]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-354dd239e73sm3995092f8f.12.2024.05.23.07.55.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 May 2024 07:55:45 -0700 (PDT) Message-ID: <2563ea6b-7c65-46a0-adf3-552f2e863c94@redhat.com> Date: Thu, 23 May 2024 16:55:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 3/6] mm/zsmalloc: use a proper page type To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , "Matthew Wilcox (Oracle)" , Mike Rapoport , Minchan Kim , Sergey Senozhatsky , Hyeonggon Yoo <42.hyeyoo@gmail.com> References: <20240522210341.1030552-1-david@redhat.com> <20240522210341.1030552-4-david@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: <20240522210341.1030552-4-david@redhat.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: 7bit X-Stat-Signature: iji8b6xk1dtfm176zkqiybokx11gc195 X-Rspamd-Queue-Id: 1B0D2140006 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1716476149-505015 X-HE-Meta: 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 v0S/E9jZ 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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 22.05.24 23:03, David Hildenbrand wrote: > Let's clean it up: use a proper page type and store our data (offset > into a page) in the lower 16 bit as documented. > > We'll have to restrict ourselves to <= 64KB base page size (so the offset > fits into 16 bit), which sounds reasonable. Unfortunately, we don't have > any space to store it elsewhere for now. > > Based on this, we should do a proper "struct zsdesc" conversion, as > proposed in [1]. > > This removes the last _mapcount/page_type offender. > > [1] https://lore.kernel.org/all/20231130101242.2590384-1-42.hyeyoo@gmail.com/ > > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Signed-off-by: David Hildenbrand > --- > include/linux/page-flags.h | 3 +++ > mm/Kconfig | 1 + > mm/zsmalloc.c | 23 +++++++++++++++++++---- > 3 files changed, 23 insertions(+), 4 deletions(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index ed9ac4b5233d..ccaf16656de9 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -959,6 +959,7 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned) > #define PG_guard 0x00080000 > #define PG_hugetlb 0x00100800 > #define PG_slab 0x00200000 > +#define PG_zsmalloc 0x00400000 > > #define PageType(page, flag) \ > ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) > @@ -1073,6 +1074,8 @@ FOLIO_TYPE_OPS(hugetlb, hugetlb) > FOLIO_TEST_FLAG_FALSE(hugetlb) > #endif > > +PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmalloc) > + > /** > * PageHuge - Determine if the page belongs to hugetlbfs > * @page: The page to test. > diff --git a/mm/Kconfig b/mm/Kconfig > index b4cb45255a54..0371d79b1b75 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -190,6 +190,7 @@ config ZSMALLOC > tristate > prompt "N:1 compression allocator (zsmalloc)" if ZSWAP > depends on MMU > + depends on PAGE_SIZE_LESS_THAN_256KB # we want <= 64KB > help > zsmalloc is a slab-based memory allocator designed to store > pages of various compression levels efficiently. It achieves > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index b42d3545ca85..6f0032e06242 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -20,7 +20,8 @@ > * page->index: links together all component pages of a zspage > * For the huge page, this is always 0, so we use this field > * to store handle. > - * page->page_type: first object offset in a subpage of zspage > + * page->page_type: PG_zsmalloc, lower 16 bit locate the first object > + * offset in a subpage of a zspage > * > * Usage of struct page flags: > * PG_private: identifies the first component page > @@ -450,14 +451,22 @@ static inline struct page *get_first_page(struct zspage *zspage) > return first_page; > } > > +static inline void reset_first_obj_offset(struct page *page) > +{ > + page->page_type |= 0xffff; > +} > + > static inline unsigned int get_first_obj_offset(struct page *page) > { > - return page->page_type; > + return page->page_type & 0xffff; > } > > static inline void set_first_obj_offset(struct page *page, unsigned int offset) > { > - page->page_type = offset; > + BUILD_BUG_ON(PAGE_SIZE & ~0xffff); Buildbot is correctly complaining with PAGE_SIZE=64KiB. We must check BUILD_BUG_ON((PAGE_SIZE -1) & ~0xffff); -- Cheers, David / dhildenb