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[2003:d8:2f25:700:d846:15f3:6ca0:8029]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e552618813sm9859106f8f.41.2025.09.08.06.45.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 08 Sep 2025 06:45:13 -0700 (PDT) Message-ID: <4e0847db-0503-406b-95b4-02ee7e8f9604@redhat.com> Date: Mon, 8 Sep 2025 15:45:11 +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 11/15] mm, swap: use the swap table for the swap cache and switch API To: Kairui Song , linux-mm@kvack.org Cc: Andrew Morton , Matthew Wilcox , Hugh Dickins , Chris Li , Barry Song , Baoquan He , Nhat Pham , Kemeng Shi , Baolin Wang , Ying Huang , Johannes Weiner , Yosry Ahmed , Lorenzo Stoakes , Zi Yan , linux-kernel@vger.kernel.org References: <20250905191357.78298-1-ryncsn@gmail.com> <20250905191357.78298-12-ryncsn@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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20250905191357.78298-12-ryncsn@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > +static inline struct swap_cluster_info *swap_cluster_lock( > + struct swap_info_struct *si, pgoff_t offset, bool irq) > +{ > + return NULL; > +} > + > +static inline struct swap_cluster_info *swap_cluster_lock_by_folio( > + struct folio *folio) I would probably call that "swap_cluster_get_and_lock" or sth like that ... > +{ > + return NULL; > +} > + > +static inline struct swap_cluster_info *swap_cluster_lock_by_folio_irq( > + struct folio *folio) > +{ ... then this would become "swap_cluster_get_and_lock_irq" Alterantively, separate the lookup from the locking of the cluster. swap_cluster_from_folio() / folio_get_swap_cluster() swap_cluster_lock() swap_cluster_lock_irq() Which might look cleaner in the end. [...] > -struct address_space *swapper_spaces[MAX_SWAPFILES] __read_mostly; > -static unsigned int nr_swapper_spaces[MAX_SWAPFILES] __read_mostly; > +struct address_space swap_space __read_mostly = { > + .a_ops = &swap_aops, > +}; > + > static bool enable_vma_readahead __read_mostly = true; > > #define SWAP_RA_ORDER_CEILING 5 > @@ -83,11 +86,21 @@ void show_swap_cache_info(void) > */ > struct folio *swap_cache_get_folio(swp_entry_t entry) > { > - struct folio *folio = filemap_get_folio(swap_address_space(entry), > - swap_cache_index(entry)); > - if (IS_ERR(folio)) > - return NULL; > - return folio; > + ^ superfluous empty line. [...] > > @@ -420,6 +421,34 @@ static inline unsigned int cluster_offset(struct swap_info_struct *si, > return cluster_index(si, ci) * SWAPFILE_CLUSTER; > } > > +static int swap_table_alloc_table(struct swap_cluster_info *ci) swap_cluster_alloc_table ? > +{ > + WARN_ON(ci->table); > + ci->table = kzalloc(sizeof(unsigned long) * SWAPFILE_CLUSTER, GFP_KERNEL); > + if (!ci->table) > + return -ENOMEM; > + return 0; > +} > + > +static void swap_cluster_free_table(struct swap_cluster_info *ci) > +{ > + unsigned int ci_off; > + unsigned long swp_tb; > + > + if (!ci->table) > + return; > + > + for (ci_off = 0; ci_off < SWAPFILE_CLUSTER; ci_off++) { > + swp_tb = __swap_table_get(ci, ci_off); > + if (!swp_tb_is_null(swp_tb)) > + pr_err_once("swap: unclean swap space on swapoff: 0x%lx", > + swp_tb); > + } > + > + kfree(ci->table); > + ci->table = NULL; > +} > + > static void move_cluster(struct swap_info_struct *si, > struct swap_cluster_info *ci, struct list_head *list, > enum swap_cluster_flags new_flags) > @@ -702,6 +731,26 @@ static bool cluster_scan_range(struct swap_info_struct *si, > return true; > } > > +/* > + * Currently, the swap table is not used for count tracking, just > + * do a sanity check here to ensure nothing leaked, so the swap > + * table should be empty upon freeing. > + */ > +static void cluster_table_check(struct swap_cluster_info *ci, > + unsigned int start, unsigned int nr) "swap_cluster_assert_table_empty()" or sth like that that makes it clearer what you are checking for. -- Cheers David / dhildenb