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[128.59.176.193]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-9106702d8f3sm43456006d6.23.2026.09.09.10.21.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Sep 2026 10:21:41 -0700 (PDT) Message-ID: Date: Wed, 9 Sep 2026 13:21:40 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/8] mm/swap: add folio_swap_entry() and folio_page_swap_entry() To: "David Hildenbrand (Arm)" , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Kiryl Shutsemau , Lorenzo Stoakes , Rik van Riel , Vlastimil Babka , Harry Yoo , Jann Horn , Johannes Weiner , Yosry Ahmed , Chengming Zhou , Catalin Marinas , Will Deacon , Mark Rutland Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20260908-folio_swap_entry-v2-0-ee6d01dfa5e1@columbia.edu> <20260908-folio_swap_entry-v2-1-ee6d01dfa5e1@columbia.edu> Content-Language: en-US From: Tal Zussman In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=M8V97Sws c=1 sm=1 tr=0 ts=6aa195a7 cx=c_pps a=g1v0Z557R90hA0UpD/5Yag==:117 a=fJxgZNdXt3opHMdyAp+FXA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=x7bEGLp0ZPQA:10 a=A0y_DWxS2BwA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=svvvyxlR1OQQkelhaPoB:22 a=umqIAqnQUIpxI_lDA3YA:9 a=QEXdDO2ut3YA:10 a=MFSWADHSvvjO3QEy5MdX:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA5MDE5MyBTYWx0ZWRfX+qfDgzHhgMP4 VO6xePv8tpTJs+G+9NL9M5ismQcnuRKZf0yCf8V9KDXIZrqKAmJ4eIqqBmsPhyltUAgRT16J+YG JH52stlsADF2LovTW8v6S9MImP9PBJ6WvXadhYdOgEJQ4GCaPsSW X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA5MDE5MyBTYWx0ZWRfX+NIvwbBVG3G0 2w+iJfdw5FzEvmH0u7/llctptPTsTH3LKdBKn3r4T9vWzVphgbXiMTW9ojVLNTqgU9GiBd/S94B hvweao2TlJnFy0cUhBItwxztukIxwwnx3YHJdhtU2wmMIrHNqizKSs7GA5zLRBc+kj/zsJNlLpx 0XNK0zTQpZQ/U1qlbLCfNvKHhbRJP8aSAayWnt3Btd65POXGW7Tnx/ZVk6SU0u0wTNZEd2IZrKV 1cnMJxvJU0O/9F+c7xrwgA7I61UUxMjRKf0l0G4CzUk3i7MHY2F2CGzp09llFNtAbuQRSaDI8nw Wiuok0kYjj9y0/v7q+wkQE8C60lWWedzIlDgXLWWc2U+q0823HfYsQdabOssheCFzg7xXWOIQoL n7mlJjmWnq5Wn0Yo62HFh/d5LM8PIQwIaPGx8IM08hn22+i4ugNxkACBUHz7ArZcjVLB3+MnIAw sKIYEb5lTOn0SrBGujA== X-Proofpoint-ORIG-GUID: -ps3O3mJcP3ysQ99_EG4oXIMtqc2rlJc X-Proofpoint-GUID: -ps3O3mJcP3ysQ99_EG4oXIMtqc2rlJc X-Proofpoint-Virus-Version: vendor=nai engine=6900 definitions=11900 signatures=596817 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=10 spamscore=0 bulkscore=10 impostorscore=10 clxscore=1015 adultscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609090193 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260909_182153_685265_104D39B5 X-CRM114-Status: GOOD ( 25.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/9/26 5:00 PM, David Hildenbrand (Arm) wrote: > On 9/8/26 17:16, Tal Zussman wrote: >> A folio in the swap cache occupies folio_nr_pages() contiguous swap >> entries starting at folio->swap, so a page's swap entry is just >> folio->swap plus the page's index in the folio. page_swap_entry() hides >> this behind a compound_head() call, and callers that already have the >> folio sometimes open-code the arithmetic instead. >> >> Add folio_swap_entry(), which takes a folio and a page index, and >> folio_page_swap_entry() for callers that have the page. >> >> Signed-off-by: Tal Zussman >> --- >> include/linux/swap.h | 33 +++++++++++++++++++++++++++++++++ >> 1 file changed, 33 insertions(+) >> >> diff --git a/include/linux/swap.h b/include/linux/swap.h >> index fc290e29e4a9..1d979e76e78a 100644 >> --- a/include/linux/swap.h >> +++ b/include/linux/swap.h >> @@ -272,6 +272,39 @@ struct swap_info_struct { >> const struct swap_ops *ops; >> }; >> >> +/** >> + * folio_swap_entry - Return the swap entry for a page within a folio. >> + * @folio: The folio. >> + * @idx: The index of the page within the folio. >> + * >> + * A folio in the swap cache occupies folio_nr_pages() contiguous swap >> + * entries starting at folio->swap. The caller must ensure the folio is >> + * in the swap cache and that @idx is within the folio. >> + */ >> +static inline >> +swp_entry_t folio_swap_entry(const struct folio *folio, unsigned long idx) >> +{ >> + swp_entry_t entry = folio->swap; >> + >> + VM_WARN_ON_ONCE_FOLIO(idx >= folio_nr_pages(folio), folio); >> + entry.val += idx; >> + return entry; >> +} >> + >> +/** >> + * folio_page_swap_entry - Return the swap entry of a page in a folio. >> + * @folio: The folio containing @page. >> + * @page: A page within @folio. >> + * >> + * The caller must ensure the folio is in the swap cache and that @page >> + * is part of @folio. >> + */ >> +static inline swp_entry_t folio_page_swap_entry(const struct folio *folio, >> + const struct page *page) >> +{ >> + return folio_swap_entry(folio, folio_page_idx(folio, page)); >> +} >> + >> static inline swp_entry_t page_swap_entry(struct page *page) >> { >> struct folio *folio = page_folio(page); >> > > "Return the swap entry for a page within a folio" vs. "Return the swap entry of > a page in a folio." > > yet only of the variants has a "page" in the name :) > > A bit confusing. > > Not immediately sure how it could be done cleaner. The minority of cases seem to > use folio_swap_entry. > Yeah... I considered naming them folio_swap_entry() and folio_swap_entry_idx() (or a variant of that) but I liked the page version more. I can update the comments to try to differentiate between the two a little more if that would help. How's "Return the swap entry at an index within a folio"? > -- > Cheers, > > David >