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Wed, 12 Nov 2025 18:48:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 8rFgAJvWFGkCNgAAD6G6ig (envelope-from ); Wed, 12 Nov 2025 18:48:59 +0000 Message-ID: Date: Wed, 12 Nov 2025 19:48:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 03/16] mm: avoid unnecessary uses of is_swap_pte() Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Peter Xu , Alexander Viro , Christian Brauner , Jan Kara , Arnd Bergmann , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Muchun Song , Oscar Salvador , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Axel Rasmussen , Yuanchu Xie , Wei Xu , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Chris Li , SeongJae Park , Matthew Wilcox , Jason Gunthorpe , Leon Romanovsky , Xu Xin , Chengming Zhou , Jann Horn , Miaohe Lin , Naoya Horiguchi , Pedro Falcato , Pasha Tatashin , Rik van Riel , Harry Yoo , Hugh Dickins , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, damon@lists.linux.dev References: <17fd6d7f46a846517fd455fadd640af47fcd7c55.1762812360.git.lorenzo.stoakes@oracle.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <17fd6d7f46a846517fd455fadd640af47fcd7c55.1762812360.git.lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspam-User: X-Rspamd-Queue-Id: 69A9EA0009 X-Stat-Signature: iondxtg4ruk9bn4raic9tfiow3sqyjwc X-HE-Tag: 1762973341-241181 X-HE-Meta: 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 QjOAf6D5 lekzU2yo70inSHAXrUxFl1hh59nEfJHIkhdCEkW6COL5bWrln8RhfI+VGzBv8PlbDtPO5gMXlGgkDCkwsThLMUf9jd8UGbaJjfApgRD6jaUWI2mOcqrnchzOehYp8Yx5nC5YDsZzj9ZT4dyfHoEdQtDdGRXht+70LkXolR4/JaOxQeb/0sbRNf9tOgqtj7nT3i/8/TbM5MasNJsqvvjMvuQxznH9aGhdY3lcWvqnuzgCCL5YiBe8pN/at1hcXdHUs+GcBt2C0pbvRI7grLuui6vCQwrju4xf1a6KhfZr5ntBA3lmNNsaQGYNU1NntZC1aiJv7m8YoH/s9oKdhiL+a1opAuq2dEdJdntDUH/lRTlTaEahS0XWrPaLOO0ne59sGndFxw4y8bQCY18qx4dDy9kN/vNSGWyNDB8PkREMxW8Jo0Jop/C1bXarYqqP7nyLUoJQO/orI6xQc0Ng6WAiYVUuS1tAwRrnaNKvQ 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 11/10/25 23:21, Lorenzo Stoakes wrote: > There's an established convention in the kernel that we treat PTEs as > containing swap entries (and the unfortunately named non-swap swap entries) > should they be neither empty (i.e. pte_none() evaluating true) nor present > (i.e. pte_present() evaluating true). > > However, there is some inconsistency in how this is applied, as we also > have the is_swap_pte() helper which explicitly performs this check: > > /* check whether a pte points to a swap entry */ > static inline int is_swap_pte(pte_t pte) > { > return !pte_none(pte) && !pte_present(pte); > } > > As this represents a predicate, and it's logical to assume that in order to > establish that a PTE entry can correctly be manipulated as a swap/non-swap > entry, this predicate seems as if it must first be checked. > > But we instead, we far more often utilise the established convention of > checking pte_none() / pte_present() before operating on entries as if they > were swap/non-swap. > > This patch works towards correcting this inconsistency by removing all uses > of is_swap_pte() where we are already in a position where we perform > pte_none()/pte_present() checks anyway or otherwise it is clearly logical > to do so. > > We also take advantage of the fact that pte_swp_uffd_wp() is only set on > swap entries. > > Additionally, update comments referencing to is_swap_pte() and > non_swap_entry(). > > No functional change intended. > > Signed-off-by: Lorenzo Stoakes LGTM (famous last words) Reviewed-by: Vlastimil Babka