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b=Fb7tKuorEh7gKXNnQi4K7eFGBeo2w8f3vgRJMdUhhqPl8rhj0zua61ZI1MLE/hL9P IXocQEGsApafUL4lQlxZ1tO6lJp71RkaiJZXmAtf/1o8kkItpPhg3TyhR8Wn8UfpUZ sZWAYh+jR/2lacJ3BhpstlHUqnnj+K19vA3Vk69fHjGi7wOH6PY73beiIkHyJrWYa1 fW4w0yhbR1ej4tzu2sNhdbCUIBnkJflAd7CvIC+gH/33s6cJoGOuHBsz6jzjRMrnzC r3p0ibbAePYx7w4LVg/xyj96Oa8q/0+2p6hGngNv0023489qEclWFXHJmDYvt6/voO nuHqWuY/CpZJA== Message-ID: Date: Mon, 11 May 2026 17:15:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 05/12] mm, swap: unify large folio allocation To: Kairui Song Cc: linux-mm@kvack.org, Andrew Morton , Zi Yan , Baolin Wang , Barry Song , Hugh Dickins , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Johannes Weiner , Youngjun Park , Chengming Zhou , Roman Gushchin , Shakeel Butt , Muchun Song , Qi Zheng , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Yosry Ahmed , Lorenzo Stoakes , Dev Jain , Lance Yang , Michal Hocko , Michal Hocko , Suren Baghdasaryan , Axel Rasmussen References: <20260421-swap-table-p4-v3-0-2f23759a76bc@tencent.com> <20260421-swap-table-p4-v3-5-2f23759a76bc@tencent.com> <675e9027-9fb5-47b5-9a2d-c9a416a27d0d@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5841B1C0011 X-Rspam-User: X-Stat-Signature: 86tq8p547wo94qj631hhj7pcdzc177ir X-HE-Tag: 1778512552-679209 X-HE-Meta: U2FsdGVkX19KLr4hWE/XcCK2nrtqUIrOzJ07mrVsdxlyjkftW+rXVDe0+j6QfPfG9jp+6RVJJ16alMnJ2F7HddKFaZHCJlAskJRz1OhAzWKy+1TPROHzyyteJNf9cpe6iq+xXhr/HbSQw2GvWj82xUSHu12qlXAWQNl3GWjmMu1Jixa29L7vFm9U/Btv52K6QIpzzqaMMP2tgxIVj9TDJ7c092iyVpHAVBP7MC4P0hOo2mW8cpieCCDQGiul+MAK/+JhImumUFFhqfeg8kQGGjn6sVsz/tTReK6iToChpiLE0fd7aHDzenWnHjmlp++QwYiosvnb+xGPmIQSwRMqoxQN5AVdeR5mKATRW00qp5c5iPC5ZKz+f45fZOeE3c9/Ccsn81jFvr8wGfjSO1wlOxO+gDo3R5rHKpjgqACRLO7p9vzZv2/M4D8CU5KECsiBnz9TdRGisBFXCpcgVrW4kbfywozDsjIEw7Uknatd14aTWnGpykCYipui9yH8xHVbesXR+5LifZJMfZpUMqsG/JOfdSnHw9nfr9pP37F+a3cJVVmFxzSSx7abURDr0+eKFqcht8d5EoNJRYPjdipISnlxnGrW8Qp63ofiaq2gjlHjwuhixoE8hC/9OBntldFvKZ4siPDaFQCBi26vAxc1idA1q6o/dzbcPAgk3sxYcRE92NCbyqZ59ykhNX3DlZa3RQzSdFDrPYSFpGlruQkePvPwiiBvk8y/LA3hFGcNTMtkANZM/0n10uyaCnXeVklPUGcz+o2gKv9gC2VSX0scF5CCJXaVYndDoHsrDplJg9Z4jQ0fPEV40H9eKbLE/6KknHsH8EGYSn/9KucbuvfyVZun2OyNpz8MVyHR/yiMBFLac9hqH6B4+9HNi42NSgrAY15Gk77lASvIc5bAlcy499pga8xfvnPC2EkD7fdvY+TZKzwZHFJvc7VGfAxW+kCH1mgYBmcQso5MzBbqRAk m6DrgHDB BoDUp5NubI1pg/yP1kQbFfEFi1gPZAk7hZxgZDJNWUEzCWCv8sxPObOAswCDCQZcPoNuPIeG6YEFi9R1fAvkphUeN/7XIbrMboCqvBAI77478o7o9m7EmGU7Kf/A8sNdYOHyuArAA9e8j1fVEDLYNCe9xCpPKra2Z9vqFzRTpOnhuHv+ulyQ7DZs16Kd083IeJRhkCL3x3qDk3QQBrCGwUxuiDWsO1U5A7t+nHIigbTMZowGcLbV5IVigoy1czbgcs+rh5Z6Zb3FcR1ohRrmfUtgj5vt83hXXgPuMpXl72Nfs86qCfFYinGf/B9nspeq12Y78H44x/ExGZnvloEjwJ5OnwSOw57zaLxLyZ9nSOwr/IbRpxsC954xwQQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/11/26 16:37, Kairui Song wrote: > On Mon, May 11, 2026 at 8:58 PM David Hildenbrand (Arm) > wrote: >> >> On 4/21/26 08:16, Kairui Song via B4 Relay wrote: >>> From: Kairui Song >>> >>> Now that direct large order allocation is supported in the swap cache, >>> both anon and shmem can use it instead of implementing their own methods. >>> This unifies the fallback and swap cache check, which also reduces the >>> TOCTOU race window of swap cache state: previously, high order swapin >>> required checking swap cache states first, then allocating and falling >>> back separately. Now all these steps happen in the same compact loop. >>> >>> Order fallback and statistics are also unified, callers just need to >>> check and pass the acceptable order bitmask. >>> >>> There is basically no behavior change. This only makes things more >>> unified and prepares for later commits. Cgroup and zero map checks can >>> also be moved into the compact loop, further reducing race windows and >>> redundancy >>> >> >> You should spell out the rename from swapin_folio() to swapin_entry() [and why >> it is done]. >> >> swapin_readahead() vs. swapin_entry() looks a bit odd, fiven that both consume >> an entry. > > Yes, the current status is a bit odd, about two years ago I also > wanted to name it `swapin_direct()`. > https://lore.kernel.org/linux-mm/20240326185032.72159-3-ryncsn@gmail.com/ > > But actually ZRAM or shmem would also benefit from supporting unified > readahead like this: > https://lore.kernel.org/linux-mm/20240102175338.62012-6-ryncsn@gmail.com/ > > So calling it `swapin_entry` seems more future-proof. At some point in > the future we might remove `swapin_readahead`. All swapin operations > could have a unified or at least a per-device readahead policy like > the one in the link above, instead of the current policy where the > caller must decide whether to perform readahead. > > But any suggestion on naming is welcome :) The other proposal https://lore.kernel.org/all/tencent_CD11FE9B4A0B362E95E776C5F679598FAA07@qq.com/ calls it swapin_synchronous_folio Maybe just swapin_sync_io()/swapin_sync() or sth like that? -- Cheers, David