From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0F2630ACEE; Mon, 11 May 2026 15:15:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778512551; cv=none; b=T8m5W6ATu4zvdmcTL8R/XL9SGazAoxnYC5tsxCKQOo2DA8vh9z27NhX5lUcbBNoNi6t4YZlTsqQi17Op45OS16JFj7R0Q8MkHwdC5J8FZ3Zp0KBxwlLnSWRZaq1IQx4p0nMfw2gpciT8ovj9pSuMznU1mjOSO5ZzG/hhvgrwDFA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778512551; c=relaxed/simple; bh=XU8h+UNIZXd2xu8Y6zOdyfGnC8dGq+kPUi+hYVKln78=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UmcNLAZvJxhtBd/INjvWmaOtE2j4yINFT0+nswdyCRt1qYB3k4XfRDrW1FWZcdEG9HFd5zgx7m9svNakJ8NmpxjrlIBuybKH41HSldudbyXhI19iu/jb3cdVQx2lJVwZbywpuvgJooyAf/6gGYk4SclKuGS2Ia7vuKx+SJ+EfI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Fb7tKuor; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Fb7tKuor" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48EA3C2BCB0; Mon, 11 May 2026 15:15:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778512551; bh=XU8h+UNIZXd2xu8Y6zOdyfGnC8dGq+kPUi+hYVKln78=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; 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 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 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 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