From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B39ACAC598 for ; Wed, 17 Sep 2025 09:25:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 946C78E0011; Wed, 17 Sep 2025 05:25:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 91E608E0001; Wed, 17 Sep 2025 05:25:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 85B378E0011; Wed, 17 Sep 2025 05:25:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 741EA8E0001 for ; Wed, 17 Sep 2025 05:25:50 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 25BC31A047B for ; Wed, 17 Sep 2025 09:25:50 +0000 (UTC) X-FDA: 83898210060.01.B043E02 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf29.hostedemail.com (Postfix) with ESMTP id A54F6120008 for ; Wed, 17 Sep 2025 09:25:48 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=UpbyHRlj; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1758101148; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HwccyQR0rU/LkW0cKwc9wrhgdLBQ0OFTOXYqtcmBuK8=; b=Y8W9EWidptjoicptoVCFqiRP7BehPZux6lStgvEWy0f30rkGjedJS6/JBR8SNUwx+D+knA SmbZ+cYVRSr+BEBSljepnpFcYP774mT+bOFwyIhPn73+Xj3qmu7sGwWgDe58rvyiT/rxWK AWV5MZQLzhjMWU8+CyyimU1gz0BekWw= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=UpbyHRlj; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1758101148; a=rsa-sha256; cv=none; b=rcZXZNUV2gBrTYjHvXSYrmIQ25axfqzl9wQNHMlQE7ygpaq0U86VtMBVsxIsE/7DOkWlHl cyvjPj9eN0hRKzcNFNoBcat4b6E+U8G29SEaMf/0W/6jb7d45sxurzTo4j4qirBb6nwntI LT++Wl1wDNFq6RVdE8PzR/uBiN9cfnE= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id CB049601DE; Wed, 17 Sep 2025 09:25:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1A34C4CEF0; Wed, 17 Sep 2025 09:25:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758101147; bh=mi+c+o3FWmHPaLJiT7Mnmm6sTZe4R8F+gNG7LUzeQcM=; h=Date:From:To:Subject:References:In-Reply-To:From; b=UpbyHRlj6I92I8jYO8q8IHg9KFI/uWkocCl/yZZihL+Pu5p5cNv9/3GUZM17ZnTEL 55OySOMRo/VxAf3J394PdGoWX6PnbU604tDshBIp4JnADYGd/Pkg31p/3oS9TTje5M 7XfdTlfu+IC1/Km3+dylN2uadA4ih0TYYSHUze4cbDLE16OZqf4/SRXFT7EkFTZb4J gH3rkjwmWpvOwW12ngJ60mDM2ggbYPEiueaZ6Bn9U9mvtgUlJrFrGEpHajgaa9UoZP ZMlPKuJYultxRbn5+7KKJOHkKr9t6sXPHiG2v0BXspJrgKTFHMr7j3ktzLyJEJoz06 rPPyl6Or7FIGA== Date: Wed, 17 Sep 2025 12:25:37 +0300 From: Mike Rapoport To: "Liam R. Howlett" , Nikita Kalyazin , Lorenzo Stoakes , Peter Xu , David Hildenbrand , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Muchun Song , Hugh Dickins , Andrew Morton , James Houghton , Michal Hocko , Andrea Arcangeli , Oscar Salvador , Axel Rasmussen , Ujwal Kundur Subject: Re: [PATCH v2 1/4] mm: Introduce vm_uffd_ops API Message-ID: References: <982f4f94-f0bf-45dd-9003-081b76e57027@lucifer.local> <289eede1-d47d-49a2-b9b6-ff8050d84893@redhat.com> <930d8830-3d5d-496d-80d8-b716ea6446bb@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: fjeh48xa1efyxtr1b87gjsicronb8p9h X-Rspam-User: X-Rspamd-Queue-Id: A54F6120008 X-Rspamd-Server: rspam04 X-HE-Tag: 1758101148-624701 X-HE-Meta: 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 jBC02kLl /Gj2XsoYj7F+eWMy+IdVjnz81zugZB1eEuzAlaLNS1yuKouOq/9wvSQsIp/NayAEbC7ED2hkVeI0I/jgzLyLu3gf/RiPMwjKqfGr4Dh5cWgHm8V0Kb9bGIbjh2HAm4WZniE5Xcs7mAjVkPlniefYe2Rf/hiSG7cCEvNad+eQrYqKR82EPvl3pj/JRoPQ2KPkMPlhigGsMRg9uSJ1Hx7PkSujG2KBNctJkasPpXMtudUZawGYn+gkgyvH9OiNknrfi5053rlPMQzoMO8A7KLlMhtj2/DzOD6Plbg2qkv6Nr6BJRmPxcvpsq+RPR/vHYBrMSERhgFNqWO3agtlEAnSQHmU861bQi7neEz1lF8AMC2g1sqq2KJiPUdHUcQ== 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: Hi Liam, On Mon, Sep 08, 2025 at 12:53:37PM -0400, Liam R. Howlett wrote: > > Reading through the patches, I'm not entirely sure what you are > proposing. > > What I was hoping to see by a generalization of the memory types is a > much simpler shared code base until the code hit memory type specific > areas where a function pointer could be used to keep things from getting > complicated (or, I guess a switch statement..). > > What we don't want is non-mm code specifying values for the function > pointer and doing what they want, or a function pointer that returns a > core mm resource (in the old example this was a vma, here it is a > folio). > > From this patch set: > + * Return: zero if succeeded, negative for errors. > + */ > + int (*uffd_get_folio)(struct inode *inode, pgoff_t pgoff, > + struct folio **folio); > > This is one of the contention points in the current scenario as the > folio would be returned. I don't see a problem with it. It's not any different from vma_ops->fault(): a callback for a filesystem to get a folio that will be mapped afterwards by the mm code. -- Sincerely yours, Mike.