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 E28A0D116F1 for ; Mon, 1 Dec 2025 08:59:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 31E006B0029; Mon, 1 Dec 2025 03:59:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F5426B0062; Mon, 1 Dec 2025 03:59:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 232446B007B; Mon, 1 Dec 2025 03:59:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 0E9746B0029 for ; Mon, 1 Dec 2025 03:59:58 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id AE9AA16018B for ; Mon, 1 Dec 2025 08:59:57 +0000 (UTC) X-FDA: 84170304834.22.7AA9116 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id EAB4840008 for ; Mon, 1 Dec 2025 08:59:55 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dUQnqU3I; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1764579596; a=rsa-sha256; cv=none; b=ii/Y7VTcoSGBUpOeUDNPasWJrps0lowuisZFM1XxqOe08TWRLUo3LXQZ2dUIMMpJUWWGvE QmWKN+bzuWztFSCFYdrLzKm26dfJ1U1Dup1qvf3Au40+cJQtdc5AwevLkl4Bu/lAa8UAFB Og8d8ZqcR1Q3+EXl9XI/QxdZ8TCzxbw= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dUQnqU3I; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1764579596; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6xRHVsGXsAklwvyjQQK8Fd2Hk6gtYMtRi82oz16QcCI=; b=xss0FybcBwt62S2O+qzRr3ATMwMcranzjHBhwyHExydICEhMjENsZrm1H00LPcOwk8YjgV JM9YescFp2ZuZDdbacyXaATkz6GWjb0uW/C0xmHkXgSkDAZMn9vWFB56TTVgY2ZQzsSGl8 VhAMzupb8YN0vsb/Tc2fHUUQLGDrOOk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id B00D444398; Mon, 1 Dec 2025 08:59:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 190FFC4CEF1; Mon, 1 Dec 2025 08:59:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764579594; bh=XFnJpvWNqT0Iil1YFGSDXH4hktrbxLGtcmxxzhqoVxQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dUQnqU3IKLkudOiVLuuIXEmlc+kZnsIYDwkJW75j8OQM+SDFYy3x3JAijGlZ9NmO1 76Baw2b68fUlUApo91neXXzMCDpf8SmPOceJp0/whw9qYqhQlIjoCNOP+h6GQ2Eyn3 gM1FXpcgAUd6+Ge6UTQuLbuZEEv64px3Y9oEkQ2Pl6S3Lmm8kx6+v4617oh88WbiY8 NIUVCvEO+SnH6RefcuOpEeWbP1dL/44xfVtywyoAV+hEFu8OAWH+WSxXvjF6Fe3UFw VtgGNpqb7MzdOSJ2XBwlvF1LWQtVzimiAEZSOcbQSV240B31+CipR8x8JMGtxLI3bp Zi88BYx5W9X4w== Message-ID: <3b1916a6-0883-4713-8334-17d3932fe3b9@kernel.org> Date: Mon, 1 Dec 2025 09:59:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/5] mm: introduce VM_FAULT_UFFD_MINOR fault reason To: Mike Rapoport , linux-mm@kvack.org Cc: Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Nikita Kalyazin , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20251130111812.699259-1-rppt@kernel.org> <20251130111812.699259-4-rppt@kernel.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251130111812.699259-4-rppt@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: EAB4840008 X-Stat-Signature: 6d5izk858f1krzaf1dehqk144zkisi5b X-Rspam-User: X-HE-Tag: 1764579595-966539 X-HE-Meta: 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 X7f2gCi3 Inpr6eFZt1nmbD7sZ2XSnLdlvSmY/yzyzyWh48uIkEQ6isGuyaVf6oG2ZDYei4JjGoF8t9bQSFuFVcHUan+nJAstxPe5hy7lgW7RKgu7r4Vdz9njIENGPB23iMEt3uvKW2XrjNEAQYaWaos6wjYCyVgVd5K2Xli14i4CH9pTV5jGk56jctVAGX109TR38nXmyPy8lHVFToqRajgQlx0YIWQ07rAowPqw5mFpBWmB+VL6xWq9kQ2Eixq+fPYLB+hBXE7rzFSgqFUy0NBeig0qJlqpxAcBWZam1zCu3SvXZpTfzZD/0hOc+wQqRb3MCOCL8psm/xRDhZPpZmcU= 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 11/30/25 12:18, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > When a VMA is registered with userfaulfd in minor mode, its ->fault() > method should check if a folio exists in the page cache and if yes > ->fault() should call handle_userfault(VM_UFFD_MINOR). > > Instead of calling handle_userfault() directly from a specific ->fault() > implementation introduce new fault reason VM_FAULT_UFFD_MINOR that will > notify the core page fault handler that it should call > handle_userfaultfd(VM_UFFD_MINOR) to complete a page fault. > > Replace a call to handle_userfault(VM_UFFD_MINOR) in shmem and use the > new VM_FAULT_UFFD_MINOR there instead. > > For configurations that don't enable CONFIG_USERFAULTFD, > VM_FAULT_UFFD_MINOR is set to 0. > > Suggested-by: David Hildenbrand (Red Hat) > Signed-off-by: Mike Rapoport (Microsoft) > --- LGTM and does not look too invasive for me. Acked-by: David Hildenbrand (Red Hat) -- Cheers David