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 5C5ED1061B37 for ; Tue, 31 Mar 2026 11:42:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C5E056B008C; Tue, 31 Mar 2026 07:42:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C0F586B0095; Tue, 31 Mar 2026 07:42:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AFD706B0096; Tue, 31 Mar 2026 07:42:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 9C2CD6B008C for ; Tue, 31 Mar 2026 07:42:16 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 1861F559C0 for ; Tue, 31 Mar 2026 11:42:16 +0000 (UTC) X-FDA: 84606169872.11.2936323 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 5A4ADA0002 for ; Tue, 31 Mar 2026 11:42:14 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Eklxj6nk; spf=pass (imf25.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 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=1774957334; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sV4bKEX3SHqLd+MsbDz9nAG/v9xodOWpOT03SIGw3yk=; b=ZV49+DUgkpWsZLuFFs2syDrWDnpg0BwODCds5NOIKF0prIRAyrb2alwfcPR7D8PxyQWoqn BG0IlQ74/F+LCqYGb7mdYSO3nr8+uKo7LyrjecqAFSHigr/1ZqNscKfNUdnkMApPaEmVon rrC30Z77tPEgS4cPdkYH7tpvTGmBrWQ= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Eklxj6nk; spf=pass (imf25.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 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=1774957334; a=rsa-sha256; cv=none; b=CNRiQU1kOUEAkaenJ6LFCUDIEUNbjBjT938oGcVvFgT5BaQ5L7N9/hbDCMAfNVfw+tYJLw g1Tc4tzpE1K69D3veu+BiguZTjE2FzopriBy0Jzy/NkTvX4fV/U5rKRoBpWMBuw7xO+0K2 VItk/kBEzEVopdG32upJr03plWbDFiY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id DD43D43E9C; Tue, 31 Mar 2026 11:42:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A17AC19423; Tue, 31 Mar 2026 11:42:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774957332; bh=v9/AUUMGVf9+nhrOWCMNuXE2J/EJf4Yx/A5I91wqayM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Eklxj6nkgag9phGSwi3AtluNOuSXDrudDeC/1PoarzkDyR4p3o0WsR5+F14ZRDl5g K2Nl5yCy0RGOJ0DRUiYL4OX7lS9rHaVpZcs/Y14YToXTDAfwhtXM5q/OBBwVM6+9rC a5PY+jeY6+oE9/UgIx8ASEbSIyVGTC4HR0AcfqfaLCYhekdoktZLfYZ2+11xgMDX/l Wejb1KLzSWw22xCDrro+pnvMhSvIuDD7yHMaAR6HJWWaIHeb/lR56OmzTWLRk1p3mj zt/MN2oV2Jzvs8jCoFDoR2DNo66mXetay7g3pMu7BgyOJjl9SFicy9OxWrV0FhxgiZ d+DZbWhjK1q1A== Date: Tue, 31 Mar 2026 14:42:01 +0300 From: Mike Rapoport To: Matthew Wilcox Cc: Andrew Morton , Andrea Arcangeli , Andrei Vagin , Axel Rasmussen , Baolin Wang , David Hildenbrand , Harry Yoo , Hugh Dickins , James Houghton , "Liam R. Howlett" , "Lorenzo Stoakes (Oracle)" , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 07/15] userfaultfd: introduce vm_uffd_ops Message-ID: References: <20260330101116.1117699-1-rppt@kernel.org> <20260330101116.1117699-8-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5A4ADA0002 X-Stat-Signature: gwc7aqp7xn3bm7opcefrorgd358sz5nr X-Rspam-User: X-HE-Tag: 1774957334-128722 X-HE-Meta: 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 XYZRB/Gy YaSf4JXyvcjCYVABGurdCeO8UG93kxMDzZEzFraDKQasinsHSJI2ftH5y3K8SbFax4dpejrGWe3jheWVsSkVi9+wVG3c86bw4CgT/nsLtQgUN3LQJEWALm6b4Le8hoxfeUSYjvf780Z6AuBOskHqZaa8/QOKIDG+kj1x1TkRttk+N+sB+mHYQW2LaNvKSsNJgeJDuuxsh97cg4Xdev6MJkm4TykyThH+2QXhYzPmF3EAw1q8CdS3erqXN438II5mre7/xJb8pQH9zAPEQ+gU9mrYxm3uqxtziF6rRuCVfpbNDf0sfZ/1dQpyrHA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 30, 2026 at 05:58:29PM +0100, Matthew Wilcox wrote: > On Mon, Mar 30, 2026 at 01:11:08PM +0300, Mike Rapoport wrote: > > First, there is no fundamental reason to limit userfaultfd support only to > > the core memory types and userfaults can be handled similarly to regular > > page faults provided a VMA owner implements appropriate callbacks. > > > > Second, historically various code paths were conditioned on > > vma_is_anonymous(), vma_is_shmem() and is_vm_hugetlb_page() and some of > > these conditions can be expressed as operations implemented by a > > particular memory type. > > > > Introduce vm_uffd_ops extension to vm_operations_struct that will delegate > > memory type specific operations to a VMA owner. > > But the VMA owner already gets control of the page fault. We don't need > the vm_uffd_ops to be accessible from the vm_operations_struct. The > page faullt handler can pass a vm_uffd_ops into the uffd functions that > it calls. Not sure I follow you here. The ops are not required by the page fault handler, they are needed for uffd ioctl handling, e.g userfaultfd_ioctl(UFFDIO_COPY) -> mfill_atomic_copy() -> vma = find_vma(); /* do VMA specific stuff */ -- Sincerely yours, Mike.