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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18A6CC433EF for ; Tue, 1 Feb 2022 09:10:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8D8DE8D005E; Tue, 1 Feb 2022 04:10:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8612E8D0054; Tue, 1 Feb 2022 04:10:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 729A78D005E; Tue, 1 Feb 2022 04:10:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0062.hostedemail.com [216.40.44.62]) by kanga.kvack.org (Postfix) with ESMTP id 610718D0054 for ; Tue, 1 Feb 2022 04:10:35 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 106AD18209A83 for ; Tue, 1 Feb 2022 09:10:35 +0000 (UTC) X-FDA: 79093640430.04.50C22B0 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf13.hostedemail.com (Postfix) with ESMTP id A1CD820004 for ; Tue, 1 Feb 2022 09:10:34 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 42151B829FF; Tue, 1 Feb 2022 09:10:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C58FCC340EB; Tue, 1 Feb 2022 09:10:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643706632; bh=HbKVe5ZxHkeeorB1SxL9qHDg13+RUUBESOBVN90dshk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fTPYx1dmsmTje/PdPs3YyjaTlFNKtKx+eQ4fG5HDreU3dYlJ6fla6pMf2Gc+DaIm3 LOReZHs/Do81ya6kEHkiauYZG1gk47VODRarUWw2KqNgxqqc95LwQqwnPE7L4S71R6 KbBK0LrLTaIUlPY+C5QYKasPmx8UBiS8ZdqSMbni0Rm+OTKnw9/KQhbemDUkx2VPXS SClsrqAGuneqcbE4fhfDm0b9THmUBGJV3asmfzvrwrFhFXTQUsM3d2kbZyIPJSByq/ jlNp7AS05GHBFaVIDs8WVii8Ou2F1opSb0IE8lMnjnklL/ieoOsIBEYBhuTrYscnFC 8TLTdWtI5CdFg== Date: Tue, 1 Feb 2022 11:10:24 +0200 From: Mike Rapoport To: Nadav Amit Cc: David Hildenbrand , Mike Rapoport , Andrea Arcangeli , Peter Xu , Linux-MM Subject: Re: userfaultfd: usability issue due to lack of UFFD events ordering Message-ID: References: <11831b20-0b46-92df-885a-1220430f9257@redhat.com> <63a8a665-4431-a13c-c320-1b46e5f62005@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: nil X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A1CD820004 X-Stat-Signature: jgq91f3kuhfgmt7okzu9fdubpodjyusb Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=fTPYx1dm; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org X-HE-Tag: 1643706634-651629 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: On Mon, Jan 31, 2022 at 02:39:01PM -0800, Nadav Amit wrote: > > On Jan 31, 2022, at 10:47 AM, Mike Rapoport wrote: > > > > On Mon, Jan 31, 2022 at 03:41:05PM +0100, David Hildenbrand wrote: > > As for me, I decided that due to the lack of ordering, I just > cannot use the UFFD events, and I have to rely on ptrace to obtain > order of these events. I might be wrong, but any solution is not > trivial and is likely to require API changes. I think you are right and any solution that will allow userspace to track the order of all events (page faults and address space changes) will require API changes. -- Sincerely yours, Mike.