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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9C60C4167B for ; Tue, 27 Dec 2022 16:39:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231589AbiL0QjP (ORCPT ); Tue, 27 Dec 2022 11:39:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229911AbiL0Qip (ORCPT ); Tue, 27 Dec 2022 11:38:45 -0500 Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06299BE21 for ; Tue, 27 Dec 2022 08:38:45 -0800 (PST) Received: by mail-wr1-x42d.google.com with SMTP id y8so12825467wrl.13 for ; Tue, 27 Dec 2022 08:38:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=9wRW7TKueArBUfnnmbZEuYC3CJj8NI6TnvFxQoqEUT0=; b=d+xPdL7coIPZRO5nn3egLZtv3PN3VOJ1gOzyBA88vkN76zmYEbmNdb7rYq3FKGyYib 2iOrcnGeRaD4g6aVanQdshfYBFpmcmkZk3xaTZgYTYkR+o5teU0meZ2Nml2vsrXU04h5 NOTcMmDdprrOZFPXI+uRWD3nX4cRr18qmGbwJOymdbC8EgUkyVEIG2rtv7BsToVxi2Yp GIF5Ped4Rh1RWbRTDe8BL4VPvbQemc6yd98J44QhIKFibik3LmMw5RmNvx0Yb7xxjdiW 5XWacGwoRjdndljAlRWYgdrLkZLpf93vpyhXVqYv5WMU9KpAhIMjpvmertNO0e6zylMa A9WA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=9wRW7TKueArBUfnnmbZEuYC3CJj8NI6TnvFxQoqEUT0=; b=qjvyFHxdEF3dFrhb21GFlvIN4PC7rISMCVKSpZBLTIz5tBlcEx1D/TQmqk7yqydGGk l4S3g381gYxnC2GGhATSJKPSjHQBjN9QWeNoWSlfsFcuc645hMSEW4oPO2aIxavnf2pB lAcbVol7NBn/8mQobpKSg3A9zipcFFQWnJuSp40mEAGC5obdZD+DPgh0pXR7U5R1pfmU 18VvBLDlIisFpUuQmpcf/XhBiyGmVJVKfcTZQX0kOChZwE9IHSUPWtx9v6SYx2caWinu 5fiDQWzgIpKWom0KoJUyQEDuYdEtKJOuDYf619PlBf10KoRDsobsXoSzbhzVspPOW7xe mG0g== X-Gm-Message-State: AFqh2koV3+JE90vJptxhyUBsmKpT/Mqvmk7J2VmV1KgAdtHAD/+uRU3t XY65CyJMeZy3nbCM1EeN7ErNi5ANMxchWgNJVo7tmg== X-Google-Smtp-Source: AMrXdXulvcqn/NRP4iH9vac6EaXPEKPPRWSKSTz2F5SIQeb7alwXkcTKKoAkkvl9ZqJaxCOXFKKZIINgT/H8rNkezn8= X-Received: by 2002:a5d:4574:0:b0:272:859c:54fb with SMTP id a20-20020a5d4574000000b00272859c54fbmr604144wrc.355.1672159123482; Tue, 27 Dec 2022 08:38:43 -0800 (PST) MIME-Version: 1.0 References: <20221021163703.3218176-1-jthoughton@google.com> <20221021163703.3218176-35-jthoughton@google.com> In-Reply-To: From: James Houghton Date: Tue, 27 Dec 2022 11:38:31 -0500 Message-ID: Subject: Re: [RFC PATCH v2 34/47] hugetlb: userfaultfd: add support for high-granularity UFFDIO_CONTINUE To: Peter Xu Cc: Mike Kravetz , Muchun Song , David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , "Zach O'Keefe" , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 23, 2022 at 1:38 PM Peter Xu wrote: > > James, > > On Fri, Oct 21, 2022 at 04:36:50PM +0000, James Houghton wrote: > > + bool use_hgm = uffd_ctx_has_hgm(&dst_vma->vm_userfaultfd_ctx) && > > + mode == MCOPY_ATOMIC_CONTINUE; > > Do you think in your new version use_hgm can work even for MISSING by > default? I don't think so -- UFFDIO_COPY will allocate a hugepage, so I'm not sure if it makes sense to allow it at high-granularity. If UFFDIO_COPY didn't allocate a new page, then it could make sense (maybe we'd need a new ioctl or new UFFDIO_COPY mode?). I think it makes most sense to add this with another series. Thanks, - James