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 7CE18C4332F for ; Wed, 16 Nov 2022 22:29:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234113AbiKPW35 (ORCPT ); Wed, 16 Nov 2022 17:29:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234029AbiKPW3z (ORCPT ); Wed, 16 Nov 2022 17:29:55 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFEA3AE5D for ; Wed, 16 Nov 2022 14:28:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668637734; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jvzvnWWvvncWVJBoG4PM/NRp2jE+Ki/mZmdWbCmPuG8=; b=E9MstKDlqJIQV86kgcd3wuf5gwO0OGJE5lSvr/ZLhX2lk3Amfle/6TD9EjXH2RnG/XNWn3 TNcQ+fnb4/plCs0DpnScrv1AUYkZwrI1Lm3RYZfN4j88PJHcLfmGdzlkx3S6Aw31Qtp6sg P6hWpoKp7JVoqB+cDClBQSIJe3ysK54= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-630-7UGhh377MyeBItNxeNqnNw-1; Wed, 16 Nov 2022 17:28:52 -0500 X-MC-Unique: 7UGhh377MyeBItNxeNqnNw-1 Received: by mail-qk1-f198.google.com with SMTP id w13-20020a05620a424d00b006e833c4fb0dso106739qko.2 for ; Wed, 16 Nov 2022 14:28:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=jvzvnWWvvncWVJBoG4PM/NRp2jE+Ki/mZmdWbCmPuG8=; b=XVhkuM+BPDlGm1ryWwWrKBzzaGE7tNGhagGObQhC68WZo4JqJ4oGRpDGCFt1oxCErt +x34HCrk78Olnwt+ga8wLA/UY6YNTRjFwH8Ce5o0h+EfOWeSvEhJ6k4woA3zdEDb50FX OeMV89LXdrqm37WjswzrQm7Z2DUPbglg5muCUoXBeBdJibV5AAmMhV0290J99IwxkhXr mQvsrbEkfp3Kyfj7PGIvsi1Ny343B+bPCiXJ0rh9v1f5pUOgLpYAYwh9068Kz67NWvvf NgonGF3ZqC/OwvNbVGBkL6360bttPHATSsL3iJ6+BJ6iDNX955vD7PlGSY5fc15ipjE0 Nz9w== X-Gm-Message-State: ANoB5pnBsvgbfiEWIpHJohASG55CLvQldHvsVXGit5m9jHCZ8odqGP6n FqNGmIgjpkOuXuNhorJBZDw+SSn/n6niEbMEzid5eLd/beVnDNf/6659y890yqo4/ybHbIntlVL LuWyRngRBhR784SP8ZmW7OQdH X-Received: by 2002:a05:6214:5e92:b0:4b4:128:3cb2 with SMTP id mm18-20020a0562145e9200b004b401283cb2mr166790qvb.80.1668637732370; Wed, 16 Nov 2022 14:28:52 -0800 (PST) X-Google-Smtp-Source: AA0mqf76RjrKtkZ6fMY9tZlOEnFl1T1XlGZf1zYhtmOtdHNRH38EER6mAoQ5O8SR1Et9FDXPjqD5rQ== X-Received: by 2002:a05:6214:5e92:b0:4b4:128:3cb2 with SMTP id mm18-20020a0562145e9200b004b401283cb2mr166759qvb.80.1668637732172; Wed, 16 Nov 2022 14:28:52 -0800 (PST) Received: from x1n (bras-base-aurron9127w-grc-46-70-31-27-79.dsl.bell.ca. [70.31.27.79]) by smtp.gmail.com with ESMTPSA id u184-20020a372ec1000000b006f9e103260dsm10617212qkh.91.2022.11.16.14.28.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Nov 2022 14:28:51 -0800 (PST) Date: Wed, 16 Nov 2022 17:28:49 -0500 From: Peter Xu To: James Houghton 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 Subject: Re: [RFC PATCH v2 33/47] userfaultfd: add UFFD_FEATURE_MINOR_HUGETLBFS_HGM Message-ID: References: <20221021163703.3218176-1-jthoughton@google.com> <20221021163703.3218176-34-jthoughton@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20221021163703.3218176-34-jthoughton@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 21, 2022 at 04:36:49PM +0000, James Houghton wrote: > Userspace must provide this new feature when it calls UFFDIO_API to > enable HGM. Userspace can check if the feature exists in > uffdio_api.features, and if it does not exist, the kernel does not > support and therefore did not enable HGM. > > Signed-off-by: James Houghton It's still slightly a pity that this can only be enabled by an uffd context plus a minor fault, so generic hugetlb users cannot directly leverage this. The patch itself looks good. -- Peter Xu