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 93A23C001DE for ; Mon, 31 Jul 2023 16:06:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 342AA6B00E1; Mon, 31 Jul 2023 12:06:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F3646B00E2; Mon, 31 Jul 2023 12:06:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1BB9B28006D; Mon, 31 Jul 2023 12:06:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0BD806B00E1 for ; Mon, 31 Jul 2023 12:06:23 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id D01961A0A91 for ; Mon, 31 Jul 2023 16:06:22 +0000 (UTC) X-FDA: 81072384204.24.5885D7A Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf12.hostedemail.com (Postfix) with ESMTP id 693BA4008F for ; Mon, 31 Jul 2023 16:05:53 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=SboVpjKR; spf=pass (imf12.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1690819553; 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=fe8D0HOECGyB0VhAiINFzMU/ctaZGX42+I+MeNC1CcY=; b=aNFfAl6w9npg8kmzfjyj12fqSXknQSOCknzaUR2C1L6uDJnmmV6AetQ84jRYBAyxfQciQc QZgoDbx7I7OG+6ZzxfSLn18qLP03fUjRQr1YBj/6I+lpX3Vn8/doVL4eseda9ASBTEnx9+ M9lBUGLsqE/XZekSbYcqqfEyjqZwvSY= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=SboVpjKR; spf=pass (imf12.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1690819553; a=rsa-sha256; cv=none; b=2slRKrZH07BgQjNTxITxGZVCfx+HVNjCj2ARErVFUufiGsGHc1VYh+eQPrywUBIu+npUAW YvY/efUP3MDMbVOPsn0Peqb/y7OOKEQQPVhWELBbAqQbl5L4IUBmGsGg9qkAJGzLh9lzu8 Pw7V78FGDwrkaTmZJo843aGE/COKRnQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1690819552; 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=fe8D0HOECGyB0VhAiINFzMU/ctaZGX42+I+MeNC1CcY=; b=SboVpjKRWwIH2r83dc4VUWFHZT0pC7sspIdP5H8F9Xlmuep0WIuwf54dbH4nRNml54WG1/ k0YsUrH0OH4VkcTyWpSvsRDwPUmfA7xDaMYgWuPEm6Hzp34r/Rv+nHUdrCT6i/klVp3PED 0NJrnz24aYPPG88MLGx7AUSNxkDqpXw= Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-619-1w9y7OuuMumlzYa_Gmn-Yg-1; Mon, 31 Jul 2023 12:05:50 -0400 X-MC-Unique: 1w9y7OuuMumlzYa_Gmn-Yg-1 Received: by mail-oo1-f70.google.com with SMTP id 006d021491bc7-56ce4f82d18so66110eaf.1 for ; Mon, 31 Jul 2023 09:05:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690819548; x=1691424348; 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=fe8D0HOECGyB0VhAiINFzMU/ctaZGX42+I+MeNC1CcY=; b=Ct+L0/dqdkblfsfT/oLqRuFHAQ7YWK4Fw6IKQEWVrG9L6iOwMA+tQlVSdjP2XyVaQ0 RF2oe+r+K+LnQyC4vL/j6aSG74H1kdNtJdllMAKh4M51AC6qkTWRHHiUnk4rzTGuXvF3 860ND7hyT/Tt3eF8MebrE9q7/K9I/uGBOyS1rjnx9CjyrNLGA0iS6Y0TbeYghHhIJSa7 0mcwQ2y58UnahrKE+4wt/WCLvs/q5MP+kQzX1kqm7vW624kzghXF1V1JsZJZjjoyYKiN iTdHgIs4s8ibCgrbMkiAG8sXEuE34N6wzLMWT2/1mzY3LoEyKtPsrG1aHBoJfdcaARvZ T9Cg== X-Gm-Message-State: ABy/qLYPZP0IUZfe/Dl4/qlm+CYQLZhIrQl5Qj+zbjNNoBaiJtEaDVzY f4NGmQbJQIyAjrSslvLmgHcpSLz85CazD/kOf7xGZcF/i4gQzCNi3woOoQ1pZsKawi/UPScZGsa XDQLZUoWS9zc= X-Received: by 2002:a4a:a585:0:b0:56c:484a:923d with SMTP id d5-20020a4aa585000000b0056c484a923dmr5539744oom.1.1690819548648; Mon, 31 Jul 2023 09:05:48 -0700 (PDT) X-Google-Smtp-Source: APBJJlHhq1hLxxabjktwI+EJsrtIcmAgGCaTSDKURV9TulXm5uBMFY0f/5Fv0jVzE69294Gd73pQkQ== X-Received: by 2002:a4a:a585:0:b0:56c:484a:923d with SMTP id d5-20020a4aa585000000b0056c484a923dmr5539724oom.1.1690819548353; Mon, 31 Jul 2023 09:05:48 -0700 (PDT) Received: from x1n (cpe5c7695f3aee0-cm5c7695f3aede.cpe.net.cable.rogers.com. [99.254.144.39]) by smtp.gmail.com with ESMTPSA id p15-20020a0ccb8f000000b0063d06253995sm3820825qvk.22.2023.07.31.09.05.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jul 2023 09:05:47 -0700 (PDT) Date: Mon, 31 Jul 2023 12:05:35 -0400 From: Peter Xu To: John Hubbard Cc: David Hildenbrand , Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , liubo , Matthew Wilcox , Hugh Dickins , Jason Gunthorpe Subject: Re: [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout Message-ID: References: <69a5f457-63b6-2d4f-e5c0-4b3de1e6c9f1@redhat.com> <118e571c-a79f-5020-b9fd-4c0a3722236d@nvidia.com> MIME-Version: 1.0 In-Reply-To: <118e571c-a79f-5020-b9fd-4c0a3722236d@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 693BA4008F X-Rspam-User: X-Stat-Signature: qbaga5s3zsydcpdz1hcnkgrjzt567zqd X-Rspamd-Server: rspam01 X-HE-Tag: 1690819553-642163 X-HE-Meta: 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 EG7fW2Fh 6flxkYWUOfIUNsS+EMvtM3u252MyxZZTnl93m14JWTurGJirBBa/4TiP4QOyK/JUwCkQngYQk7ojnh+vLqRX3QBRa5W0LozRtILRW8O85JMIj649yt1CzqRhggfXD2uxNDg7fuJ3rh8HF8eFXnSWkwpys2VEHP9wJDIkEpJCXU/1SPhZSWHz9Tt6GdmjuDwrixpua72smgTS24/vFL5lxp52XBosljEZQkpeypa98hotbPZLKTBqQSbWsQxJUSzuVckOu2fTnNHFvQsZ7hjGmYXEgGo9kHSdnzDrOMy9geb+cJnTjlFdOO6fInq7rtwy33WrQ8U6eqJOHj33Z2pBFjl7SJ4LLg5hmHPZJaxiYHeDMOS7T4JDryd+WZ5Jws9vF5bXtr99UCkGRtt05IKEz8cB5LsyRJqRfak6Z 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 Fri, Jul 28, 2023 at 03:00:04PM -0700, John Hubbard wrote: > On 7/28/23 14:49, Peter Xu wrote: > > > The story of how FOLL_NUMA and FOLL_FORCE became entangled was enlightening, > > > by the way, and now that I've read it I don't want to go back. :) > > > > Yeah I fully agree we should hopefully remove the NUMA / FORCE > > tangling.. even if we want to revert back to the FOLL_NUMA flag we may want > > to not revive that specific part. I had a feeling that we're all on the > > same page there. > > > > Yes, I think so. :) > > > It's more about the further step to make FOLL_NUMA opt-in for GUP. > > Let's say "FOLL_HONOR_NUMA_FAULT" for this next discussion, but yes. So > given that our API allows passing in FOLL_ flags, I don't understand the > objection to letting different callers pass in, or not pass in, that > flag. > > It's the perfect way to clean up the whole thing. As Linus suggested > slightly earlier here, there can be a comment at the call site, > explaining why KVM needs FOLL_HONOR_NUMA_FAULT, and you're good, right? I'm good even if we want to experiment anything, as long as (at least) kvm is all covered then I'm not against it, not yet strongly. But again, IMHO we're not only talking about "cleaning up" of any flag - if that falls into "cleanup" first, which I'm not 100% sure yet - we're takling about changing GUP abi. What I wanted to point out to be careful is we're literally changing the GUP abi for all kernel modules on numa implications. Thanks, -- Peter Xu