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[70.27.3.10]) by smtp.gmail.com with ESMTPSA id y6-20020a05620a25c600b006b59f02224asm2017524qko.60.2022.08.26.08.55.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Aug 2022 08:55:44 -0700 (PDT) Date: Fri, 26 Aug 2022 11:55:42 -0400 From: Peter Xu To: David Hildenbrand Subject: Re: [PATCH v3 2/3] mm/migrate_device.c: Copy pte dirty bit to page Message-ID: References: <3b01af093515ce2960ac39bb16ff77473150d179.1661309831.git-series.apopple@nvidia.com> <8735dkeyyg.fsf@nvdebian.thelocal> <8735dj7qwb.fsf@nvdebian.thelocal> <72146725-3d70-0427-50d4-165283a5a85d@redhat.com> MIME-Version: 1.0 In-Reply-To: <72146725-3d70-0427-50d4-165283a5a85d@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Sierra Guiza, Alejandro \(Alex\)" , Huang Ying , Ralph Campbell , linuxppc-dev@lists.ozlabs.org, Lyude Paul , Karol Herbst , Nadav Amit , Felix Kuehling , Alistair Popple , LKML , Matthew Wilcox , linux-mm@kvack.org, Logan Gunthorpe , Ben Skeggs , Jason Gunthorpe , John Hubbard , stable@vger.kernel.org, akpm@linux-foundation.org, huang ying Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Aug 26, 2022 at 04:47:22PM +0200, David Hildenbrand wrote: > > To me anon exclusive only shows this mm exclusively owns this page. I > > didn't quickly figure out why that requires different handling on tlb > > flushs. Did I perhaps miss something? > > GUP-fast is the magic bit, we have to make sure that we won't see new > GUP pins, thus the TLB flush. > > include/linux/mm.h:gup_must_unshare() contains documentation. Hmm.. Shouldn't ptep_get_and_clear() (e.g., xchg() on x86_64) already guarantees that no other process/thread will see this pte anymore afterwards? -- Peter Xu 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 0B1A0ECAAA3 for ; Fri, 26 Aug 2022 15:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344606AbiHZPzv (ORCPT ); Fri, 26 Aug 2022 11:55:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232426AbiHZPzt (ORCPT ); Fri, 26 Aug 2022 11:55:49 -0400 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 81B638C445 for ; Fri, 26 Aug 2022 08:55:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1661529347; 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=kxP+Dmq/9QrBSNE7t25KnXniHyhrvm0D5T7RzuSjQVM=; b=BckzJXwoci2ns9E9yfw/86jPHpQKs9xHUuTgB04a61ObWrE/GjkMlfGkizRzrgeLSh6102 VdSC3T9bWcjGy7OR0WNyWSqiVx2RAs0lCXToLlpNWFoVMEccbDnSOcXLmDFE66DjJo9J91 N5ugMYbRfRuHR/fSe59qGNfWsRmTfxo= Received: from mail-qt1-f199.google.com (mail-qt1-f199.google.com [209.85.160.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-388-eSZqlwEINguu82ycH68fFA-1; Fri, 26 Aug 2022 11:55:46 -0400 X-MC-Unique: eSZqlwEINguu82ycH68fFA-1 Received: by mail-qt1-f199.google.com with SMTP id fy12-20020a05622a5a0c00b00344569022f7so1562973qtb.17 for ; Fri, 26 Aug 2022 08:55:46 -0700 (PDT) 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; bh=kxP+Dmq/9QrBSNE7t25KnXniHyhrvm0D5T7RzuSjQVM=; b=4qbTvvWmxL3RZ4PqkblBuUMLJzUg/tUcefbfD3Bhx58tQvtcJVWxsoeG2jjgO0M7yX VLV7VoD5Qk+C9vDDiDFvF0TuuLUz51YeSBeN/jFisX2cptmtMAbk5iSDK0BBdI50LHoN GwF2A22bbTgGA1DIOKY4ySWUi7TBZ6+4eX6OjNobUeJg3MYMaeu3Oir/AOh1UXMK9Bwq NpwRsGuQe8VU3MtdghrfORnE97hbttzqgW/fl5vV1xdbyZiSpTOzeqULIgu3hZMiZQpv j/kb9FN4iQZC5MAO4rIFLxW+PMkIS7dZwfPm1+0i0dZpjynfH0oDFZCKzGCXRFgufQGj Qscw== X-Gm-Message-State: ACgBeo07mny62lxUIsQst3xyqBLm6QxL8RTBTldwF+PFyfO2e/gFeWNK cNWEutG0zs2CbYfoHFgwUstyWfSubat7ifXOX4L1JB0z3iRha/lxGYGZtxaXzoXXNak9/7uLPmd E9aET2gV3Fk9Rv1o6 X-Received: by 2002:a05:620a:4549:b0:6bb:bcd5:bebd with SMTP id u9-20020a05620a454900b006bbbcd5bebdmr237494qkp.281.1661529345624; Fri, 26 Aug 2022 08:55:45 -0700 (PDT) X-Google-Smtp-Source: AA6agR7ptvaOj1PH8113xcy+IwXkhfYIf0njU7CP9Dg6jANrLlzn5ahE+pvxpqeln6UJrgFHbun7Bg== X-Received: by 2002:a05:620a:4549:b0:6bb:bcd5:bebd with SMTP id u9-20020a05620a454900b006bbbcd5bebdmr237473qkp.281.1661529345399; Fri, 26 Aug 2022 08:55:45 -0700 (PDT) Received: from xz-m1.local (bras-base-aurron9127w-grc-35-70-27-3-10.dsl.bell.ca. [70.27.3.10]) by smtp.gmail.com with ESMTPSA id y6-20020a05620a25c600b006b59f02224asm2017524qko.60.2022.08.26.08.55.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Aug 2022 08:55:44 -0700 (PDT) Date: Fri, 26 Aug 2022 11:55:42 -0400 From: Peter Xu To: David Hildenbrand Cc: Alistair Popple , linux-mm@kvack.org, akpm@linux-foundation.org, Nadav Amit , huang ying , LKML , "Sierra Guiza, Alejandro (Alex)" , Felix Kuehling , Jason Gunthorpe , John Hubbard , Ralph Campbell , Matthew Wilcox , Karol Herbst , Lyude Paul , Ben Skeggs , Logan Gunthorpe , paulus@ozlabs.org, linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org, Huang Ying Subject: Re: [PATCH v3 2/3] mm/migrate_device.c: Copy pte dirty bit to page Message-ID: References: <3b01af093515ce2960ac39bb16ff77473150d179.1661309831.git-series.apopple@nvidia.com> <8735dkeyyg.fsf@nvdebian.thelocal> <8735dj7qwb.fsf@nvdebian.thelocal> <72146725-3d70-0427-50d4-165283a5a85d@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <72146725-3d70-0427-50d4-165283a5a85d@redhat.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Aug 26, 2022 at 04:47:22PM +0200, David Hildenbrand wrote: > > To me anon exclusive only shows this mm exclusively owns this page. I > > didn't quickly figure out why that requires different handling on tlb > > flushs. Did I perhaps miss something? > > GUP-fast is the magic bit, we have to make sure that we won't see new > GUP pins, thus the TLB flush. > > include/linux/mm.h:gup_must_unshare() contains documentation. Hmm.. Shouldn't ptep_get_and_clear() (e.g., xchg() on x86_64) already guarantees that no other process/thread will see this pte anymore afterwards? -- Peter Xu