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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27DCDC433FE for ; Tue, 28 Sep 2021 19:47:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D63A6134F for ; Tue, 28 Sep 2021 19:47:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242537AbhI1Tst (ORCPT ); Tue, 28 Sep 2021 15:48:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242470AbhI1Tst (ORCPT ); Tue, 28 Sep 2021 15:48:49 -0400 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D40AC06161C for ; Tue, 28 Sep 2021 12:47:09 -0700 (PDT) Received: by mail-qk1-x730.google.com with SMTP id 73so41965325qki.4 for ; Tue, 28 Sep 2021 12:47:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=EVzDoSDqJZmi4ToqJEIddbvRD+vlWsRISaT7f2OXukE=; b=EO1kDwzeZuMv1jUFt2pmKX8GvyZQAUMBJiLy1x1SVytxwcplVnv2ywT1ffuJvbGzDe SqreChLnqXdZ3bmpOGx1lq6jv+yPr/cOeERvwxCekQ+2pAL/hPpshqhIf/ZGdT33EAIM lOon8sIgHYjE/rwWroGijsvQ3Sfl16uYtuTJKv69ByO+2IJKaQCkRs4E+itlOn/VuGnJ ObcFwFaFhFQuJrFju9q8374g29cj0NSSZZgWhx88Ckt7Rqd+521BC3qoxSNjSsHzeMSW tdbGfXJrW/lc1jL/isk876EABn7Hc3z0lVBV5inoZjNRJpGnlQE9c49iUQf8C8yixnTL 5Dyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=EVzDoSDqJZmi4ToqJEIddbvRD+vlWsRISaT7f2OXukE=; b=GyXWykbfh6OH0ccE+LEb8Yn3LR06XJtnqdxB9PTzfqtQ16iQHirLjnEEmaBLDGnQi6 xvYlqIJrZM2PpSUTZwuzicVTzg9DBVqn+CUO3gm3mM1iakrqiX6GaqH2RbdVUK7lYghj OTCqczw4kRhBR47FdGz+gPdrTsBIQokbXFraf6a9k6E0nHbATf+d8ER2mJvX11XV1K5C 5JUj5dI5oebzfE8ygJPOkivMA+c0y32Fza674enXq9SgO1VjBObdohukwQtcuGglVBz8 2ku/IEAqSmw8mpQPZcpP7NcsTIzgoKc++lPO9iABs38UmNN6s5pUu0s1TNfb9B++pw1P 7LvQ== X-Gm-Message-State: AOAM5311O0jw5CK01X/DDZGKXviOyLZzuaT+OJuuywcJkdp0v3XVXz20 F+fUxxJRcFw5NOZYIEK7d/4qwQ== X-Google-Smtp-Source: ABdhPJxxZpC5AepjHCbAmIQaz4Zogx1HRof8bzNZRXH/My30paIzwcLwvreCcb7Df5Gio9BelRE2TQ== X-Received: by 2002:a37:8242:: with SMTP id e63mr1886625qkd.294.1632858428465; Tue, 28 Sep 2021 12:47:08 -0700 (PDT) Received: from ziepe.ca ([206.223.160.26]) by smtp.gmail.com with ESMTPSA id d14sm79297qkg.49.2021.09.28.12.47.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Sep 2021 12:47:08 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mVJ4F-007GbK-31; Tue, 28 Sep 2021 16:47:07 -0300 Date: Tue, 28 Sep 2021 16:47:07 -0300 From: Jason Gunthorpe To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , Christian =?utf-8?B?S8O2bmln?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni Subject: Re: [PATCH v3 14/20] mm: introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages Message-ID: <20210928194707.GU3544071@ziepe.ca> References: <20210916234100.122368-1-logang@deltatee.com> <20210916234100.122368-15-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210916234100.122368-15-logang@deltatee.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Sep 16, 2021 at 05:40:54PM -0600, Logan Gunthorpe wrote: > Callers that expect PCI P2PDMA pages can now set FOLL_PCI_P2PDMA to > allow obtaining P2PDMA pages. If a caller does not set this flag > and tries to map P2PDMA pages it will fail. > > This is implemented by adding a flag and a check to get_dev_pagemap(). I would like to see the get_dev_pagemap() deleted from GUP in the first place. Why isn't this just a simple check of the page->pgmap type after acquiring a valid page reference? See my prior note Jason