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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05E14C2D0A3 for ; Fri, 6 Nov 2020 10:02:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E5A721707 for ; Fri, 6 Nov 2020 10:02:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="JxYI6LDo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726535AbgKFKCJ (ORCPT ); Fri, 6 Nov 2020 05:02:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726321AbgKFKCJ (ORCPT ); Fri, 6 Nov 2020 05:02:09 -0500 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B0E8C0613D2 for ; Fri, 6 Nov 2020 02:02:09 -0800 (PST) Received: by mail-ot1-x344.google.com with SMTP id f16so736741otl.11 for ; Fri, 06 Nov 2020 02:02:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Pk2kOuIDyNkJ29R6DHQ3ZwTfwhAfAev58wxOeRlEcVQ=; b=JxYI6LDoYBIyKAFkO0mmU5GO0vKXW+XCgfB3nhMPB/96K75h8XEzFsF5vfwoI9o4Aa YXO5ScRni4mdNnVG7TEPzZnkXGbky0dU2v6WgMTgqxnDpBRtAtlXHbhIcZNyR+EoGosa 88KCvZizdR0CJdRqQAGfzd4+9xfkExbEg2qoA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Pk2kOuIDyNkJ29R6DHQ3ZwTfwhAfAev58wxOeRlEcVQ=; b=MhkXeJSPt0oh2tIeS1LAa2ANnOkh8oz2PItPJU/M6F3bexxiBAYo9go/0KuinqTNIK ATLao/dvlqHwgXE30avg+Zc8ZSayjgrgi8p3WrMkvSVC3tofcLXIGzw5FMG9UHuzmD1s dAadIsupdL/rP+QwZ+QhzebHKS+Yk30+JfYOKW165aH4GryQghiiZd0KomaEhkl7qJM6 nGkm4voB4XKKS1XyfATVNE/ePO5B7dGsWT0OAmXk8GHDHl1ddrEFlhON+KO4xkYWVRp0 1rEeyxpMbSC1SH9gfCqDxxR7BH+gnp7mNeTNefglJfjTdXCRvw8BpW4Pq9rCloybXlLG hpIA== X-Gm-Message-State: AOAM531nYxyU9XGLP1i8Kkjx1c31Cc3YoHigIiwB25yu6UMzOY1T43yT exv0mlgp4EjFuEsf2fwMTvqT7fOkW80lY5DE6Iv0MQ== X-Google-Smtp-Source: ABdhPJy9+JOeNi7tvqFhbCecRqz/u5D2Qj576z0eBlCGtTEM4NmQBII1FIZeWz8GCbRUxBcA/Ididy+MZpD88l6oJcg= X-Received: by 2002:a9d:6a19:: with SMTP id g25mr586779otn.303.1604656928858; Fri, 06 Nov 2020 02:02:08 -0800 (PST) MIME-Version: 1.0 References: <20201104140023.GQ36674@ziepe.ca> <20201104162125.GA13007@infradead.org> <20201104163758.GA17425@infradead.org> <20201104164119.GA18218@infradead.org> <20201104181708.GU36674@ziepe.ca> <20201105092524.GQ401619@phenom.ffwll.local> <20201105124950.GZ36674@ziepe.ca> <7ae3486d-095e-cf4e-6b0f-339d99709996@nvidia.com> In-Reply-To: <7ae3486d-095e-cf4e-6b0f-339d99709996@nvidia.com> From: Daniel Vetter Date: Fri, 6 Nov 2020 11:01:57 +0100 Message-ID: Subject: Re: [PATCH v5 05/15] mm/frame-vector: Use FOLL_LONGTERM To: John Hubbard Cc: Jason Gunthorpe , Christoph Hellwig , "J??r??me Glisse" , linux-samsung-soc , Jan Kara , Pawel Osciak , KVM list , Mauro Carvalho Chehab , LKML , DRI Development , Tomasz Figa , Linux MM , Kyungmin Park , Daniel Vetter , Andrew Morton , Marek Szyprowski , Dan Williams , Linux ARM , "open list:DMA BUFFER SHARING FRAMEWORK" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org On Fri, Nov 6, 2020 at 5:08 AM John Hubbard wrote: > > On 11/5/20 4:49 AM, Jason Gunthorpe wrote: > > On Thu, Nov 05, 2020 at 10:25:24AM +0100, Daniel Vetter wrote: > >>> /* > >>> * If we can't determine whether or not a pte is special, then fail immediately > >>> * for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not > >>> * to be special. > >>> * > >>> * For a futex to be placed on a THP tail page, get_futex_key requires a > >>> * get_user_pages_fast_only implementation that can pin pages. Thus it's still > >>> * useful to have gup_huge_pmd even if we can't operate on ptes. > >>> */ > >> > >> We support hugepage faults in gpu drivers since recently, and I'm not > >> seeing a pud_mkhugespecial anywhere. So not sure this works, but probably > >> just me missing something again. > > > > It means ioremap can't create an IO page PUD, it has to be broken up. > > > > Does ioremap even create anything larger than PTEs? gpu drivers also tend to use vmf_insert_pfn* directly, so we can do on-demand paging and move buffers around. From what I glanced for lowest level we to the pte_mkspecial correctly (I think I convinced myself that vm_insert_pfn does that), but for pud/pmd levels it seems just yolo. remap_pfn_range seems to indeed split down to pte level always. > From my reading, yes. See ioremap_try_huge_pmd(). The ioremap here shouldn't matter, since this is for kernel-internal mappings. So that's all fine I think. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch