From patchwork Fri Oct 2 17:53:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 267501 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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 936A9C4727F for ; Fri, 2 Oct 2020 17:53:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CE4620795 for ; Fri, 2 Oct 2020 17:53:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="FeyUVdPt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388265AbgJBRxq (ORCPT ); Fri, 2 Oct 2020 13:53:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388369AbgJBRxo (ORCPT ); Fri, 2 Oct 2020 13:53:44 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48155C0613E2 for ; Fri, 2 Oct 2020 10:53:44 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id c18so2703944wrm.9 for ; Fri, 02 Oct 2020 10:53:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=mCTncko5YOfdd1hOhILVAexx/vlJaiXxqeCzAQ94in0=; b=FeyUVdPtM4srxB1+dn7I4h3H7Wfi8/fg99I+ABCtisEx3wHtPquZTvZ16RuGWwmZzE vz2bLh2sThVwHVg4NCZu/QZBQT8Z+HfU/9rp+qgb6Lzuk41uNLg5YV0/kZAopqb77csM ge7J8s4JsvsrgpI2ThI5QqsYkQlmjW4Kii0Bw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=mCTncko5YOfdd1hOhILVAexx/vlJaiXxqeCzAQ94in0=; b=JyAwg0v5ZErCDj+DYkiY0RESiMyMouow+AM1SWELPu8rE5W68m1YpxKycE3+YjXzcx L6oEGEz1MVfFZQxPCF9Rt9EjRkx8dCUhxCunOuKlgOqGz+eh/gVkAjyd7qLKbSnLD2wI jNqLC8UdE7mR0EDeZXqM9HSi5zq1OArpECtvlazOiYdykYSUSrQ9rnvI6dYhJKILKlbG qgtISmcAcFixHzriaSHQyvj6wSxRgebrMdsl2peX21DVW6SQLq8cODcEZF52XMISj1Mz G0CIm4I6ZKSTA3PRiw7GVKPGYy3Bc4zJRAuAOfavfIhqpQJx3hnVbjvp5Xyqwa1hYHar 5E8A== X-Gm-Message-State: AOAM530lAUML3Fj4KS53hKrWSGLtSLbZ80av1q96xYnRLeN9kevuu+Jw 4G2MlThdYYC0ZxofZHf2VsB4/g== X-Google-Smtp-Source: ABdhPJxqlu8ijgg5+4avDVYjjircN8ixFnEQp9RW1tMzahfcEDBuGAuy7tAthp9rZCHLP+C5s3jDnQ== X-Received: by 2002:a5d:4603:: with SMTP id t3mr4212688wrq.424.1601661223009; Fri, 02 Oct 2020 10:53:43 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id m10sm2585429wmc.9.2020.10.02.10.53.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Oct 2020 10:53:42 -0700 (PDT) From: Daniel Vetter To: DRI Development Cc: LKML , Daniel Vetter , Daniel Vetter , Andrew Morton , John Hubbard , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Dan Williams , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org Subject: [PATCH 2/2] mm/frame-vec: use FOLL_LONGTERM Date: Fri, 2 Oct 2020 19:53:03 +0200 Message-Id: <20201002175303.390363-2-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201002175303.390363-1-daniel.vetter@ffwll.ch> References: <20201002175303.390363-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org For $reasons I've stumbled over this code and I'm not sure the change to the new gup functions in 55a650c35fea ("mm/gup: frame_vector: convert get_user_pages() --> pin_user_pages()") was entirely correct. This here is used for long term buffers (not just quick I/O) like RDMA, and John notes this in his patch. But I thought the rule for these is that they need to add FOLL_LONGTERM, which John's patch didn't do. There is already a dax specific check (added in b7f0554a56f2 ("mm: fail get_vaddr_frames() for filesystem-dax mappings")), so this seems like the prudent thing to do. Signed-off-by: Daniel Vetter Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org --- Hi all, I stumbled over this and figured typing this patch can't hurt. Really just to maybe learn a few things about how gup/pup is supposed to be used (we have a bit of that in drivers/gpu), this here isn't really ralated to anything I'm doing. I'm also wondering whether the explicit dax check should be removed, since FOLL_LONGTERM should take care of that already. -Daniel --- mm/frame_vector.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 5d34c9047e9c..3507e09cb3ff 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -35,7 +35,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; - unsigned int gup_flags = FOLL_WRITE | FOLL_FORCE; + unsigned int gup_flags = FOLL_WRITE | FOLL_FORCE | FOLL_LONGTERM; int ret = 0; int err; int locked;