From patchwork Mon Dec 9 22:53:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11280929 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 79DB5930 for ; Mon, 9 Dec 2019 22:57:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 592C120721 for ; Mon, 9 Dec 2019 22:57:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="TwbYjuNx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727406AbfLIW53 (ORCPT ); Mon, 9 Dec 2019 17:57:29 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:9138 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726950AbfLIWyD (ORCPT ); Mon, 9 Dec 2019 17:54:03 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 09 Dec 2019 14:53:42 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 09 Dec 2019 14:54:02 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 09 Dec 2019 14:54:02 -0800 Received: from HQMAIL107.nvidia.com (172.20.187.13) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 9 Dec 2019 22:53:57 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Mon, 9 Dec 2019 22:53:57 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Mon, 09 Dec 2019 14:53:56 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?utf-8?b?QmrDtnJuIFQ=?= =?utf-8?b?w7ZwZWw=?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , "Mauro Carvalho Chehab" , Michael Ellerman , Michal Hocko , Mike Kravetz , "Paul Mackerras" , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard , Christoph Hellwig , Leon Romanovsky Subject: [PATCH v8 08/26] mm/gup: allow FOLL_FORCE for get_user_pages_fast() Date: Mon, 9 Dec 2019 14:53:26 -0800 Message-ID: <20191209225344.99740-9-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191209225344.99740-1-jhubbard@nvidia.com> References: <20191209225344.99740-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1575932022; bh=8yMeFiIYMbIInu28JyKhLAF6qs4QGFVvzis+XDEEE9w=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=TwbYjuNxLCNiku9hlj7Cg/pJ/IpeV4xiPpYuvKt8MTqelgsBfJLDpYOGbCDudB4Le liqarKq31qZIpvYqiqMLE+vqavFd9qoKhGR7g2gqLA/yVd2+6rjxjR17o0INhL8VVi SLT5lIZRfnum04N96WfLBhg4hGSv2O1wDoQLhhU3voDklCEBjq5Z93GEcKra1OQ8cK Rc1+yiQk2G0oy0pDHhNFPFnmKweogxWyAHTrvO7JLXf/6pFp+kuUbrghVdp/Gy01ff Mj0NtfAW+IUuWf+4wxxDLU1dchVOYwP2qmtddp6oJAFnDHYfpsrVgyxGp33Ba7OQ0j xLoz8AJeDDZBg== Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Commit 817be129e6f2 ("mm: validate get_user_pages_fast flags") allowed only FOLL_WRITE and FOLL_LONGTERM to be passed to get_user_pages_fast(). This, combined with the fact that get_user_pages_fast() falls back to "slow gup", which *does* accept FOLL_FORCE, leads to an odd situation: if you need FOLL_FORCE, you cannot call get_user_pages_fast(). There does not appear to be any reason for filtering out FOLL_FORCE. There is nothing in the _fast() implementation that requires that we avoid writing to the pages. So it appears to have been an oversight. Fix by allowing FOLL_FORCE to be set for get_user_pages_fast(). Fixes: 817be129e6f2 ("mm: validate get_user_pages_fast flags") Cc: Christoph Hellwig Reviewed-by: Leon Romanovsky Signed-off-by: John Hubbard Reviewed-by: Jan Kara --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index c0c56888e7cc..958ab0757389 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2414,7 +2414,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, unsigned long addr, len, end; int nr = 0, ret = 0; - if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) + if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | + FOLL_FORCE))) return -EINVAL; start = untagged_addr(start) & PAGE_MASK;