From patchwork Tue Jan 7 22:45:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11322131 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 AC6216C1 for ; Tue, 7 Jan 2020 22:47:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 874092080A for ; Tue, 7 Jan 2020 22:47:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="mG+9fbuP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728160AbgAGWr3 (ORCPT ); Tue, 7 Jan 2020 17:47:29 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:4865 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727727AbgAGWqO (ORCPT ); Tue, 7 Jan 2020 17:46:14 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 07 Jan 2020 14:45:48 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 07 Jan 2020 14:46:05 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 07 Jan 2020 14:46:05 -0800 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 22:46:04 +0000 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 22:46:00 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 7 Jan 2020 22:46:00 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 07 Jan 2020 14:46:00 -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?= , "Kirill A . Shutemov" , "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 v12 08/22] mm/gup: allow FOLL_FORCE for get_user_pages_fast() Date: Tue, 7 Jan 2020 14:45:44 -0800 Message-ID: <20200107224558.2362728-9-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107224558.2362728-1-jhubbard@nvidia.com> References: <20200107224558.2362728-1-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=1578437148; bh=TKqZFchMOwUlq4p7fLQxPoHAtQiavcs6JsnhT764GJ8=; 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=mG+9fbuPmRlJzn1vkUiL8z+GBw7cTMpiOq//DKxiIsJyjBuW9nskzY9Db1uGxi6bP 3ZIAqNsLjmLRXPSbZYVOBFeMoUwUnDTSa2wxsZxFLuqr5GC9/g9zXt/3Cl7pp+uB71 +IADVEr0VJBH1KiohQW5IgXZN2GTRvi5Xhu9ckuMd8e+2RukQAYcLu5Bad1ZsQoRx5 Z3jS4qtWjHSMNbGSC8r3PEh6d5BoRfQGRPbEhr7FdaPV1nqridJwm1WzOvlvps8ckB t1Bggqn6B8DKgBmn4XZpBuPSSSwSbgVZdTWliRoZQ/RSe00MsS0frDzgg6WKn0Gpod Ob3FCZwyu+hXw== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@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 Reviewed-by: Jan Kara Signed-off-by: John Hubbard Reviewed-by: Christoph Hellwig --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index b61bd5c469ae..a594bc708367 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2411,7 +2411,8 @@ 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;