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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 49F4CC43331 for ; Thu, 2 Apr 2020 04:05:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 054D120776 for ; Thu, 2 Apr 2020 04:05:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="cH6tSdME" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 054D120776 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AD0A38E002A; Thu, 2 Apr 2020 00:05:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A81518E000D; Thu, 2 Apr 2020 00:05:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9986F8E002A; Thu, 2 Apr 2020 00:05:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0075.hostedemail.com [216.40.44.75]) by kanga.kvack.org (Postfix) with ESMTP id 7A5648E000D for ; Thu, 2 Apr 2020 00:05:28 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 37A94181AC9CC for ; Thu, 2 Apr 2020 04:05:28 +0000 (UTC) X-FDA: 76661575536.17.sort57_2fb528e897155 X-HE-Tag: sort57_2fb528e897155 X-Filterd-Recvd-Size: 4806 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:05:27 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5127920757; Thu, 2 Apr 2020 04:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800327; bh=YAQ6Dt7+DNsQNe9g4k2Nh5ic2NDzPTaeOMb45w4CLCA=; h=Date:From:To:Subject:In-Reply-To:From; b=cH6tSdMEZj9brtUMbiF8ghEgsfkT6/HZ1143B0/QyOxGRVcSr0txDkITH3XkGg61n wrl1JwR0xCSpsyy3zl5iB3HUNnwPnFM9T4AQf210OK0u20Eaij64ZKUZpAvfh/BCn8 7AnyjnSnAGpKgzEHnwppSIZqCs64k7zO7eAzG6As= Date: Wed, 01 Apr 2020 21:05:25 -0700 From: Andrew Morton To: akpm@linux-foundation.org, corbet@lwn.net, dan.j.williams@intel.com, david@fromorbit.com, hch@infradead.org, ira.weiny@intel.com, jack@suse.cz, jgg@ziepe.ca, jglisse@redhat.com, jhubbard@nvidia.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mhocko@suse.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, shuah@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, viro@zeniv.linux.org.uk, willy@infradead.org Subject: [patch 042/155] mm/gup: require FOLL_GET for get_user_pages_fast() Message-ID: <20200402040525._b4dZ1F8q%akpm@linux-foundation.org> In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: =46rom: John Hubbard Subject: mm/gup: require FOLL_GET for get_user_pages_fast() Internal to mm/gup.c, require that get_user_pages_fast() and __get_user_pages_fast() identify themselves, by setting FOLL_GET. This is required in order to be able to make decisions based on "FOLL_PIN, or FOLL_GET, or both or neither are set", in upcoming patches. Link: http://lkml.kernel.org/r/20200211001536.1027652-6-jhubbard@nvidia.com Signed-off-by: John Hubbard Acked-by: Kirill A. Shutemov Reviewed-by: Jan Kara Cc: Ira Weiny Cc: J=C3=A9r=C3=B4me Glisse Cc: "Matthew Wilcox (Oracle)" Cc: Al Viro Cc: Christoph Hellwig Cc: Dan Williams Cc: Dave Chinner Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Michal Hocko Cc: Mike Kravetz Cc: Shuah Khan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/gup.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) --- a/mm/gup.c~mm-gup-require-foll_get-for-get_user_pages_fast +++ a/mm/gup.c @@ -2390,6 +2390,14 @@ int __get_user_pages_fast(unsigned long unsigned long len, end; unsigned long flags; int nr =3D 0; + /* + * Internally (within mm/gup.c), gup fast variants must set FOLL_GET, + * because gup fast is always a "pin with a +1 page refcount" request. + */ + unsigned int gup_flags =3D FOLL_GET; + + if (write) + gup_flags |=3D FOLL_WRITE; =20 start =3D untagged_addr(start) & PAGE_MASK; len =3D (unsigned long) nr_pages << PAGE_SHIFT; @@ -2415,7 +2423,7 @@ int __get_user_pages_fast(unsigned long if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { local_irq_save(flags); - gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr); + gup_pgd_range(start, end, gup_flags, pages, &nr); local_irq_restore(flags); } =20 @@ -2454,7 +2462,7 @@ static int internal_get_user_pages_fast( int nr =3D 0, ret =3D 0; =20 if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | - FOLL_FORCE | FOLL_PIN))) + FOLL_FORCE | FOLL_PIN | FOLL_GET))) return -EINVAL; =20 start =3D untagged_addr(start) & PAGE_MASK; @@ -2521,6 +2529,13 @@ int get_user_pages_fast(unsigned long st if (WARN_ON_ONCE(gup_flags & FOLL_PIN)) return -EINVAL; =20 + /* + * The caller may or may not have explicitly set FOLL_GET; either way is + * OK. However, internally (within mm/gup.c), gup fast variants must set + * FOLL_GET, because gup fast is always a "pin with a +1 page refcount" + * request. + */ + gup_flags |=3D FOLL_GET; return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); } EXPORT_SYMBOL_GPL(get_user_pages_fast); _