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Sun, 31 May 2020 22:48:29 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sun, 31 May 2020 22:48:29 +0000 Received: from sandstorm.nvidia.com (Not Verified[10.2.56.10]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Sun, 31 May 2020 15:48:29 -0700 From: John Hubbard To: Andrew Morton CC: Andy Walls , Mauro Carvalho Chehab , Souptick Joarder , , LKML , , John Hubbard Subject: [PATCH v2 1/2] mm/gup: introduce pin_user_pages_unlocked Date: Sun, 31 May 2020 15:48:26 -0700 Message-ID: <20200531224827.769427-2-jhubbard@nvidia.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200531224827.769427-1-jhubbard@nvidia.com> References: <20200531224827.769427-1-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=1590965215; bh=V53v56y9lJXy8Ev50du65kbxD+j1cmQc1YhH71s5Kv8=; 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=OtxxSXSKgIPisVTVmn6pmBnG+uyjI9ccPbrXFSxcz+rpwSv3CFnLtIdjgxZxSSv2p 5ks5OVP/8liP8Ad+e2VVOvJRaW0ctGiBqlegn/Nddg008DoU0xK+QBtWD6enAeS3iR NLE6UZpUXfQsHUiXRMRiAHKD3jw+v3ltspRBycmnMcq8AT6q22UNcAig/yL8rS5moz EKvyLMII8e0BxV1LIGrZo5ZKcrkq1WsvzWN2KI8AElOamFIxHoCkLForTeMcfZiOha UPiTGflB11+Rttp+fbJrz8IoNvXbsPm5XABDBtkW2ghMU25oxrzsBFHYSLbJ9M4NfS 39k1p7v/16HCQ== X-Rspamd-Queue-Id: 199C26C2C X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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: Introduce pin_user_pages_unlocked(), which is nearly identical to the get_user_pages_unlocked() that it wraps, except that it sets FOLL_PIN and rejects FOLL_GET. As with other pairs of get_user_pages*() and pin_user_pages() API calls, it's prudent to assert that FOLL_PIN is *not* set in the get_user_pages*() call, so add that as part of this. Cc: Souptick Joarder Signed-off-by: John Hubbard --- include/linux/mm.h | 2 ++ mm/gup.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index f3fe7371855c..a84befdb54b2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1713,6 +1713,8 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, unsigned int gup_flags, struct page **pages, int *locked); long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, struct page **pages, unsigned int gup_flags); +long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, + struct page **pages, unsigned int gup_flags); int get_user_pages_fast(unsigned long start, int nr_pages, unsigned int gup_flags, struct page **pages); diff --git a/mm/gup.c b/mm/gup.c index 87a6a59fe667..8ae5d09adb6b 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2030,6 +2030,12 @@ long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, */ if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM)) return -EINVAL; + /* + * FOLL_PIN must only be set internally by the pin_user_pages*() APIs, + * never directly by the caller, so enforce that: + */ + if (WARN_ON_ONCE(gup_flags & FOLL_PIN)) + return -EINVAL; down_read(&mm->mmap_sem); ret = __get_user_pages_locked(current, mm, start, nr_pages, pages, NULL, @@ -2939,3 +2945,20 @@ long pin_user_pages(unsigned long start, unsigned long nr_pages, pages, vmas, gup_flags); } EXPORT_SYMBOL(pin_user_pages); + +/* + * pin_user_pages_unlocked() is the FOLL_PIN variant of + * get_user_pages_unlocked(). Behavior is the same, except that this one sets + * FOLL_PIN and rejects FOLL_GET. + */ +long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, + struct page **pages, unsigned int gup_flags) +{ + /* FOLL_GET and FOLL_PIN are mutually exclusive. */ + if (WARN_ON_ONCE(gup_flags & FOLL_GET)) + return -EINVAL; + + gup_flags |= FOLL_PIN; + return get_user_pages_unlocked(start, nr_pages, pages, gup_flags); +} +EXPORT_SYMBOL(pin_user_pages_unlocked);