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=-12.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 05E59C433E1 for ; Sat, 22 Aug 2020 04:21:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B3D682071A for ; Sat, 22 Aug 2020 04:21:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="ClifxiVu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3D682071A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 262F48D000E; Sat, 22 Aug 2020 00:21:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 211AA8D0002; Sat, 22 Aug 2020 00:21:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0B1E18D0007; Sat, 22 Aug 2020 00:21:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id E5F7E8D0001 for ; Sat, 22 Aug 2020 00:21:08 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9AD7B824556B for ; Sat, 22 Aug 2020 04:21:08 +0000 (UTC) X-FDA: 77176904616.18.step47_150bcaf2703f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id 7127C100EC668 for ; Sat, 22 Aug 2020 04:21:08 +0000 (UTC) X-HE-Tag: step47_150bcaf2703f X-Filterd-Recvd-Size: 5355 Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Sat, 22 Aug 2020 04:21:07 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 21 Aug 2020 21:20:52 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Fri, 21 Aug 2020 21:21:06 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Fri, 21 Aug 2020 21:21:06 -0700 Received: from HQMAIL111.nvidia.com (172.20.187.18) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 22 Aug 2020 04:21:05 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sat, 22 Aug 2020 04:21:05 +0000 Received: from sandstorm.nvidia.com (Not Verified[10.2.94.162]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Fri, 21 Aug 2020 21:21:05 -0700 From: John Hubbard To: Andrew Morton CC: Alexander Viro , Christoph Hellwig , Ilya Dryomov , Jens Axboe , Jeff Layton , , , , , , LKML , John Hubbard Subject: [PATCH 2/5] mm/gup: introduce pin_user_page() Date: Fri, 21 Aug 2020 21:20:56 -0700 Message-ID: <20200822042059.1805541-3-jhubbard@nvidia.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200822042059.1805541-1-jhubbard@nvidia.com> References: <20200822042059.1805541-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: quoted-printable Content-Type: text/plain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1598070052; bh=AWm7U3a8aov4PNZrSYviqR5QtvQW/uLd0HXBmgxRGZY=; 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=ClifxiVuABBkqvc/rqX6402hmxTySQe6DZT+CO3/xTn9dndqsYA1/DERMczpJhmKX w/8FUE9ErK/3jA+GCZ1sqGBiLhg1zK1miQSti1fNYmBrsGzfSIRJRNWrpn+/ZeDWfK TDoAVUzZ0qPKq3O6BsfpzF+8d1pZMxybo8DE7gmn+fs1bAuvDstlmdsNbUGYPknySA /BbmcP7B/8lyEAKIYiK2UytD7Seeb5X4Lehc9g9Zl7nD3ix63Pbzf3Zm082f3faLgm IEDZaKiUXd/f8B1uccRquX40ku0FMN1PIKsVxxzJTPfSIIFO6Q14lYldC9vvpPg89F JlFf893Gw976g== X-Rspamd-Queue-Id: 7127C100EC668 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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: pin_user_page() is the FOLL_PIN equivalent of get_page(). This was always a missing piece of the pin/unpin API calls (early reviewers of pin_user_pages() asked about it, in fact), but until now, it just wasn't needed. Finally though, now that the Direct IO pieces in block/bio are about to be converted to use FOLL_PIN, it turns out that there are some cases in which get_page() and get_user_pages_fast() were both used. Converting those sites requires a drop-in replacement for get_page(), which this patch supplies. [1] and [2] provide some background about pin_user_pages() in general. [1] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ [2] Documentation/core-api/pin_user_pages.rst Signed-off-by: John Hubbard --- include/linux/mm.h | 2 ++ mm/gup.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 32 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1983e08f5906..bee26614f430 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1149,6 +1149,8 @@ static inline void get_page(struct page *page) page_ref_inc(page); } =20 +void pin_user_page(struct page *page); + bool __must_check try_grab_page(struct page *page, unsigned int flags); =20 static inline __must_check bool try_get_page(struct page *page) diff --git a/mm/gup.c b/mm/gup.c index ae096ea7583f..2cae5bbbc862 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -123,6 +123,36 @@ static __maybe_unused struct page *try_grab_compound_h= ead(struct page *page, return NULL; } =20 +/* + * pin_user_page() - elevate the page refcount, and mark as FOLL_PIN + * + * This the FOLL_PIN equivalent of get_page(). It is intended for use when= the + * page will be released via unpin_user_page(). + */ +void pin_user_page(struct page *page) +{ + int refs =3D 1; + + page =3D compound_head(page); + + VM_BUG_ON_PAGE(page_ref_count(page) <=3D 0, page); + + if (hpage_pincount_available(page)) + hpage_pincount_add(page, 1); + else + refs =3D GUP_PIN_COUNTING_BIAS; + + /* + * Similar to try_grab_compound_head(): even if using the + * hpage_pincount_add/_sub() routines, be sure to + * *also* increment the normal page refcount field at least + * once, so that the page really is pinned. + */ + page_ref_add(page, refs); + + mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, 1); +} + /** * try_grab_page() - elevate a page's refcount by a flag-dependent amount * --=20 2.28.0