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 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 7472CC433E0 for ; Mon, 8 Jun 2020 04:41:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2AEF8206D5 for ; Mon, 8 Jun 2020 04:41:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bXVeQsPE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AEF8206D5 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 C6C7F6B000A; Mon, 8 Jun 2020 00:41:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BF5656B0085; Mon, 8 Jun 2020 00:41:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE5196B0087; Mon, 8 Jun 2020 00:41:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0068.hostedemail.com [216.40.44.68]) by kanga.kvack.org (Postfix) with ESMTP id 8FD816B000A for ; Mon, 8 Jun 2020 00:41:17 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 54C33801A1EB for ; Mon, 8 Jun 2020 04:41:17 +0000 (UTC) X-FDA: 76904795394.08.judge66_47059be26db7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id 321351807EE23 for ; Mon, 8 Jun 2020 04:41:17 +0000 (UTC) X-HE-Tag: judge66_47059be26db7 X-Filterd-Recvd-Size: 3576 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Mon, 8 Jun 2020 04:41:16 +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 9442920825; Mon, 8 Jun 2020 04:41:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591591276; bh=J5h/VqF2fNIf2GrbFaLAXsQZNcYSt0W+Kxd/qNVxt7I=; h=Date:From:To:Subject:In-Reply-To:From; b=bXVeQsPEsEGLqmlh6oWD7X33de0v/JO5+0VePdrT86EN9RbcfFrvWD+1h8SVex3nc AAI9ShVVdoJD0/qO9momuqfxByrzOPI5PKIAsxu7n00Da907AO/gOQ/UJC+V+m4Q8J 0C3AJ+whRY1iSEezYw3/5k7Yn2phD2bw+63rVqIk= Date: Sun, 07 Jun 2020 21:41:15 -0700 From: Andrew Morton To: akpm@linux-foundation.org, corbet@lwn.net, david@fromorbit.com, jack@suse.cz, jasowang@redhat.com, jglisse@redhat.com, jhubbard@nvidia.com, jrdr.linux@gmail.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, mst@redhat.com, pankaj.gupta.linux@gmail.com, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 22/54] vhost: convert get_user_pages() --> pin_user_pages() Message-ID: <20200608044115.tMvGFNio5%akpm@linux-foundation.org> In-Reply-To: <20200607212615.b050e41fac139a1e16fe00bd@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-Rspamd-Queue-Id: 321351807EE23 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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: vhost: convert get_user_pages() --> pin_user_pages() This code was using get_user_pages*(), in approximately a "Case 5" scenario (accessing the data within a page), using the categorization from [1]. That means that it's time to convert the get_user_pages*() + put_page() calls to pin_user_pages*() + unpin_user_pages() calls. There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Link: http://lkml.kernel.org/r/20200529234309.484480-3-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: Jan Kara Acked-by: Michael S. Tsirkin Acked-by: Pankaj Gupta Cc: Jason Wang Cc: Dave Chinner Cc: J=C3=A9r=C3=B4me Glisse Cc: Jonathan Corbet Cc: Souptick Joarder Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- drivers/vhost/vhost.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/drivers/vhost/vhost.c~vhost-convert-get_user_pages-pin_user_pages +++ a/drivers/vhost/vhost.c @@ -1762,15 +1762,14 @@ static int set_bit_to_user(int nr, void int bit =3D nr + (log % PAGE_SIZE) * 8; int r; =20 - r =3D get_user_pages_fast(log, 1, FOLL_WRITE, &page); + r =3D pin_user_pages_fast(log, 1, FOLL_WRITE, &page); if (r < 0) return r; BUG_ON(r !=3D 1); base =3D kmap_atomic(page); set_bit(bit, base); kunmap_atomic(base); - set_page_dirty_lock(page); - put_page(page); + unpin_user_pages_dirty_lock(&page, 1, true); return 0; } =20 _