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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97A1DECAAA1 for ; Tue, 6 Sep 2022 07:48:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E247D80263; Tue, 6 Sep 2022 03:48:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DD3FB80224; Tue, 6 Sep 2022 03:48:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C9C2280263; Tue, 6 Sep 2022 03:48:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id BA54780224 for ; Tue, 6 Sep 2022 03:48:58 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 922BC8048F for ; Tue, 6 Sep 2022 07:48:58 +0000 (UTC) X-FDA: 79880884356.23.40985F6 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf03.hostedemail.com (Postfix) with ESMTP id 406A120068 for ; Tue, 6 Sep 2022 07:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=//VHbIAzK137JUV3wdYi+bkIg+RFNtTNOapoAnB6JWQ=; b=ClmaQqYV3Rr7HMvl1VZYIfZnCR jRe7hf3xcMU++YZlWuqWFGV7yOxXgIpw5cfVwrcGrONCrbaLvQbyG3imcg0L5ArK9A2drD7kyElWW nXQKaVxFJrG3tR0Z4U4Px3R7OpWn36TNcpqBIShyq99RxBc7AjqZgGjYsk8t2hNNt06e5WjA8H/ty RyHuTiOQV01VXnapEk24jH+CnWL3HTVChFhLI0VOiL1YDAush7xV3xHWLUNZICcRFCQ+31s25Ab2f NJZGx1AeyvkBlwLScjl7adl9Vy5CQ+Nyntlh4EwdZzr43wsKaXw1wEaH0wDR88TobrWWo+qXS2DCW PiCuP0Rg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVTKD-00Avjf-6M; Tue, 06 Sep 2022 07:48:49 +0000 Date: Tue, 6 Sep 2022 00:48:49 -0700 From: Christoph Hellwig To: John Hubbard Cc: Christoph Hellwig , Andrew Morton , Jens Axboe , Alexander Viro , Miklos Szeredi , "Darrick J . Wong" , Trond Myklebust , Anna Schumaker , Jan Kara , David Hildenbrand , Logan Gunthorpe , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, LKML Subject: Re: [PATCH v2 4/7] iov_iter: new iov_iter_pin_pages*() routines Message-ID: References: <20220831041843.973026-1-jhubbard@nvidia.com> <20220831041843.973026-5-jhubbard@nvidia.com> <103fe662-3dc8-35cb-1a68-dda8af95c518@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <103fe662-3dc8-35cb-1a68-dda8af95c518@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662450538; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=//VHbIAzK137JUV3wdYi+bkIg+RFNtTNOapoAnB6JWQ=; b=mJTr64hsL6CbyNQnaRc9YZkNa1t7AuHh2jRgJcG8tkMcFQRYTI6gdDznuWXXbhEf67FjfA 3avxto5F0bh7HttiMN0skbquUsRgD4BygrXPDhBktOj8mfWf3hfnDBkouWslzKJMG1ebbq SkvtApzCFjoVP9yFocktPCa/YM157O4= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ClmaQqYV; spf=none (imf03.hostedemail.com: domain of BATV+3c9dadc9e27e1b9c7a6f+6953+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+3c9dadc9e27e1b9c7a6f+6953+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662450538; a=rsa-sha256; cv=none; b=2TBGR+rbxhkhmKgReJUOm2yGP4yAeKPbz+ftvS+i93rJVYEPubH3RWhtEFPa+Pn+ZNlFtd Pp1aT38EOnS917OKKYEAiuddfUx1cFV9v8PwHYlLeeuuTiFDpihE9LD4n0+FJvu9/+EYDP JnGHmKSfYV9HibFRj57j6G6syrGCCCg= X-Stat-Signature: 33si4eri8in5adnsuyywqncw1csdkrqm X-Rspamd-Queue-Id: 406A120068 X-Rspam-User: Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ClmaQqYV; spf=none (imf03.hostedemail.com: domain of BATV+3c9dadc9e27e1b9c7a6f+6953+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+3c9dadc9e27e1b9c7a6f+6953+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none X-Rspamd-Server: rspam03 X-HE-Tag: 1662450538-424690 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: On Tue, Sep 06, 2022 at 12:44:28AM -0700, John Hubbard wrote: > OK, that part is clear. > > > - for the pin case don't use the existing bvec helper at all, but > > copy the logic for the block layer for not pinning. > > I'm almost, but not quite sure I get the idea above. Overall, what > happens to bvec pages? Leave the get_page() pin in place for FOLL_GET > (or USE_FOLL_GET), I suppose, but do...what, for FOLL_PIN callers? Do not change anyhing for FOLL_GET callers, as they are on the way out anyway. For FOLL_PIN callers, never pin bvec and kvec pages: For file systems not acquiring a reference is obviously safe, and the other callers will need an audit, but I can't think of why it woul ever be unsafe.