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 43D39C6FA82 for ; Thu, 22 Sep 2022 14:36:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ACEB3940007; Thu, 22 Sep 2022 10:36:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A55E46B0074; Thu, 22 Sep 2022 10:36:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F5F4940007; Thu, 22 Sep 2022 10:36:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 7CDF76B0073 for ; Thu, 22 Sep 2022 10:36:28 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 50877A1527 for ; Thu, 22 Sep 2022 14:36:28 +0000 (UTC) X-FDA: 79939972056.03.D733B9F Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf15.hostedemail.com (Postfix) with ESMTP id 0F889A000C for ; Thu, 22 Sep 2022 14:36:27 +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=02+QEmbVk9AVv9jEQgWKTTpXwGOiCyNcTFilArR3/C0=; b=POG8m7fdprEJLvFevbUlMRiZP0 1WqOY/+mhbT6uL6MLBd2M+9I++CBs1HDQYdONcZ3V0xwcZgXu+85xDEBnJHS37XJJRnqcKLU0SsWp wkSvLy6u88CwMk1WkgPa4W0wmkxh4n+NUa7jKeQ0EKrIhFhPImmCug7TT8YbE/fz5n+sAqaTI7tjV IztsB6PCr1wt4VGkjoE3msb8tbK0qVBl9TTz1Jl8llcH2HiRHQyAR8QuHbde3VMsu+B+rpHNxG1E9 Tm4Vb0V7JkeAKKqqBB4tTzV1V5LOXBmYkriDO6x65Hk/KS4XGO8woeVzT+PoapOYprl1c4tyjSBeA RVCrwhGg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1obNJI-00G5Be-RS; Thu, 22 Sep 2022 14:36:16 +0000 Date: Thu, 22 Sep 2022 07:36:16 -0700 From: Christoph Hellwig To: Al Viro Cc: Jan Kara , Christoph Hellwig , John Hubbard , Andrew Morton , Jens Axboe , Miklos Szeredi , "Darrick J . Wong" , Trond Myklebust , Anna Schumaker , 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: <103fe662-3dc8-35cb-1a68-dda8af95c518@nvidia.com> <20220906102106.q23ovgyjyrsnbhkp@quack3> <20220914145233.cyeljaku4egeu4x2@quack3> <20220915081625.6a72nza6yq4l5etp@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663857388; a=rsa-sha256; cv=none; b=V1RUKnibib5DDXroVeHj3xGvW1IhI3nGTXpxn0Ewi82eZm5fq9gMrLyu2TcI8hQMgA3Zdq RxMfR7bEhfKd0Jb/ULzqwghJ8RPWYk7BBKbcAKbuL621XqMbdsHqa3u/+Y/WUcTvHFNqPO Rv3hvYI423tM5uqR+798tdJX4ia9GoQ= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=POG8m7fd; spf=none (imf15.hostedemail.com: domain of BATV+ecf30307a2904c53da59+6969+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+ecf30307a2904c53da59+6969+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663857388; 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=02+QEmbVk9AVv9jEQgWKTTpXwGOiCyNcTFilArR3/C0=; b=AArR2/5GqqWSfhYtA3LYboNH50n3paYDk9WBZ2bRNMecgj3WF+2vAcrxC5yteqtZ0G/Eti ++qll+yt8c9UCRUY0gZAOqJJrLRPmd5ZzY9MM3u6hZfdwxa3fLK5k12iMK6LCx4cE7nHMp ikJWYEFXJxQfI/dCvcl2LBwyl2RXMQ4= Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=POG8m7fd; spf=none (imf15.hostedemail.com: domain of BATV+ecf30307a2904c53da59+6969+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+ecf30307a2904c53da59+6969+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none X-Rspam-User: X-Stat-Signature: k7qwtmcc1ur9wd6wfhifkzxh3f77w8sb X-Rspamd-Queue-Id: 0F889A000C X-Rspamd-Server: rspam02 X-HE-Tag: 1663857387-492883 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 20, 2022 at 06:02:11AM +0100, Al Viro wrote: > nvme target: nvme read requests end up with somebody allocating and filling > sglist, followed by reading from file into it (using ITER_BVEC). Then the > pages are sent out, presumably Yes. > . I would be very surprised if it turned out > to be anything other than anon pages allocated by the driver, but I'd like > to see that confirmed by nvme folks. Probably doesn't need pinning. They are anon pages allocated by the driver using sgl_alloc(). > drivers/target/target_core_file.c:292: iov_iter_bvec(&iter, is_write, aio_cmd->bvecs, sgl_nents, len); Same as nvme target. > The picture so far looks like we mostly need to take care of pinning when > we obtain the references from iov_iter_get_pages(). What's more, it looks > like ITER_BVEC/ITER_XARRAY/ITER_PIPE we really don't need to pin anything on > get_pages/pin_pages - they are already protected (or, in case of ITER_PIPE, > allocated by iov_iter itself and not reachable by anybody outside). That's what I've been trying to say for a while..