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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 298AAC43334 for ; Wed, 29 Jun 2022 06:49:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lN/MIYjKW9MZMK0inIUxxF3vHxyHrlf3M+uqEEBMv4s=; b=jTgAMw7dsWKbH7w8oz88hyXTm1 0miCr80IAONmf6xEL0p1rTbC3VjaCwCSMUirqkrNmpElT5e/WMUHMgofBBhb8BFpQ/8umMSogI2+F dhVjfV4xR+Iy4HrgGEqbLL3S3XvCUY8v3vJ5MxSXch01Eo9DwlX+4BUJcrPQHvtXGUJciQSSNvpYO ZjmzKwxR/8BqMzSZNvFJymGnO38CJ7Cs8JVbvPRXBQg0AzXff1I5Jrr8gKVCjzDMrxixEvi/tOQGa q1RCeVmCcmnA8LPQvTLT+2t3qnVils4cGH6XMAtV6rfHD0lMHSqntQEdMOfKDMUchmf03fbqAxie2 EUUEKNvg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o6RVW-009tA1-ID; Wed, 29 Jun 2022 06:49:02 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o6RVT-009t80-Tv for linux-nvme@lists.infradead.org; Wed, 29 Jun 2022 06:49:01 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id D89A267373; Wed, 29 Jun 2022 08:48:54 +0200 (CEST) Date: Wed, 29 Jun 2022 08:48:54 +0200 From: Christoph Hellwig To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Bjorn Helgaas Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() Message-ID: <20220629064854.GD17576@lst.de> References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-21-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220615161233.17527-21-logang@deltatee.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220628_234900_192418_CC5A2740 X-CRM114-Status: GOOD ( 14.46 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jun 15, 2022 at 10:12:32AM -0600, Logan Gunthorpe wrote: > A pseudo mount is used to allocate an inode for each PCI device. The > inode's address_space is used in the file doing the mmap so that all > VMAs are collected and can be unmapped if the PCI device is unbound. > After unmapping, the VMAs are iterated through and their pages are > put so the device can continue to be unbound. An active flag is used > to signal to VMAs not to allocate any further P2P memory once the > removal process starts. The flag is synchronized with concurrent > access with an RCU lock. Can't we come up with a way of doing this without all the pseudo-fs garbagage? I really hate all the overhead for that in the next nvme patch as well.