From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH v4 2/9] x86: support kmap_atomic_pfn_t() for persistent memory Date: Wed, 10 Jun 2015 11:03:35 -0400 Message-ID: <20150610150334.GK2729@linux.intel.com> References: <20150605205052.20751.77149.stgit@dwillia2-desk3.amr.corp.intel.com> <20150605211912.20751.35406.stgit@dwillia2-desk3.amr.corp.intel.com> <20150610121202.GA9190@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga02.intel.com ([134.134.136.20]:62111 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752623AbbFJPEZ (ORCPT ); Wed, 10 Jun 2015 11:04:25 -0400 Content-Disposition: inline In-Reply-To: <20150610121202.GA9190@lst.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Hellwig Cc: Dan Williams , linux-kernel@vger.kernel.org, axboe@kernel.dk, boaz@plexistor.com, david@fromorbit.com, linux-arch@vger.kernel.org, arnd@arndb.de, ross.zwisler@linux.intel.com, linux-nvdimm@lists.01.org, benh@kernel.crashing.org, linux-fsdevel@vger.kernel.org, heiko.carstens@de.ibm.com, tj@kernel.org, paulus@samba.org, hpa@zytor.com, schwidefsky@de.ibm.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, mingo@kernel.org On Wed, Jun 10, 2015 at 02:12:02PM +0200, Christoph Hellwig wrote: > Btw, I don't think this actually is safe without refcounting your kmap > structure. > > The driver model ->remove callback can be called at any time, which > will ioremap the memory and remap the kmap structure. But at this > point a user might still be using it. Won't the device data structures be pinned by the refcount on the bdev?