Date: Wed, 10 Jun 2015 11:03:35 -0400
From: Matthew Wilcox <willy@linux.intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>, 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@ml01.01.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
Subject: Re: [PATCH v4 2/9] x86: support kmap_atomic_pfn_t() for persistent
 memory
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>
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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?
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