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Date: Thu, 27 Jun 2019 10:50:47 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 11/25] memremap: lift the devmap_enable manipulation
 into devm_memremap_pages
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To: Ira Weiny <ira.weiny@intel.com>
Cc: linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>, Jason Gunthorpe <jgg@mellanox.com>, Ben Skeggs <bskeggs@redhat.com>, nouveau@lists.freedesktop.org, Christoph Hellwig <hch@lst.de>
List-ID: <linux-nvdimm@lists.01.org>

On Wed, Jun 26, 2019 at 12:04:46PM -0700, Ira Weiny wrote:
> > +static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
> > +{
> > +	if (!pgmap->ops->page_free) {
> 
> NIT: later on you add the check for pgmap->ops...  it should probably be here.
> 
> But not sure that bisection will be an issue here.

At this point we do not allow a NULL ops pointer.  That only becomes
a valid option one the internal refcount is added.  Until then a NULL
->ops pointer leads to an error return from devm_memremap_pages.
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