From: Dan Williams <dan.j.williams@intel.com>
To: alexander.h.duyck@linux.intel.com
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Zhang Yi" <yi.z.zhang@linux.intel.com>,
"Barret Rhoden" <brho@google.com>,
"KVM list" <kvm@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Linux MM" <linux-mm@kvack.org>,
"Dave Jiang" <dave.jiang@intel.com>,
"Zhang, Yu C" <yu.c.zhang@intel.com>,
"Pankaj Gupta" <pagupta@redhat.com>,
"David Hildenbrand" <david@redhat.com>, "Jan Kara" <jack@suse.cz>,
"Christoph Hellwig" <hch@lst.de>,
rkrcmar@redhat.com, "Jérôme Glisse" <jglisse@redhat.com>
Subject: Re: [PATCH RFC 2/3] mm: Add support for exposing if dev_pagemap supports refcount pinning
Date: Mon, 3 Dec 2018 11:47:37 -0800 [thread overview]
Message-ID: <CAPcyv4gZkx9zRsKkVhrmPG7SyjPEycp0neFnECmSADZNLuDOpQ@mail.gmail.com> (raw)
In-Reply-To: <154386513120.27193.7977541941078967487.stgit@ahduyck-desk1.amr.corp.intel.com>
On Mon, Dec 3, 2018 at 11:25 AM Alexander Duyck
<alexander.h.duyck@linux.intel.com> wrote:
>
> Add a means of exposing if a pagemap supports refcount pinning. I am doing
> this to expose if a given pagemap has backing struct pages that will allow
> for the reference count of the page to be incremented to lock the page
> into place.
>
> The KVM code already has several spots where it was trying to use a
> pfn_valid check combined with a PageReserved check to determien if it could
> take a reference on the page. I am adding this check so in the case of the
> page having the reserved flag checked we can check the pagemap for the page
> to determine if we might fall into the special DAX case.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> drivers/nvdimm/pfn_devs.c | 2 ++
> include/linux/memremap.h | 5 ++++-
> include/linux/mm.h | 11 +++++++++++
> 3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index 6f22272e8d80..7a4a85bcf7f4 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -640,6 +640,8 @@ static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
> } else
> return -ENXIO;
>
> + pgmap->support_refcount_pinning = true;
> +
There should be no dev_pagemap instance instance where this isn't
true, so I'm missing why this is needed?
next prev parent reply other threads:[~2018-12-03 19:47 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 19:25 [PATCH RFC 0/3] Fix KVM misinterpreting Reserved page as an MMIO page Alexander Duyck
2018-12-03 19:25 ` [PATCH RFC 1/3] kvm: Split use cases for kvm_is_reserved_pfn to kvm_is_refcounted_pfn Alexander Duyck
2018-12-03 19:25 ` [PATCH RFC 2/3] mm: Add support for exposing if dev_pagemap supports refcount pinning Alexander Duyck
2018-12-03 19:47 ` Dan Williams [this message]
2018-12-03 20:21 ` Alexander Duyck
2018-12-03 20:31 ` Dan Williams
2018-12-03 20:53 ` Alexander Duyck
2018-12-03 21:05 ` Dan Williams
2018-12-03 21:50 ` Alexander Duyck
2018-12-04 19:08 ` Dan Williams
2018-12-04 22:51 ` Alexander Duyck
2018-12-04 23:24 ` Barret Rhoden
2018-12-05 0:01 ` Alexander Duyck
2018-12-05 0:26 ` Dan Williams
2018-12-05 8:13 ` David Hildenbrand
2018-12-03 19:25 ` [PATCH RFC 3/3] kvm: Add additional check to determine if a page is refcounted Alexander Duyck
2018-12-04 6:59 ` [PATCH RFC 0/3] Fix KVM misinterpreting Reserved page as an MMIO page Yi Zhang
2018-12-04 18:45 ` Alexander Duyck
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