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From: Jan Kara <jack@suse.cz>
To: Zhang Yi <yi.z.zhang@linux.intel.com>
Cc: jack@suse.cz, yu.c.zhang@intel.com, kvm@vger.kernel.org,
	linux-nvdimm@lists.01.org, rkrcmar@redhat.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	pbonzini@redhat.com, hch@lst.de, yi.z.zhang@intel.com
Subject: Re: [PATCH V2 2/4] mm: introduce memory type MEMORY_DEVICE_DEV_DAX
Date: Tue, 7 Aug 2018 11:11:20 +0200	[thread overview]
Message-ID: <20180807091120.ybne44o2fy2mxcch@quack2.suse.cz> (raw)
In-Reply-To: <7e20d862f96662e1a7736dbb747a71949933dcd4.1531241281.git.yi.z.zhang@linux.intel.com>

On Wed 11-07-18 01:01:59, Zhang Yi wrote:
> Currently, NVDIMM pages will be marked 'PageReserved'. However, unlike
> other reserved PFNs, pages on NVDIMM shall still behave like normal ones
> in many cases, i.e. when used as backend memory of KVM guest. This patch
> introduces a new memory type, MEMORY_DEVICE_DEV_DAX. And set this flag
> while dax driver hotplug the device memory.
> 
> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
> Signed-off-by: Zhang Yu <yu.c.zhang@linux.intel.com>
> ---
>  drivers/dax/pmem.c       | 1 +
>  include/linux/memremap.h | 9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
> index fd49b24..fb3f363 100644
> --- a/drivers/dax/pmem.c
> +++ b/drivers/dax/pmem.c
> @@ -111,6 +111,7 @@ static int dax_pmem_probe(struct device *dev)
>  		return rc;
>  
>  	dax_pmem->pgmap.ref = &dax_pmem->ref;
> +	dax_pmem->pgmap.type = MEMORY_DEVICE_DEV_DAX;
>  	addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
>  	if (IS_ERR(addr))
>  		return PTR_ERR(addr);
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index 5ebfff6..a36bce8 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -53,11 +53,20 @@ struct vmem_altmap {
>   * wakeup event whenever a page is unpinned and becomes idle. This
>   * wakeup is used to coordinate physical address space management (ex:
>   * fs truncate/hole punch) vs pinned pages (ex: device dma).
> + *
> + * MEMORY_DEVICE_DEV_DAX:
> + * DAX driver hotplug the device memory and move it to memory zone, these
> + * pages will be marked reserved flag. However, some other kernel componet
> + * will misconceive these pages are reserved mmio (ex: we map these dev_dax
> + * or fs_dax pages to kvm for DIMM/NVDIMM backend). Together with the type
> + * MEMORY_DEVICE_FS_DAX, we can differentiate the pages on NVDIMM with the
> + * normal reserved pages.

So I believe the description should be in terms of what kind of memory is
the MEMORY_DEVICE_DEV_DAX type, not how users use this type. See comments
for other memory types...

								Honza

>   */
>  enum memory_type {
>  	MEMORY_DEVICE_PRIVATE = 1,
>  	MEMORY_DEVICE_PUBLIC,
>  	MEMORY_DEVICE_FS_DAX,
> +	MEMORY_DEVICE_DEV_DAX,
>  };
>  
>  /*
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
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  reply	other threads:[~2018-08-07  9:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 17:01 [PATCH V2 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio Zhang Yi
2018-07-10 17:01 ` [PATCH V2 1/4] kvm: remove redundant reserved page check Zhang Yi
2018-07-10 17:01 ` [PATCH V2 2/4] mm: introduce memory type MEMORY_DEVICE_DEV_DAX Zhang Yi
2018-08-07  9:11   ` Jan Kara [this message]
2018-08-08  9:22     ` Zhang,Yi
2018-07-10 17:03 ` [PATCH V2 3/4] mm: add a function to differentiate the pages is from DAX device memory Zhang Yi
2018-08-07  9:13   ` Jan Kara
     [not found] ` <cover.1531241281.git.yi.z.zhang-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-07-10 17:03   ` Zhang Yi
2018-07-10 17:04 ` [PATCH V2 4/4] kvm: add a check if pfn is from NVDIMM pmem Zhang Yi
2018-07-13 14:29 ` [PATCH V2 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio Zhang,Yi
2018-07-20 14:11 ` Zhang,Yi
2018-07-20  8:32   ` Paolo Bonzini
2018-07-20 16:24     ` Zhang,Yi

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