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@xxxxxxxxxxxxxxx>
> Signed-off-by: Zhang Yu <yu.c.zhang@xxxxxxxxxxxxxxx>
> ---
> 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@xxxxxxxx>
SUSE Labs, CR
