On Fri, Jan 6, 2017 at 8:46 AM, Jérôme Glisse <jglisse@xxxxxxxxxx> wrote:
> Some device driver manage multiple physical devices memory from a single
> fake device driver. In that case the fake device might outlive the real
> device and ZONE_DEVICE and its resource allocated for a real device would
> waste resources in the meantime.
>
> This patch allow early removal of ZONE_DEVICE and associated resource,
> before device driver is tear down.
>
> Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> ---
> include/linux/memremap.h | 7 +++++++
> kernel/memremap.c | 14 ++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index f7e0609..32314d2 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -53,6 +53,7 @@ struct dev_pagemap {
> void *devm_memremap_pages(struct device *dev, struct resource *res,
> struct percpu_ref *ref, struct vmem_altmap *altmap);
> struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
> +int devm_memremap_pages_remove(struct device *dev, struct dev_pagemap *pgmap);
>
> static inline bool dev_page_allow_migrate(const struct page *page)
> {
> @@ -78,6 +79,12 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
> return NULL;
> }
>
> +static inline int devm_memremap_pages_remove(struct device *dev,
> + struct dev_pagemap *pgmap)
> +{
> + return -EINVAL;
> +}
> +
> static inline bool dev_page_allow_migrate(const struct page *page)
> {
> return false;
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index 07665eb..250ef25 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -387,6 +387,20 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
> }
> EXPORT_SYMBOL(devm_memremap_pages);
>
> +static int devm_page_map_match(struct device *dev, void *data, void *match_data)
> +{
> + struct page_map *page_map = data;
> +
> + return &page_map->pgmap == match_data;
> +}
> +
> +int devm_memremap_pages_remove(struct device *dev, struct dev_pagemap *pgmap)
> +{
> + return devres_release(dev, &devm_memremap_pages_release,
> + &devm_page_map_match, pgmap);
> +}
> +EXPORT_SYMBOL(devm_memremap_pages_remove);
I think this should be called devm_memunmap_pages() to mirror
devm_memunmap(), and it should take the virtual address returned from
devm_memremap_pages() not pgmap which is an internal detail.
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