When a ZONE_DEVICE page refcount reach 1 it means it is free and nobody is holding a reference on it (only device to which the memory belong do). Add a callback and call it when that happen so device driver can implement their own free page management.
Changed since v1: - Do not update devm_memremap_pages() to take extra argument Signed-off-by: Jérôme Glisse <[email protected]> Cc: Dan Williams <[email protected]> Cc: Ross Zwisler <[email protected]> --- include/linux/memremap.h | 8 +++++++- kernel/memremap.c | 8 ++++++++ 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/memremap.h b/include/linux/memremap.h index f7e0609..06fa74b 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -35,23 +35,29 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start) } #endif +typedef void (*dev_page_free_t)(struct page *page, void *data); + /** * struct dev_pagemap - metadata for ZONE_DEVICE mappings + * @page_free: free page callback when page refcount reach 1 * @altmap: pre-allocated/reserved memory for vmemmap allocations * @res: physical address range covered by @ref * @ref: reference count that pins the devm_memremap_pages() mapping * @dev: host device of the mapping for debug + * @data: privata data pointer for page_free */ struct dev_pagemap { + dev_page_free_t page_free; struct vmem_altmap *altmap; const struct resource *res; struct percpu_ref *ref; struct device *dev; + void *data; }; #ifdef CONFIG_ZONE_DEVICE void *devm_memremap_pages(struct device *dev, struct resource *res, - struct percpu_ref *ref, struct vmem_altmap *altmap); + struct percpu_ref *ref, struct vmem_altmap *altmap); struct dev_pagemap *find_dev_pagemap(resource_size_t phys); static inline bool dev_page_allow_migrate(const struct page *page) diff --git a/kernel/memremap.c b/kernel/memremap.c index 07665eb..2f37c92 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -190,6 +190,12 @@ EXPORT_SYMBOL(get_zone_device_page); void put_zone_device_page(struct page *page) { + /* + * If refcount is 1 then page is freed and refcount is stable as nobody + * holds a reference on the page. + */ + if (page->pgmap->page_free && page_count(page) == 1) + page->pgmap->page_free(page, page->pgmap->data); put_dev_pagemap(page->pgmap); } EXPORT_SYMBOL(put_zone_device_page); @@ -322,6 +328,8 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, } pgmap->ref = ref; pgmap->res = &page_map->res; + pgmap->page_free = NULL; + pgmap->data = NULL; mutex_lock(&pgmap_lock); error = 0; -- 2.4.3
