This patch introduces a new Vmemmap page-type. It also introduces some functions to ease the handling of vmemmap pages:
- vmemmap_nr_sections: Returns the number of sections that used vmemmap. - vmemmap_nr_pages: Allows us to retrieve the amount of vmemmap pages derivated from any vmemmap-page in the section. Useful for accounting and to know how much to we have to skip in the case where vmemmap pages need to be ignored. - vmemmap_head: Returns the vmemmap head page - SetPageVmemmap: Sets Reserved flag bit, and sets page->type to Vmemmap. Setting the Reserved flag bit is just for extra protection, actually we do not expect anyone to use these pages for anything. - ClearPageVmemmap: Clears Reserved flag bit and page->type. Only used when sections containing vmemmap pages are removed. These functions will be used for the code handling Vmemmap pages. Signed-off-by: Oscar Salvador <[email protected]> --- include/linux/mm.h | 17 +++++++++++++++++ include/linux/mm_types.h | 5 +++++ include/linux/page-flags.h | 19 +++++++++++++++++++ 3 files changed, 41 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 45f0ab0ed4f7..432175f8f8d2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2904,6 +2904,23 @@ static inline bool debug_guardpage_enabled(void) { return false; } static inline bool page_is_guard(struct page *page) { return false; } #endif /* CONFIG_DEBUG_PAGEALLOC */ +static __always_inline struct page *vmemmap_head(struct page *page) +{ + return (struct page *)page->vmemmap_head; +} + +static __always_inline unsigned long vmemmap_nr_sections(struct page *page) +{ + struct page *head = vmemmap_head(page); + return head->vmemmap_sections; +} + +static __always_inline unsigned long vmemmap_nr_pages(struct page *page) +{ + struct page *head = vmemmap_head(page); + return head->vmemmap_pages - (page - head); +} + #if MAX_NUMNODES > 1 void __init setup_nr_node_ids(void); #else diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 6a7a1083b6fb..51dd227f2a6b 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -170,6 +170,11 @@ struct page { * pmem backed DAX files are mapped. */ }; + struct { /* Vmemmap pages */ + unsigned long vmemmap_head; + unsigned long vmemmap_sections; /* Number of sections */ + unsigned long vmemmap_pages; /* Number of pages */ + }; /** @rcu_head: You can use this to free a page by RCU. */ struct rcu_head rcu_head; diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index f91cb8898ff0..75f302a532f9 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -708,6 +708,7 @@ PAGEFLAG_FALSE(DoubleMap) #define PG_kmemcg 0x00000200 #define PG_table 0x00000400 #define PG_guard 0x00000800 +#define PG_vmemmap 0x00001000 #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) @@ -764,6 +765,24 @@ PAGE_TYPE_OPS(Table, table) */ PAGE_TYPE_OPS(Guard, guard) +/* + * Vmemmap pages refers to those pages that are used to create the memmap + * array, and reside within the same memory range that was hotppluged, so + * they are self-hosted. (see include/linux/memory_hotplug.h) + */ +PAGE_TYPE_OPS(Vmemmap, vmemmap) +static __always_inline void SetPageVmemmap(struct page *page) +{ + __SetPageVmemmap(page); + __SetPageReserved(page); +} + +static __always_inline void ClearPageVmemmap(struct page *page) +{ + __ClearPageVmemmap(page); + __ClearPageReserved(page); +} + extern bool is_free_buddy_page(struct page *page); __PAGEFLAG(Isolated, isolated, PF_ANY); -- 2.12.3
