mm/huge_memory: replace can_split_folio() with direct refcount calculation

can_split_folio() is just a refcount comparison, making sure only the split caller holds an extra pin. Open code it with folio_expected_ref_count() != folio_ref_count() - 1. For the extra_pins used by folio_ref_freeze(), add folio_cache_ref_count() to calculate it. Also replace folio_expected_ref_count() with folio_cache_ref_count() used by folio_ref_unfreeze(), since they are returning the same values when a folio is frozen and folio_cache_ref_count() does not have unnecessary folio_mapcount() in its implementation.

Zi Yan committed 11 months ago

Commit 5842bcb1 parent bdd0d693 files · +22 −34Browse files

Showing the changes to include/linux (1 of 3 files). Show all

Unified · Split

include/linux/huge_mm.h+0−1

@@ -369,7 +369,6 @@ enum split_type { · 368 unmodified lines
369	SPLIT_TYPE_NON_UNIFORM,	369	SPLIT_TYPE_NON_UNIFORM,
370	};	370	};
371		371
372	bool can_split_folio(struct folio folio, int caller_pins, int pextra_pins);
373	int __split_huge_page_to_list_to_order(struct page page, struct list_head list,	372	int __split_huge_page_to_list_to_order(struct page page, struct list_head list,
374	unsigned int new_order);	373	unsigned int new_order);
375	int folio_split_unmapped(struct folio *folio, unsigned int new_order);	374	int folio_split_unmapped(struct folio *folio, unsigned int new_order);