Commit a08d93e5 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

mm: simplify PageDoubleMap with PF_SECOND policy 



Introduce the new page policy of PF_SECOND which lets us use the normal
pageflags generation machinery to create the various DoubleMap
manipulation functions.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Link: https://lkml.kernel.org/r/20200629151933.15671-3-willy@infradead.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e18c45ff

include/linux/page-flags.h

+10 −30
Original line number Diff line number Diff line
@@ -235,6 +235,9 @@ static inline void page_init_poison(struct page *page, size_t size) 
 *

 * PF_NO_COMPOUND:

 *     the page flag is not relevant for compound pages.

 *

 * PF_SECOND:

 *     the page flag is stored in the first tail page.

 */

#define PF_POISONED_CHECK(page) ({					\

		VM_BUG_ON_PGFLAGS(PagePoisoned(page), page);		\
@@ -250,6 +253,9 @@ static inline void page_init_poison(struct page *page, size_t size) 
#define PF_NO_COMPOUND(page, enforce) ({				\

		VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page);	\

		PF_POISONED_CHECK(page); })

#define PF_SECOND(page, enforce) ({					\

		VM_BUG_ON_PGFLAGS(!PageHead(page), page);		\

		PF_POISONED_CHECK(&page[1]); })



/*

 * Macros to create function definitions for page flags
@@ -688,42 +694,15 @@ static inline int PageTransTail(struct page *page) 
 *

 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().

 */

static inline int PageDoubleMap(struct page *page)

{

	return PageHead(page) && test_bit(PG_double_map, &page[1].flags);

}



static inline void SetPageDoubleMap(struct page *page)

{

	VM_BUG_ON_PAGE(!PageHead(page), page);

	set_bit(PG_double_map, &page[1].flags);

}



static inline void ClearPageDoubleMap(struct page *page)

{

	VM_BUG_ON_PAGE(!PageHead(page), page);

	clear_bit(PG_double_map, &page[1].flags);

}

static inline int TestSetPageDoubleMap(struct page *page)

{

	VM_BUG_ON_PAGE(!PageHead(page), page);

	return test_and_set_bit(PG_double_map, &page[1].flags);

}



static inline int TestClearPageDoubleMap(struct page *page)

{

	VM_BUG_ON_PAGE(!PageHead(page), page);

	return test_and_clear_bit(PG_double_map, &page[1].flags);

}



PAGEFLAG(DoubleMap, double_map, PF_SECOND)

	TESTSCFLAG(DoubleMap, double_map, PF_SECOND)

#else

TESTPAGEFLAG_FALSE(TransHuge)

TESTPAGEFLAG_FALSE(TransCompound)

TESTPAGEFLAG_FALSE(TransCompoundMap)

TESTPAGEFLAG_FALSE(TransTail)

PAGEFLAG_FALSE(DoubleMap)

	TESTSETFLAG_FALSE(DoubleMap)

	TESTCLEARFLAG_FALSE(DoubleMap)

	TESTSCFLAG_FALSE(DoubleMap)

#endif



/*
@@ -888,6 +867,7 @@ static inline int page_has_private(struct page *page) 
#undef PF_ONLY_HEAD

#undef PF_NO_TAIL

#undef PF_NO_COMPOUND

#undef PF_SECOND

#endif /* !__GENERATING_BOUNDS_H */



#endif	/* PAGE_FLAGS_H */