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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: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Link: https://lkml.kernel.org/r/20200629151933.15671-3-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-10-13 16:53:54 -07:00 committed by Linus Torvalds
parent e18c45ffcf
commit a08d93e575
1 changed files with 10 additions and 30 deletions
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40
include/linux/page-flags.h
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@ -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 */