diff options
Diffstat (limited to 'include/linux/mm.h')
| -rw-r--r-- | include/linux/mm.h | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 58f2263de4de..858ce84ac7c5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -549,11 +549,6 @@ static inline void *kvmalloc_array(size_t n, size_t size, gfp_t flags) extern void kvfree(const void *addr); -static inline atomic_t *compound_mapcount_ptr(struct page *page) -{ - return &page[1].compound_mapcount; -} - static inline int compound_mapcount(struct page *page) { VM_BUG_ON_PAGE(!PageCompound(page), page); @@ -824,6 +819,10 @@ static inline bool is_device_public_page(const struct page *page) #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */ +/* 127: arbitrary random number, small enough to assemble well */ +#define page_ref_zero_or_close_to_overflow(page) \ + ((unsigned int) page_ref_count(page) + 127u <= 127u) + static inline void get_page(struct page *page) { page = compound_head(page); @@ -831,10 +830,19 @@ static inline void get_page(struct page *page) * Getting a normal page or the head of a compound page * requires to already have an elevated page->_refcount. */ - VM_BUG_ON_PAGE(page_ref_count(page) <= 0, page); + VM_BUG_ON_PAGE(page_ref_zero_or_close_to_overflow(page), page); page_ref_inc(page); } +static inline __must_check bool try_get_page(struct page *page) +{ + page = compound_head(page); + if (WARN_ON_ONCE(page_ref_count(page) <= 0)) + return false; + page_ref_inc(page); + return true; +} + static inline void put_page(struct page *page) { page = compound_head(page); |