diff options
Diffstat (limited to 'mm/util.c')
| -rw-r--r-- | mm/util.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/mm/util.c b/mm/util.c index 2d28f7930043..6d1f9200f74e 100644 --- a/mm/util.c +++ b/mm/util.c @@ -386,7 +386,9 @@ struct anon_vma *page_anon_vma(struct page *page) struct address_space *page_mapping(struct page *page) { - unsigned long mapping; + struct address_space *mapping; + + page = compound_head(page); /* This happens if someone calls flush_dcache_page on slab page */ if (unlikely(PageSlab(page))) @@ -399,11 +401,25 @@ struct address_space *page_mapping(struct page *page) return swap_address_space(entry); } - mapping = (unsigned long)page->mapping; - if (mapping & PAGE_MAPPING_FLAGS) + mapping = page->mapping; + if ((unsigned long)mapping & PAGE_MAPPING_FLAGS) return NULL; - return page->mapping; + return mapping; +} + +/* Slow path of page_mapcount() for compound pages */ +int __page_mapcount(struct page *page) +{ + int ret; + + ret = atomic_read(&page->_mapcount) + 1; + page = compound_head(page); + ret += atomic_read(compound_mapcount_ptr(page)) + 1; + if (PageDoubleMap(page)) + ret--; + return ret; } +EXPORT_SYMBOL_GPL(__page_mapcount); int overcommit_ratio_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, |