diff options
| -rw-r--r-- | include/linux/poison.h | 4 | ||||
| -rw-r--r-- | mm/huge_memory.c | 2 | ||||
| -rw-r--r-- | mm/memory.c | 2 | ||||
| -rw-r--r-- | mm/page_alloc.c | 6 | ||||
| -rw-r--r-- | mm/util.c | 10 |
5 files changed, 18 insertions, 6 deletions
diff --git a/include/linux/poison.h b/include/linux/poison.h index 317e16de09e5..76c3b6c38c16 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -32,6 +32,10 @@ /********** mm/debug-pagealloc.c **********/ #define PAGE_POISON 0xaa +/********** mm/page_alloc.c ************/ + +#define TAIL_MAPPING ((void *) 0x01014A11 + POISON_POINTER_DELTA) + /********** mm/slab.c **********/ /* * Magic nums for obj red zoning. diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f952f055fdcf..370d44a5e25b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1805,7 +1805,7 @@ static void __split_huge_page_refcount(struct page *page, */ page_tail->_mapcount = page->_mapcount; - BUG_ON(page_tail->mapping); + BUG_ON(page_tail->mapping != TAIL_MAPPING); page_tail->mapping = page->mapping; page_tail->index = page->index + i; diff --git a/mm/memory.c b/mm/memory.c index d4e4d37c1989..f9360dde6967 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3096,7 +3096,7 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, * pinned by vma->vm_file's reference. We rely on unlock_page()'s * release semantics to prevent the compiler from undoing this copying. */ - mapping = fault_page->mapping; + mapping = page_rmapping(fault_page); unlock_page(fault_page); if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ce63d603820f..d02d6436add0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -466,6 +466,7 @@ void prep_compound_page(struct page *page, unsigned int order) for (i = 1; i < nr_pages; i++) { struct page *p = page + i; set_page_count(p, 0); + p->mapping = TAIL_MAPPING; set_compound_head(p, page); } } @@ -856,6 +857,10 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) ret = 0; goto out; } + if (page->mapping != TAIL_MAPPING) { + bad_page(page, "corrupted mapping in tail page", 0); + goto out; + } if (unlikely(!PageTail(page))) { bad_page(page, "PageTail not set", 0); goto out; @@ -866,6 +871,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) } ret = 0; out: + page->mapping = NULL; clear_compound_head(page); return ret; } diff --git a/mm/util.c b/mm/util.c index 2d28f7930043..8acb936a52c8 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))) @@ -399,10 +401,10 @@ 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; } int overcommit_ratio_handler(struct ctl_table *table, int write, |