diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index ebdf582ef18..2e38e904832 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -204,7 +204,7 @@ struct anon_vma *page_lock_anon_vma(struct page *page) unsigned long anon_mapping; rcu_read_lock(); - anon_mapping = (unsigned long) page->mapping; + anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) goto out; if (!page_mapped(page)) @@ -666,7 +666,9 @@ static void __page_check_anon_rmap(struct page *page, * @address: the user virtual address mapped * * The caller needs to hold the pte lock, and the page must be locked in - * the anon_vma case: to serialize mapping,index checking after setting. + * the anon_vma case: to serialize mapping,index checking after setting, + * and to ensure that PageAnon is not being upgraded racily to PageKsm + * (but PageKsm is never downgraded to PageAnon). */ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) |