diff options
| -rw-r--r-- | include/linux/rmap.h | 1 | ||||
| -rw-r--r-- | mm/memory.c | 7 | ||||
| -rw-r--r-- | mm/rmap.c | 24 |
3 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 62da2001d55..72be23b1480 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -125,6 +125,7 @@ static inline void anon_vma_merge(struct vm_area_struct *vma, /* * rmap interfaces called when adding or removing pte of page */ +void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); void page_add_file_rmap(struct page *); diff --git a/mm/memory.c b/mm/memory.c index dc785b438d7..d1153e37e9b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2138,6 +2138,13 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, page_cache_release(old_page); } reuse = reuse_swap_page(old_page); + if (reuse) + /* + * The page is all ours. Move it to our anon_vma so + * the rmap code will not search our parent or siblings. + * Protected against the rmap code by the page lock. + */ + page_move_anon_rmap(old_page, vma, address); unlock_page(old_page); } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED))) { diff --git a/mm/rmap.c b/mm/rmap.c index 23ecd0a892d..28bcdc433d8 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -716,6 +716,30 @@ int page_mkclean(struct page *page) EXPORT_SYMBOL_GPL(page_mkclean); /** + * page_move_anon_rmap - move a page to our anon_vma + * @page: the page to move to our anon_vma + * @vma: the vma the page belongs to + * @address: the user virtual address mapped + * + * When a page belongs exclusively to one process after a COW event, + * that page can be moved into the anon_vma that belongs to just that + * process, so the rmap code will not search the parent or sibling + * processes. + */ +void page_move_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + struct anon_vma *anon_vma = vma->anon_vma; + + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!anon_vma); + VM_BUG_ON(page->index != linear_page_index(vma, address)); + + anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; + page->mapping = (struct address_space *) anon_vma; +} + +/** * __page_set_anon_rmap - setup new anonymous rmap * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added |