diff options
| -rw-r--r-- | fs/exec.c | 2 | ||||
| -rw-r--r-- | include/linux/rmap.h | 1 | ||||
| -rw-r--r-- | mm/memory.c | 6 | ||||
| -rw-r--r-- | mm/rmap.c | 49 |
4 files changed, 43 insertions, 15 deletions
diff --git a/fs/exec.c b/fs/exec.c index 22533cce0611..e75a9548da8e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -324,7 +324,7 @@ void install_arg_page(struct vm_area_struct *vma, lru_cache_add_active(page); set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte( page, vma->vm_page_prot)))); - page_add_anon_rmap(page, vma, address); + page_add_new_anon_rmap(page, vma, address); pte_unmap_unlock(pte, ptl); /* no need for flush_tlb */ diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 33261f1d2239..9d6fbeef2104 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -71,6 +71,7 @@ void __anon_vma_link(struct vm_area_struct *); * rmap interfaces called when adding or removing pte of page */ 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 *); void page_remove_rmap(struct page *); diff --git a/mm/memory.c b/mm/memory.c index e249088908c4..d7ca7de10f4d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1498,7 +1498,7 @@ gotten: update_mmu_cache(vma, address, entry); lazy_mmu_prot_update(entry); lru_cache_add_active(new_page); - page_add_anon_rmap(new_page, vma, address); + page_add_new_anon_rmap(new_page, vma, address); /* Free the old page.. */ new_page = old_page; @@ -1978,7 +1978,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, inc_mm_counter(mm, anon_rss); lru_cache_add_active(page); SetPageReferenced(page); - page_add_anon_rmap(page, vma, address); + page_add_new_anon_rmap(page, vma, address); } else { /* Map the ZERO_PAGE - vm_page_prot is readonly */ page = ZERO_PAGE(address); @@ -2109,7 +2109,7 @@ retry: if (anon) { inc_mm_counter(mm, anon_rss); lru_cache_add_active(new_page); - page_add_anon_rmap(new_page, vma, address); + page_add_new_anon_rmap(new_page, vma, address); } else { inc_mm_counter(mm, file_rss); page_add_file_rmap(new_page); diff --git a/mm/rmap.c b/mm/rmap.c index f853c6def159..4107f64ff749 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -435,6 +435,26 @@ int page_referenced(struct page *page, int is_locked) } /** + * 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 + * @address: the user virtual address mapped + */ +static void __page_set_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + struct anon_vma *anon_vma = vma->anon_vma; + + BUG_ON(!anon_vma); + anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; + page->mapping = (struct address_space *) anon_vma; + + page->index = linear_page_index(vma, address); + + inc_page_state(nr_mapped); +} + +/** * page_add_anon_rmap - add pte mapping to an anonymous page * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added @@ -445,20 +465,27 @@ int page_referenced(struct page *page, int is_locked) void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { - if (atomic_inc_and_test(&page->_mapcount)) { - struct anon_vma *anon_vma = vma->anon_vma; - - BUG_ON(!anon_vma); - anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; - page->mapping = (struct address_space *) anon_vma; - - page->index = linear_page_index(vma, address); - - inc_page_state(nr_mapped); - } + if (atomic_inc_and_test(&page->_mapcount)) + __page_set_anon_rmap(page, vma, address); /* else checking page index and mapping is racy */ } +/* + * page_add_new_anon_rmap - add pte mapping to a new anonymous page + * @page: the page to add the mapping to + * @vma: the vm area in which the mapping is added + * @address: the user virtual address mapped + * + * Same as page_add_anon_rmap but must only be called on *new* pages. + * This means the inc-and-test can be bypassed. + */ +void page_add_new_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ + __page_set_anon_rmap(page, vma, address); +} + /** * page_add_file_rmap - add pte mapping to a file page * @page: the page to add the mapping to |