diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/mm/memory.c b/mm/memory.c index 109e9866237e..fa941b169071 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1458,14 +1458,19 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, { struct page *old_page, *new_page; pte_t entry; - int reuse, ret = VM_FAULT_MINOR; + int reuse = 0, ret = VM_FAULT_MINOR; + struct page *dirty_page = NULL; old_page = vm_normal_page(vma, address, orig_pte); if (!old_page) goto gotten; - if (unlikely((vma->vm_flags & (VM_SHARED|VM_WRITE)) == - (VM_SHARED|VM_WRITE))) { + /* + * Only catch write-faults on shared writable pages, read-only + * shared pages can get COWed by get_user_pages(.write=1, .force=1). + */ + if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == + (VM_WRITE|VM_SHARED))) { if (vma->vm_ops && vma->vm_ops->page_mkwrite) { /* * Notify the address space that the page is about to @@ -1494,13 +1499,12 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, if (!pte_same(*page_table, orig_pte)) goto unlock; } - + dirty_page = old_page; + get_page(dirty_page); reuse = 1; } else if (PageAnon(old_page) && !TestSetPageLocked(old_page)) { reuse = can_share_swap_page(old_page); unlock_page(old_page); - } else { - reuse = 0; } if (reuse) { @@ -1566,6 +1570,10 @@ gotten: page_cache_release(old_page); unlock: pte_unmap_unlock(page_table, ptl); + if (dirty_page) { + set_page_dirty(dirty_page); + put_page(dirty_page); + } return ret; oom: if (old_page) @@ -2098,6 +2106,7 @@ static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned int sequence = 0; int ret = VM_FAULT_MINOR; int anon = 0; + struct page *dirty_page = NULL; pte_unmap(page_table); BUG_ON(vma->vm_flags & VM_PFNMAP); @@ -2192,6 +2201,10 @@ retry: } else { inc_mm_counter(mm, file_rss); page_add_file_rmap(new_page); + if (write_access) { + dirty_page = new_page; + get_page(dirty_page); + } } } else { /* One of our sibling threads was faster, back out. */ @@ -2204,6 +2217,10 @@ retry: lazy_mmu_prot_update(entry); unlock: pte_unmap_unlock(page_table, ptl); + if (dirty_page) { + set_page_dirty(dirty_page); + put_page(dirty_page); + } return ret; oom: page_cache_release(new_page); |