diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c index 9144fae9a68b..b8f97b8575b7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3299,7 +3299,12 @@ int make_pages_present(unsigned long addr, unsigned long end) vma = find_vma(current->mm, addr); if (!vma) return -ENOMEM; - write = (vma->vm_flags & VM_WRITE) != 0; + /* + * We want to touch writable mappings with a write fault in order + * to break COW, except for shared mappings because these don't COW + * and we would not want to dirty them for nothing. + */ + write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE; BUG_ON(addr >= end); BUG_ON(end > vma->vm_end); len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; |