mm: track vma changes with VM_SOFTDIRTY bit

[linux-2.6-block.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 13926a5a6901c94a61c376c365bfa341c9bcebdc..51958d192a48ba9ec0636eb86f5c1dfc995f5433 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1609,6 +1609,15 @@ out:
        if (file)
                uprobe_mmap(vma);
 
+       /*
+        * New (or expanded) vma always get soft dirty status.
+        * Otherwise user-space soft-dirty page tracker won't
+        * be able to distinguish situation when vma area unmapped,
+        * then new mapped in-place (which must be aimed as
+        * a completely new data area).
+        */
+       vma->vm_flags |= VM_SOFTDIRTY;
+
        return addr;
 
 unmap_and_free_vma:
@@ -2652,6 +2661,7 @@ out:
        mm->total_vm += len >> PAGE_SHIFT;
        if (flags & VM_LOCKED)
                mm->locked_vm += (len >> PAGE_SHIFT);
+       vma->vm_flags |= VM_SOFTDIRTY;
        return addr;
 }
 
@@ -2916,7 +2926,7 @@ int install_special_mapping(struct mm_struct *mm,
        vma->vm_start = addr;
        vma->vm_end = addr + len;
 
-       vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
+       vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
        vma->vm_ops = &special_mapping_vmops;