From: Hugh Dickins <hugh@veritas.com>
When mprotect shifts the boundary between vmas (merging the reprotected
area into the vma before or the vma after), make sure that the expanding
vma has anon_vma if the shrinking vma had, to cover anon pages imported.
Thanks to Andrea for alerting us to this oversight.
Cc: <andrea@suse.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/mmap.c | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletion(-)
diff -puN mm/mmap.c~mprotect-propagate-anon_vma mm/mmap.c
--- 25/mm/mmap.c~mprotect-propagate-anon_vma 2004-06-19 14:05:08.312704448 -0700
+++ 25-akpm/mm/mmap.c 2004-06-19 14:05:08.317703688 -0700
@@ -362,6 +362,7 @@ void vma_adjust(struct vm_area_struct *v
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *next = vma->vm_next;
+ struct vm_area_struct *importer = NULL;
struct address_space *mapping = NULL;
struct prio_tree_root *root = NULL;
struct file *file = vma->vm_file;
@@ -385,6 +386,7 @@ again: remove_next = 1 + (end > next->
*/
adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
anon_vma = next->anon_vma;
+ importer = vma;
} else if (end < vma->vm_end) {
/*
* vma shrinks, and !insert tells it's not
@@ -393,6 +395,7 @@ again: remove_next = 1 + (end > next->
*/
adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
anon_vma = next->anon_vma;
+ importer = next;
}
}
@@ -418,8 +421,18 @@ again: remove_next = 1 + (end > next->
*/
if (vma->anon_vma)
anon_vma = vma->anon_vma;
- if (anon_vma)
+ if (anon_vma) {
spin_lock(&anon_vma->lock);
+ /*
+ * Easily overlooked: when mprotect shifts the boundary,
+ * make sure the expanding vma has anon_vma set if the
+ * shrinking vma had, to cover any anon pages imported.
+ */
+ if (importer && !importer->anon_vma) {
+ importer->anon_vma = anon_vma;
+ __anon_vma_link(importer);
+ }
+ }
if (root) {
flush_dcache_mmap_lock(mapping);
_