Make sure we copy pages inserted with "vm_insert_page()" on fork
The logic that decides that a fork() might be able to avoid copying a VM
area when it can be re-created by page faults didn't know about the new
vm_insert_page() case.
Also make some things a bit more anal wrt VM_PFNMAP.
Pointed out by Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e5677f4..a06a84d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -163,6 +163,7 @@
#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
+#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
diff --git a/mm/memory.c b/mm/memory.c
index d22f78c..d8dde07 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -574,7 +574,7 @@
* readonly mappings. The tradeoff is that copy_page_range is more
* efficient than faulting.
*/
- if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP))) {
+ if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
if (!vma->anon_vma)
return 0;
}
@@ -1228,6 +1228,7 @@
return -EFAULT;
if (!page_count(page))
return -EINVAL;
+ vma->vm_flags |= VM_INSERTPAGE;
return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_page);
diff --git a/mm/mmap.c b/mm/mmap.c
index 11ca592..64ba4db 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -611,7 +611,7 @@
* If the vma has a ->close operation then the driver probably needs to release
* per-vma resources, so we don't attempt to merge those.
*/
-#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)
+#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags)
diff --git a/mm/mremap.c b/mm/mremap.c
index b535438..ddaeee9 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -323,7 +323,7 @@
/* We can't remap across vm area boundaries */
if (old_len > vma->vm_end - addr)
goto out;
- if (vma->vm_flags & VM_DONTEXPAND) {
+ if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
if (new_len > old_len)
goto out;
}