When vm_ops->page_mkwrite is defined, and called from wp_page_shared and
do_shared_fault, the set_page_dirty must already called by page_mkwrite.
Then in fault_dirty_shared_page, avoid this repeated call.
Signed-off-by: Li Xinhai <lixinhai.lxh@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
---
mm/memory.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 606da18..34a83d7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2300,10 +2300,11 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
struct vm_area_struct *vma = vmf->vma;
struct address_space *mapping;
struct page *page = vmf->page;
- bool dirtied;
+ bool dirtied = false;
bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
- dirtied = set_page_dirty(page);
+ if(!page_mkwrite)
+ dirtied = set_page_dirty(page);
VM_BUG_ON_PAGE(PageAnon(page), page);
/*
* Take a local copy of the address_space - page.mapping may be zeroed
@@ -3645,7 +3646,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
* Check if the backing address space wants to know that the page is
* about to become writable
*/
- if (vma->vm_ops->page_mkwrite) {
+ if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
unlock_page(vmf->page);
tmp = do_page_mkwrite(vmf);
if (unlikely(!tmp ||
--
1.8.3.1
