1 files changed, 33 insertions, 9 deletions

diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
index 6113c47e095..073c9b408cf 100644
--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -66,7 +66,7 @@ static int fb_deferred_io_fault(struct vm_area_struct *vma,
 	return 0;
 }
 
-int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
+int fb_deferred_io_fsync(struct file *file, int datasync)
 {
 	struct fb_info *info = file->private_data;
 
@@ -155,25 +155,41 @@ static void fb_deferred_io_work(struct work_struct *work)
 {
 	struct fb_info *info = container_of(work, struct fb_info,
 						deferred_work.work);
-	struct list_head *node, *next;
-	struct page *cur;
 	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct page *page, *tmp_page;
+	struct list_head *node, *tmp_node;
+	struct list_head non_dirty;
+
+	INIT_LIST_HEAD(&non_dirty);
 
 	/* here we mkclean the pages, then do all deferred IO */
 	mutex_lock(&fbdefio->lock);
-	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
-		lock_page(cur);
-		page_mkclean(cur);
-		unlock_page(cur);
+	list_for_each_entry_safe(page, tmp_page, &fbdefio->pagelist, lru) {
+		lock_page(page);
+		/*
+		 * The workqueue callback can be triggered after a
+		 * ->page_mkwrite() call but before the PTE has been marked
+		 * dirty. In this case page_mkclean() won't "rearm" the page.
+		 *
+		 * To avoid this, remove those "non-dirty" pages from the
+		 * pagelist before calling the driver's callback, then add
+		 * them back to get processed on the next work iteration.
+		 * At that time, their PTEs will hopefully be dirty for real.
+		 */
+		if (!page_mkclean(page))
+			list_move_tail(&page->lru, &non_dirty);
+		unlock_page(page);
 	}
 
 	/* driver's callback with pagelist */
 	fbdefio->deferred_io(info, &fbdefio->pagelist);
 
-	/* clear the list */
-	list_for_each_safe(node, next, &fbdefio->pagelist) {
+	/* clear the list... */
+	list_for_each_safe(node, tmp_node, &fbdefio->pagelist) {
 		list_del(node);
 	}
+	/* ... and add back the "non-dirty" pages to the list */
+	list_splice_tail(&non_dirty, &fbdefio->pagelist);
 	mutex_unlock(&fbdefio->lock);
 }
 
@@ -202,6 +218,7 @@ EXPORT_SYMBOL_GPL(fb_deferred_io_open);
 void fb_deferred_io_cleanup(struct fb_info *info)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct list_head *node, *tmp_node;
 	struct page *page;
 	int i;
 
@@ -209,6 +226,13 @@ void fb_deferred_io_cleanup(struct fb_info *info)
 	cancel_delayed_work(&info->deferred_work);
 	flush_scheduled_work();
 
+	/*  the list may have still some non-dirty pages at this point */
+	mutex_lock(&fbdefio->lock);
+	list_for_each_safe(node, tmp_node, &fbdefio->pagelist) {
+		list_del(node);
+	}
+	mutex_unlock(&fbdefio->lock);
+
 	/* clear out the mapping that we setup */
 	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
 		page = fb_deferred_io_page(info, i);