--- a/drivers/video/omap/omapfb_main.c
+++ b/drivers/video/omap/omapfb_main.c
@@ -420,10 +420,10 @@ static void set_fb_fix(struct fb_info *f
 	fbi->screen_base	= rg->vaddr;
 
 	if (!from_init) {
-		mutex_lock(&fbi->mm_lock);
+		preempt_disable();
 		fix->smem_start		= rg->paddr;
 		fix->smem_len		= rg->size;
-		mutex_unlock(&fbi->mm_lock);
+		preempt_enable();
 	} else {
 		fix->smem_start		= rg->paddr;
 		fix->smem_len		= rg->size;
@@ -933,10 +933,10 @@ static int omapfb_setup_mem(struct fb_in
 				 * plane memory is dealloce'd, the other
 				 * screen parameters in var / fix are invalid.
 				 */
-				mutex_lock(&fbi->mm_lock);
+				preempt_disable();
 				fbi->fix.smem_start = 0;
 				fbi->fix.smem_len = 0;
-				mutex_unlock(&fbi->mm_lock);
+				preempt_enable();
 			}
 		}
 	}
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1383,8 +1383,10 @@ fb_mmap(struct file *file, struct vm_are
 	}
 
 	/* frame buffer memory */
+	preempt_disable();
 	start = info->fix.smem_start;
 	len = PAGE_ALIGN((start & ~PAGE_MASK) + info->fix.smem_len);
+	preempt_enable();
 	if (off >= len) {
 		/* memory mapped io */
 		off -= len;
