diff --git a/linux/include/linux/sched.h b/linux/include/linux/sched.h
index 772646a..ea9fd3d 100644
--- a/linux/include/linux/sched.h
+++ b/linux/include/linux/sched.h
@@ -104,8 +104,20 @@ struct task_struct {
 	struct desc_struct ldt[3];
 /* tss for this task */
 	struct tss_struct tss;
+	struct mmap_struct *mmap;
+	struct mmap_struct *mmap_tail;
 };
 
+struct mmap_struct
+{
+	//映射区域以4096字节为单位  (endaddr-address)%4096=0 ，每个进程addr起始地址0x2000000 + n*0x1000
+	unsigned long address;
+	unsigned long endaddr; 
+	int rw;//
+	int ps;//private or shared
+	struct mmap_struct *next;
+	int size;
+};
 /*
  *  INIT_TASK is used to set up the first task table, touch at
  * your own risk!. Base=0, limit=0x9ffff (=640kB)
@@ -131,6 +143,8 @@ struct task_struct {
 	 _LDT(0),0x80000000, \
 		{} \
 	}, \
+/*mmap*/  NULL,	\
+/*mmap_tail*/	NULL,\
 }
 
 extern struct task_struct *task[NR_TASKS];
diff --git a/linux/kernel/sys.c b/linux/kernel/sys.c
index 01283e9..3a7a7b0 100644
--- a/linux/kernel/sys.c
+++ b/linux/kernel/sys.c
@@ -463,7 +463,7 @@ int sys_umask(int mask)
 	return (old);
 }
 
-
+// rememeber to sync when munmap exit manual 
 long sys_mmap(void * start,size_t len,...)// int prot,int flags,int fd,off_t off
 {
 	printk("start mmaping\n");
@@ -481,6 +481,7 @@ long sys_mmap(void * start,size_t len,...)// int prot,int flags,int fd,off_t off
 	char *temp,*p1,*p2;
 	void * buf=start;
 	int tempprot=0;
+	//因为new.h和namei.c定义不一样，要修改
 	if(prot &PROT_READ) tempprot |=4;
 	if(prot &PROT_EXEC) tempprot |=1;
 	if(prot &PROT_WRITE) tempprot |=2;
@@ -504,53 +505,38 @@ long sys_mmap(void * start,size_t len,...)// int prot,int flags,int fd,off_t off
 		printk("error permission.");
 		return MAP_FAILED;
 	}
+	//end of permission check
 	printk("end of permissions\n");
 	if(start<=current->brk || start>=current->start_stack-0x8000 || start==NULL) 
 	{
-		buf=0x2000000;
-	}	
+		if(!current->mmap_tail)
+			buf=0x2000000;
+		else
+			buf=current->mmap_tail->endaddr;
+	}
+	struct mmap_struct *mmap=(struct mmap_struct *)malloc(sizeof(struct mmap_struct));
+	mmap->address=buf;mmap->size=len;
+	mmap->endaddr=buf+(len + 0xfff)&0xfffff000;
+	mmap->rw=prot;mmap->ps=flags;
+	mmap->next=NULL;
+	if(!current->mmap) 
+		{current->mmap=current->mapp_tail=mapp;}
+	else 
+		current->mmap_tail->next=mapp;
 	printk("buf: %x\n",(unsigned long )buf);
 	
+	//read and put in 
 	if (!(block = inode->i_zone[0]))
 		return NULL;
 	if (!(bh = bread(inode->i_dev,block)))
 		return NULL;
 	temp = (char *) bh->b_data;
-	/* int nr[4];
-	unsigned long page;
-	int i;
-	unsigned long address=current->start_code+(unsigned long)buf;
-	printk("start of page\n");
-	//this part comes from do_no_page as achievement of immediate loading of cs and ds
-	while(address<=current->start_code+len+(unsigned long)buf)
-	{
-		printk("address: %x\n",address);
-		address &= 0xfffff000;
-		if (!(page = get_free_page()))
-			return MAP_FAILED;
-		for (i=0 ; i<4 ; block++,i++)
-			nr[i] = bmap(inode,block);
-		bread_page(page,inode->i_dev,nr);
-		if (!put_page(page,address))
-		{
-			free_page(page);
-			return MAP_FAILED;
-		}
-		int k=0;char c=0;
-		while(k++<60){c=get_fs_byte(address-current->start_code);printk("%c",c);}
-		printk("\n");
-		address+=PAGE_SIZE;
-		k=0;
-		while(k++<60)printk("%c",(char*)(page+k));
-		printk("\n");
-	} */
 	printk("end of mmap\n");
 	p1=temp;p2=buf;
 	while(l--)
 		put_fs_byte(*(p1++),p2++);
 	printk("%s\n",temp);
 	return buf;
-	return MAP_FAILED;
 }
 int sys_munmap()
 {