来自本人的旧博客: http://blog.163.com/awaken_ing/blog/static/12061319720151129103139710

1. 问题

linux-3.10.86/kernel/kthread.c

static int kthread(void *_create)
{
...
    /* we can't just return, we must preserve "self" on stack */
    do_exit(ret);
}

这里注释说不能省略do_exit(), why?

2. 解

2.1 内核创建

来自本人的旧博客: http://blog.163.com/awaken_ing/blog/static/120613197201511307274526

上图为smpbootregisterpercputhread(), kthreadcreateoncpu(), kthreadcreateon_node(), kthreadd()和kthread()之间的关系.

上图为cpu hotplug对内核线程的操作, 以smpbootthreadfn()为例.

内核启动时, smpbootregisterpercputhread()创建,绑定并启动primary cpu的内核线程, 并挂到链表hotplugthreads上.

linux-3.10.86/kernel/smpboot.c

smpboot_register_percpu_thread
{
    __smpboot_create_thread(plug_thread, cpu);
    smpboot_unpark_thread(plug_thread, cpu);
    list_add(&plug_thread->list, &hotplug_threads);
}

1. 问题引入

这里从一个地址空间 到另一个地址空间, 是为啥?

generic_file_fsync
{
    struct inode *inode = file->f_mapping->host;
    ret = sync_mapping_buffers(inode->i_mapping);

}

sync_mapping_buffers(struct address_space *mapping)
{
    struct address_space *buffer_mapping = mapping->private_data;

}

2. 解

linux-3.10.86/include/linux/fs.h