What is the size of struct thread_info in linux-initialization-4?

[spacewander]

In that chapter it says:

thread_info defined as:

struct thread_info {
        struct task_struct      *task;
        struct exec_domain      *exec_domain;
        __u32                   flags; 
        __u32                   status;
        __u32                   cpu;
        int                     saved_preempt_count;
        mm_segment_t            addr_limit;
        struct restart_block    restart_block;
        void __user             *sysenter_return;
        unsigned int            sig_on_uaccess_error:1;
        unsigned int            uaccess_err:1;
};

and occupies 52 bytes.

However, then it says:

The remaining thread_size will be 16 killobytes - 62 bytes = 16332 bytes.

At first I thought it as a typo. But, it seems that the size of thread_info is not less than 56 bytes whatever the size of struct restart_block is, because of memory alignment.
And its size can not be 62 bytes, again because of memory alignment. Its size should be the multiple of 8 bytes.

[hitmoon]

Actually in kernel 4.0.0(x86), there is no restart_block field in struct thread_info. Any way, the 62 bytes said above is not correct !

[0xAX]

Hello @spacewander and @hitmoon, you are right, there is error.

I'm using Linux kernel from master, and for me, the thread_info is 40 bytes size. It defined as:

struct thread_info {
    struct task_struct  *task;      /* main task structure */
    __u32           flags;      /* low level flags */
    __u32           status;     /* thread synchronous flags */
    __u32           cpu;        /* current CPU */
    mm_segment_t        addr_limit;
    unsigned int        sig_on_uaccess_error:1;
    unsigned int        uaccess_err:1;  /* uaccess failed */
};

Will fix it soon. Thank you.