Yes, current->mm points to user space context for the current process.

Now for a kernel threads there is no user space context and for them current->mm would be NULL.

Thanks,

Chetan Nanda

On Fri, Nov 15, 2013 at 9:54 PM, Paul Davies C <pauldaviesc@gmail.com> wrote:

Hi,
    I happen to find this code snippet in the kernel source :

    struct mm_struct *mm=current->mm;

    /* some other code */

    if(mm){ /*<==Why is this here? */
        /*read the contents by locking*/
    }

The if checks whether the mm_struct of the current process is NULL or not. That means the mm_struct of a process can become NULL. How can that happen?

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