you are right of course. this is kernel API. it can't be called from user space.
but when you call it from kernel space, you must be calling with a
process context.
e.g. calling from init_module is ok.
calling from the timer interrupt handler is not ok.
Yes, I know that.
But the task_struct{}'s mm field of kernel thread is NULL. In another
word, kernel
thread has no user space address. However a user thread must have the user
space addresses, so where the mm struct of the user thread comes from when a
kernel thread becomes a user thread? I didn't find the code from
call_usermodehelper() function.
Thanks in advance!
Regards,
Cheng
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