Answer and Explanation:
Yes, We have observed in the discussion of ULTs versus KLTs, that it was pointed out that a disadvantage of ULTs is that when a ULT executes a system call, not only is that thread blocked, but also all of the threads within the process are blocked.
Because
The user process functions separately from Kernel processes.
It is a kind of thread structure process, So it is not visible to the OS/kernel, which schedules on the basis of processes.
Here According to me the book says that:
" The kernel continues to schedule the process as a unit and assigns a single execution state like the thread will be in (Ready, Running, Blocked, etc.) to that process "
If unfortunately one thread is blocked, then the whole process is going to get blocked and parallely all threads in that process are going to get blocked.