Question on IS_ERR

["jidong xiao" <jidong.xiao@gmail.com>]

I saw we call IS_ERR(ptr) after executing kthread_run() each time.
But we don't need to call IS_ERR(ptr) after kmalloc().

My understanding is,
the kernel pointer ptr for IS_ERR to check should be page aligned, so
its kernel address should be less than 0xfffff000(or 0xffff ffff ffff
f000, 64bits),

kthread_run returns a struct task_struct pointer,which is always page aligned,
however the pointer returned by kmalloc() might not be page aligned,
so we cannot use IS_ERR to check.

Is my understanding correct?

Thanks
Jason