I was going through the vmalloc fault handling for x86_64 and am unclear about the following lines in the vmalloc_fault() function.

pgd = pgd_offset(current->mm ?: &init_mm, address);
pgd_ref = pgd_offset_k(address);

Here the intention is to get the pgd corresponding to the current process and sync it up with the pgd in init_mm(obtained from pgd_offset_k). However, for kernel threads current->mm is NULL and hence
pgd = pgd_offset(init_mm, address) = pgd_ref which means the fault handler returns without setting the pgd entry in the MM structure in the context of which the kernel thread has faulted. This could lead to never-ending faults and busy looping of kernel threads like pdflush.
So, shouldn't the
pgd = pgd_offset(current->mm ?: &init_mm, address);
be
pgd = pgd_offset(current->active_mm ?: &init_mm, address);