is_user detection wrong when modprobe

[thehajime]

As nommu kernel doesn't recognize the start/end parameter of execmem used by modules, memory location for modules mixes up with the one of userspace programs.

need some info in execmem_arch_setup() ?

https://lore.kernel.org/linux-um/87da1cab734b9d92d17210abdeddc10afd533a0f.camel@sipsolutions.net/

static void *__execmem_alloc(struct execmem_range *range, size_t size)
{
	bool kasan = range->flags & EXECMEM_KASAN_SHADOW;
	unsigned long vm_flags  = VM_FLUSH_RESET_PERMS;
	gfp_t gfp_flags = GFP_KERNEL | __GFP_NOWARN;
	unsigned long start = range->start;
	unsigned long end = range->end;
	unsigned int align = range->alignment;