ptr_pack_bits
f->syncobj = ptr_pack_bits(syncobj, user_fence.flags, 2);
f->syncobj = ptr_pack_bits(syncobj, user_fence.flags, 2);
tl->retire = ptr_pack_bits(first, 1, 1);
#define page_pack_bits(ptr, bits) ptr_pack_bits(ptr, bits, PAGE_SHIFT)