__swap_count
extern int __swap_count(swp_entry_t entry);
VM_WARN_ON_ONCE_FOLIO(__swap_count(entry) != 1, folio);
if (unlikely(!__swap_count(swp_entry(swp_type(entry), offset)))) {
if (__swap_count(swp_entry(si->type,
if (!__swap_count(entry))