PG_swapcache
#define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache))
test_bit(PG_swapcache, const_folio_flags(folio, 0));
VMCOREINFO_NUMBER(PG_swapcache);
(1L << PG_swapcache) |
#define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked))