Machine check recovery broken in v6.9-rc1

[Tony Luck]

v6.8 works. v6.9-rc1 fails with:

kernel BUG at include/linux/swapops.h:119

117 static inline unsigned long swp_offset_pfn(swp_entry_t entry)
118 {
119         VM_BUG_ON(!is_pfn_swap_entry(entry));
120         return swp_offset(entry) & SWP_PFN_MASK;
121 }


I've messed up the bisection three times now and ended up
pointing at some innocent looking commit. So I wonder if
anyone else has noticed and tried debugging.

-Tony