On 3/4/21 9:02 AM, Dave Hansen wrote: >> +#define PAGE_UNUSED 0xFD >> +/* >> + * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges >> + * from unused_pmd_start to next PMD_SIZE boundary. >> + */ >> +static unsigned long unused_pmd_start __meminitdata; > This whole 'unused_pmd_start' thing was unmentioned in the changelog. One tiny suggestion: *Sometimes* for these optimizations, it's easiest to write the code up without it in one patch, then add the optimization in the next patch. It makes it 100% clear what is part of the "core" algorithm and what is pure optimization. I don't know if it will work here, but it might be worth taking a look.
