kalloc.c
void
freerange(void *vstart, void *vend)
{
  char *p;
  p = (char*)PGROUNDUP((uint)vstart);
  for(; p + PGSIZE <= (char*)vend; p += PGSIZE*2) // free every OTHER page
    kfree(p);
}
// free all pages within the range vstart, vend and add to freelist
free all pages within the range vstart, vend and add to freelist
free all pages within the range vstart vend and add to freelist
void
freerange(void *vstart, void *vend)
{
  char *p;
  p = (char*)PGROUNDUP((uint)vstart);
  for(; p + PGSIZE <= (char*)vend; p += PGSIZE*2) 
    kfree(p);
}
void freerange ( void * vstart , void * vend ) { char * p ; p = ( char * ) PGROUNDUP ( ( uint ) vstart ) ; for ( ; p + PGSIZE <= ( char * ) vend ; p += PGSIZE * 2 ) kfree ( p ) ; }
free all pages within the range vstart, vend and add to freelist
free all pages within the range vstart vend and add to freelist
// free every OTHER page