mm/mm_init.c: don't initialize page->lru again

Current page initialization call flow looks like this with some
simplification:

setup_arch()
  paging_init()
    free_area_init()
      memmap_init()
        memmap_init_zone_range()
	  memmap_init_range()
	    defer_init()
	    __init_single_page()
mm_core_init()
  mem_init()
    memblock_free_all()
      free_low_memory_core_early()
        memmap_init_reserved_pages()
          reserve_bootmem_region()
	    init_reserved_page()
	      __init_single_page()

There two cases depends on CONFIG_DEFERRED_STRUCT_PAGE_INIT.

  * If CONFIG_DEFERRED_STRUCT_PAGE_INIT, pages after first_init_pfn is
    skipped at defer_init(). Then init_reserved_page() is defined to
    call __init_single_page() for them.
  * If !CONFIG_DEFERRED_STRUCT_PAGE_INIT, pages are all initialized by
    memmap_init_range().

In both cases, after init_reserved_page(), we expect __init_single_page()
has done its work to the page, which already initialize page->lru properly.

We don't need to do it again.

Signed-off-by: Wei Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport (IBM) <[email protected]>

Author: RichardWeiYang

mm/mm_init.c

@@ -760,9 +760,6 @@ void __meminit reserve_bootmem_region(phys_addr_t start,
 
 			init_reserved_page(start_pfn, nid);
 
-			/* Avoid false-positive PageTail() */
-			INIT_LIST_HEAD(&page->lru);
-
 			/*
 			 * no need for atomic set_bit because the struct
 			 * page is not visible yet so nobody should