Commit ba914f48 authored Dec 12, 2014 by Zhong Hongbo Committed by Linus Torvalds Dec 13, 2014

mm: remove the highmem zones' memmap in the highmem zone



Since 01cefaef ("mm: provide more accurate estimation
of pages occupied by memmap") allocate the pages from lowmem for the
highmem zones' memmap. So It is not need to reserver the memmap's for
the highmem.

A 2G DDR3 for the arm platform:
On node 0 totalpages: 524288
free_area_init_node: node 0, pgdat 80ccd380, node_mem_map 80d38000
  DMA zone: 3568 pages used for memmap
  DMA zone: 0 pages reserved
  DMA zone: 456704 pages, LIFO batch:31
  HighMem zone: 528 pages used for memmap
  HighMem zone: 67584 pages, LIFO batch:15

On node 0 totalpages: 524288
free_area_init_node: node 0, pgdat 80cd6f40, node_mem_map 80d42000
  DMA zone: 3568 pages used for memmap
  DMA zone: 0 pages reserved
  DMA zone: 456704 pages, LIFO batch:31
  HighMem zone: 67584 pages, LIFO batch:15

Signed-off-by: Hongbo Zhong <hongbo.zhong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 2ebba6b7

mm/page_alloc.c

+12 −10

Original line number	Diff line number	Diff line
		@@ -4937,6 +4937,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
		* and per-cpu initialisations
		*/
		memmap_pages = calc_memmap_size(size, realsize);
		if (!is_highmem_idx(j)) {
		if (freesize >= memmap_pages) {
		freesize -= memmap_pages;
		if (memmap_pages)
		@@ -4947,6 +4948,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
		printk(KERN_WARNING
		" %s zone: %lu pages exceeds freesize %lu\n",
		zone_names[j], memmap_pages, freesize);
		}

		/* Account for reserved pages */
		if (j == 0 && freesize > dma_reserve) {

Admin message