delete unnecessary bootmem struct page array

From: Honggang Li <[email protected]>

The patch based on linux-next-20140530.

Honggang Li (1):
delete unnecessary bootmem struct page array

 arch/um/kernel/um_arch.c | 6 ------
 1 file changed, 6 deletions(-)

1.8.3.1

From: Honggang Li <[email protected]>

1) uml kernel bootmem managed through bootmem_data->node_bootmem_map, not the struct page array, so the array is unnecessary.

2) the bootmem struct page array has been pointed by a *local* pointer, struct page *map, in init_maps function. The array can be accessed only in init_maps's scope. As a result, uml kernel wastes about 1% of total memory.

---
 arch/um/kernel/um_arch.c | 6 ------
 1 file changed, 6 deletions(-)

index 6043c76..5aa2d82 100644
@@ -338,12 +338,6 @@ int __init linux_main(int argc, char **argv)
 	start_vm = VMALLOC_START;
 
 	setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
-	if (init_maps(physmem_size, iomem_size, highmem)) {
-		printf("Failed to allocate mem_map for %Lu bytes of physical "
-		       "memory and %Lu bytes of highmem\n", physmem_size,
-		       highmem);
-		exit(1);
-	}
 
 	virtmem_size = physmem_size;
 	stack = (unsigned long) argv;

1.8.3.1

Am 01.06.2014 15:08, schrieb Real Name:

I reread your patch again.
You missed one important point. init_maps() setups max_mapnr which is used by virt_addr_valid().

We have to be extremely careful here to not introduce a subtle fuckup.

Thanks,
//richard