[PATCH] delete unnecessary bootmem struct page array

Real Name
2014-06-03T05:31:24Z

From: Honggang Li <enjoymindful@gmail.com>

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.

Signed-off-by: Honggang Li <enjoymindful@gmail.com>
---
arch/um/include/shared/mem_user.h | 2 +-
arch/um/kernel/physmem.c | 32 ++++++--------------------------
arch/um/kernel/um_arch.c | 7 +------
3 files changed, 8 insertions(+), 33 deletions(-)

diff --git a/arch/um/include/shared/mem_user.h b/arch/um/include/shared/mem_user.h
index 46384ac..cb84414 100644
--- a/arch/um/include/shared/mem_user.h
+++ b/arch/um/include/shared/mem_user.h
@@ -49,7 +49,7 @@ extern int iomem_size;
extern int init_mem_user(void);
extern void setup_memory(void *entry);
extern unsigned long find_iomem(char *driver, unsigned long *len_out);
-extern int init_maps(unsigned long physmem, unsigned long iomem,
+extern void mem_total_pages(unsigned long physmem, unsigned long iomem,
unsigned long highmem);
extern unsigned long get_vm(unsigned long len);
extern void setup_physmem(unsigned long start, unsigned long usable,
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 30fdd5d..549ecf3 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -22,39 +22,19 @@ EXPORT_SYMBOL(high_physmem);

extern unsigned long long physmem_size;

-int __init init_maps(unsigned long physmem, unsigned long iomem,
+void __init mem_total_pages(unsigned long physmem, unsigned long iomem,
unsigned long highmem)
{
- struct page *p, *map;
- unsigned long phys_len, phys_pages, highmem_len, highmem_pages;
- unsigned long iomem_len, iomem_pages, total_len, total_pages;
- int i;
-
- phys_pages = physmem >> PAGE_SHIFT;
- phys_len = phys_pages * sizeof(struct page);
-
- iomem_pages = iomem >> PAGE_SHIFT;
- iomem_len = iomem_pages * sizeof(struct page);
+ unsigned long phys_pages, highmem_pages;
+ unsigned long iomem_pages, total_pages;

+ phys_pages = physmem >> PAGE_SHIFT;
+ iomem_pages = iomem >> PAGE_SHIFT;
highmem_pages = highmem >> PAGE_SHIFT;
- highmem_len = highmem_pages * sizeof(struct page);
-
- total_pages = phys_pages + iomem_pages + highmem_pages;
- total_len = phys_len + iomem_len + highmem_len;

- map = alloc_bootmem_low_pages(total_len);
- if (map == NULL)
- return -ENOMEM;
-
- for (i = 0; i < total_pages; i++) {
- p = &map[i];
- memset(p, 0, sizeof(struct page));
- SetPageReserved(p);
- INIT_LIST_HEAD(&p->lru);
- }
+ total_pages = phys_pages + iomem_pages + highmem_pages;

max_mapnr = total_pages;
- return 0;
}

void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 6043c76..dbd5bda 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -338,12 +338,7 @@ 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);
- }
+ mem_total_pages(physmem_size, iomem_size, highmem);

virtmem_size = physmem_size;
stack = (unsigned long) argv;
--
1.8.3.1