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Date: Thu, 1 Feb 2018 15:19:56 +0800
From: Baoquan He <bhe@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org,
kirill.shutemov@...ux.intel.com, mhocko@...e.com,
tglx@...utronix.de, douly.fnst@...fujitsu.com,
Baoquan He <bhe@...hat.com>
Subject: [PATCH 2/2] mm/sparse.c: Add nr_present_sections to change the mem_map allocation
In sparse_init(), we allocate usemap_map and map_map which are pointer
array with the size of NR_MEM_SECTIONS. The memory consumption can be
ignorable in 4-level paging mode. While in 5-level paging, this costs
much memory, 512M. Kdump kernel even can't boot up with a normal
'crashkernel=' setting.
Here add a new variable to record the number of present sections. Let's
allocate the usemap_map and map_map with the size of nr_present_sections.
We only need to make sure that for the ith present section, usemap_map[i]
and map_map[i] store its usemap and mem_map separately.
This change can save much memory on most of systems. Anytime, we should
avoid to define array or allocate memory with the size of NR_MEM_SECTIONS.
Signed-off-by: Baoquan He <bhe@...hat.com>
---
mm/sparse-vmemmap.c | 8 +++++---
mm/sparse.c | 39 +++++++++++++++++++++++++--------------
2 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 315bea91e276..5bb7b63276b3 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -302,6 +302,7 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
unsigned long pnum;
unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
void *vmemmap_buf_start;
+ int i = 0;
size = ALIGN(size, PMD_SIZE);
vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
@@ -312,14 +313,15 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
vmemmap_buf_end = vmemmap_buf_start + size * map_count;
}
- for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+ for (pnum = pnum_begin; pnum < pnum_end && i < map_count; pnum++) {
struct mem_section *ms;
if (!present_section_nr(pnum))
continue;
- map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
- if (map_map[pnum])
+ i++;
+ map_map[i-1] = sparse_mem_map_populate(pnum, nodeid);
+ if (map_map[i-1])
continue;
ms = __nr_to_section(pnum);
pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
diff --git a/mm/sparse.c b/mm/sparse.c
index 54eba92b72a1..18273261be6d 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -202,6 +202,7 @@ static inline int next_present_section_nr(int section_nr)
(section_nr <= __highest_present_section_nr)); \
section_nr = next_present_section_nr(section_nr))
+static int nr_present_sections;
/* Record a memory area against a node. */
void __init memory_present(int nid, unsigned long start, unsigned long end)
{
@@ -231,6 +232,7 @@ void __init memory_present(int nid, unsigned long start, unsigned long end)
ms->section_mem_map = sparse_encode_early_nid(nid) |
SECTION_IS_ONLINE;
section_mark_present(ms);
+ nr_present_sections++;
}
}
}
@@ -399,6 +401,7 @@ static void __init sparse_early_usemaps_alloc_node(void *data,
unsigned long pnum;
unsigned long **usemap_map = (unsigned long **)data;
int size = usemap_size();
+ int i = 0;
usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nodeid),
size * usemap_count);
@@ -407,12 +410,13 @@ static void __init sparse_early_usemaps_alloc_node(void *data,
return;
}
- for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+ for (pnum = pnum_begin; pnum < pnum_end && i < usemap_count; pnum++) {
if (!present_section_nr(pnum))
continue;
- usemap_map[pnum] = usemap;
+ usemap_map[i] = usemap;
usemap += size;
- check_usemap_section_nr(nodeid, usemap_map[pnum]);
+ check_usemap_section_nr(nodeid, usemap_map[i]);
+ i++;
}
}
@@ -440,13 +444,15 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
void *map;
unsigned long pnum;
unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
+ int i;
map = alloc_remap(nodeid, size * map_count);
if (map) {
- for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+ i = 0;
+ for (pnum = pnum_begin; pnum < pnum_end && i < map_count; pnum++) {
if (!present_section_nr(pnum))
continue;
- map_map[pnum] = map;
+ map_map[i] = map;
map += size;
}
return;
@@ -457,23 +463,26 @@ void __init sparse_mem_maps_populate_node(struct page **map_map,
PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
BOOTMEM_ALLOC_ACCESSIBLE, nodeid);
if (map) {
- for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+ i = 0;
+ for (pnum = pnum_begin; pnum < pnum_end && i < map_count; pnum++) {
if (!present_section_nr(pnum))
continue;
- map_map[pnum] = map;
+ map_map[i] = map;
map += size;
}
return;
}
/* fallback */
- for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+ i = 0;
+ for (pnum = pnum_begin; pnum < pnum_end && i < map_count; pnum++) {
struct mem_section *ms;
if (!present_section_nr(pnum))
continue;
- map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
- if (map_map[pnum])
+ i++;
+ map_map[i-1] = sparse_mem_map_populate(pnum, nodeid);
+ if (map_map[i-1])
continue;
ms = __nr_to_section(pnum);
pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
@@ -552,6 +561,7 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func)
/* new start, update count etc*/
nodeid_begin = nodeid;
pnum_begin = pnum;
+ data += map_count;
map_count = 1;
}
/* ok, last chunk */
@@ -570,6 +580,7 @@ void __init sparse_init(void)
unsigned long *usemap;
unsigned long **usemap_map;
int size;
+ int i = 0;
#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
int size2;
struct page **map_map;
@@ -592,7 +603,7 @@ void __init sparse_init(void)
* powerpc need to call sparse_init_one_section right after each
* sparse_early_mem_map_alloc, so allocate usemap_map at first.
*/
- size = sizeof(unsigned long *) * NR_MEM_SECTIONS;
+ size = sizeof(unsigned long *) * nr_present_sections;
usemap_map = memblock_virt_alloc(size, 0);
if (!usemap_map)
panic("can not allocate usemap_map\n");
@@ -600,7 +611,7 @@ void __init sparse_init(void)
(void *)usemap_map);
#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
- size2 = sizeof(struct page *) * NR_MEM_SECTIONS;
+ size2 = sizeof(struct page *) * nr_present_sections;
map_map = memblock_virt_alloc(size2, 0);
if (!map_map)
panic("can not allocate map_map\n");
@@ -611,7 +622,7 @@ void __init sparse_init(void)
for_each_present_section_nr(0, pnum) {
struct mem_section *ms;
ms = __nr_to_section(pnum);
- usemap = usemap_map[pnum];
+ usemap = usemap_map[i];
if (!usemap) {
#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
ms->section_mem_map = 0;
@@ -620,7 +631,7 @@ void __init sparse_init(void)
}
#ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
- map = map_map[pnum];
+ map = map_map[i];
#else
map = sparse_early_mem_map_alloc(pnum);
#endif
--
2.13.6
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