[PATCH 3.17 039/141] mem-hotplug: reset node managed pages when hot-adding a new pgdat

Greg Kroah-Hartman
2014-11-19T22:28:15Z

From: Tang Chen <tangchen@cn.fujitsu.com>

commit f784a3f19613901ca4539a5b0eed3bdc700e6ee7 upstream.

In free_area_init_core(), zone->managed_pages is set to an approximate
value for lowmem, and will be adjusted when the bootmem allocator frees
pages into the buddy system.

But free_area_init_core() is also called by hotadd_new_pgdat() when
hot-adding memory. As a result, zone->managed_pages of the newly added
node's pgdat is set to an approximate value in the very beginning.

Even if the memory on that node has node been onlined,
/sys/device/system/node/nodeXXX/meminfo has wrong value:

hot-add node2 (memory not onlined)
cat /sys/device/system/node/node2/meminfo
Node 2 MemTotal: 33554432 kB
Node 2 MemFree: 0 kB
Node 2 MemUsed: 33554432 kB
Node 2 Active: 0 kB

This patch fixes this problem by reset node managed pages to 0 after
hot-adding a new node.

1. Move reset_managed_pages_done from reset_node_managed_pages() to
reset_all_zones_managed_pages()
2. Make reset_node_managed_pages() non-static
3. Call reset_node_managed_pages() in hotadd_new_pgdat() after pgdat
is initialized

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/bootmem.h | 1 +
mm/bootmem.c | 9 +++++----
mm/memory_hotplug.c | 9 +++++++++
mm/nobootmem.c | 8 +++++---
4 files changed, 20 insertions(+), 7 deletions(-)

--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -46,6 +46,7 @@ extern unsigned long init_bootmem_node(p
extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);

extern unsigned long free_all_bootmem(void);
+extern void reset_node_managed_pages(pg_data_t *pgdat);
extern void reset_all_zones_managed_pages(void);

extern void free_bootmem_node(pg_data_t *pgdat,
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -243,13 +243,10 @@ static unsigned long __init free_all_boo

static int reset_managed_pages_done __initdata;

-static inline void __init reset_node_managed_pages(pg_data_t *pgdat)
+void reset_node_managed_pages(pg_data_t *pgdat)
{
struct zone *z;

- if (reset_managed_pages_done)
- return;
-
for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
z->managed_pages = 0;
}
@@ -258,8 +255,12 @@ void __init reset_all_zones_managed_page
{
struct pglist_data *pgdat;

+ if (reset_managed_pages_done)
+ return;
+
for_each_online_pgdat(pgdat)
reset_node_managed_pages(pgdat);
+
reset_managed_pages_done = 1;
}

--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -31,6 +31,7 @@
#include <linux/stop_machine.h>
#include <linux/hugetlb.h>
#include <linux/memblock.h>
+#include <linux/bootmem.h>

#include <asm/tlbflush.h>

@@ -1096,6 +1097,14 @@ static pg_data_t __ref *hotadd_new_pgdat
build_all_zonelists(pgdat, NULL);
mutex_unlock(&zonelists_mutex);

+ /*
+ * zone->managed_pages is set to an approximate value in
+ * free_area_init_core(), which will cause
+ * /sys/device/system/node/nodeX/meminfo has wrong data.
+ * So reset it to 0 before any memory is onlined.
+ */
+ reset_node_managed_pages(pgdat);
+
return pgdat;
}

--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -145,12 +145,10 @@ static unsigned long __init free_low_mem

static int reset_managed_pages_done __initdata;

-static inline void __init reset_node_managed_pages(pg_data_t *pgdat)
+void reset_node_managed_pages(pg_data_t *pgdat)
{
struct zone *z;

- if (reset_managed_pages_done)
- return;
for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
z->managed_pages = 0;
}
@@ -159,8 +157,12 @@ void __init reset_all_zones_managed_page
{
struct pglist_data *pgdat;

+ if (reset_managed_pages_done)
+ return;
+
for_each_online_pgdat(pgdat)
reset_node_managed_pages(pgdat);
+
reset_managed_pages_done = 1;
}