The patch titled
Subject: memory-hotplug: add zone_for_memory() for selecting zone for new memory
has been added to the -mm tree. Its filename is
memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory.patch
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------------------------------------------------------
From: Wang Nan <wangnan0@xxxxxxxxxx>
Subject: memory-hotplug: add zone_for_memory() for selecting zone for new memory
This series of patches fixes a problem when adding memory in bad manner.
For example: for a x86_64 machine booted with "mem=400M" and with 2GiB
memory installed, following commands cause problem:
# echo 0x40000000 > /sys/devices/system/memory/probe
[ 28.613895] init_memory_mapping: [mem 0x40000000-0x47ffffff]
# echo 0x48000000 > /sys/devices/system/memory/probe
[ 28.693675] init_memory_mapping: [mem 0x48000000-0x4fffffff]
# echo online_movable > /sys/devices/system/memory/memory9/state
# echo 0x50000000 > /sys/devices/system/memory/probe
[ 29.084090] init_memory_mapping: [mem 0x50000000-0x57ffffff]
# echo 0x58000000 > /sys/devices/system/memory/probe
[ 29.151880] init_memory_mapping: [mem 0x58000000-0x5fffffff]
# echo online_movable > /sys/devices/system/memory/memory11/state
# echo online> /sys/devices/system/memory/memory8/state
# echo online> /sys/devices/system/memory/memory10/state
# echo offline> /sys/devices/system/memory/memory9/state
[ 30.558819] Offlined Pages 32768
# free
total used free shared buffers cached
Mem: 780588 18014398509432020 830552 0 0 51180
-/+ buffers/cache: 18014398509380840 881732
Swap: 0 0 0
This is because the above commands probe higher memory after online a
section with online_movable, which causes ZONE_HIGHMEM (or ZONE_NORMAL for
systems without ZONE_HIGHMEM) overlaps ZONE_MOVABLE.
After the second online_movable, the problem can be observed from
zoneinfo:
# cat /proc/zoneinfo
...
Node 0, zone Movable
pages free 65491
min 250
low 312
high 375
scanned 0
spanned 18446744073709518848
present 65536
managed 65536
...
This series of patches solve the problem by checking ZONE_MOVABLE when
choosing zone for new memory. If new memory is inside or higher than
ZONE_MOVABLE, makes it go there instead.
After applying this series of patches, following are free and zoneinfo
result (after offlining memory9):
bash-4.2# free
total used free shared buffers cached
Mem: 780956 80112 700844 0 0 51180
-/+ buffers/cache: 28932 752024
Swap: 0 0 0
bash-4.2# cat /proc/zoneinfo
Node 0, zone DMA
pages free 3389
min 14
low 17
high 21
scanned 0
spanned 4095
present 3998
managed 3977
nr_free_pages 3389
...
start_pfn: 1
inactive_ratio: 1
Node 0, zone DMA32
pages free 73724
min 341
low 426
high 511
scanned 0
spanned 98304
present 98304
managed 92958
nr_free_pages 73724
...
start_pfn: 4096
inactive_ratio: 1
Node 0, zone Normal
pages free 32630
min 120
low 150
high 180
scanned 0
spanned 32768
present 32768
managed 32768
nr_free_pages 32630
...
start_pfn: 262144
inactive_ratio: 1
Node 0, zone Movable
pages free 65476
min 241
low 301
high 361
scanned 0
spanned 98304
present 65536
managed 65536
nr_free_pages 65476
...
start_pfn: 294912
inactive_ratio: 1
This patch (of 7):
Introduce zone_for_memory() in arch independent code for arch_add_memory()
use.
Many arch_add_memory() function simply selects ZONE_HIGHMEM or ZONE_NORMAL
and add new memory into it. However, with the existance of ZONE_MOVABLE,
the selection method should be carefully considered: if new, higher memory
is added after ZONE_MOVABLE is setup, the default zone and ZONE_MOVABLE
may overlap each other.
should_add_memory_movable() checks the status of ZONE_MOVABLE. If it has
already contain memory, compare the address of new memory and movable
memory. If new memory is higher than movable, it should be added into
ZONE_MOVABLE instead of default zone.
Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: "Mel Gorman" <mgorman@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: "Dave Hansen" <dave.hansen@xxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memory_hotplug.h | 1 +
mm/memory_hotplug.c | 28 ++++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff -puN include/linux/memory_hotplug.h~memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory include/linux/memory_hotplug.h
--- a/include/linux/memory_hotplug.h~memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory
+++ a/include/linux/memory_hotplug.h
@@ -259,6 +259,7 @@ static inline void remove_memory(int nid
extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
void *arg, int (*func)(struct memory_block *, void *));
extern int add_memory(int nid, u64 start, u64 size);
+extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default);
extern int arch_add_memory(int nid, u64 start, u64 size);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern bool is_memblock_offlined(struct memory_block *mem);
diff -puN mm/memory_hotplug.c~memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory
+++ a/mm/memory_hotplug.c
@@ -1159,6 +1159,34 @@ static int check_hotplug_memory_range(u6
return 0;
}
+/*
+ * If movable zone has already been setup, newly added memory should be check.
+ * If its address is higher than movable zone, it should be added as movable.
+ * Without this check, movable zone may overlap with other zone.
+ */
+static int should_add_memory_movable(int nid, u64 start, u64 size)
+{
+ unsigned long start_pfn = start >> PAGE_SHIFT;
+ pg_data_t *pgdat = NODE_DATA(nid);
+ struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE;
+
+ if (zone_is_empty(movable_zone))
+ return 0;
+
+ if (movable_zone->zone_start_pfn <= start_pfn)
+ return 1;
+
+ return 0;
+}
+
+int zone_for_memory(int nid, u64 start, u64 size, int zone_default)
+{
+ if (should_add_memory_movable(nid, start, size))
+ return ZONE_MOVABLE;
+
+ return zone_default;
+}
+
/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
int __ref add_memory(int nid, u64 start, u64 size)
{
_
Patches currently in -mm which might be from wangnan0@xxxxxxxxxx are
mem-hotplug-improve-zone_movable_is_highmem-logic.patch
memory-hotplug-add-zone_for_memory-for-selecting-zone-for-new-memory.patch
memory-hotplug-x86_64-suitable-memory-should-go-to-zone_movable.patch
memory-hotplug-x86_32-suitable-memory-should-go-to-zone_movable.patch
memory-hotplug-ia64-suitable-memory-should-go-to-zone_movable.patch
memory-hotplug-ppc-suitable-memory-should-go-to-zone_movable.patch
memory-hotplug-sh-suitable-memory-should-go-to-zone_movable.patch
memory-hotplug-tile-suitable-memory-should-go-to-zone_movable.patch
linux-next.patch
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