From: Yasuaki Ishimatsu <yasu.isimatu@xxxxxxxxx>
Subject: memory_hotplug: make zone_can_shift() return a boolean value
online_{kernel|movable} is used to change the memory zone to
ZONE_{NORMAL|MOVABLE} and online the memory.
To check that memory zone can be changed, zone_can_shift() is used.
Currently the function returns minus integer value, plus integer
value and 0. When the function returns minus or plus integer value,
it means that the memory zone can be changed to ZONE_{NORNAL|MOVABLE}.
But when the function returns 0, there is 2 meanings.
One of the meanings is that the memory zone does not need to be changed.
For example, when memory is in ZONE_NORMAL and onlined by online_kernel
the memory zone does not need to be changed.
Another meaning is that the memory zone cannot be changed. When memory
is in ZONE_NORMAL and onlined by online_movable, the memory zone may
not be changed to ZONE_MOVALBE due to memory online limitation(see
Documentation/memory-hotplug.txt). In this case, memory must not be
onlined.
The patch changes the return type of zone_can_shift() so that memory
online operation fails when memory zone cannot be changed as follows:
Before applying patch:
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
<snip>
node_scanned 0
spanned 8388608
present 7864320
managed 7864320
# echo online_movable > memory4097/state
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
<snip>
node_scanned 0
spanned 8388608
present 8388608
managed 8388608
online_movable operation succeeded. But memory is onlined as
ZONE_NORMAL, not ZONE_MOVABLE.
After applying patch:
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
<snip>
node_scanned 0
spanned 8388608
present 7864320
managed 7864320
# echo online_movable > memory4097/state
bash: echo: write error: Invalid argument
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
<snip>
node_scanned 0
spanned 8388608
present 7864320
managed 7864320
online_movable operation failed because of failure of changing
the memory zone from ZONE_NORMAL to ZONE_MOVABLE
Fixes: df429ac03936 ("memory-hotplug: more general validation of zone during online")
Link: http://lkml.kernel.org/r/2f9c3837-33d7-b6e5-59c0-6ca4372b2d84@xxxxxxxxx
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Reviewed-by: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/memory.c | 4 ++--
include/linux/memory_hotplug.h | 4 ++--
mm/memory_hotplug.c | 28 +++++++++++++++++-----------
3 files changed, 21 insertions(+), 15 deletions(-)
diff -puN drivers/base/memory.c~memory_hotplug-zone_can_shift-returns-boolean-value drivers/base/memory.c
--- a/drivers/base/memory.c~memory_hotplug-zone_can_shift-returns-boolean-value
+++ a/drivers/base/memory.c
@@ -408,14 +408,14 @@ static ssize_t show_valid_zones(struct d
sprintf(buf, "%s", zone->name);
/* MMOP_ONLINE_KERNEL */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_NORMAL);
+ zone_can_shift(start_pfn, nr_pages, ZONE_NORMAL, &zone_shift);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
}
/* MMOP_ONLINE_MOVABLE */
- zone_shift = zone_can_shift(start_pfn, nr_pages, ZONE_MOVABLE);
+ zone_can_shift(start_pfn, nr_pages, ZONE_MOVABLE, &zone_shift);
if (zone_shift) {
strcat(buf, " ");
strcat(buf, (zone + zone_shift)->name);
diff -puN include/linux/memory_hotplug.h~memory_hotplug-zone_can_shift-returns-boolean-value include/linux/memory_hotplug.h
--- a/include/linux/memory_hotplug.h~memory_hotplug-zone_can_shift-returns-boolean-value
+++ a/include/linux/memory_hotplug.h
@@ -284,7 +284,7 @@ extern void sparse_remove_one_section(st
unsigned long map_offset);
extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
unsigned long pnum);
-extern int zone_can_shift(unsigned long pfn, unsigned long nr_pages,
- enum zone_type target);
+extern bool zone_can_shift(unsigned long pfn, unsigned long nr_pages,
+ enum zone_type target, int *zone_shift);
#endif /* __LINUX_MEMORY_HOTPLUG_H */
diff -puN mm/memory_hotplug.c~memory_hotplug-zone_can_shift-returns-boolean-value mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~memory_hotplug-zone_can_shift-returns-boolean-value
+++ a/mm/memory_hotplug.c
@@ -1033,36 +1033,39 @@ static void node_states_set_node(int nod
node_set_state(node, N_MEMORY);
}
-int zone_can_shift(unsigned long pfn, unsigned long nr_pages,
- enum zone_type target)
+bool zone_can_shift(unsigned long pfn, unsigned long nr_pages,
+ enum zone_type target, int *zone_shift)
{
struct zone *zone = page_zone(pfn_to_page(pfn));
enum zone_type idx = zone_idx(zone);
int i;
+ *zone_shift = 0;
+
if (idx < target) {
/* pages must be at end of current zone */
if (pfn + nr_pages != zone_end_pfn(zone))
- return 0;
+ return false;
/* no zones in use between current zone and target */
for (i = idx + 1; i < target; i++)
if (zone_is_initialized(zone - idx + i))
- return 0;
+ return false;
}
if (target < idx) {
/* pages must be at beginning of current zone */
if (pfn != zone->zone_start_pfn)
- return 0;
+ return false;
/* no zones in use between current zone and target */
for (i = target + 1; i < idx; i++)
if (zone_is_initialized(zone - idx + i))
- return 0;
+ return false;
}
- return target - idx;
+ *zone_shift = target - idx;
+ return true;
}
/* Must be protected by mem_hotplug_begin() */
@@ -1089,10 +1092,13 @@ int __ref online_pages(unsigned long pfn
!can_online_high_movable(zone))
return -EINVAL;
- if (online_type == MMOP_ONLINE_KERNEL)
- zone_shift = zone_can_shift(pfn, nr_pages, ZONE_NORMAL);
- else if (online_type == MMOP_ONLINE_MOVABLE)
- zone_shift = zone_can_shift(pfn, nr_pages, ZONE_MOVABLE);
+ if (online_type == MMOP_ONLINE_KERNEL) {
+ if (!zone_can_shift(pfn, nr_pages, ZONE_NORMAL, &zone_shift))
+ return -EINVAL;
+ } else if (online_type == MMOP_ONLINE_MOVABLE) {
+ if (!zone_can_shift(pfn, nr_pages, ZONE_MOVABLE, &zone_shift))
+ return -EINVAL;
+ }
zone = move_pfn_range(zone_shift, pfn, pfn + nr_pages);
if (!zone)
_
--
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