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Subject[PART1 Patch 1/3] mm, memory-hotplug: dynamic configure movable memory and portion memory
Date
From: Lai Jiangshan <laijs@cn.fujitsu.com>

Add online_movable and online_kernel for logic memory hotplug.
This is the dynamic version of "movablecore" & "kernelcore".

We have the same reason to introduce it as to introduce "movablecore" & "kernelcore".
It has the same motive as "movablecore" & "kernelcore", but it is dynamic/running-time:

o We can configure memory as kernelcore or movablecore after boot.

Userspace workload is increased, we need more hugepage, we can't
use "online_movable" to add memory and allow the system use more
THP(transparent-huge-page), vice-verse when kernel workload is increase.

Also help for virtualization to dynamic configure host/guest's memory,
to save/(reduce waste) memory.

Memory capacity on Demand

o When a new node is physically online after boot, we need to use
"online_movable" or "online_kernel" to configure/portion it
as we expected when we logic-online it.

This configuration also helps for physically-memory-migrate.

o all benefit as the same as existed "movablecore" & "kernelcore".

o Preparing for movable-node, which is very important for power-saving,
hardware partitioning and high-available-system(hardware fault management).

(Note, we don't introduce movable-node here.)

Action behavior:
When a memoryblock/memorysection is onlined by "online_movable", the kernel
will not have directly reference to the page of the memoryblock,
thus we can remove that memory any time when needed.

When it is online by "online_kernel", the kernel can use it.
When it is online by "online", the zone type doesn't changed.

Current constraints:
Only the memoryblock which is adjacent to the ZONE_MOVABLE
can be online from ZONE_NORMAL to ZONE_MOVABLE.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
Documentation/memory-hotplug.txt | 14 +++++-
drivers/base/memory.c | 27 +++++++----
include/linux/memory_hotplug.h | 13 ++++-
mm/memory_hotplug.c | 101 ++++++++++++++++++++++++++++++++++++++-
4 files changed, 142 insertions(+), 13 deletions(-)

diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt
index 6e6cbc7..c6f993d 100644
--- a/Documentation/memory-hotplug.txt
+++ b/Documentation/memory-hotplug.txt
@@ -161,7 +161,8 @@ a recent addition and not present on older kernels.
in the memory block.
'state' : read-write
at read: contains online/offline state of memory.
- at write: user can specify "online", "offline" command
+ at write: user can specify "online_kernel",
+ "online_movable", "online", "offline" command
which will be performed on al sections in the block.
'phys_device' : read-only: designed to show the name of physical memory
device. This is not well implemented now.
@@ -255,6 +256,17 @@ For onlining, you have to write "online" to the section's state file as:

% echo online > /sys/devices/system/memory/memoryXXX/state

+This onlining will not change the ZONE type of the target memory section,
+If the memory section is in ZONE_NORMAL, you can change it to ZONE_MOVABLE:
+
+% echo online_movable > /sys/devices/system/memory/memoryXXX/state
+(NOTE: current limit: this memory section must be adjacent to ZONE_MOVABLE)
+
+And if the memory section is in ZONE_MOVABLE, you can change it to ZONE_NORMAL:
+
+% echo online_kernel > /sys/devices/system/memory/memoryXXX/state
+(NOTE: current limit: this memory section must be adjacent to ZONE_NORMAL)
+
After this, section memoryXXX's state will be 'online' and the amount of
available memory will be increased.

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 86c8821..15a1dd7 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -246,7 +246,7 @@ static bool pages_correctly_reserved(unsigned long start_pfn,
* OK to have direct references to sparsemem variables in here.
*/
static int
-memory_block_action(unsigned long phys_index, unsigned long action)
+memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
{
unsigned long start_pfn;
unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
@@ -261,7 +261,7 @@ memory_block_action(unsigned long phys_index, unsigned long action)
if (!pages_correctly_reserved(start_pfn, nr_pages))
return -EBUSY;

- ret = online_pages(start_pfn, nr_pages);
+ ret = online_pages(start_pfn, nr_pages, online_type);
break;
case MEM_OFFLINE:
ret = offline_pages(start_pfn, nr_pages);
@@ -276,7 +276,8 @@ memory_block_action(unsigned long phys_index, unsigned long action)
}

static int __memory_block_change_state(struct memory_block *mem,
- unsigned long to_state, unsigned long from_state_req)
+ unsigned long to_state, unsigned long from_state_req,
+ int online_type)
{
int ret = 0;

@@ -288,7 +289,7 @@ static int __memory_block_change_state(struct memory_block *mem,
if (to_state == MEM_OFFLINE)
mem->state = MEM_GOING_OFFLINE;

- ret = memory_block_action(mem->start_section_nr, to_state);
+ ret = memory_block_action(mem->start_section_nr, to_state, online_type);

if (ret) {
mem->state = from_state_req;
@@ -311,12 +312,14 @@ out:
}

static int memory_block_change_state(struct memory_block *mem,
- unsigned long to_state, unsigned long from_state_req)
+ unsigned long to_state, unsigned long from_state_req,
+ int online_type)
{
int ret;

mutex_lock(&mem->state_mutex);
- ret = __memory_block_change_state(mem, to_state, from_state_req);
+ ret = __memory_block_change_state(mem, to_state, from_state_req,
+ online_type);
mutex_unlock(&mem->state_mutex);

return ret;
@@ -330,10 +333,14 @@ store_mem_state(struct device *dev,

mem = container_of(dev, struct memory_block, dev);

- if (!strncmp(buf, "online", min((int)count, 6)))
- ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
+ if (!strncmp(buf, "online_kernel", min((int)count, 13)))
+ ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE, ONLINE_KERNEL);
+ else if (!strncmp(buf, "online_movable", min((int)count, 14)))
+ ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE, ONLINE_MOVABLE);
+ else if (!strncmp(buf, "online", min((int)count, 6)))
+ ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE, ONLINE_KEEP);
else if(!strncmp(buf, "offline", min((int)count, 7)))
- ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
+ ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE, -1);

if (ret)
return ret;
@@ -669,7 +676,7 @@ int offline_memory_block(struct memory_block *mem)

mutex_lock(&mem->state_mutex);
if (mem->state != MEM_OFFLINE)
- ret = __memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
+ ret = __memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE, -1);
mutex_unlock(&mem->state_mutex);

return ret;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 95573ec..4a45c4e 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -26,6 +26,13 @@ enum {
MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE = NODE_INFO,
};

+/* Types for control the zone type of onlined memory */
+enum {
+ ONLINE_KEEP,
+ ONLINE_KERNEL,
+ ONLINE_MOVABLE,
+};
+
/*
* pgdat resizing functions
*/
@@ -46,6 +53,10 @@ void pgdat_resize_init(struct pglist_data *pgdat)
}
/*
* Zone resizing functions
+ *
+ * Note: any attempt to resize a zone should has pgdat_resize_lock()
+ * zone_span_writelock() both held. This ensure the size of a zone
+ * can't be changed while pgdat_resize_lock() held.
*/
static inline unsigned zone_span_seqbegin(struct zone *zone)
{
@@ -71,7 +82,7 @@ extern int zone_grow_free_lists(struct zone *zone, unsigned long new_nr_pages);
extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
/* VM interface that may be used by firmware interface */
-extern int online_pages(unsigned long, unsigned long);
+extern int online_pages(unsigned long, unsigned long, int);
extern void __offline_isolated_pages(unsigned long, unsigned long);

typedef void (*online_page_callback_t)(struct page *page);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dfa6a91..4900025 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -221,6 +221,89 @@ static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
zone_span_writeunlock(zone);
}

+static void resize_zone(struct zone *zone, unsigned long start_pfn,
+ unsigned long end_pfn)
+{
+
+ zone_span_writelock(zone);
+
+ zone->zone_start_pfn = start_pfn;
+ zone->spanned_pages = end_pfn - start_pfn;
+
+ zone_span_writeunlock(zone);
+}
+
+static void fix_zone_id(struct zone *zone, unsigned long start_pfn,
+ unsigned long end_pfn)
+{
+ enum zone_type zid = zone_idx(zone);
+ int nid = zone->zone_pgdat->node_id;
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn++)
+ set_page_links(pfn_to_page(pfn), zid, nid, pfn);
+}
+
+static int move_pfn_range_left(struct zone *z1, struct zone *z2,
+ unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long flags;
+
+ pgdat_resize_lock(z1->zone_pgdat, &flags);
+
+ /* can't move pfns which are higher than @z2 */
+ if (end_pfn > z2->zone_start_pfn + z2->spanned_pages)
+ goto out_fail;
+ /* the move out part mast at the left most of @z2 */
+ if (start_pfn > z2->zone_start_pfn)
+ goto out_fail;
+ /* must included/overlap */
+ if (end_pfn <= z2->zone_start_pfn)
+ goto out_fail;
+
+ resize_zone(z1, z1->zone_start_pfn, end_pfn);
+ resize_zone(z2, end_pfn, z2->zone_start_pfn + z2->spanned_pages);
+
+ pgdat_resize_unlock(z1->zone_pgdat, &flags);
+
+ fix_zone_id(z1, start_pfn, end_pfn);
+
+ return 0;
+out_fail:
+ pgdat_resize_unlock(z1->zone_pgdat, &flags);
+ return -1;
+}
+
+static int move_pfn_range_right(struct zone *z1, struct zone *z2,
+ unsigned long start_pfn, unsigned long end_pfn)
+{
+ unsigned long flags;
+
+ pgdat_resize_lock(z1->zone_pgdat, &flags);
+
+ /* can't move pfns which are lower than @z1 */
+ if (z1->zone_start_pfn > start_pfn)
+ goto out_fail;
+ /* the move out part mast at the right most of @z1 */
+ if (z1->zone_start_pfn + z1->spanned_pages > end_pfn)
+ goto out_fail;
+ /* must included/overlap */
+ if (start_pfn >= z1->zone_start_pfn + z1->spanned_pages)
+ goto out_fail;
+
+ resize_zone(z1, z1->zone_start_pfn, start_pfn);
+ resize_zone(z2, start_pfn, z2->zone_start_pfn + z2->spanned_pages);
+
+ pgdat_resize_unlock(z1->zone_pgdat, &flags);
+
+ fix_zone_id(z2, start_pfn, end_pfn);
+
+ return 0;
+out_fail:
+ pgdat_resize_unlock(z1->zone_pgdat, &flags);
+ return -1;
+}
+
static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
unsigned long end_pfn)
{
@@ -515,7 +598,7 @@ static void node_states_set_node(int node, struct memory_notify *arg)
}


-int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
{
unsigned long onlined_pages = 0;
struct zone *zone;
@@ -532,6 +615,22 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
*/
zone = page_zone(pfn_to_page(pfn));

+ if (online_type == ONLINE_KERNEL && zone_idx(zone) == ZONE_MOVABLE) {
+ if (move_pfn_range_left(zone - 1, zone, pfn, pfn + nr_pages)) {
+ unlock_memory_hotplug();
+ return -1;
+ }
+ }
+ if (online_type == ONLINE_MOVABLE && zone_idx(zone) == ZONE_MOVABLE - 1) {
+ if (move_pfn_range_right(zone, zone + 1, pfn, pfn + nr_pages)) {
+ unlock_memory_hotplug();
+ return -1;
+ }
+ }
+
+ /* Previous code may changed the zone of the pfn range */
+ zone = page_zone(pfn_to_page(pfn));
+
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
node_states_check_changes_online(nr_pages, zone, &arg);
--
1.8.0


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