[RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE

[RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE

[Michal Hocko]

Hi,
I am continuing to cleanup the memory hotplug code and
CONFIG_MOVABLE_NODE seems dubious at best. The following two patches
simply removes the flag and make it de-facto always enabled.

The current semantic of the config option is twofold 1) it automatically
binds hotplugable nodes to have memory in zone_movable by default when
movable_node is enabled 2) forbids memory hotplug to online all the memory
as movable when !CONFIG_MOVABLE_NODE.

The later restriction is quite dubious because there is no clear cut of
how much normal memory do we need for a reasonable system operation. A
single memory block which is sufficient to allow further movable
onlines is far from sufficient (e.g a node with >2GB and memblocks
128MB will fill up this zone with struct pages leaving nothing for
other allocations). Removing the config option will not only reduce the
configuration space it also removes quite some code.

The semantic of the movable_node command line parameter is preserved.

The first patch removes the restriction mentioned above and the second
one simply removes all the CONFIG_MOVABLE_NODE related stuff.

Shortlog
Michal Hocko (2):
      mm, memory_hotplug: drop artificial restriction on online/offline
      mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

Diffstat:
 Documentation/admin-guide/kernel-parameters.txt |  7 ++-
 drivers/base/node.c                             |  4 --
 include/linux/memblock.h                        | 18 -------
 include/linux/nodemask.h                        |  4 --
 mm/Kconfig                                      | 26 -----------
 mm/memblock.c                                   |  2 -
 mm/memory_hotplug.c                             | 62 -------------------------
 mm/page_alloc.c                                 |  2 -
 8 files changed, 5 insertions(+), 120 deletions(-)

[RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE

[Michal Hocko]

Hi,
I am continuing to cleanup the memory hotplug code and
CONFIG_MOVABLE_NODE seems dubious at best. The following two patches
simply removes the flag and make it de-facto always enabled.

The current semantic of the config option is twofold 1) it automatically
binds hotplugable nodes to have memory in zone_movable by default when
movable_node is enabled 2) forbids memory hotplug to online all the memory
as movable when !CONFIG_MOVABLE_NODE.

The later restriction is quite dubious because there is no clear cut of
how much normal memory do we need for a reasonable system operation. A
single memory block which is sufficient to allow further movable
onlines is far from sufficient (e.g a node with >2GB and memblocks
128MB will fill up this zone with struct pages leaving nothing for
other allocations). Removing the config option will not only reduce the
configuration space it also removes quite some code.

The semantic of the movable_node command line parameter is preserved.

The first patch removes the restriction mentioned above and the second
one simply removes all the CONFIG_MOVABLE_NODE related stuff.

Shortlog
Michal Hocko (2):
      mm, memory_hotplug: drop artificial restriction on online/offline
      mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

Diffstat:
 Documentation/admin-guide/kernel-parameters.txt |  7 ++-
 drivers/base/node.c                             |  4 --
 include/linux/memblock.h                        | 18 -------
 include/linux/nodemask.h                        |  4 --
 mm/Kconfig                                      | 26 -----------
 mm/memblock.c                                   |  2 -
 mm/memory_hotplug.c                             | 62 -------------------------
 mm/page_alloc.c                                 |  2 -
 8 files changed, 5 insertions(+), 120 deletions(-)


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

From: Michal Hocko <mhocko@suse.com>

74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
memory") has added can_offline_normal which checks the amount of
memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
It disallows to offline memory if there is nothing left with a
justification that "memory-management acts bad when we have nodes which
is online but don't have any normal memory".

74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
memory") has introduced a restriction that every numa node has to have
at least some memory in !movable zones before a first movable memory
can be onlined if !CONFIG_MOVABLE_NODE with the same justification

While it is true that not having _any_ memory for kernel allocations on
a NUMA node is far from great and such a node would be quite subotimal
because all kernel allocations will have to fallback to another NUMA
node but there is no reason to disallow such a configuration in
principle.

Besides that there is not really a big difference to have one memblock
for ZONE_NORMAL available or none. With 128MB size memblocks the system
might trash on the kernel allocations requests anyway. It is really
hard to draw a line on how much normal memory is really sufficient so
we have to rely on administrator to configure system sanely therefore
drop the artificial restriction and remove can_offline_normal and
can_online_high_movable altogether.

Signed-off-by: Michal Hocko <mhocko@suse.com>

mm, memory_hotplug: drop can_online_high_movable

 because "memory-management acts
bad when we have nodes which is online but don't have any normal memory.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 58 -----------------------------------------------------
 1 file changed, 58 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 599c675ad538..10052c2fd400 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 	return 0;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
- * normal memory.
- */
-static bool can_online_high_movable(int nid)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure every online node has NORMAL memory */
-static bool can_online_high_movable(int nid)
-{
-	return node_state(nid, N_NORMAL_MEMORY);
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 /* check which state of node_states will be changed when online memory */
 static void node_states_check_changes_online(unsigned long nr_pages,
 	struct zone *zone, struct memory_notify *arg)
@@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type))
 		return -EINVAL;
 
-	if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid))
-		return -EINVAL;
-
 	/* associate pfn range with the zone */
 	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
 
@@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 	return offlined;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
- * normal memory.
- */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure the node has NORMAL memory if it is still online */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	struct pglist_data *pgdat = zone->zone_pgdat;
-	unsigned long present_pages = 0;
-	enum zone_type zt;
-
-	for (zt = 0; zt <= ZONE_NORMAL; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	if (present_pages > nr_pages)
-		return true;
-
-	present_pages = 0;
-	for (; zt <= ZONE_MOVABLE; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	/*
-	 * we can't offline the last normal memory until all
-	 * higher memory is offlined.
-	 */
-	return present_pages == 0;
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 static int __init cmdline_parse_movable_node(char *p)
 {
 #ifdef CONFIG_MOVABLE_NODE
@@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	node = zone_to_nid(zone);
 	nr_pages = end_pfn - start_pfn;
 
-	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
-		return -EINVAL;
-
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn,
 				       MIGRATE_MOVABLE, true);
-- 
2.11.0

[RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

From: Michal Hocko <mhocko@suse.com>

74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
memory") has added can_offline_normal which checks the amount of
memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
It disallows to offline memory if there is nothing left with a
justification that "memory-management acts bad when we have nodes which
is online but don't have any normal memory".

74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
memory") has introduced a restriction that every numa node has to have
at least some memory in !movable zones before a first movable memory
can be onlined if !CONFIG_MOVABLE_NODE with the same justification

While it is true that not having _any_ memory for kernel allocations on
a NUMA node is far from great and such a node would be quite subotimal
because all kernel allocations will have to fallback to another NUMA
node but there is no reason to disallow such a configuration in
principle.

Besides that there is not really a big difference to have one memblock
for ZONE_NORMAL available or none. With 128MB size memblocks the system
might trash on the kernel allocations requests anyway. It is really
hard to draw a line on how much normal memory is really sufficient so
we have to rely on administrator to configure system sanely therefore
drop the artificial restriction and remove can_offline_normal and
can_online_high_movable altogether.

Signed-off-by: Michal Hocko <mhocko@suse.com>

mm, memory_hotplug: drop can_online_high_movable

 because "memory-management acts
bad when we have nodes which is online but don't have any normal memory.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 58 -----------------------------------------------------
 1 file changed, 58 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 599c675ad538..10052c2fd400 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 	return 0;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
- * normal memory.
- */
-static bool can_online_high_movable(int nid)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure every online node has NORMAL memory */
-static bool can_online_high_movable(int nid)
-{
-	return node_state(nid, N_NORMAL_MEMORY);
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 /* check which state of node_states will be changed when online memory */
 static void node_states_check_changes_online(unsigned long nr_pages,
 	struct zone *zone, struct memory_notify *arg)
@@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type))
 		return -EINVAL;
 
-	if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid))
-		return -EINVAL;
-
 	/* associate pfn range with the zone */
 	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
 
@@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 	return offlined;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
- * normal memory.
- */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure the node has NORMAL memory if it is still online */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	struct pglist_data *pgdat = zone->zone_pgdat;
-	unsigned long present_pages = 0;
-	enum zone_type zt;
-
-	for (zt = 0; zt <= ZONE_NORMAL; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	if (present_pages > nr_pages)
-		return true;
-
-	present_pages = 0;
-	for (; zt <= ZONE_MOVABLE; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	/*
-	 * we can't offline the last normal memory until all
-	 * higher memory is offlined.
-	 */
-	return present_pages == 0;
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 static int __init cmdline_parse_movable_node(char *p)
 {
 #ifdef CONFIG_MOVABLE_NODE
@@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	node = zone_to_nid(zone);
 	nr_pages = end_pfn - start_pfn;
 
-	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
-		return -EINVAL;
-
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn,
 				       MIGRATE_MOVABLE, true);
-- 
2.11.0

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

From: Michal Hocko <mhocko@suse.com>

20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
why it is actually useful. It makes a lot of sense to make movable node
semantic opt in but we already have that because the feature has to be
explicitly enabled on the kernel command line. A config option on top
only makes the configuration space larger without a good reason. It also
adds an additional ifdefery that pollutes the code. Just drop the config
option and make it de-facto always enabled. This shouldn't introduce any
change to the semantic.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  7 +++++--
 drivers/base/node.c                             |  4 ----
 include/linux/memblock.h                        | 18 -----------------
 include/linux/nodemask.h                        |  4 ----
 mm/Kconfig                                      | 26 -------------------------
 mm/memblock.c                                   |  2 --
 mm/memory_hotplug.c                             |  4 ----
 mm/page_alloc.c                                 |  2 --
 8 files changed, 5 insertions(+), 62 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index facc20a3f962..ec7d6ae01c96 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2246,8 +2246,11 @@
 			that the amount of memory usable for all allocations
 			is not too small.
 
-	movable_node	[KNL] Boot-time switch to enable the effects
-			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
+	movable_node	[KNL] Boot-time switch to make hotplugable to be
+			movable. This means that the memory of such nodes
+			will be usable only for movable allocations which
+			rules out almost all kernel allocations. Use with
+			caution!
 
 	MTD_Partition=	[MTD]
 			Format: <name>,<region-number>,<size>,<offset>
diff --git a/drivers/base/node.c b/drivers/base/node.c
index dff5b53f7905..26f4b9c02f2c 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -639,9 +639,7 @@ static struct node_attr node_state_attr[] = {
 #ifdef CONFIG_HIGHMEM
 	[N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	[N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
-#endif
 	[N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
 };
 
@@ -652,9 +650,7 @@ static struct attribute *node_state_attrs[] = {
 #ifdef CONFIG_HIGHMEM
 	&node_state_attr[N_HIGH_MEMORY].attr.attr,
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	&node_state_attr[N_MEMORY].attr.attr,
-#endif
 	&node_state_attr[N_CPU].attr.attr,
 	NULL
 };
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index bdfc65af4152..9622fb8c101b 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,10 +57,8 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-#ifdef CONFIG_MOVABLE_NODE
 /* If movable_node boot option specified */
 extern bool movable_node_enabled;
-#endif /* CONFIG_MOVABLE_NODE */
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -168,7 +166,6 @@ void __next_reserved_mem_region(u64 *idx, phys_addr_t *out_start,
 	     i != (u64)ULLONG_MAX;					\
 	     __next_reserved_mem_region(&i, p_start, p_end))
 
-#ifdef CONFIG_MOVABLE_NODE
 static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_HOTPLUG;
@@ -178,16 +175,6 @@ static inline bool __init_memblock movable_node_is_enabled(void)
 {
 	return movable_node_enabled;
 }
-#else
-static inline bool memblock_is_hotpluggable(struct memblock_region *m)
-{
-	return false;
-}
-static inline bool movable_node_is_enabled(void)
-{
-	return false;
-}
-#endif
 
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
@@ -295,7 +282,6 @@ phys_addr_t memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid)
 
 phys_addr_t memblock_alloc(phys_addr_t size, phys_addr_t align);
 
-#ifdef CONFIG_MOVABLE_NODE
 /*
  * Set the allocation direction to bottom-up or top-down.
  */
@@ -313,10 +299,6 @@ static inline bool memblock_bottom_up(void)
 {
 	return memblock.bottom_up;
 }
-#else
-static inline void __init memblock_set_bottom_up(bool enable) {}
-static inline bool memblock_bottom_up(void) { return false; }
-#endif
 
 /* Flags for memblock_alloc_base() amd __memblock_alloc_base() */
 #define MEMBLOCK_ALLOC_ANYWHERE	(~(phys_addr_t)0)
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index f746e44d4046..cf0b91c3ec12 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -387,11 +387,7 @@ enum node_states {
 #else
 	N_HIGH_MEMORY = N_NORMAL_MEMORY,
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	N_MEMORY,		/* The node has memory(regular, high, movable) */
-#else
-	N_MEMORY = N_HIGH_MEMORY,
-#endif
 	N_CPU,		/* The node has one or more cpus */
 	NR_NODE_STATES
 };
diff --git a/mm/Kconfig b/mm/Kconfig
index 0354a4be5a55..99645f42dc62 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -149,32 +149,6 @@ config NO_BOOTMEM
 config MEMORY_ISOLATION
 	bool
 
-config MOVABLE_NODE
-	bool "Enable to assign a node which has only movable memory"
-	depends on HAVE_MEMBLOCK
-	depends on NO_BOOTMEM
-	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
-	depends on NUMA
-	default n
-	help
-	  Allow a node to have only movable memory.  Pages used by the kernel,
-	  such as direct mapping pages cannot be migrated.  So the corresponding
-	  memory device cannot be hotplugged.  This option allows the following
-	  two things:
-	  - When the system is booting, node full of hotpluggable memory can
-	  be arranged to have only movable memory so that the whole node can
-	  be hot-removed. (need movable_node boot option specified).
-	  - After the system is up, the option allows users to online all the
-	  memory of a node as movable memory so that the whole node can be
-	  hot-removed.
-
-	  Users who don't use the memory hotplug feature are fine with this
-	  option on since they don't specify movable_node boot option or they
-	  don't online memory as movable.
-
-	  Say Y here if you want to hotplug a whole node.
-	  Say N here if you want kernel to use memory on all nodes evenly.
-
 #
 # Only be set on architectures that have completely implemented memory hotplug
 # feature. If you are not sure, don't touch it.
diff --git a/mm/memblock.c b/mm/memblock.c
index 696f06d17c4e..4895f5a6cf7e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,9 +54,7 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-#ifdef CONFIG_MOVABLE_NODE
 bool movable_node_enabled __initdata_memblock = false;
-#endif
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 10052c2fd400..2a14f8c18a22 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1561,11 +1561,7 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 
 static int __init cmdline_parse_movable_node(char *p)
 {
-#ifdef CONFIG_MOVABLE_NODE
 	movable_node_enabled = true;
-#else
-	pr_warn("movable_node option not supported\n");
-#endif
 	return 0;
 }
 early_param("movable_node", cmdline_parse_movable_node);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a26e19c3e1ff..02f5757bf253 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -112,9 +112,7 @@ nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
 #ifdef CONFIG_HIGHMEM
 	[N_HIGH_MEMORY] = { { [0] = 1UL } },
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	[N_MEMORY] = { { [0] = 1UL } },
-#endif
 	[N_CPU] = { { [0] = 1UL } },
 #endif	/* NUMA */
 };
-- 
2.11.0

[RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

From: Michal Hocko <mhocko@suse.com>

20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
why it is actually useful. It makes a lot of sense to make movable node
semantic opt in but we already have that because the feature has to be
explicitly enabled on the kernel command line. A config option on top
only makes the configuration space larger without a good reason. It also
adds an additional ifdefery that pollutes the code. Just drop the config
option and make it de-facto always enabled. This shouldn't introduce any
change to the semantic.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  7 +++++--
 drivers/base/node.c                             |  4 ----
 include/linux/memblock.h                        | 18 -----------------
 include/linux/nodemask.h                        |  4 ----
 mm/Kconfig                                      | 26 -------------------------
 mm/memblock.c                                   |  2 --
 mm/memory_hotplug.c                             |  4 ----
 mm/page_alloc.c                                 |  2 --
 8 files changed, 5 insertions(+), 62 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index facc20a3f962..ec7d6ae01c96 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2246,8 +2246,11 @@
 			that the amount of memory usable for all allocations
 			is not too small.
 
-	movable_node	[KNL] Boot-time switch to enable the effects
-			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
+	movable_node	[KNL] Boot-time switch to make hotplugable to be
+			movable. This means that the memory of such nodes
+			will be usable only for movable allocations which
+			rules out almost all kernel allocations. Use with
+			caution!
 
 	MTD_Partition=	[MTD]
 			Format: <name>,<region-number>,<size>,<offset>
diff --git a/drivers/base/node.c b/drivers/base/node.c
index dff5b53f7905..26f4b9c02f2c 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -639,9 +639,7 @@ static struct node_attr node_state_attr[] = {
 #ifdef CONFIG_HIGHMEM
 	[N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	[N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
-#endif
 	[N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
 };
 
@@ -652,9 +650,7 @@ static struct attribute *node_state_attrs[] = {
 #ifdef CONFIG_HIGHMEM
 	&node_state_attr[N_HIGH_MEMORY].attr.attr,
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	&node_state_attr[N_MEMORY].attr.attr,
-#endif
 	&node_state_attr[N_CPU].attr.attr,
 	NULL
 };
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index bdfc65af4152..9622fb8c101b 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,10 +57,8 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-#ifdef CONFIG_MOVABLE_NODE
 /* If movable_node boot option specified */
 extern bool movable_node_enabled;
-#endif /* CONFIG_MOVABLE_NODE */
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -168,7 +166,6 @@ void __next_reserved_mem_region(u64 *idx, phys_addr_t *out_start,
 	     i != (u64)ULLONG_MAX;					\
 	     __next_reserved_mem_region(&i, p_start, p_end))
 
-#ifdef CONFIG_MOVABLE_NODE
 static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_HOTPLUG;
@@ -178,16 +175,6 @@ static inline bool __init_memblock movable_node_is_enabled(void)
 {
 	return movable_node_enabled;
 }
-#else
-static inline bool memblock_is_hotpluggable(struct memblock_region *m)
-{
-	return false;
-}
-static inline bool movable_node_is_enabled(void)
-{
-	return false;
-}
-#endif
 
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
@@ -295,7 +282,6 @@ phys_addr_t memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid)
 
 phys_addr_t memblock_alloc(phys_addr_t size, phys_addr_t align);
 
-#ifdef CONFIG_MOVABLE_NODE
 /*
  * Set the allocation direction to bottom-up or top-down.
  */
@@ -313,10 +299,6 @@ static inline bool memblock_bottom_up(void)
 {
 	return memblock.bottom_up;
 }
-#else
-static inline void __init memblock_set_bottom_up(bool enable) {}
-static inline bool memblock_bottom_up(void) { return false; }
-#endif
 
 /* Flags for memblock_alloc_base() amd __memblock_alloc_base() */
 #define MEMBLOCK_ALLOC_ANYWHERE	(~(phys_addr_t)0)
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index f746e44d4046..cf0b91c3ec12 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -387,11 +387,7 @@ enum node_states {
 #else
 	N_HIGH_MEMORY = N_NORMAL_MEMORY,
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	N_MEMORY,		/* The node has memory(regular, high, movable) */
-#else
-	N_MEMORY = N_HIGH_MEMORY,
-#endif
 	N_CPU,		/* The node has one or more cpus */
 	NR_NODE_STATES
 };
diff --git a/mm/Kconfig b/mm/Kconfig
index 0354a4be5a55..99645f42dc62 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -149,32 +149,6 @@ config NO_BOOTMEM
 config MEMORY_ISOLATION
 	bool
 
-config MOVABLE_NODE
-	bool "Enable to assign a node which has only movable memory"
-	depends on HAVE_MEMBLOCK
-	depends on NO_BOOTMEM
-	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
-	depends on NUMA
-	default n
-	help
-	  Allow a node to have only movable memory.  Pages used by the kernel,
-	  such as direct mapping pages cannot be migrated.  So the corresponding
-	  memory device cannot be hotplugged.  This option allows the following
-	  two things:
-	  - When the system is booting, node full of hotpluggable memory can
-	  be arranged to have only movable memory so that the whole node can
-	  be hot-removed. (need movable_node boot option specified).
-	  - After the system is up, the option allows users to online all the
-	  memory of a node as movable memory so that the whole node can be
-	  hot-removed.
-
-	  Users who don't use the memory hotplug feature are fine with this
-	  option on since they don't specify movable_node boot option or they
-	  don't online memory as movable.
-
-	  Say Y here if you want to hotplug a whole node.
-	  Say N here if you want kernel to use memory on all nodes evenly.
-
 #
 # Only be set on architectures that have completely implemented memory hotplug
 # feature. If you are not sure, don't touch it.
diff --git a/mm/memblock.c b/mm/memblock.c
index 696f06d17c4e..4895f5a6cf7e 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,9 +54,7 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-#ifdef CONFIG_MOVABLE_NODE
 bool movable_node_enabled __initdata_memblock = false;
-#endif
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 10052c2fd400..2a14f8c18a22 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1561,11 +1561,7 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 
 static int __init cmdline_parse_movable_node(char *p)
 {
-#ifdef CONFIG_MOVABLE_NODE
 	movable_node_enabled = true;
-#else
-	pr_warn("movable_node option not supported\n");
-#endif
 	return 0;
 }
 early_param("movable_node", cmdline_parse_movable_node);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a26e19c3e1ff..02f5757bf253 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -112,9 +112,7 @@ nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
 #ifdef CONFIG_HIGHMEM
 	[N_HIGH_MEMORY] = { { [0] = 1UL } },
 #endif
-#ifdef CONFIG_MOVABLE_NODE
 	[N_MEMORY] = { { [0] = 1UL } },
-#endif
 	[N_CPU] = { { [0] = 1UL } },
 #endif	/* NUMA */
 };
-- 
2.11.0

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Vlastimil Babka]

On 05/24/2017 02:24 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> memory") has added can_offline_normal which checks the amount of
> memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> It disallows to offline memory if there is nothing left with a
> justification that "memory-management acts bad when we have nodes which
> is online but don't have any normal memory".
> 
> 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> memory")

That's the same commit as above... one of them should be different?

> has introduced a restriction that every numa node has to have
> at least some memory in !movable zones before a first movable memory
> can be onlined if !CONFIG_MOVABLE_NODE with the same justification
> 
> While it is true that not having _any_ memory for kernel allocations on
> a NUMA node is far from great and such a node would be quite subotimal
> because all kernel allocations will have to fallback to another NUMA
> node but there is no reason to disallow such a configuration in
> principle.
> 
> Besides that there is not really a big difference to have one memblock
> for ZONE_NORMAL available or none. With 128MB size memblocks the system
> might trash on the kernel allocations requests anyway. It is really
> hard to draw a line on how much normal memory is really sufficient so
> we have to rely on administrator to configure system sanely therefore
> drop the artificial restriction and remove can_offline_normal and
> can_online_high_movable altogether.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

-

> mm, memory_hotplug: drop can_online_high_movable
> 
>  because "memory-management acts
> bad when we have nodes which is online but don't have any normal memory.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

-
Some editing issue?

Otherwise makes sense to me.
Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/memory_hotplug.c | 58 -----------------------------------------------------
>  1 file changed, 58 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 599c675ad538..10052c2fd400 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
>  	return 0;
>  }
>  
> -#ifdef CONFIG_MOVABLE_NODE
> -/*
> - * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
> - * normal memory.
> - */
> -static bool can_online_high_movable(int nid)
> -{
> -	return true;
> -}
> -#else /* CONFIG_MOVABLE_NODE */
> -/* ensure every online node has NORMAL memory */
> -static bool can_online_high_movable(int nid)
> -{
> -	return node_state(nid, N_NORMAL_MEMORY);
> -}
> -#endif /* CONFIG_MOVABLE_NODE */
> -
>  /* check which state of node_states will be changed when online memory */
>  static void node_states_check_changes_online(unsigned long nr_pages,
>  	struct zone *zone, struct memory_notify *arg)
> @@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
>  	if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type))
>  		return -EINVAL;
>  
> -	if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid))
> -		return -EINVAL;
> -
>  	/* associate pfn range with the zone */
>  	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
>  
> @@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
>  	return offlined;
>  }
>  
> -#ifdef CONFIG_MOVABLE_NODE
> -/*
> - * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
> - * normal memory.
> - */
> -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
> -{
> -	return true;
> -}
> -#else /* CONFIG_MOVABLE_NODE */
> -/* ensure the node has NORMAL memory if it is still online */
> -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
> -{
> -	struct pglist_data *pgdat = zone->zone_pgdat;
> -	unsigned long present_pages = 0;
> -	enum zone_type zt;
> -
> -	for (zt = 0; zt <= ZONE_NORMAL; zt++)
> -		present_pages += pgdat->node_zones[zt].present_pages;
> -
> -	if (present_pages > nr_pages)
> -		return true;
> -
> -	present_pages = 0;
> -	for (; zt <= ZONE_MOVABLE; zt++)
> -		present_pages += pgdat->node_zones[zt].present_pages;
> -
> -	/*
> -	 * we can't offline the last normal memory until all
> -	 * higher memory is offlined.
> -	 */
> -	return present_pages == 0;
> -}
> -#endif /* CONFIG_MOVABLE_NODE */
> -
>  static int __init cmdline_parse_movable_node(char *p)
>  {
>  #ifdef CONFIG_MOVABLE_NODE
> @@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  	node = zone_to_nid(zone);
>  	nr_pages = end_pfn - start_pfn;
>  
> -	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
> -		return -EINVAL;
> -
>  	/* set above range as isolated */
>  	ret = start_isolate_page_range(start_pfn, end_pfn,
>  				       MIGRATE_MOVABLE, true);
> 

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Vlastimil Babka]

On 05/24/2017 02:24 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> memory") has added can_offline_normal which checks the amount of
> memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> It disallows to offline memory if there is nothing left with a
> justification that "memory-management acts bad when we have nodes which
> is online but don't have any normal memory".
> 
> 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> memory")

That's the same commit as above... one of them should be different?

> has introduced a restriction that every numa node has to have
> at least some memory in !movable zones before a first movable memory
> can be onlined if !CONFIG_MOVABLE_NODE with the same justification
> 
> While it is true that not having _any_ memory for kernel allocations on
> a NUMA node is far from great and such a node would be quite subotimal
> because all kernel allocations will have to fallback to another NUMA
> node but there is no reason to disallow such a configuration in
> principle.
> 
> Besides that there is not really a big difference to have one memblock
> for ZONE_NORMAL available or none. With 128MB size memblocks the system
> might trash on the kernel allocations requests anyway. It is really
> hard to draw a line on how much normal memory is really sufficient so
> we have to rely on administrator to configure system sanely therefore
> drop the artificial restriction and remove can_offline_normal and
> can_online_high_movable altogether.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

-

> mm, memory_hotplug: drop can_online_high_movable
> 
>  because "memory-management acts
> bad when we have nodes which is online but don't have any normal memory.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

-
Some editing issue?

Otherwise makes sense to me.
Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/memory_hotplug.c | 58 -----------------------------------------------------
>  1 file changed, 58 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 599c675ad538..10052c2fd400 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
>  	return 0;
>  }
>  
> -#ifdef CONFIG_MOVABLE_NODE
> -/*
> - * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
> - * normal memory.
> - */
> -static bool can_online_high_movable(int nid)
> -{
> -	return true;
> -}
> -#else /* CONFIG_MOVABLE_NODE */
> -/* ensure every online node has NORMAL memory */
> -static bool can_online_high_movable(int nid)
> -{
> -	return node_state(nid, N_NORMAL_MEMORY);
> -}
> -#endif /* CONFIG_MOVABLE_NODE */
> -
>  /* check which state of node_states will be changed when online memory */
>  static void node_states_check_changes_online(unsigned long nr_pages,
>  	struct zone *zone, struct memory_notify *arg)
> @@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
>  	if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type))
>  		return -EINVAL;
>  
> -	if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid))
> -		return -EINVAL;
> -
>  	/* associate pfn range with the zone */
>  	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
>  
> @@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
>  	return offlined;
>  }
>  
> -#ifdef CONFIG_MOVABLE_NODE
> -/*
> - * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
> - * normal memory.
> - */
> -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
> -{
> -	return true;
> -}
> -#else /* CONFIG_MOVABLE_NODE */
> -/* ensure the node has NORMAL memory if it is still online */
> -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
> -{
> -	struct pglist_data *pgdat = zone->zone_pgdat;
> -	unsigned long present_pages = 0;
> -	enum zone_type zt;
> -
> -	for (zt = 0; zt <= ZONE_NORMAL; zt++)
> -		present_pages += pgdat->node_zones[zt].present_pages;
> -
> -	if (present_pages > nr_pages)
> -		return true;
> -
> -	present_pages = 0;
> -	for (; zt <= ZONE_MOVABLE; zt++)
> -		present_pages += pgdat->node_zones[zt].present_pages;
> -
> -	/*
> -	 * we can't offline the last normal memory until all
> -	 * higher memory is offlined.
> -	 */
> -	return present_pages == 0;
> -}
> -#endif /* CONFIG_MOVABLE_NODE */
> -
>  static int __init cmdline_parse_movable_node(char *p)
>  {
>  #ifdef CONFIG_MOVABLE_NODE
> @@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  	node = zone_to_nid(zone);
>  	nr_pages = end_pfn - start_pfn;
>  
> -	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
> -		return -EINVAL;
> -
>  	/* set above range as isolated */
>  	ret = start_isolate_page_range(start_pfn, end_pfn,
>  				       MIGRATE_MOVABLE, true);
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/24/2017 02:24 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
> node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
> why it is actually useful. It makes a lot of sense to make movable node
> semantic opt in but we already have that because the feature has to be
> explicitly enabled on the kernel command line. A config option on top
> only makes the configuration space larger without a good reason. It also
> adds an additional ifdefery that pollutes the code. Just drop the config
> option and make it de-facto always enabled. This shouldn't introduce any
> change to the semantic.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

I agree with the intention.

> ---
>  Documentation/admin-guide/kernel-parameters.txt |  7 +++++--
>  drivers/base/node.c                             |  4 ----
>  include/linux/memblock.h                        | 18 -----------------
>  include/linux/nodemask.h                        |  4 ----
>  mm/Kconfig                                      | 26 -------------------------
>  mm/memblock.c                                   |  2 --
>  mm/memory_hotplug.c                             |  4 ----
>  mm/page_alloc.c                                 |  2 --
>  8 files changed, 5 insertions(+), 62 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
>  			that the amount of memory usable for all allocations
>  			is not too small.
>  
> -	movable_node	[KNL] Boot-time switch to enable the effects
> -			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
> +	movable_node	[KNL] Boot-time switch to make hotplugable to be

			hotplugable what, memory? nodes?

> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
>  
>  	MTD_Partition=	[MTD]
>  			Format: <name>,<region-number>,<size>,<offset>

...

> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -149,32 +149,6 @@ config NO_BOOTMEM
>  config MEMORY_ISOLATION
>  	bool
>  
> -config MOVABLE_NODE
> -	bool "Enable to assign a node which has only movable memory"
> -	depends on HAVE_MEMBLOCK
> -	depends on NO_BOOTMEM
> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> -	depends on NUMA

That's a lot of depends. What happens if some of them are not met and
the movable_node bootparam is used?

> -	default n
> -	help
> -	  Allow a node to have only movable memory.  Pages used by the kernel,
> -	  such as direct mapping pages cannot be migrated.  So the corresponding
> -	  memory device cannot be hotplugged.  This option allows the following
> -	  two things:
> -	  - When the system is booting, node full of hotpluggable memory can
> -	  be arranged to have only movable memory so that the whole node can
> -	  be hot-removed. (need movable_node boot option specified).

> -	  - After the system is up, the option allows users to online all the
> -	  memory of a node as movable memory so that the whole node can be
> -	  hot-removed.

Strictly speaking this part is already gone with patch 1/2. Only matters
in case this one is rejected for some reason.

> -	  Users who don't use the memory hotplug feature are fine with this
> -	  option on since they don't specify movable_node boot option or they
> -	  don't online memory as movable.
> -
> -	  Say Y here if you want to hotplug a whole node.
> -	  Say N here if you want kernel to use memory on all nodes evenly.
> -
>  #
>  # Only be set on architectures that have completely implemented memory hotplug
>  # feature. If you are not sure, don't touch it.

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/24/2017 02:24 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> 20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
> node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
> why it is actually useful. It makes a lot of sense to make movable node
> semantic opt in but we already have that because the feature has to be
> explicitly enabled on the kernel command line. A config option on top
> only makes the configuration space larger without a good reason. It also
> adds an additional ifdefery that pollutes the code. Just drop the config
> option and make it de-facto always enabled. This shouldn't introduce any
> change to the semantic.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

I agree with the intention.

> ---
>  Documentation/admin-guide/kernel-parameters.txt |  7 +++++--
>  drivers/base/node.c                             |  4 ----
>  include/linux/memblock.h                        | 18 -----------------
>  include/linux/nodemask.h                        |  4 ----
>  mm/Kconfig                                      | 26 -------------------------
>  mm/memblock.c                                   |  2 --
>  mm/memory_hotplug.c                             |  4 ----
>  mm/page_alloc.c                                 |  2 --
>  8 files changed, 5 insertions(+), 62 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
>  			that the amount of memory usable for all allocations
>  			is not too small.
>  
> -	movable_node	[KNL] Boot-time switch to enable the effects
> -			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
> +	movable_node	[KNL] Boot-time switch to make hotplugable to be

			hotplugable what, memory? nodes?

> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
>  
>  	MTD_Partition=	[MTD]
>  			Format: <name>,<region-number>,<size>,<offset>

...

> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -149,32 +149,6 @@ config NO_BOOTMEM
>  config MEMORY_ISOLATION
>  	bool
>  
> -config MOVABLE_NODE
> -	bool "Enable to assign a node which has only movable memory"
> -	depends on HAVE_MEMBLOCK
> -	depends on NO_BOOTMEM
> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> -	depends on NUMA

That's a lot of depends. What happens if some of them are not met and
the movable_node bootparam is used?

> -	default n
> -	help
> -	  Allow a node to have only movable memory.  Pages used by the kernel,
> -	  such as direct mapping pages cannot be migrated.  So the corresponding
> -	  memory device cannot be hotplugged.  This option allows the following
> -	  two things:
> -	  - When the system is booting, node full of hotpluggable memory can
> -	  be arranged to have only movable memory so that the whole node can
> -	  be hot-removed. (need movable_node boot option specified).

> -	  - After the system is up, the option allows users to online all the
> -	  memory of a node as movable memory so that the whole node can be
> -	  hot-removed.

Strictly speaking this part is already gone with patch 1/2. Only matters
in case this one is rejected for some reason.

> -	  Users who don't use the memory hotplug feature are fine with this
> -	  option on since they don't specify movable_node boot option or they
> -	  don't online memory as movable.
> -
> -	  Say Y here if you want to hotplug a whole node.
> -	  Say N here if you want kernel to use memory on all nodes evenly.
> -
>  #
>  # Only be set on architectures that have completely implemented memory hotplug
>  # feature. If you are not sure, don't touch it.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

On Wed 24-05-17 14:44:34, Vlastimil Babka wrote:
> On 05/24/2017 02:24 PM, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> > memory") has added can_offline_normal which checks the amount of
> > memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> > It disallows to offline memory if there is nothing left with a
> > justification that "memory-management acts bad when we have nodes which
> > is online but don't have any normal memory".
> > 
> > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> > memory")
> 
> That's the same commit as above... one of them should be different?

This used to be two different patches which I decided to fold together
and I didn't realize that both online and offline paths were introduced
by the same patch.
[...]
> Some editing issue?

yes result of merging two commits.

> Otherwise makes sense to me.
> Acked-by: Vlastimil Babka <vbabka@suse.cz>

Thanks! Updated version follows
---
>From 5196f9e206d780ac473075aa0ad88308409f5acb Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Tue, 23 May 2017 10:32:04 +0200
Subject: [PATCH] mm, memory_hotplug: drop artificial restriction on
 online/offline

74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
memory") has introduced a restriction that every numa node has to have
at least some memory in !movable zones before a first movable memory can
be onlined if !CONFIG_MOVABLE_NODE. Likewise_offline_normal checks the
amount of normal memory in !movable zones and it disallows to offline
memory if there is no normal memory left with a justification that
"memory-management acts bad when we have nodes which is online but don't
have any normal memory".

While it is true that not having _any_ memory for kernel allocations on
a NUMA node is far from great and such a node would be quite subotimal
because all kernel allocations will have to fallback to another NUMA
node but there is no reason to disallow such a configuration in
principle.

Besides that there is not really a big difference to have one memblock
for ZONE_NORMAL available or none. With 128MB size memblocks the system
might trash on the kernel allocations requests anyway. It is really
hard to draw a line on how much normal memory is really sufficient so
we have to rely on administrator to configure system sanely therefore
drop the artificial restriction and remove can_offline_normal and
can_online_high_movable altogether.

Acked-by: Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 58 -----------------------------------------------------
 1 file changed, 58 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 599c675ad538..10052c2fd400 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 	return 0;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
- * normal memory.
- */
-static bool can_online_high_movable(int nid)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure every online node has NORMAL memory */
-static bool can_online_high_movable(int nid)
-{
-	return node_state(nid, N_NORMAL_MEMORY);
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 /* check which state of node_states will be changed when online memory */
 static void node_states_check_changes_online(unsigned long nr_pages,
 	struct zone *zone, struct memory_notify *arg)
@@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type))
 		return -EINVAL;
 
-	if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid))
-		return -EINVAL;
-
 	/* associate pfn range with the zone */
 	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
 
@@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 	return offlined;
 }
 
-#ifdef CONFIG_MOVABLE_NODE
-/*
- * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have
- * normal memory.
- */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	return true;
-}
-#else /* CONFIG_MOVABLE_NODE */
-/* ensure the node has NORMAL memory if it is still online */
-static bool can_offline_normal(struct zone *zone, unsigned long nr_pages)
-{
-	struct pglist_data *pgdat = zone->zone_pgdat;
-	unsigned long present_pages = 0;
-	enum zone_type zt;
-
-	for (zt = 0; zt <= ZONE_NORMAL; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	if (present_pages > nr_pages)
-		return true;
-
-	present_pages = 0;
-	for (; zt <= ZONE_MOVABLE; zt++)
-		present_pages += pgdat->node_zones[zt].present_pages;
-
-	/*
-	 * we can't offline the last normal memory until all
-	 * higher memory is offlined.
-	 */
-	return present_pages == 0;
-}
-#endif /* CONFIG_MOVABLE_NODE */
-
 static int __init cmdline_parse_movable_node(char *p)
 {
 #ifdef CONFIG_MOVABLE_NODE
@@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	node = zone_to_nid(zone);
 	nr_pages = end_pfn - start_pfn;
 
-	if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages))
-		return -EINVAL;
-
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn,
 				       MIGRATE_MOVABLE, true);
-- 
2.11.0

-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

On Wed 24-05-17 14:44:34, Vlastimil Babka wrote:
> On 05/24/2017 02:24 PM, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> > memory") has added can_offline_normal which checks the amount of
> > memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> > It disallows to offline memory if there is nothing left with a
> > justification that "memory-management acts bad when we have nodes which
> > is online but don't have any normal memory".
> > 
> > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> > memory")
> 
> That's the same commit as above... one of them should be different?

This used to be two different patches which I decided to fold together
and I didn't realize that both online and offline paths were introduced
by the same patch.
[...]
> Some editing issue?

yes result of merging two commits.

> Otherwise makes sense to me.
> Acked-by: Vlastimil Babka <vbabka@suse.cz>

Thanks! Updated version follows
---

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Igor Mammedov]

On Wed, 24 May 2017 14:24:11 +0200
Michal Hocko <mhocko@kernel.org> wrote:

[...]
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
[...]
> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
maybe dumb question but, is it really true that kernel won't ever
do kernel allocations from movable zone?

looking at kmalloc(slab): we can get here:

get_page_from_freelist() ->
    rmqueue() ->
        __rmqueue() ->
            __rmqueue_fallback() ->
                find_suitable_fallback()

and it might return movable fallback and page could be stolen from there.

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Igor Mammedov]

On Wed, 24 May 2017 14:24:11 +0200
Michal Hocko <mhocko@kernel.org> wrote:

[...]
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
[...]
> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
maybe dumb question but, is it really true that kernel won't ever
do kernel allocations from movable zone?

looking at kmalloc(slab): we can get here:

get_page_from_freelist() ->
    rmqueue() ->
        __rmqueue() ->
            __rmqueue_fallback() ->
                find_suitable_fallback()

and it might return movable fallback and page could be stolen from there.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 14:53:57, Vlastimil Babka wrote:
> On 05/24/2017 02:24 PM, Michal Hocko wrote:
[...]
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index facc20a3f962..ec7d6ae01c96 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2246,8 +2246,11 @@
> >  			that the amount of memory usable for all allocations
> >  			is not too small.
> >  
> > -	movable_node	[KNL] Boot-time switch to enable the effects
> > -			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
> > +	movable_node	[KNL] Boot-time switch to make hotplugable to be
> 
> 			hotplugable what, memory? nodes?


diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ec7d6ae01c96..64aed7386fe4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2246,11 +2246,11 @@
 			that the amount of memory usable for all allocations
 			is not too small.
 
-	movable_node	[KNL] Boot-time switch to make hotplugable to be
-			movable. This means that the memory of such nodes
-			will be usable only for movable allocations which
-			rules out almost all kernel allocations. Use with
-			caution!
+	movable_node	[KNL] Boot-time switch to make hotplugable memory
+			NUMA nodes to be movable. This means that the memory
+			of such nodes will be usable only for movable
+			allocations which rules out almost all kernel
+			allocations. Use with caution!
 
 	MTD_Partition=	[MTD]
 			Format: <name>,<region-number>,<size>,<offset>

Better?

[...]
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -149,32 +149,6 @@ config NO_BOOTMEM
> >  config MEMORY_ISOLATION
> >  	bool
> >  
> > -config MOVABLE_NODE
> > -	bool "Enable to assign a node which has only movable memory"
> > -	depends on HAVE_MEMBLOCK
> > -	depends on NO_BOOTMEM
> > -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> > -	depends on NUMA
> 
> That's a lot of depends. What happens if some of them are not met and
> the movable_node bootparam is used?

Good question. I haven't explored that, to be honest. Now that I am looking closer
I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
mark hotpluggable memory"). NUMA is less clear to me because
MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
NO_BOOTMEM is also not clear to me because zones layout
doesn't really depend on the specific boot time allocator.

So we are left with HAVE_MEMBLOCK which seems to be there because
movable_node_enabled is defined there while the parameter handling is in
the hotplug proper. But there is no real reason to have it like that.
This compiles but I will have to put throw my full compile battery on it
to be sure. I will make it a separate patch.

Thanks!
--- 
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 9622fb8c101b..071692894254 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,8 +57,6 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-/* If movable_node boot option specified */
-extern bool movable_node_enabled;
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 	return m->flags & MEMBLOCK_HOTPLUG;
 }
 
-static inline bool __init_memblock movable_node_is_enabled(void)
-{
-	return movable_node_enabled;
-}
-
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_MIRROR;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 9e0249d0f5e4..9c1ac94f857b 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
 extern int try_online_node(int nid);
 
 extern bool memhp_auto_online;
+/* If movable_node boot option specified */
+extern bool movable_node_enabled;
+static inline bool movable_node_is_enabled(void)
+{
+	return movable_node_enabled;
+}
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
@@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
 static inline void mem_hotplug_begin(void) {}
 static inline void mem_hotplug_done(void) {}
 
+static inline bool __init_memblock movable_node_is_enabled(void)
+{
+	return false;
+}
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
diff --git a/mm/memblock.c b/mm/memblock.c
index 4895f5a6cf7e..8c52fb11510c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-bool movable_node_enabled __initdata_memblock = false;
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2a14f8c18a22..b0d2bf3256d0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -79,6 +79,8 @@ static struct {
 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
 
+bool movable_node_enabled = false;
+
 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
 bool memhp_auto_online;
 #else

-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 14:53:57, Vlastimil Babka wrote:
> On 05/24/2017 02:24 PM, Michal Hocko wrote:
[...]
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index facc20a3f962..ec7d6ae01c96 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2246,8 +2246,11 @@
> >  			that the amount of memory usable for all allocations
> >  			is not too small.
> >  
> > -	movable_node	[KNL] Boot-time switch to enable the effects
> > -			of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
> > +	movable_node	[KNL] Boot-time switch to make hotplugable to be
> 
> 			hotplugable what, memory? nodes?


diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ec7d6ae01c96..64aed7386fe4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2246,11 +2246,11 @@
 			that the amount of memory usable for all allocations
 			is not too small.
 
-	movable_node	[KNL] Boot-time switch to make hotplugable to be
-			movable. This means that the memory of such nodes
-			will be usable only for movable allocations which
-			rules out almost all kernel allocations. Use with
-			caution!
+	movable_node	[KNL] Boot-time switch to make hotplugable memory
+			NUMA nodes to be movable. This means that the memory
+			of such nodes will be usable only for movable
+			allocations which rules out almost all kernel
+			allocations. Use with caution!
 
 	MTD_Partition=	[MTD]
 			Format: <name>,<region-number>,<size>,<offset>

Better?

[...]
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -149,32 +149,6 @@ config NO_BOOTMEM
> >  config MEMORY_ISOLATION
> >  	bool
> >  
> > -config MOVABLE_NODE
> > -	bool "Enable to assign a node which has only movable memory"
> > -	depends on HAVE_MEMBLOCK
> > -	depends on NO_BOOTMEM
> > -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> > -	depends on NUMA
> 
> That's a lot of depends. What happens if some of them are not met and
> the movable_node bootparam is used?

Good question. I haven't explored that, to be honest. Now that I am looking closer
I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
mark hotpluggable memory"). NUMA is less clear to me because
MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
NO_BOOTMEM is also not clear to me because zones layout
doesn't really depend on the specific boot time allocator.

So we are left with HAVE_MEMBLOCK which seems to be there because
movable_node_enabled is defined there while the parameter handling is in
the hotplug proper. But there is no real reason to have it like that.
This compiles but I will have to put throw my full compile battery on it
to be sure. I will make it a separate patch.

Thanks!
--- 
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 9622fb8c101b..071692894254 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,8 +57,6 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-/* If movable_node boot option specified */
-extern bool movable_node_enabled;
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 	return m->flags & MEMBLOCK_HOTPLUG;
 }
 
-static inline bool __init_memblock movable_node_is_enabled(void)
-{
-	return movable_node_enabled;
-}
-
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_MIRROR;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 9e0249d0f5e4..9c1ac94f857b 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
 extern int try_online_node(int nid);
 
 extern bool memhp_auto_online;
+/* If movable_node boot option specified */
+extern bool movable_node_enabled;
+static inline bool movable_node_is_enabled(void)
+{
+	return movable_node_enabled;
+}
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
@@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
 static inline void mem_hotplug_begin(void) {}
 static inline void mem_hotplug_done(void) {}
 
+static inline bool __init_memblock movable_node_is_enabled(void)
+{
+	return false;
+}
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
diff --git a/mm/memblock.c b/mm/memblock.c
index 4895f5a6cf7e..8c52fb11510c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-bool movable_node_enabled __initdata_memblock = false;
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2a14f8c18a22..b0d2bf3256d0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -79,6 +79,8 @@ static struct {
 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
 
+bool movable_node_enabled = false;
+
 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
 bool memhp_auto_online;
 #else

-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 15:30:17, Igor Mammedov wrote:
> On Wed, 24 May 2017 14:24:11 +0200
> Michal Hocko <mhocko@kernel.org> wrote:
> 
> [...]
> > index facc20a3f962..ec7d6ae01c96 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2246,8 +2246,11 @@
> [...]
> > +			movable. This means that the memory of such nodes
> > +			will be usable only for movable allocations which
> > +			rules out almost all kernel allocations. Use with
> > +			caution!
> maybe dumb question but, is it really true that kernel won't ever
> do kernel allocations from movable zone?
> 
> looking at kmalloc(slab): we can get here:
> 
> get_page_from_freelist() ->
>     rmqueue() ->
>         __rmqueue() ->
>             __rmqueue_fallback() ->
>                 find_suitable_fallback()
> 
> and it might return movable fallback and page could be stolen from there.

No, you are mixing movable/unmovable pageblocks and movable zones.
Movable zone basically works the same way as the Highmem zone. Have a
look at gfp_zone() and high_zoneidx usage in get_page_from_freelist
-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 15:30:17, Igor Mammedov wrote:
> On Wed, 24 May 2017 14:24:11 +0200
> Michal Hocko <mhocko@kernel.org> wrote:
> 
> [...]
> > index facc20a3f962..ec7d6ae01c96 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2246,8 +2246,11 @@
> [...]
> > +			movable. This means that the memory of such nodes
> > +			will be usable only for movable allocations which
> > +			rules out almost all kernel allocations. Use with
> > +			caution!
> maybe dumb question but, is it really true that kernel won't ever
> do kernel allocations from movable zone?
> 
> looking at kmalloc(slab): we can get here:
> 
> get_page_from_freelist() ->
>     rmqueue() ->
>         __rmqueue() ->
>             __rmqueue_fallback() ->
>                 find_suitable_fallback()
> 
> and it might return movable fallback and page could be stolen from there.

No, you are mixing movable/unmovable pageblocks and movable zones.
Movable zone basically works the same way as the Highmem zone. Have a
look at gfp_zone() and high_zoneidx usage in get_page_from_freelist
-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/24/2017 03:42 PM, Michal Hocko wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index ec7d6ae01c96..64aed7386fe4 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,11 +2246,11 @@
>  			that the amount of memory usable for all allocations
>  			is not too small.
>  
> -	movable_node	[KNL] Boot-time switch to make hotplugable to be
> -			movable. This means that the memory of such nodes
> -			will be usable only for movable allocations which
> -			rules out almost all kernel allocations. Use with
> -			caution!
> +	movable_node	[KNL] Boot-time switch to make hotplugable memory
> +			NUMA nodes to be movable. This means that the memory
> +			of such nodes will be usable only for movable
> +			allocations which rules out almost all kernel
> +			allocations. Use with caution!
>  
>  	MTD_Partition=	[MTD]
>  			Format: <name>,<region-number>,<size>,<offset>
> 
> Better?

Yes, thanks.

> [...]
>>> --- a/mm/Kconfig
>>> +++ b/mm/Kconfig
>>> @@ -149,32 +149,6 @@ config NO_BOOTMEM
>>>  config MEMORY_ISOLATION
>>>  	bool
>>>  
>>> -config MOVABLE_NODE
>>> -	bool "Enable to assign a node which has only movable memory"
>>> -	depends on HAVE_MEMBLOCK
>>> -	depends on NO_BOOTMEM
>>> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
>>> -	depends on NUMA
>>
>> That's a lot of depends. What happens if some of them are not met and
>> the movable_node bootparam is used?
> 
> Good question. I haven't explored that, to be honest. Now that I am looking closer
> I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
> is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
> mark hotpluggable memory"). NUMA is less clear to me because
> MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
> NO_BOOTMEM is also not clear to me because zones layout
> doesn't really depend on the specific boot time allocator.
> 
> So we are left with HAVE_MEMBLOCK which seems to be there because
> movable_node_enabled is defined there while the parameter handling is in
> the hotplug proper. But there is no real reason to have it like that.
> This compiles but I will have to put throw my full compile battery on it
> to be sure. I will make it a separate patch.

I'd expect stuff might compile and work (run without crash), just in
some cases the boot option could be effectively ignored? In that case
it's just a matter of documenting the option, possibly also some warning
when used, e.g. "node_movable was ignored because CONFIG_FOO is not
enabled"?

Vlastimil

> Thanks!
> --- 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 9622fb8c101b..071692894254 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -57,8 +57,6 @@ struct memblock {
>  
>  extern struct memblock memblock;
>  extern int memblock_debug;
> -/* If movable_node boot option specified */
> -extern bool movable_node_enabled;
>  
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
>  #define __init_memblock __meminit
> @@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
>  	return m->flags & MEMBLOCK_HOTPLUG;
>  }
>  
> -static inline bool __init_memblock movable_node_is_enabled(void)
> -{
> -	return movable_node_enabled;
> -}
> -
>  static inline bool memblock_is_mirror(struct memblock_region *m)
>  {
>  	return m->flags & MEMBLOCK_MIRROR;
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 9e0249d0f5e4..9c1ac94f857b 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
>  extern int try_online_node(int nid);
>  
>  extern bool memhp_auto_online;
> +/* If movable_node boot option specified */
> +extern bool movable_node_enabled;
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return movable_node_enabled;
> +}
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  extern bool is_pageblock_removable_nolock(struct page *page);
> @@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
>  static inline void mem_hotplug_begin(void) {}
>  static inline void mem_hotplug_done(void) {}
>  
> +static inline bool __init_memblock movable_node_is_enabled(void)
> +{
> +	return false;
> +}
>  #endif /* ! CONFIG_MEMORY_HOTPLUG */
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 4895f5a6cf7e..8c52fb11510c 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
>  };
>  
>  int memblock_debug __initdata_memblock;
> -bool movable_node_enabled __initdata_memblock = false;
>  static bool system_has_some_mirror __initdata_memblock = false;
>  static int memblock_can_resize __initdata_memblock;
>  static int memblock_memory_in_slab __initdata_memblock = 0;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 2a14f8c18a22..b0d2bf3256d0 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -79,6 +79,8 @@ static struct {
>  #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
>  #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
>  
> +bool movable_node_enabled = false;
> +
>  #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
>  bool memhp_auto_online;
>  #else
> 

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/24/2017 03:42 PM, Michal Hocko wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index ec7d6ae01c96..64aed7386fe4 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,11 +2246,11 @@
>  			that the amount of memory usable for all allocations
>  			is not too small.
>  
> -	movable_node	[KNL] Boot-time switch to make hotplugable to be
> -			movable. This means that the memory of such nodes
> -			will be usable only for movable allocations which
> -			rules out almost all kernel allocations. Use with
> -			caution!
> +	movable_node	[KNL] Boot-time switch to make hotplugable memory
> +			NUMA nodes to be movable. This means that the memory
> +			of such nodes will be usable only for movable
> +			allocations which rules out almost all kernel
> +			allocations. Use with caution!
>  
>  	MTD_Partition=	[MTD]
>  			Format: <name>,<region-number>,<size>,<offset>
> 
> Better?

Yes, thanks.

> [...]
>>> --- a/mm/Kconfig
>>> +++ b/mm/Kconfig
>>> @@ -149,32 +149,6 @@ config NO_BOOTMEM
>>>  config MEMORY_ISOLATION
>>>  	bool
>>>  
>>> -config MOVABLE_NODE
>>> -	bool "Enable to assign a node which has only movable memory"
>>> -	depends on HAVE_MEMBLOCK
>>> -	depends on NO_BOOTMEM
>>> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
>>> -	depends on NUMA
>>
>> That's a lot of depends. What happens if some of them are not met and
>> the movable_node bootparam is used?
> 
> Good question. I haven't explored that, to be honest. Now that I am looking closer
> I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
> is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
> mark hotpluggable memory"). NUMA is less clear to me because
> MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
> NO_BOOTMEM is also not clear to me because zones layout
> doesn't really depend on the specific boot time allocator.
> 
> So we are left with HAVE_MEMBLOCK which seems to be there because
> movable_node_enabled is defined there while the parameter handling is in
> the hotplug proper. But there is no real reason to have it like that.
> This compiles but I will have to put throw my full compile battery on it
> to be sure. I will make it a separate patch.

I'd expect stuff might compile and work (run without crash), just in
some cases the boot option could be effectively ignored? In that case
it's just a matter of documenting the option, possibly also some warning
when used, e.g. "node_movable was ignored because CONFIG_FOO is not
enabled"?

Vlastimil

> Thanks!
> --- 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 9622fb8c101b..071692894254 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -57,8 +57,6 @@ struct memblock {
>  
>  extern struct memblock memblock;
>  extern int memblock_debug;
> -/* If movable_node boot option specified */
> -extern bool movable_node_enabled;
>  
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
>  #define __init_memblock __meminit
> @@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
>  	return m->flags & MEMBLOCK_HOTPLUG;
>  }
>  
> -static inline bool __init_memblock movable_node_is_enabled(void)
> -{
> -	return movable_node_enabled;
> -}
> -
>  static inline bool memblock_is_mirror(struct memblock_region *m)
>  {
>  	return m->flags & MEMBLOCK_MIRROR;
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 9e0249d0f5e4..9c1ac94f857b 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
>  extern int try_online_node(int nid);
>  
>  extern bool memhp_auto_online;
> +/* If movable_node boot option specified */
> +extern bool movable_node_enabled;
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return movable_node_enabled;
> +}
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  extern bool is_pageblock_removable_nolock(struct page *page);
> @@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
>  static inline void mem_hotplug_begin(void) {}
>  static inline void mem_hotplug_done(void) {}
>  
> +static inline bool __init_memblock movable_node_is_enabled(void)
> +{
> +	return false;
> +}
>  #endif /* ! CONFIG_MEMORY_HOTPLUG */
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 4895f5a6cf7e..8c52fb11510c 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
>  };
>  
>  int memblock_debug __initdata_memblock;
> -bool movable_node_enabled __initdata_memblock = false;
>  static bool system_has_some_mirror __initdata_memblock = false;
>  static int memblock_can_resize __initdata_memblock;
>  static int memblock_memory_in_slab __initdata_memblock = 0;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 2a14f8c18a22..b0d2bf3256d0 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -79,6 +79,8 @@ static struct {
>  #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
>  #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
>  
> +bool movable_node_enabled = false;
> +
>  #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
>  bool memhp_auto_online;
>  #else
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Reza Arbab]

On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote:
>74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
>memory") has added can_offline_normal which checks the amount of
>memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
>It disallows to offline memory if there is nothing left with a
>justification that "memory-management acts bad when we have nodes which
>is online but don't have any normal memory".
>
>74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
>memory") has introduced a restriction that every numa node has to have
>at least some memory in !movable zones before a first movable memory
>can be onlined if !CONFIG_MOVABLE_NODE with the same justification
>
>While it is true that not having _any_ memory for kernel allocations on
>a NUMA node is far from great and such a node would be quite subotimal
>because all kernel allocations will have to fallback to another NUMA
>node but there is no reason to disallow such a configuration in
>principle.
>
>Besides that there is not really a big difference to have one memblock
>for ZONE_NORMAL available or none. With 128MB size memblocks the system
>might trash on the kernel allocations requests anyway. It is really
>hard to draw a line on how much normal memory is really sufficient so
>we have to rely on administrator to configure system sanely therefore
>drop the artificial restriction and remove can_offline_normal and
>can_online_high_movable altogether.

I'm really liking all this cleanup of the memory hotplug code. Thanks!  
Much appreciated.

Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

-- 
Reza Arbab

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Reza Arbab]

On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote:
>74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
>memory") has added can_offline_normal which checks the amount of
>memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
>It disallows to offline memory if there is nothing left with a
>justification that "memory-management acts bad when we have nodes which
>is online but don't have any normal memory".
>
>74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
>memory") has introduced a restriction that every numa node has to have
>at least some memory in !movable zones before a first movable memory
>can be onlined if !CONFIG_MOVABLE_NODE with the same justification
>
>While it is true that not having _any_ memory for kernel allocations on
>a NUMA node is far from great and such a node would be quite subotimal
>because all kernel allocations will have to fallback to another NUMA
>node but there is no reason to disallow such a configuration in
>principle.
>
>Besides that there is not really a big difference to have one memblock
>for ZONE_NORMAL available or none. With 128MB size memblocks the system
>might trash on the kernel allocations requests anyway. It is really
>hard to draw a line on how much normal memory is really sufficient so
>we have to rely on administrator to configure system sanely therefore
>drop the artificial restriction and remove can_offline_normal and
>can_online_high_movable altogether.

I'm really liking all this cleanup of the memory hotplug code. Thanks!  
Much appreciated.

Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

-- 
Reza Arbab

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Reza Arbab]

On Wed, May 24, 2017 at 02:24:11PM +0200, Michal Hocko wrote:
>20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
>node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
>why it is actually useful. It makes a lot of sense to make movable node
>semantic opt in but we already have that because the feature has to be
>explicitly enabled on the kernel command line. A config option on top
>only makes the configuration space larger without a good reason. It also
>adds an additional ifdefery that pollutes the code. Just drop the config
>option and make it de-facto always enabled. This shouldn't introduce any
>change to the semantic.

Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

-- 
Reza Arbab

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Reza Arbab]

On Wed, May 24, 2017 at 02:24:11PM +0200, Michal Hocko wrote:
>20b2f52b73fe ("numa: add CONFIG_MOVABLE_NODE for movable-dedicated
>node") has introduced CONFIG_MOVABLE_NODE without a good explanation on
>why it is actually useful. It makes a lot of sense to make movable node
>semantic opt in but we already have that because the feature has to be
>explicitly enabled on the kernel command line. A config option on top
>only makes the configuration space larger without a good reason. It also
>adds an additional ifdefery that pollutes the code. Just drop the config
>option and make it de-facto always enabled. This shouldn't introduce any
>change to the semantic.

Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

-- 
Reza Arbab

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 17:17:08, Vlastimil Babka wrote:
> On 05/24/2017 03:42 PM, Michal Hocko wrote:
[...]
> >>> --- a/mm/Kconfig
> >>> +++ b/mm/Kconfig
> >>> @@ -149,32 +149,6 @@ config NO_BOOTMEM
> >>>  config MEMORY_ISOLATION
> >>>  	bool
> >>>  
> >>> -config MOVABLE_NODE
> >>> -	bool "Enable to assign a node which has only movable memory"
> >>> -	depends on HAVE_MEMBLOCK
> >>> -	depends on NO_BOOTMEM
> >>> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> >>> -	depends on NUMA
> >>
> >> That's a lot of depends. What happens if some of them are not met and
> >> the movable_node bootparam is used?
> > 
> > Good question. I haven't explored that, to be honest. Now that I am looking closer
> > I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
> > is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
> > mark hotpluggable memory"). NUMA is less clear to me because
> > MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
> > NO_BOOTMEM is also not clear to me because zones layout
> > doesn't really depend on the specific boot time allocator.
> > 
> > So we are left with HAVE_MEMBLOCK which seems to be there because
> > movable_node_enabled is defined there while the parameter handling is in
> > the hotplug proper. But there is no real reason to have it like that.
> > This compiles but I will have to put throw my full compile battery on it
> > to be sure. I will make it a separate patch.
> 
> I'd expect stuff might compile and work (run without crash), just in
> some cases the boot option could be effectively ignored? In that case
> it's just a matter of documenting the option, possibly also some warning
> when used, e.g. "node_movable was ignored because CONFIG_FOO is not
> enabled"?

Hmm, I can make the cmd parameter available only when
CONFIG_HAVE_MEMBLOCK_NODE_MAP but I am not sure how helpful it would be.
AFAIR unrecognized options are just ignored. On the other hand debugging
why the parameter doesn't do anything might be really frustrating. Here
is the patch I will put on top of the two posted. Strictly speaking it
breaks the bisection but swithing the order would be kind of pointless
ifdefery game and I do not see it would matter all that much. I can
rework if you guys think otherwise though.
---
>From 4ed5cca9399f9b1e616478160ed5320d3951ec29 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Wed, 24 May 2017 15:43:49 +0200
Subject: [PATCH] mm, memory_hotplug: move movable_node to the hotplug proper

movable_node_is_enabled is defined in memblock proper while it
is initialized from the memory hotplug proper. This is quite messy
and it makes a dependency between the two so move movable_node along
with the helper functions to memory_hotplug.

To make it more entertaining the kernel parameter is ignored unless
CONFIG_HAVE_MEMBLOCK_NODE_MAP=y because we do not have the node
information for each memblock otherwise. So let's warn when the option
is disabled.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/memblock.h       |  7 -------
 include/linux/memory_hotplug.h | 10 ++++++++++
 mm/memblock.c                  |  1 -
 mm/memory_hotplug.c            |  6 ++++++
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 9622fb8c101b..071692894254 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,8 +57,6 @@ struct memblock {
 
 extern struct memblock memblock;
 extern int memblock_debug;
-/* If movable_node boot option specified */
-extern bool movable_node_enabled;
 
 #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
 #define __init_memblock __meminit
@@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
 	return m->flags & MEMBLOCK_HOTPLUG;
 }
 
-static inline bool __init_memblock movable_node_is_enabled(void)
-{
-	return movable_node_enabled;
-}
-
 static inline bool memblock_is_mirror(struct memblock_region *m)
 {
 	return m->flags & MEMBLOCK_MIRROR;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 9e0249d0f5e4..d6e5e63b31d5 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
 extern int try_online_node(int nid);
 
 extern bool memhp_auto_online;
+/* If movable_node boot option specified */
+extern bool movable_node_enabled;
+static inline bool movable_node_is_enabled(void)
+{
+	return movable_node_enabled;
+}
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
@@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
 static inline void mem_hotplug_begin(void) {}
 static inline void mem_hotplug_done(void) {}
 
+static inline bool movable_node_is_enabled(void)
+{
+	return false;
+}
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
diff --git a/mm/memblock.c b/mm/memblock.c
index 4895f5a6cf7e..8c52fb11510c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
 };
 
 int memblock_debug __initdata_memblock;
-bool movable_node_enabled __initdata_memblock = false;
 static bool system_has_some_mirror __initdata_memblock = false;
 static int memblock_can_resize __initdata_memblock;
 static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2a14f8c18a22..1a148b35e8a3 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -79,6 +79,8 @@ static struct {
 #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
 #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
 
+bool movable_node_enabled = false;
+
 #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
 bool memhp_auto_online;
 #else
@@ -1561,7 +1563,11 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 
 static int __init cmdline_parse_movable_node(char *p)
 {
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 	movable_node_enabled = true;
+#else
+	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
+#endif
 	return 0;
 }
 early_param("movable_node", cmdline_parse_movable_node);
-- 
2.11.0

-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Michal Hocko]

On Wed 24-05-17 17:17:08, Vlastimil Babka wrote:
> On 05/24/2017 03:42 PM, Michal Hocko wrote:
[...]
> >>> --- a/mm/Kconfig
> >>> +++ b/mm/Kconfig
> >>> @@ -149,32 +149,6 @@ config NO_BOOTMEM
> >>>  config MEMORY_ISOLATION
> >>>  	bool
> >>>  
> >>> -config MOVABLE_NODE
> >>> -	bool "Enable to assign a node which has only movable memory"
> >>> -	depends on HAVE_MEMBLOCK
> >>> -	depends on NO_BOOTMEM
> >>> -	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> >>> -	depends on NUMA
> >>
> >> That's a lot of depends. What happens if some of them are not met and
> >> the movable_node bootparam is used?
> > 
> > Good question. I haven't explored that, to be honest. Now that I am looking closer
> > I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
> > is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
> > mark hotpluggable memory"). NUMA is less clear to me because
> > MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
> > NO_BOOTMEM is also not clear to me because zones layout
> > doesn't really depend on the specific boot time allocator.
> > 
> > So we are left with HAVE_MEMBLOCK which seems to be there because
> > movable_node_enabled is defined there while the parameter handling is in
> > the hotplug proper. But there is no real reason to have it like that.
> > This compiles but I will have to put throw my full compile battery on it
> > to be sure. I will make it a separate patch.
> 
> I'd expect stuff might compile and work (run without crash), just in
> some cases the boot option could be effectively ignored? In that case
> it's just a matter of documenting the option, possibly also some warning
> when used, e.g. "node_movable was ignored because CONFIG_FOO is not
> enabled"?

Hmm, I can make the cmd parameter available only when
CONFIG_HAVE_MEMBLOCK_NODE_MAP but I am not sure how helpful it would be.
AFAIR unrecognized options are just ignored. On the other hand debugging
why the parameter doesn't do anything might be really frustrating. Here
is the patch I will put on top of the two posted. Strictly speaking it
breaks the bisection but swithing the order would be kind of pointless
ifdefery game and I do not see it would matter all that much. I can
rework if you guys think otherwise though.
---

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

On Wed 24-05-17 16:50:56, Reza Arbab wrote:
> On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote:
> >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> >memory") has added can_offline_normal which checks the amount of
> >memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> >It disallows to offline memory if there is nothing left with a
> >justification that "memory-management acts bad when we have nodes which
> >is online but don't have any normal memory".
> >
> >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> >memory") has introduced a restriction that every numa node has to have
> >at least some memory in !movable zones before a first movable memory
> >can be onlined if !CONFIG_MOVABLE_NODE with the same justification
> >
> >While it is true that not having _any_ memory for kernel allocations on
> >a NUMA node is far from great and such a node would be quite subotimal
> >because all kernel allocations will have to fallback to another NUMA
> >node but there is no reason to disallow such a configuration in
> >principle.
> >
> >Besides that there is not really a big difference to have one memblock
> >for ZONE_NORMAL available or none. With 128MB size memblocks the system
> >might trash on the kernel allocations requests anyway. It is really
> >hard to draw a line on how much normal memory is really sufficient so
> >we have to rely on administrator to configure system sanely therefore
> >drop the artificial restriction and remove can_offline_normal and
> >can_online_high_movable altogether.
> 
> I'm really liking all this cleanup of the memory hotplug code. Thanks!  Much
> appreciated.

I am glad to hear that and more is to come.

> Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

Thanks!
-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline

[Michal Hocko]

On Wed 24-05-17 16:50:56, Reza Arbab wrote:
> On Wed, May 24, 2017 at 02:24:10PM +0200, Michal Hocko wrote:
> >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> >memory") has added can_offline_normal which checks the amount of
> >memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable.
> >It disallows to offline memory if there is nothing left with a
> >justification that "memory-management acts bad when we have nodes which
> >is online but don't have any normal memory".
> >
> >74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL
> >memory") has introduced a restriction that every numa node has to have
> >at least some memory in !movable zones before a first movable memory
> >can be onlined if !CONFIG_MOVABLE_NODE with the same justification
> >
> >While it is true that not having _any_ memory for kernel allocations on
> >a NUMA node is far from great and such a node would be quite subotimal
> >because all kernel allocations will have to fallback to another NUMA
> >node but there is no reason to disallow such a configuration in
> >principle.
> >
> >Besides that there is not really a big difference to have one memblock
> >for ZONE_NORMAL available or none. With 128MB size memblocks the system
> >might trash on the kernel allocations requests anyway. It is really
> >hard to draw a line on how much normal memory is really sufficient so
> >we have to rely on administrator to configure system sanely therefore
> >drop the artificial restriction and remove can_offline_normal and
> >can_online_high_movable altogether.
> 
> I'm really liking all this cleanup of the memory hotplug code. Thanks!  Much
> appreciated.

I am glad to hear that and more is to come.

> Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>

Thanks!
-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/25/2017 08:27 AM, Michal Hocko wrote:
> On Wed 24-05-17 17:17:08, Vlastimil Babka wrote:
>> On 05/24/2017 03:42 PM, Michal Hocko wrote:
> [...]
>>
>> I'd expect stuff might compile and work (run without crash), just in
>> some cases the boot option could be effectively ignored? In that case
>> it's just a matter of documenting the option, possibly also some warning
>> when used, e.g. "node_movable was ignored because CONFIG_FOO is not
>> enabled"?
> 
> Hmm, I can make the cmd parameter available only when
> CONFIG_HAVE_MEMBLOCK_NODE_MAP but I am not sure how helpful it would be.
> AFAIR unrecognized options are just ignored. On the other hand debugging
> why the parameter doesn't do anything might be really frustrating. Here
> is the patch I will put on top of the two posted. Strictly speaking it
> breaks the bisection but swithing the order would be kind of pointless
> ifdefery game and I do not see it would matter all that much. I can
> rework if you guys think otherwise though.

Sounds good, thanks!

> ---
> From 4ed5cca9399f9b1e616478160ed5320d3951ec29 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Wed, 24 May 2017 15:43:49 +0200
> Subject: [PATCH] mm, memory_hotplug: move movable_node to the hotplug proper
> 
> movable_node_is_enabled is defined in memblock proper while it
> is initialized from the memory hotplug proper. This is quite messy
> and it makes a dependency between the two so move movable_node along
> with the helper functions to memory_hotplug.
> 
> To make it more entertaining the kernel parameter is ignored unless
> CONFIG_HAVE_MEMBLOCK_NODE_MAP=y because we do not have the node
> information for each memblock otherwise. So let's warn when the option
> is disabled.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  include/linux/memblock.h       |  7 -------
>  include/linux/memory_hotplug.h | 10 ++++++++++
>  mm/memblock.c                  |  1 -
>  mm/memory_hotplug.c            |  6 ++++++
>  4 files changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 9622fb8c101b..071692894254 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -57,8 +57,6 @@ struct memblock {
>  
>  extern struct memblock memblock;
>  extern int memblock_debug;
> -/* If movable_node boot option specified */
> -extern bool movable_node_enabled;
>  
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
>  #define __init_memblock __meminit
> @@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
>  	return m->flags & MEMBLOCK_HOTPLUG;
>  }
>  
> -static inline bool __init_memblock movable_node_is_enabled(void)
> -{
> -	return movable_node_enabled;
> -}
> -
>  static inline bool memblock_is_mirror(struct memblock_region *m)
>  {
>  	return m->flags & MEMBLOCK_MIRROR;
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 9e0249d0f5e4..d6e5e63b31d5 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
>  extern int try_online_node(int nid);
>  
>  extern bool memhp_auto_online;
> +/* If movable_node boot option specified */
> +extern bool movable_node_enabled;
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return movable_node_enabled;
> +}
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  extern bool is_pageblock_removable_nolock(struct page *page);
> @@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
>  static inline void mem_hotplug_begin(void) {}
>  static inline void mem_hotplug_done(void) {}
>  
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return false;
> +}
>  #endif /* ! CONFIG_MEMORY_HOTPLUG */
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 4895f5a6cf7e..8c52fb11510c 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
>  };
>  
>  int memblock_debug __initdata_memblock;
> -bool movable_node_enabled __initdata_memblock = false;
>  static bool system_has_some_mirror __initdata_memblock = false;
>  static int memblock_can_resize __initdata_memblock;
>  static int memblock_memory_in_slab __initdata_memblock = 0;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 2a14f8c18a22..1a148b35e8a3 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -79,6 +79,8 @@ static struct {
>  #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
>  #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
>  
> +bool movable_node_enabled = false;
> +
>  #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
>  bool memhp_auto_online;
>  #else
> @@ -1561,7 +1563,11 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
>  
>  static int __init cmdline_parse_movable_node(char *p)
>  {
> +#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
>  	movable_node_enabled = true;
> +#else
> +	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
> +#endif
>  	return 0;
>  }
>  early_param("movable_node", cmdline_parse_movable_node);
> 

Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE

[Vlastimil Babka]

On 05/25/2017 08:27 AM, Michal Hocko wrote:
> On Wed 24-05-17 17:17:08, Vlastimil Babka wrote:
>> On 05/24/2017 03:42 PM, Michal Hocko wrote:
> [...]
>>
>> I'd expect stuff might compile and work (run without crash), just in
>> some cases the boot option could be effectively ignored? In that case
>> it's just a matter of documenting the option, possibly also some warning
>> when used, e.g. "node_movable was ignored because CONFIG_FOO is not
>> enabled"?
> 
> Hmm, I can make the cmd parameter available only when
> CONFIG_HAVE_MEMBLOCK_NODE_MAP but I am not sure how helpful it would be.
> AFAIR unrecognized options are just ignored. On the other hand debugging
> why the parameter doesn't do anything might be really frustrating. Here
> is the patch I will put on top of the two posted. Strictly speaking it
> breaks the bisection but swithing the order would be kind of pointless
> ifdefery game and I do not see it would matter all that much. I can
> rework if you guys think otherwise though.

Sounds good, thanks!

> ---
> From 4ed5cca9399f9b1e616478160ed5320d3951ec29 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Wed, 24 May 2017 15:43:49 +0200
> Subject: [PATCH] mm, memory_hotplug: move movable_node to the hotplug proper
> 
> movable_node_is_enabled is defined in memblock proper while it
> is initialized from the memory hotplug proper. This is quite messy
> and it makes a dependency between the two so move movable_node along
> with the helper functions to memory_hotplug.
> 
> To make it more entertaining the kernel parameter is ignored unless
> CONFIG_HAVE_MEMBLOCK_NODE_MAP=y because we do not have the node
> information for each memblock otherwise. So let's warn when the option
> is disabled.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  include/linux/memblock.h       |  7 -------
>  include/linux/memory_hotplug.h | 10 ++++++++++
>  mm/memblock.c                  |  1 -
>  mm/memory_hotplug.c            |  6 ++++++
>  4 files changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index 9622fb8c101b..071692894254 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -57,8 +57,6 @@ struct memblock {
>  
>  extern struct memblock memblock;
>  extern int memblock_debug;
> -/* If movable_node boot option specified */
> -extern bool movable_node_enabled;
>  
>  #ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
>  #define __init_memblock __meminit
> @@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
>  	return m->flags & MEMBLOCK_HOTPLUG;
>  }
>  
> -static inline bool __init_memblock movable_node_is_enabled(void)
> -{
> -	return movable_node_enabled;
> -}
> -
>  static inline bool memblock_is_mirror(struct memblock_region *m)
>  {
>  	return m->flags & MEMBLOCK_MIRROR;
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 9e0249d0f5e4..d6e5e63b31d5 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
>  extern int try_online_node(int nid);
>  
>  extern bool memhp_auto_online;
> +/* If movable_node boot option specified */
> +extern bool movable_node_enabled;
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return movable_node_enabled;
> +}
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  extern bool is_pageblock_removable_nolock(struct page *page);
> @@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
>  static inline void mem_hotplug_begin(void) {}
>  static inline void mem_hotplug_done(void) {}
>  
> +static inline bool movable_node_is_enabled(void)
> +{
> +	return false;
> +}
>  #endif /* ! CONFIG_MEMORY_HOTPLUG */
>  
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 4895f5a6cf7e..8c52fb11510c 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
>  };
>  
>  int memblock_debug __initdata_memblock;
> -bool movable_node_enabled __initdata_memblock = false;
>  static bool system_has_some_mirror __initdata_memblock = false;
>  static int memblock_can_resize __initdata_memblock;
>  static int memblock_memory_in_slab __initdata_memblock = 0;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 2a14f8c18a22..1a148b35e8a3 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -79,6 +79,8 @@ static struct {
>  #define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
>  #define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
>  
> +bool movable_node_enabled = false;
> +
>  #ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
>  bool memhp_auto_online;
>  #else
> @@ -1561,7 +1563,11 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
>  
>  static int __init cmdline_parse_movable_node(char *p)
>  {
> +#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
>  	movable_node_enabled = true;
> +#else
> +	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
> +#endif
>  	return 0;
>  }
>  early_param("movable_node", cmdline_parse_movable_node);
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE

[Michal Hocko]

JFYI, I am waiting for some additional feedback and if there is none I
will re-send next week.
-- 
Michal Hocko
SUSE Labs

Re: [RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE

[Michal Hocko]

JFYI, I am waiting for some additional feedback and if there is none I
will re-send next week.
-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>