Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 732 insertions, 0 deletions

diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
new file mode 100644
index 000000000..c734658c6
--- /dev/null
+++ b/mm/memory-tiers.c
@@ -0,0 +1,732 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/slab.h>
+#include <linux/lockdep.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/memory.h>
+#include <linux/memory-tiers.h>
+
+#include "internal.h"
+
+struct memory_tier {
+	/* hierarchy of memory tiers */
+	struct list_head list;
+	/* list of all memory types part of this tier */
+	struct list_head memory_types;
+	/*
+	 * start value of abstract distance. memory tier maps
+	 * an abstract distance  range,
+	 * adistance_start .. adistance_start + MEMTIER_CHUNK_SIZE
+	 */
+	int adistance_start;
+	struct device dev;
+	/* All the nodes that are part of all the lower memory tiers. */
+	nodemask_t lower_tier_mask;
+};
+
+struct demotion_nodes {
+	nodemask_t preferred;
+};
+
+struct node_memory_type_map {
+	struct memory_dev_type *memtype;
+	int map_count;
+};
+
+static DEFINE_MUTEX(memory_tier_lock);
+static LIST_HEAD(memory_tiers);
+static struct node_memory_type_map node_memory_types[MAX_NUMNODES];
+static struct memory_dev_type *default_dram_type;
+
+static struct bus_type memory_tier_subsys = {
+	.name = "memory_tiering",
+	.dev_name = "memory_tier",
+};
+
+#ifdef CONFIG_MIGRATION
+static int top_tier_adistance;
+/*
+ * node_demotion[] examples:
+ *
+ * Example 1:
+ *
+ * Node 0 & 1 are CPU + DRAM nodes, node 2 & 3 are PMEM nodes.
+ *
+ * node distances:
+ * node   0    1    2    3
+ *    0  10   20   30   40
+ *    1  20   10   40   30
+ *    2  30   40   10   40
+ *    3  40   30   40   10
+ *
+ * memory_tiers0 = 0-1
+ * memory_tiers1 = 2-3
+ *
+ * node_demotion[0].preferred = 2
+ * node_demotion[1].preferred = 3
+ * node_demotion[2].preferred = <empty>
+ * node_demotion[3].preferred = <empty>
+ *
+ * Example 2:
+ *
+ * Node 0 & 1 are CPU + DRAM nodes, node 2 is memory-only DRAM node.
+ *
+ * node distances:
+ * node   0    1    2
+ *    0  10   20   30
+ *    1  20   10   30
+ *    2  30   30   10
+ *
+ * memory_tiers0 = 0-2
+ *
+ * node_demotion[0].preferred = <empty>
+ * node_demotion[1].preferred = <empty>
+ * node_demotion[2].preferred = <empty>
+ *
+ * Example 3:
+ *
+ * Node 0 is CPU + DRAM nodes, Node 1 is HBM node, node 2 is PMEM node.
+ *
+ * node distances:
+ * node   0    1    2
+ *    0  10   20   30
+ *    1  20   10   40
+ *    2  30   40   10
+ *
+ * memory_tiers0 = 1
+ * memory_tiers1 = 0
+ * memory_tiers2 = 2
+ *
+ * node_demotion[0].preferred = 2
+ * node_demotion[1].preferred = 0
+ * node_demotion[2].preferred = <empty>
+ *
+ */
+static struct demotion_nodes *node_demotion __read_mostly;
+#endif /* CONFIG_MIGRATION */
+
+static inline struct memory_tier *to_memory_tier(struct device *device)
+{
+	return container_of(device, struct memory_tier, dev);
+}
+
+static __always_inline nodemask_t get_memtier_nodemask(struct memory_tier *memtier)
+{
+	nodemask_t nodes = NODE_MASK_NONE;
+	struct memory_dev_type *memtype;
+
+	list_for_each_entry(memtype, &memtier->memory_types, tier_sibiling)
+		nodes_or(nodes, nodes, memtype->nodes);
+
+	return nodes;
+}
+
+static void memory_tier_device_release(struct device *dev)
+{
+	struct memory_tier *tier = to_memory_tier(dev);
+	/*
+	 * synchronize_rcu in clear_node_memory_tier makes sure
+	 * we don't have rcu access to this memory tier.
+	 */
+	kfree(tier);
+}
+
+static ssize_t nodelist_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	int ret;
+	nodemask_t nmask;
+
+	mutex_lock(&memory_tier_lock);
+	nmask = get_memtier_nodemask(to_memory_tier(dev));
+	ret = sysfs_emit(buf, "%*pbl\n", nodemask_pr_args(&nmask));
+	mutex_unlock(&memory_tier_lock);
+	return ret;
+}
+static DEVICE_ATTR_RO(nodelist);
+
+static struct attribute *memtier_dev_attrs[] = {
+	&dev_attr_nodelist.attr,
+	NULL
+};
+
+static const struct attribute_group memtier_dev_group = {
+	.attrs = memtier_dev_attrs,
+};
+
+static const struct attribute_group *memtier_dev_groups[] = {
+	&memtier_dev_group,
+	NULL
+};
+
+static struct memory_tier *find_create_memory_tier(struct memory_dev_type *memtype)
+{
+	int ret;
+	bool found_slot = false;
+	struct memory_tier *memtier, *new_memtier;
+	int adistance = memtype->adistance;
+	unsigned int memtier_adistance_chunk_size = MEMTIER_CHUNK_SIZE;
+
+	lockdep_assert_held_once(&memory_tier_lock);
+
+	adistance = round_down(adistance, memtier_adistance_chunk_size);
+	/*
+	 * If the memtype is already part of a memory tier,
+	 * just return that.
+	 */
+	if (!list_empty(&memtype->tier_sibiling)) {
+		list_for_each_entry(memtier, &memory_tiers, list) {
+			if (adistance == memtier->adistance_start)
+				return memtier;
+		}
+		WARN_ON(1);
+		return ERR_PTR(-EINVAL);
+	}
+
+	list_for_each_entry(memtier, &memory_tiers, list) {
+		if (adistance == memtier->adistance_start) {
+			goto link_memtype;
+		} else if (adistance < memtier->adistance_start) {
+			found_slot = true;
+			break;
+		}
+	}
+
+	new_memtier = kzalloc(sizeof(struct memory_tier), GFP_KERNEL);
+	if (!new_memtier)
+		return ERR_PTR(-ENOMEM);
+
+	new_memtier->adistance_start = adistance;
+	INIT_LIST_HEAD(&new_memtier->list);
+	INIT_LIST_HEAD(&new_memtier->memory_types);
+	if (found_slot)
+		list_add_tail(&new_memtier->list, &memtier->list);
+	else
+		list_add_tail(&new_memtier->list, &memory_tiers);
+
+	new_memtier->dev.id = adistance >> MEMTIER_CHUNK_BITS;
+	new_memtier->dev.bus = &memory_tier_subsys;
+	new_memtier->dev.release = memory_tier_device_release;
+	new_memtier->dev.groups = memtier_dev_groups;
+
+	ret = device_register(&new_memtier->dev);
+	if (ret) {
+		list_del(&memtier->list);
+		put_device(&memtier->dev);
+		return ERR_PTR(ret);
+	}
+	memtier = new_memtier;
+
+link_memtype:
+	list_add(&memtype->tier_sibiling, &memtier->memory_types);
+	return memtier;
+}
+
+static struct memory_tier *__node_get_memory_tier(int node)
+{
+	pg_data_t *pgdat;
+
+	pgdat = NODE_DATA(node);
+	if (!pgdat)
+		return NULL;
+	/*
+	 * Since we hold memory_tier_lock, we can avoid
+	 * RCU read locks when accessing the details. No
+	 * parallel updates are possible here.
+	 */
+	return rcu_dereference_check(pgdat->memtier,
+				     lockdep_is_held(&memory_tier_lock));
+}
+
+#ifdef CONFIG_MIGRATION
+bool node_is_toptier(int node)
+{
+	bool toptier;
+	pg_data_t *pgdat;
+	struct memory_tier *memtier;
+
+	pgdat = NODE_DATA(node);
+	if (!pgdat)
+		return false;
+
+	rcu_read_lock();
+	memtier = rcu_dereference(pgdat->memtier);
+	if (!memtier) {
+		toptier = true;
+		goto out;
+	}
+	if (memtier->adistance_start <= top_tier_adistance)
+		toptier = true;
+	else
+		toptier = false;
+out:
+	rcu_read_unlock();
+	return toptier;
+}
+
+void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets)
+{
+	struct memory_tier *memtier;
+
+	/*
+	 * pg_data_t.memtier updates includes a synchronize_rcu()
+	 * which ensures that we either find NULL or a valid memtier
+	 * in NODE_DATA. protect the access via rcu_read_lock();
+	 */
+	rcu_read_lock();
+	memtier = rcu_dereference(pgdat->memtier);
+	if (memtier)
+		*targets = memtier->lower_tier_mask;
+	else
+		*targets = NODE_MASK_NONE;
+	rcu_read_unlock();
+}
+
+/**
+ * next_demotion_node() - Get the next node in the demotion path
+ * @node: The starting node to lookup the next node
+ *
+ * Return: node id for next memory node in the demotion path hierarchy
+ * from @node; NUMA_NO_NODE if @node is terminal.  This does not keep
+ * @node online or guarantee that it *continues* to be the next demotion
+ * target.
+ */
+int next_demotion_node(int node)
+{
+	struct demotion_nodes *nd;
+	int target;
+
+	if (!node_demotion)
+		return NUMA_NO_NODE;
+
+	nd = &node_demotion[node];
+
+	/*
+	 * node_demotion[] is updated without excluding this
+	 * function from running.
+	 *
+	 * Make sure to use RCU over entire code blocks if
+	 * node_demotion[] reads need to be consistent.
+	 */
+	rcu_read_lock();
+	/*
+	 * If there are multiple target nodes, just select one
+	 * target node randomly.
+	 *
+	 * In addition, we can also use round-robin to select
+	 * target node, but we should introduce another variable
+	 * for node_demotion[] to record last selected target node,
+	 * that may cause cache ping-pong due to the changing of
+	 * last target node. Or introducing per-cpu data to avoid
+	 * caching issue, which seems more complicated. So selecting
+	 * target node randomly seems better until now.
+	 */
+	target = node_random(&nd->preferred);
+	rcu_read_unlock();
+
+	return target;
+}
+
+static void disable_all_demotion_targets(void)
+{
+	struct memory_tier *memtier;
+	int node;
+
+	for_each_node_state(node, N_MEMORY) {
+		node_demotion[node].preferred = NODE_MASK_NONE;
+		/*
+		 * We are holding memory_tier_lock, it is safe
+		 * to access pgda->memtier.
+		 */
+		memtier = __node_get_memory_tier(node);
+		if (memtier)
+			memtier->lower_tier_mask = NODE_MASK_NONE;
+	}
+	/*
+	 * Ensure that the "disable" is visible across the system.
+	 * Readers will see either a combination of before+disable
+	 * state or disable+after.  They will never see before and
+	 * after state together.
+	 */
+	synchronize_rcu();
+}
+
+/*
+ * Find an automatic demotion target for all memory
+ * nodes. Failing here is OK.  It might just indicate
+ * being at the end of a chain.
+ */
+static void establish_demotion_targets(void)
+{
+	struct memory_tier *memtier;
+	struct demotion_nodes *nd;
+	int target = NUMA_NO_NODE, node;
+	int distance, best_distance;
+	nodemask_t tier_nodes, lower_tier;
+
+	lockdep_assert_held_once(&memory_tier_lock);
+
+	if (!node_demotion || !IS_ENABLED(CONFIG_MIGRATION))
+		return;
+
+	disable_all_demotion_targets();
+
+	for_each_node_state(node, N_MEMORY) {
+		best_distance = -1;
+		nd = &node_demotion[node];
+
+		memtier = __node_get_memory_tier(node);
+		if (!memtier || list_is_last(&memtier->list, &memory_tiers))
+			continue;
+		/*
+		 * Get the lower memtier to find the  demotion node list.
+		 */
+		memtier = list_next_entry(memtier, list);
+		tier_nodes = get_memtier_nodemask(memtier);
+		/*
+		 * find_next_best_node, use 'used' nodemask as a skip list.
+		 * Add all memory nodes except the selected memory tier
+		 * nodelist to skip list so that we find the best node from the
+		 * memtier nodelist.
+		 */
+		nodes_andnot(tier_nodes, node_states[N_MEMORY], tier_nodes);
+
+		/*
+		 * Find all the nodes in the memory tier node list of same best distance.
+		 * add them to the preferred mask. We randomly select between nodes
+		 * in the preferred mask when allocating pages during demotion.
+		 */
+		do {
+			target = find_next_best_node(node, &tier_nodes);
+			if (target == NUMA_NO_NODE)
+				break;
+
+			distance = node_distance(node, target);
+			if (distance == best_distance || best_distance == -1) {
+				best_distance = distance;
+				node_set(target, nd->preferred);
+			} else {
+				break;
+			}
+		} while (1);
+	}
+	/*
+	 * Promotion is allowed from a memory tier to higher
+	 * memory tier only if the memory tier doesn't include
+	 * compute. We want to skip promotion from a memory tier,
+	 * if any node that is part of the memory tier have CPUs.
+	 * Once we detect such a memory tier, we consider that tier
+	 * as top tiper from which promotion is not allowed.
+	 */
+	list_for_each_entry_reverse(memtier, &memory_tiers, list) {
+		tier_nodes = get_memtier_nodemask(memtier);
+		nodes_and(tier_nodes, node_states[N_CPU], tier_nodes);
+		if (!nodes_empty(tier_nodes)) {
+			/*
+			 * abstract distance below the max value of this memtier
+			 * is considered toptier.
+			 */
+			top_tier_adistance = memtier->adistance_start +
+						MEMTIER_CHUNK_SIZE - 1;
+			break;
+		}
+	}
+	/*
+	 * Now build the lower_tier mask for each node collecting node mask from
+	 * all memory tier below it. This allows us to fallback demotion page
+	 * allocation to a set of nodes that is closer the above selected
+	 * perferred node.
+	 */
+	lower_tier = node_states[N_MEMORY];
+	list_for_each_entry(memtier, &memory_tiers, list) {
+		/*
+		 * Keep removing current tier from lower_tier nodes,
+		 * This will remove all nodes in current and above
+		 * memory tier from the lower_tier mask.
+		 */
+		tier_nodes = get_memtier_nodemask(memtier);
+		nodes_andnot(lower_tier, lower_tier, tier_nodes);
+		memtier->lower_tier_mask = lower_tier;
+	}
+}
+
+#else
+static inline void disable_all_demotion_targets(void) {}
+static inline void establish_demotion_targets(void) {}
+#endif /* CONFIG_MIGRATION */
+
+static inline void __init_node_memory_type(int node, struct memory_dev_type *memtype)
+{
+	if (!node_memory_types[node].memtype)
+		node_memory_types[node].memtype = memtype;
+	/*
+	 * for each device getting added in the same NUMA node
+	 * with this specific memtype, bump the map count. We
+	 * Only take memtype device reference once, so that
+	 * changing a node memtype can be done by droping the
+	 * only reference count taken here.
+	 */
+
+	if (node_memory_types[node].memtype == memtype) {
+		if (!node_memory_types[node].map_count++)
+			kref_get(&memtype->kref);
+	}
+}
+
+static struct memory_tier *set_node_memory_tier(int node)
+{
+	struct memory_tier *memtier;
+	struct memory_dev_type *memtype;
+	pg_data_t *pgdat = NODE_DATA(node);
+
+
+	lockdep_assert_held_once(&memory_tier_lock);
+
+	if (!node_state(node, N_MEMORY))
+		return ERR_PTR(-EINVAL);
+
+	__init_node_memory_type(node, default_dram_type);
+
+	memtype = node_memory_types[node].memtype;
+	node_set(node, memtype->nodes);
+	memtier = find_create_memory_tier(memtype);
+	if (!IS_ERR(memtier))
+		rcu_assign_pointer(pgdat->memtier, memtier);
+	return memtier;
+}
+
+static void destroy_memory_tier(struct memory_tier *memtier)
+{
+	list_del(&memtier->list);
+	device_unregister(&memtier->dev);
+}
+
+static bool clear_node_memory_tier(int node)
+{
+	bool cleared = false;
+	pg_data_t *pgdat;
+	struct memory_tier *memtier;
+
+	pgdat = NODE_DATA(node);
+	if (!pgdat)
+		return false;
+
+	/*
+	 * Make sure that anybody looking at NODE_DATA who finds
+	 * a valid memtier finds memory_dev_types with nodes still
+	 * linked to the memtier. We achieve this by waiting for
+	 * rcu read section to finish using synchronize_rcu.
+	 * This also enables us to free the destroyed memory tier
+	 * with kfree instead of kfree_rcu
+	 */
+	memtier = __node_get_memory_tier(node);
+	if (memtier) {
+		struct memory_dev_type *memtype;
+
+		rcu_assign_pointer(pgdat->memtier, NULL);
+		synchronize_rcu();
+		memtype = node_memory_types[node].memtype;
+		node_clear(node, memtype->nodes);
+		if (nodes_empty(memtype->nodes)) {
+			list_del_init(&memtype->tier_sibiling);
+			if (list_empty(&memtier->memory_types))
+				destroy_memory_tier(memtier);
+		}
+		cleared = true;
+	}
+	return cleared;
+}
+
+static void release_memtype(struct kref *kref)
+{
+	struct memory_dev_type *memtype;
+
+	memtype = container_of(kref, struct memory_dev_type, kref);
+	kfree(memtype);
+}
+
+struct memory_dev_type *alloc_memory_type(int adistance)
+{
+	struct memory_dev_type *memtype;
+
+	memtype = kmalloc(sizeof(*memtype), GFP_KERNEL);
+	if (!memtype)
+		return ERR_PTR(-ENOMEM);
+
+	memtype->adistance = adistance;
+	INIT_LIST_HEAD(&memtype->tier_sibiling);
+	memtype->nodes  = NODE_MASK_NONE;
+	kref_init(&memtype->kref);
+	return memtype;
+}
+EXPORT_SYMBOL_GPL(alloc_memory_type);
+
+void destroy_memory_type(struct memory_dev_type *memtype)
+{
+	kref_put(&memtype->kref, release_memtype);
+}
+EXPORT_SYMBOL_GPL(destroy_memory_type);
+
+void init_node_memory_type(int node, struct memory_dev_type *memtype)
+{
+
+	mutex_lock(&memory_tier_lock);
+	__init_node_memory_type(node, memtype);
+	mutex_unlock(&memory_tier_lock);
+}
+EXPORT_SYMBOL_GPL(init_node_memory_type);
+
+void clear_node_memory_type(int node, struct memory_dev_type *memtype)
+{
+	mutex_lock(&memory_tier_lock);
+	if (node_memory_types[node].memtype == memtype)
+		node_memory_types[node].map_count--;
+	/*
+	 * If we umapped all the attached devices to this node,
+	 * clear the node memory type.
+	 */
+	if (!node_memory_types[node].map_count) {
+		node_memory_types[node].memtype = NULL;
+		kref_put(&memtype->kref, release_memtype);
+	}
+	mutex_unlock(&memory_tier_lock);
+}
+EXPORT_SYMBOL_GPL(clear_node_memory_type);
+
+static int __meminit memtier_hotplug_callback(struct notifier_block *self,
+					      unsigned long action, void *_arg)
+{
+	struct memory_tier *memtier;
+	struct memory_notify *arg = _arg;
+
+	/*
+	 * Only update the node migration order when a node is
+	 * changing status, like online->offline.
+	 */
+	if (arg->status_change_nid < 0)
+		return notifier_from_errno(0);
+
+	switch (action) {
+	case MEM_OFFLINE:
+		mutex_lock(&memory_tier_lock);
+		if (clear_node_memory_tier(arg->status_change_nid))
+			establish_demotion_targets();
+		mutex_unlock(&memory_tier_lock);
+		break;
+	case MEM_ONLINE:
+		mutex_lock(&memory_tier_lock);
+		memtier = set_node_memory_tier(arg->status_change_nid);
+		if (!IS_ERR(memtier))
+			establish_demotion_targets();
+		mutex_unlock(&memory_tier_lock);
+		break;
+	}
+
+	return notifier_from_errno(0);
+}
+
+static int __init memory_tier_init(void)
+{
+	int ret, node;
+	struct memory_tier *memtier;
+
+	ret = subsys_virtual_register(&memory_tier_subsys, NULL);
+	if (ret)
+		panic("%s() failed to register memory tier subsystem\n", __func__);
+
+#ifdef CONFIG_MIGRATION
+	node_demotion = kcalloc(nr_node_ids, sizeof(struct demotion_nodes),
+				GFP_KERNEL);
+	WARN_ON(!node_demotion);
+#endif
+	mutex_lock(&memory_tier_lock);
+	/*
+	 * For now we can have 4 faster memory tiers with smaller adistance
+	 * than default DRAM tier.
+	 */
+	default_dram_type = alloc_memory_type(MEMTIER_ADISTANCE_DRAM);
+	if (IS_ERR(default_dram_type))
+		panic("%s() failed to allocate default DRAM tier\n", __func__);
+
+	/*
+	 * Look at all the existing N_MEMORY nodes and add them to
+	 * default memory tier or to a tier if we already have memory
+	 * types assigned.
+	 */
+	for_each_node_state(node, N_MEMORY) {
+		memtier = set_node_memory_tier(node);
+		if (IS_ERR(memtier))
+			/*
+			 * Continue with memtiers we are able to setup
+			 */
+			break;
+	}
+	establish_demotion_targets();
+	mutex_unlock(&memory_tier_lock);
+
+	hotplug_memory_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRI);
+	return 0;
+}
+subsys_initcall(memory_tier_init);
+
+bool numa_demotion_enabled = false;
+
+#ifdef CONFIG_MIGRATION
+#ifdef CONFIG_SYSFS
+static ssize_t numa_demotion_enabled_show(struct kobject *kobj,
+					  struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+			  numa_demotion_enabled ? "true" : "false");
+}
+
+static ssize_t numa_demotion_enabled_store(struct kobject *kobj,
+					   struct kobj_attribute *attr,
+					   const char *buf, size_t count)
+{
+	ssize_t ret;
+
+	ret = kstrtobool(buf, &numa_demotion_enabled);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static struct kobj_attribute numa_demotion_enabled_attr =
+	__ATTR(demotion_enabled, 0644, numa_demotion_enabled_show,
+	       numa_demotion_enabled_store);
+
+static struct attribute *numa_attrs[] = {
+	&numa_demotion_enabled_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group numa_attr_group = {
+	.attrs = numa_attrs,
+};
+
+static int __init numa_init_sysfs(void)
+{
+	int err;
+	struct kobject *numa_kobj;
+
+	numa_kobj = kobject_create_and_add("numa", mm_kobj);
+	if (!numa_kobj) {
+		pr_err("failed to create numa kobject\n");
+		return -ENOMEM;
+	}
+	err = sysfs_create_group(numa_kobj, &numa_attr_group);
+	if (err) {
+		pr_err("failed to register numa group\n");
+		goto delete_obj;
+	}
+	return 0;
+
+delete_obj:
+	kobject_put(numa_kobj);
+	return err;
+}
+subsys_initcall(numa_init_sysfs);
+#endif /* CONFIG_SYSFS */
+#endif