Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/admin-guide/mm/cma_debugfs.rst b/Documentation/admin-guide/mm/cma_debugfs.rst
new file mode 100644
index 0000000..4e06ffa
--- /dev/null
+++ b/Documentation/admin-guide/mm/cma_debugfs.rst
@@ -0,0 +1,25 @@
+=====================
+CMA Debugfs Interface
+=====================
+
+The CMA debugfs interface is useful to retrieve basic information out of the
+different CMA areas and to test allocation/release in each of the areas.
+
+Each CMA zone represents a directory under <debugfs>/cma/, indexed by the
+kernel's CMA index. So the first CMA zone would be:
+
+ <debugfs>/cma/cma-0
+
+The structure of the files created under that directory is as follows:
+
+ - [RO] base_pfn: The base PFN (Page Frame Number) of the zone.
+ - [RO] count: Amount of memory in the CMA area.
+ - [RO] order_per_bit: Order of pages represented by one bit.
+ - [RO] bitmap: The bitmap of page states in the zone.
+ - [WO] alloc: Allocate N pages from that CMA area. For example::
+
+ echo 5 > <debugfs>/cma/cma-2/alloc
+
+would try to allocate 5 pages from the cma-2 area.
+
+ - [WO] free: Free N pages from that CMA area, similar to the above.
diff --git a/Documentation/admin-guide/mm/concepts.rst b/Documentation/admin-guide/mm/concepts.rst
index 291699c..c2531b1 100644
--- a/Documentation/admin-guide/mm/concepts.rst
+++ b/Documentation/admin-guide/mm/concepts.rst
@@ -4,13 +4,13 @@
Concepts overview
=================
-The memory management in Linux is complex system that evolved over the
-years and included more and more functionality to support variety of
+The memory management in Linux is a complex system that evolved over the
+years and included more and more functionality to support a variety of
systems from MMU-less microcontrollers to supercomputers. The memory
-management for systems without MMU is called ``nommu`` and it
+management for systems without an MMU is called ``nommu`` and it
definitely deserves a dedicated document, which hopefully will be
eventually written. Yet, although some of the concepts are the same,
-here we assume that MMU is available and CPU can translate a virtual
+here we assume that an MMU is available and a CPU can translate a virtual
address to a physical address.
.. contents:: :local:
@@ -21,10 +21,10 @@
The physical memory in a computer system is a limited resource and
even for systems that support memory hotplug there is a hard limit on
the amount of memory that can be installed. The physical memory is not
-necessary contiguous, it might be accessible as a set of distinct
+necessarily contiguous; it might be accessible as a set of distinct
address ranges. Besides, different CPU architectures, and even
-different implementations of the same architecture have different view
-how these address ranges defined.
+different implementations of the same architecture have different views
+of how these address ranges are defined.
All this makes dealing directly with physical memory quite complex and
to avoid this complexity a concept of virtual memory was developed.
@@ -48,8 +48,8 @@
Each physical memory page can be mapped as one or more virtual
pages. These mappings are described by page tables that allow
-translation from virtual address used by programs to real address in
-the physical memory. The page tables organized hierarchically.
+translation from a virtual address used by programs to the physical
+memory address. The page tables are organized hierarchically.
The tables at the lowest level of the hierarchy contain physical
addresses of actual pages used by the software. The tables at higher
@@ -121,8 +121,8 @@
Many multi-processor machines are NUMA - Non-Uniform Memory Access -
systems. In such systems the memory is arranged into banks that have
different access latency depending on the "distance" from the
-processor. Each bank is referred as `node` and for each node Linux
-constructs an independent memory management subsystem. A node has it's
+processor. Each bank is referred to as a `node` and for each node Linux
+constructs an independent memory management subsystem. A node has its
own set of zones, lists of free and used pages and various statistics
counters. You can find more details about NUMA in
:ref:`Documentation/vm/numa.rst <numa>` and in
@@ -149,9 +149,9 @@
call. Usually, the anonymous mappings only define virtual memory areas
that the program is allowed to access. The read accesses will result
in creation of a page table entry that references a special physical
-page filled with zeroes. When the program performs a write, regular
+page filled with zeroes. When the program performs a write, a regular
physical page will be allocated to hold the written data. The page
-will be marked dirty and if the kernel will decide to repurpose it,
+will be marked dirty and if the kernel decides to repurpose it,
the dirty page will be swapped out.
Reclaim
@@ -181,8 +181,8 @@
The process of freeing the reclaimable physical memory pages and
repurposing them is called (surprise!) `reclaim`. Linux can reclaim
pages either asynchronously or synchronously, depending on the state
-of the system. When system is not loaded, most of the memory is free
-and allocation request will be satisfied immediately from the free
+of the system. When the system is not loaded, most of the memory is free
+and allocation requests will be satisfied immediately from the free
pages supply. As the load increases, the amount of the free pages goes
down and when it reaches a certain threshold (high watermark), an
allocation request will awaken the ``kswapd`` daemon. It will
@@ -190,7 +190,7 @@
they contain is available elsewhere, or evict to the backing storage
device (remember those dirty pages?). As memory usage increases even
more and reaches another threshold - min watermark - an allocation
-will trigger the `direct reclaim`. In this case allocation is stalled
+will trigger `direct reclaim`. In this case allocation is stalled
until enough memory pages are reclaimed to satisfy the request.
Compaction
@@ -200,7 +200,7 @@
fragmented. Although with virtual memory it is possible to present
scattered physical pages as virtually contiguous range, sometimes it is
necessary to allocate large physically contiguous memory areas. Such
-need may arise, for instance, when a device driver requires large
+need may arise, for instance, when a device driver requires a large
buffer for DMA, or when THP allocates a huge page. Memory `compaction`
addresses the fragmentation issue. This mechanism moves occupied pages
from the lower part of a memory zone to free pages in the upper part
@@ -208,15 +208,16 @@
together at the beginning of the zone and allocations of large
physically contiguous areas become possible.
-Like reclaim, the compaction may happen asynchronously in ``kcompactd``
-daemon or synchronously as a result of memory allocation request.
+Like reclaim, the compaction may happen asynchronously in the ``kcompactd``
+daemon or synchronously as a result of a memory allocation request.
OOM killer
==========
-It may happen, that on a loaded machine memory will be exhausted. When
-the kernel detects that the system runs out of memory (OOM) it invokes
-`OOM killer`. Its mission is simple: all it has to do is to select a
-task to sacrifice for the sake of the overall system health. The
-selected task is killed in a hope that after it exits enough memory
-will be freed to continue normal operation.
+It is possible that on a loaded machine memory will be exhausted and the
+kernel will be unable to reclaim enough memory to continue to operate. In
+order to save the rest of the system, it invokes the `OOM killer`.
+
+The `OOM killer` selects a task to sacrifice for the sake of the overall
+system health. The selected task is killed in a hope that after it exits
+enough memory will be freed to continue normal operation.
diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst
index ceead68..11db464 100644
--- a/Documentation/admin-guide/mm/index.rst
+++ b/Documentation/admin-guide/mm/index.rst
@@ -11,7 +11,7 @@
Linux memory management is a complex system with many configurable
settings. Most of these settings are available via ``/proc``
filesystem and can be quired and adjusted using ``sysctl``. These APIs
-are described in Documentation/sysctl/vm.txt and in `man 5 proc`_.
+are described in Documentation/admin-guide/sysctl/vm.rst and in `man 5 proc`_.
.. _man 5 proc: http://man7.org/linux/man-pages/man5/proc.5.html
@@ -26,10 +26,13 @@
:maxdepth: 1
concepts
+ cma_debugfs
hugetlbpage
idle_page_tracking
ksm
+ memory-hotplug
numa_memory_policy
+ numaperf
pagemap
soft-dirty
transhuge
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index 9303786..874eb0c 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -59,7 +59,7 @@
If a region of memory must be split into at least one new MADV_MERGEABLE
or MADV_UNMERGEABLE region, the madvise may return ENOMEM if the process
-will exceed ``vm.max_map_count`` (see Documentation/sysctl/vm.txt).
+will exceed ``vm.max_map_count`` (see Documentation/admin-guide/sysctl/vm.rst).
Like other madvise calls, they are intended for use on mapped areas of
the user address space: they will report ENOMEM if the specified range
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
new file mode 100644
index 0000000..5c4432c
--- /dev/null
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -0,0 +1,444 @@
+.. _admin_guide_memory_hotplug:
+
+==============
+Memory Hotplug
+==============
+
+:Created: Jul 28 2007
+:Updated: Add some details about locking internals: Aug 20 2018
+
+This document is about memory hotplug including how-to-use and current status.
+Because Memory Hotplug is still under development, contents of this text will
+be changed often.
+
+.. contents:: :local:
+
+.. note::
+
+ (1) x86_64's has special implementation for memory hotplug.
+ This text does not describe it.
+ (2) This text assumes that sysfs is mounted at ``/sys``.
+
+
+Introduction
+============
+
+Purpose of memory hotplug
+-------------------------
+
+Memory Hotplug allows users to increase/decrease the amount of memory.
+Generally, there are two purposes.
+
+(A) For changing the amount of memory.
+ This is to allow a feature like capacity on demand.
+(B) For installing/removing DIMMs or NUMA-nodes physically.
+ This is to exchange DIMMs/NUMA-nodes, reduce power consumption, etc.
+
+(A) is required by highly virtualized environments and (B) is required by
+hardware which supports memory power management.
+
+Linux memory hotplug is designed for both purpose.
+
+Phases of memory hotplug
+------------------------
+
+There are 2 phases in Memory Hotplug:
+
+ 1) Physical Memory Hotplug phase
+ 2) Logical Memory Hotplug phase.
+
+The First phase is to communicate hardware/firmware and make/erase
+environment for hotplugged memory. Basically, this phase is necessary
+for the purpose (B), but this is good phase for communication between
+highly virtualized environments too.
+
+When memory is hotplugged, the kernel recognizes new memory, makes new memory
+management tables, and makes sysfs files for new memory's operation.
+
+If firmware supports notification of connection of new memory to OS,
+this phase is triggered automatically. ACPI can notify this event. If not,
+"probe" operation by system administration is used instead.
+(see :ref:`memory_hotplug_physical_mem`).
+
+Logical Memory Hotplug phase is to change memory state into
+available/unavailable for users. Amount of memory from user's view is
+changed by this phase. The kernel makes all memory in it as free pages
+when a memory range is available.
+
+In this document, this phase is described as online/offline.
+
+Logical Memory Hotplug phase is triggered by write of sysfs file by system
+administrator. For the hot-add case, it must be executed after Physical Hotplug
+phase by hand.
+(However, if you writes udev's hotplug scripts for memory hotplug, these
+phases can be execute in seamless way.)
+
+Unit of Memory online/offline operation
+---------------------------------------
+
+Memory hotplug uses SPARSEMEM memory model which allows memory to be divided
+into chunks of the same size. These chunks are called "sections". The size of
+a memory section is architecture dependent. For example, power uses 16MiB, ia64
+uses 1GiB.
+
+Memory sections are combined into chunks referred to as "memory blocks". The
+size of a memory block is architecture dependent and represents the logical
+unit upon which memory online/offline operations are to be performed. The
+default size of a memory block is the same as memory section size unless an
+architecture specifies otherwise. (see :ref:`memory_hotplug_sysfs_files`.)
+
+To determine the size (in bytes) of a memory block please read this file::
+
+ /sys/devices/system/memory/block_size_bytes
+
+Kernel Configuration
+====================
+
+To use memory hotplug feature, kernel must be compiled with following
+config options.
+
+- For all memory hotplug:
+ - Memory model -> Sparse Memory (``CONFIG_SPARSEMEM``)
+ - Allow for memory hot-add (``CONFIG_MEMORY_HOTPLUG``)
+
+- To enable memory removal, the following are also necessary:
+ - Allow for memory hot remove (``CONFIG_MEMORY_HOTREMOVE``)
+ - Page Migration (``CONFIG_MIGRATION``)
+
+- For ACPI memory hotplug, the following are also necessary:
+ - Memory hotplug (under ACPI Support menu) (``CONFIG_ACPI_HOTPLUG_MEMORY``)
+ - This option can be kernel module.
+
+- As a related configuration, if your box has a feature of NUMA-node hotplug
+ via ACPI, then this option is necessary too.
+
+ - ACPI0004,PNP0A05 and PNP0A06 Container Driver (under ACPI Support menu)
+ (``CONFIG_ACPI_CONTAINER``).
+
+ This option can be kernel module too.
+
+
+.. _memory_hotplug_sysfs_files:
+
+sysfs files for memory hotplug
+==============================
+
+All memory blocks have their device information in sysfs. Each memory block
+is described under ``/sys/devices/system/memory`` as::
+
+ /sys/devices/system/memory/memoryXXX
+
+where XXX is the memory block id.
+
+For the memory block covered by the sysfs directory. It is expected that all
+memory sections in this range are present and no memory holes exist in the
+range. Currently there is no way to determine if there is a memory hole, but
+the existence of one should not affect the hotplug capabilities of the memory
+block.
+
+For example, assume 1GiB memory block size. A device for a memory starting at
+0x100000000 is ``/sys/device/system/memory/memory4``::
+
+ (0x100000000 / 1Gib = 4)
+
+This device covers address range [0x100000000 ... 0x140000000)
+
+Under each memory block, you can see 5 files:
+
+- ``/sys/devices/system/memory/memoryXXX/phys_index``
+- ``/sys/devices/system/memory/memoryXXX/phys_device``
+- ``/sys/devices/system/memory/memoryXXX/state``
+- ``/sys/devices/system/memory/memoryXXX/removable``
+- ``/sys/devices/system/memory/memoryXXX/valid_zones``
+
+=================== ============================================================
+``phys_index`` read-only and contains memory block id, same as XXX.
+``state`` read-write
+
+ - at read: contains online/offline state of memory.
+ - at write: user can specify "online_kernel",
+
+ "online_movable", "online", "offline" command
+ which will be performed on all sections in the block.
+``phys_device`` read-only: designed to show the name of physical memory
+ device. This is not well implemented now.
+``removable`` read-only: contains an integer value indicating
+ whether the memory block is removable or not
+ removable. A value of 1 indicates that the memory
+ block is removable and a value of 0 indicates that
+ it is not removable. A memory block is removable only if
+ every section in the block is removable.
+``valid_zones`` read-only: designed to show which zones this memory block
+ can be onlined to.
+
+ The first column shows it`s default zone.
+
+ "memory6/valid_zones: Normal Movable" shows this memoryblock
+ can be onlined to ZONE_NORMAL by default and to ZONE_MOVABLE
+ by online_movable.
+
+ "memory7/valid_zones: Movable Normal" shows this memoryblock
+ can be onlined to ZONE_MOVABLE by default and to ZONE_NORMAL
+ by online_kernel.
+=================== ============================================================
+
+.. note::
+
+ These directories/files appear after physical memory hotplug phase.
+
+If CONFIG_NUMA is enabled the memoryXXX/ directories can also be accessed
+via symbolic links located in the ``/sys/devices/system/node/node*`` directories.
+
+For example::
+
+ /sys/devices/system/node/node0/memory9 -> ../../memory/memory9
+
+A backlink will also be created::
+
+ /sys/devices/system/memory/memory9/node0 -> ../../node/node0
+
+.. _memory_hotplug_physical_mem:
+
+Physical memory hot-add phase
+=============================
+
+Hardware(Firmware) Support
+--------------------------
+
+On x86_64/ia64 platform, memory hotplug by ACPI is supported.
+
+In general, the firmware (ACPI) which supports memory hotplug defines
+memory class object of _HID "PNP0C80". When a notify is asserted to PNP0C80,
+Linux's ACPI handler does hot-add memory to the system and calls a hotplug udev
+script. This will be done automatically.
+
+But scripts for memory hotplug are not contained in generic udev package(now).
+You may have to write it by yourself or online/offline memory by hand.
+Please see :ref:`memory_hotplug_how_to_online_memory` and
+:ref:`memory_hotplug_how_to_offline_memory`.
+
+If firmware supports NUMA-node hotplug, and defines an object _HID "ACPI0004",
+"PNP0A05", or "PNP0A06", notification is asserted to it, and ACPI handler
+calls hotplug code for all of objects which are defined in it.
+If memory device is found, memory hotplug code will be called.
+
+Notify memory hot-add event by hand
+-----------------------------------
+
+On some architectures, the firmware may not notify the kernel of a memory
+hotplug event. Therefore, the memory "probe" interface is supported to
+explicitly notify the kernel. This interface depends on
+CONFIG_ARCH_MEMORY_PROBE and can be configured on powerpc, sh, and x86
+if hotplug is supported, although for x86 this should be handled by ACPI
+notification.
+
+Probe interface is located at::
+
+ /sys/devices/system/memory/probe
+
+You can tell the physical address of new memory to the kernel by::
+
+ % echo start_address_of_new_memory > /sys/devices/system/memory/probe
+
+Then, [start_address_of_new_memory, start_address_of_new_memory +
+memory_block_size] memory range is hot-added. In this case, hotplug script is
+not called (in current implementation). You'll have to online memory by
+yourself. Please see :ref:`memory_hotplug_how_to_online_memory`.
+
+Logical Memory hot-add phase
+============================
+
+State of memory
+---------------
+
+To see (online/offline) state of a memory block, read 'state' file::
+
+ % cat /sys/device/system/memory/memoryXXX/state
+
+
+- If the memory block is online, you'll read "online".
+- If the memory block is offline, you'll read "offline".
+
+
+.. _memory_hotplug_how_to_online_memory:
+
+How to online memory
+--------------------
+
+When the memory is hot-added, the kernel decides whether or not to "online"
+it according to the policy which can be read from "auto_online_blocks" file::
+
+ % cat /sys/devices/system/memory/auto_online_blocks
+
+The default depends on the CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
+option. If it is disabled the default is "offline" which means the newly added
+memory is not in a ready-to-use state and you have to "online" the newly added
+memory blocks manually. Automatic onlining can be requested by writing "online"
+to "auto_online_blocks" file::
+
+ % echo online > /sys/devices/system/memory/auto_online_blocks
+
+This sets a global policy and impacts all memory blocks that will subsequently
+be hotplugged. Currently offline blocks keep their state. It is possible, under
+certain circumstances, that some memory blocks will be added but will fail to
+online. User space tools can check their "state" files
+(``/sys/devices/system/memory/memoryXXX/state``) and try to online them manually.
+
+If the automatic onlining wasn't requested, failed, or some memory block was
+offlined it is possible to change the individual block's state by writing to the
+"state" file::
+
+ % echo online > /sys/devices/system/memory/memoryXXX/state
+
+This onlining will not change the ZONE type of the target memory block,
+If the memory block doesn't belong to any zone an appropriate kernel zone
+(usually ZONE_NORMAL) will be used unless movable_node kernel command line
+option is specified when ZONE_MOVABLE will be used.
+
+You can explicitly request to associate it with ZONE_MOVABLE by::
+
+ % echo online_movable > /sys/devices/system/memory/memoryXXX/state
+
+.. note:: current limit: this memory block must be adjacent to ZONE_MOVABLE
+
+Or you can explicitly request a kernel zone (usually ZONE_NORMAL) by::
+
+ % echo online_kernel > /sys/devices/system/memory/memoryXXX/state
+
+.. note:: current limit: this memory block must be adjacent to ZONE_NORMAL
+
+An explicit zone onlining can fail (e.g. when the range is already within
+and existing and incompatible zone already).
+
+After this, memory block XXX's state will be 'online' and the amount of
+available memory will be increased.
+
+This may be changed in future.
+
+Logical memory remove
+=====================
+
+Memory offline and ZONE_MOVABLE
+-------------------------------
+
+Memory offlining is more complicated than memory online. Because memory offline
+has to make the whole memory block be unused, memory offline can fail if
+the memory block includes memory which cannot be freed.
+
+In general, memory offline can use 2 techniques.
+
+(1) reclaim and free all memory in the memory block.
+(2) migrate all pages in the memory block.
+
+In the current implementation, Linux's memory offline uses method (2), freeing
+all pages in the memory block by page migration. But not all pages are
+migratable. Under current Linux, migratable pages are anonymous pages and
+page caches. For offlining a memory block by migration, the kernel has to
+guarantee that the memory block contains only migratable pages.
+
+Now, a boot option for making a memory block which consists of migratable pages
+is supported. By specifying "kernelcore=" or "movablecore=" boot option, you can
+create ZONE_MOVABLE...a zone which is just used for movable pages.
+(See also Documentation/admin-guide/kernel-parameters.rst)
+
+Assume the system has "TOTAL" amount of memory at boot time, this boot option
+creates ZONE_MOVABLE as following.
+
+1) When kernelcore=YYYY boot option is used,
+ Size of memory not for movable pages (not for offline) is YYYY.
+ Size of memory for movable pages (for offline) is TOTAL-YYYY.
+
+2) When movablecore=ZZZZ boot option is used,
+ Size of memory not for movable pages (not for offline) is TOTAL - ZZZZ.
+ Size of memory for movable pages (for offline) is ZZZZ.
+
+.. note::
+
+ Unfortunately, there is no information to show which memory block belongs
+ to ZONE_MOVABLE. This is TBD.
+
+.. _memory_hotplug_how_to_offline_memory:
+
+How to offline memory
+---------------------
+
+You can offline a memory block by using the same sysfs interface that was used
+in memory onlining::
+
+ % echo offline > /sys/devices/system/memory/memoryXXX/state
+
+If offline succeeds, the state of the memory block is changed to be "offline".
+If it fails, some error core (like -EBUSY) will be returned by the kernel.
+Even if a memory block does not belong to ZONE_MOVABLE, you can try to offline
+it. If it doesn't contain 'unmovable' memory, you'll get success.
+
+A memory block under ZONE_MOVABLE is considered to be able to be offlined
+easily. But under some busy state, it may return -EBUSY. Even if a memory
+block cannot be offlined due to -EBUSY, you can retry offlining it and may be
+able to offline it (or not). (For example, a page is referred to by some kernel
+internal call and released soon.)
+
+Consideration:
+ Memory hotplug's design direction is to make the possibility of memory
+ offlining higher and to guarantee unplugging memory under any situation. But
+ it needs more work. Returning -EBUSY under some situation may be good because
+ the user can decide to retry more or not by himself. Currently, memory
+ offlining code does some amount of retry with 120 seconds timeout.
+
+Physical memory remove
+======================
+
+Need more implementation yet....
+ - Notification completion of remove works by OS to firmware.
+ - Guard from remove if not yet.
+
+
+Locking Internals
+=================
+
+When adding/removing memory that uses memory block devices (i.e. ordinary RAM),
+the device_hotplug_lock should be held to:
+
+- synchronize against online/offline requests (e.g. via sysfs). This way, memory
+ block devices can only be accessed (.online/.state attributes) by user
+ space once memory has been fully added. And when removing memory, we
+ know nobody is in critical sections.
+- synchronize against CPU hotplug and similar (e.g. relevant for ACPI and PPC)
+
+Especially, there is a possible lock inversion that is avoided using
+device_hotplug_lock when adding memory and user space tries to online that
+memory faster than expected:
+
+- device_online() will first take the device_lock(), followed by
+ mem_hotplug_lock
+- add_memory_resource() will first take the mem_hotplug_lock, followed by
+ the device_lock() (while creating the devices, during bus_add_device()).
+
+As the device is visible to user space before taking the device_lock(), this
+can result in a lock inversion.
+
+onlining/offlining of memory should be done via device_online()/
+device_offline() - to make sure it is properly synchronized to actions
+via sysfs. Holding device_hotplug_lock is advised (to e.g. protect online_type)
+
+When adding/removing/onlining/offlining memory or adding/removing
+heterogeneous/device memory, we should always hold the mem_hotplug_lock in
+write mode to serialise memory hotplug (e.g. access to global/zone
+variables).
+
+In addition, mem_hotplug_lock (in contrast to device_hotplug_lock) in read
+mode allows for a quite efficient get_online_mems/put_online_mems
+implementation, so code accessing memory can protect from that memory
+vanishing.
+
+
+Future Work
+===========
+
+ - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
+ sysctl or new control file.
+ - showing memory block and physical device relationship.
+ - test and make it better memory offlining.
+ - support HugeTLB page migration and offlining.
+ - memmap removing at memory offline.
+ - physical remove memory.
diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst
index d78c5b3..8463f55 100644
--- a/Documentation/admin-guide/mm/numa_memory_policy.rst
+++ b/Documentation/admin-guide/mm/numa_memory_policy.rst
@@ -15,7 +15,7 @@
support.
Memory policies should not be confused with cpusets
-(``Documentation/cgroup-v1/cpusets.txt``)
+(``Documentation/admin-guide/cgroup-v1/cpusets.rst``)
which is an administrative mechanism for restricting the nodes from which
memory may be allocated by a set of processes. Memory policies are a
programming interface that a NUMA-aware application can take advantage of. When
diff --git a/Documentation/admin-guide/mm/numaperf.rst b/Documentation/admin-guide/mm/numaperf.rst
new file mode 100644
index 0000000..a80c3c3
--- /dev/null
+++ b/Documentation/admin-guide/mm/numaperf.rst
@@ -0,0 +1,170 @@
+.. _numaperf:
+
+=============
+NUMA Locality
+=============
+
+Some platforms may have multiple types of memory attached to a compute
+node. These disparate memory ranges may share some characteristics, such
+as CPU cache coherence, but may have different performance. For example,
+different media types and buses affect bandwidth and latency.
+
+A system supports such heterogeneous memory by grouping each memory type
+under different domains, or "nodes", based on locality and performance
+characteristics. Some memory may share the same node as a CPU, and others
+are provided as memory only nodes. While memory only nodes do not provide
+CPUs, they may still be local to one or more compute nodes relative to
+other nodes. The following diagram shows one such example of two compute
+nodes with local memory and a memory only node for each of compute node::
+
+ +------------------+ +------------------+
+ | Compute Node 0 +-----+ Compute Node 1 |
+ | Local Node0 Mem | | Local Node1 Mem |
+ +--------+---------+ +--------+---------+
+ | |
+ +--------+---------+ +--------+---------+
+ | Slower Node2 Mem | | Slower Node3 Mem |
+ +------------------+ +--------+---------+
+
+A "memory initiator" is a node containing one or more devices such as
+CPUs or separate memory I/O devices that can initiate memory requests.
+A "memory target" is a node containing one or more physical address
+ranges accessible from one or more memory initiators.
+
+When multiple memory initiators exist, they may not all have the same
+performance when accessing a given memory target. Each initiator-target
+pair may be organized into different ranked access classes to represent
+this relationship. The highest performing initiator to a given target
+is considered to be one of that target's local initiators, and given
+the highest access class, 0. Any given target may have one or more
+local initiators, and any given initiator may have multiple local
+memory targets.
+
+To aid applications matching memory targets with their initiators, the
+kernel provides symlinks to each other. The following example lists the
+relationship for the access class "0" memory initiators and targets::
+
+ # symlinks -v /sys/devices/system/node/nodeX/access0/targets/
+ relative: /sys/devices/system/node/nodeX/access0/targets/nodeY -> ../../nodeY
+
+ # symlinks -v /sys/devices/system/node/nodeY/access0/initiators/
+ relative: /sys/devices/system/node/nodeY/access0/initiators/nodeX -> ../../nodeX
+
+A memory initiator may have multiple memory targets in the same access
+class. The target memory's initiators in a given class indicate the
+nodes' access characteristics share the same performance relative to other
+linked initiator nodes. Each target within an initiator's access class,
+though, do not necessarily perform the same as each other.
+
+================
+NUMA Performance
+================
+
+Applications may wish to consider which node they want their memory to
+be allocated from based on the node's performance characteristics. If
+the system provides these attributes, the kernel exports them under the
+node sysfs hierarchy by appending the attributes directory under the
+memory node's access class 0 initiators as follows::
+
+ /sys/devices/system/node/nodeY/access0/initiators/
+
+These attributes apply only when accessed from nodes that have the
+are linked under the this access's inititiators.
+
+The performance characteristics the kernel provides for the local initiators
+are exported are as follows::
+
+ # tree -P "read*|write*" /sys/devices/system/node/nodeY/access0/initiators/
+ /sys/devices/system/node/nodeY/access0/initiators/
+ |-- read_bandwidth
+ |-- read_latency
+ |-- write_bandwidth
+ `-- write_latency
+
+The bandwidth attributes are provided in MiB/second.
+
+The latency attributes are provided in nanoseconds.
+
+The values reported here correspond to the rated latency and bandwidth
+for the platform.
+
+==========
+NUMA Cache
+==========
+
+System memory may be constructed in a hierarchy of elements with various
+performance characteristics in order to provide large address space of
+slower performing memory cached by a smaller higher performing memory. The
+system physical addresses memory initiators are aware of are provided
+by the last memory level in the hierarchy. The system meanwhile uses
+higher performing memory to transparently cache access to progressively
+slower levels.
+
+The term "far memory" is used to denote the last level memory in the
+hierarchy. Each increasing cache level provides higher performing
+initiator access, and the term "near memory" represents the fastest
+cache provided by the system.
+
+This numbering is different than CPU caches where the cache level (ex:
+L1, L2, L3) uses the CPU-side view where each increased level is lower
+performing. In contrast, the memory cache level is centric to the last
+level memory, so the higher numbered cache level corresponds to memory
+nearer to the CPU, and further from far memory.
+
+The memory-side caches are not directly addressable by software. When
+software accesses a system address, the system will return it from the
+near memory cache if it is present. If it is not present, the system
+accesses the next level of memory until there is either a hit in that
+cache level, or it reaches far memory.
+
+An application does not need to know about caching attributes in order
+to use the system. Software may optionally query the memory cache
+attributes in order to maximize the performance out of such a setup.
+If the system provides a way for the kernel to discover this information,
+for example with ACPI HMAT (Heterogeneous Memory Attribute Table),
+the kernel will append these attributes to the NUMA node memory target.
+
+When the kernel first registers a memory cache with a node, the kernel
+will create the following directory::
+
+ /sys/devices/system/node/nodeX/memory_side_cache/
+
+If that directory is not present, the system either does not not provide
+a memory-side cache, or that information is not accessible to the kernel.
+
+The attributes for each level of cache is provided under its cache
+level index::
+
+ /sys/devices/system/node/nodeX/memory_side_cache/indexA/
+ /sys/devices/system/node/nodeX/memory_side_cache/indexB/
+ /sys/devices/system/node/nodeX/memory_side_cache/indexC/
+
+Each cache level's directory provides its attributes. For example, the
+following shows a single cache level and the attributes available for
+software to query::
+
+ # tree sys/devices/system/node/node0/memory_side_cache/
+ /sys/devices/system/node/node0/memory_side_cache/
+ |-- index1
+ | |-- indexing
+ | |-- line_size
+ | |-- size
+ | `-- write_policy
+
+The "indexing" will be 0 if it is a direct-mapped cache, and non-zero
+for any other indexed based, multi-way associativity.
+
+The "line_size" is the number of bytes accessed from the next cache
+level on a miss.
+
+The "size" is the number of bytes provided by this cache level.
+
+The "write_policy" will be 0 for write-back, and non-zero for
+write-through caching.
+
+========
+See Also
+========
+
+[1] https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf
+- Section 5.2.27
diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index 3f7bade..340a5ae 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -75,9 +75,10 @@
20. NOPAGE
21. KSM
22. THP
- 23. BALLOON
+ 23. OFFLINE
24. ZERO_PAGE
25. IDLE
+ 26. PGTABLE
* ``/proc/kpagecgroup``. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
@@ -118,8 +119,8 @@
identical memory pages dynamically shared between one or more processes
22 - THP
contiguous pages which construct transparent hugepages
-23 - BALLOON
- balloon compaction page
+23 - OFFLINE
+ page is logically offline
24 - ZERO_PAGE
zero page for pfn_zero or huge_zero page
25 - IDLE
@@ -128,6 +129,8 @@
Note that this flag may be stale in case the page was accessed via
a PTE. To make sure the flag is up-to-date one has to read
``/sys/kernel/mm/page_idle/bitmap`` first.
+26 - PGTABLE
+ page is in use as a page table
IO related page flags
---------------------
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 7ab93a8..bd57145 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -53,7 +53,7 @@
collapses sequences of basic pages into huge pages.
The THP behaviour is controlled via :ref:`sysfs <thp_sysfs>`
-interface and using madivse(2) and prctl(2) system calls.
+interface and using madvise(2) and prctl(2) system calls.
Transparent Hugepage Support maximizes the usefulness of free memory
if compared to the reservation approach of hugetlbfs by allowing all