diff options
Diffstat (limited to 'Documentation/admin-guide')
19 files changed, 452 insertions, 58 deletions
diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst index f93a467db628..dc7088451f9d 100644 --- a/Documentation/admin-guide/LSM/ipe.rst +++ b/Documentation/admin-guide/LSM/ipe.rst @@ -423,7 +423,7 @@ Field descriptions: Event Example:: - type=1422 audit(1653425529.927:53): policy_name="boot_verified" policy_version=0.0.0 policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F26765076DD8EED7B8F4DB auid=4294967295 ses=4294967295 lsm=ipe res=1 + type=1422 audit(1653425529.927:53): policy_name="boot_verified" policy_version=0.0.0 policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F26765076DD8EED7B8F4DB auid=4294967295 ses=4294967295 lsm=ipe res=1 errno=0 type=1300 audit(1653425529.927:53): arch=c000003e syscall=1 success=yes exit=2567 a0=3 a1=5596fcae1fb0 a2=a07 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null) type=1327 audit(1653425529.927:53): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2E @@ -433,24 +433,55 @@ This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record Field descriptions: -+----------------+------------+-----------+---------------------------------------------------+ -| Field | Value Type | Optional? | Description of Value | -+================+============+===========+===================================================+ -| policy_name | string | No | The policy_name | -+----------------+------------+-----------+---------------------------------------------------+ -| policy_version | string | No | The policy_version | -+----------------+------------+-----------+---------------------------------------------------+ -| policy_digest | string | No | The policy hash | -+----------------+------------+-----------+---------------------------------------------------+ -| auid | integer | No | The login user ID | -+----------------+------------+-----------+---------------------------------------------------+ -| ses | integer | No | The login session ID | -+----------------+------------+-----------+---------------------------------------------------+ -| lsm | string | No | The lsm name associated with the event | -+----------------+------------+-----------+---------------------------------------------------+ -| res | integer | No | The result of the audited operation(success/fail) | -+----------------+------------+-----------+---------------------------------------------------+ - ++----------------+------------+-----------+-------------------------------------------------------------+ +| Field | Value Type | Optional? | Description of Value | ++================+============+===========+=============================================================+ +| policy_name | string | Yes | The policy_name | ++----------------+------------+-----------+-------------------------------------------------------------+ +| policy_version | string | Yes | The policy_version | ++----------------+------------+-----------+-------------------------------------------------------------+ +| policy_digest | string | Yes | The policy hash | ++----------------+------------+-----------+-------------------------------------------------------------+ +| auid | integer | No | The login user ID | ++----------------+------------+-----------+-------------------------------------------------------------+ +| ses | integer | No | The login session ID | ++----------------+------------+-----------+-------------------------------------------------------------+ +| lsm | string | No | The lsm name associated with the event | ++----------------+------------+-----------+-------------------------------------------------------------+ +| res | integer | No | The result of the audited operation(success/fail) | ++----------------+------------+-----------+-------------------------------------------------------------+ +| errno | integer | No | Error code from policy loading operations (see table below) | ++----------------+------------+-----------+-------------------------------------------------------------+ + +Policy error codes (errno): + +The following table lists the error codes that may appear in the errno field while loading or updating the policy: + ++----------------+--------------------------------------------------------+ +| Error Code | Description | ++================+========================================================+ +| 0 | Success | ++----------------+--------------------------------------------------------+ +| -EPERM | Insufficient permission | ++----------------+--------------------------------------------------------+ +| -EEXIST | Same name policy already deployed | ++----------------+--------------------------------------------------------+ +| -EBADMSG | Policy is invalid | ++----------------+--------------------------------------------------------+ +| -ENOMEM | Out of memory (OOM) | ++----------------+--------------------------------------------------------+ +| -ERANGE | Policy version number overflow | ++----------------+--------------------------------------------------------+ +| -EINVAL | Policy version parsing error | ++----------------+--------------------------------------------------------+ +| -ENOKEY | Key used to sign the IPE policy not found in keyring | ++----------------+--------------------------------------------------------+ +| -EKEYREJECTED | Policy signature verification failed | ++----------------+--------------------------------------------------------+ +| -ESTALE | Attempting to update an IPE policy with older version | ++----------------+--------------------------------------------------------+ +| -ENOENT | Policy was deleted while updating | ++----------------+--------------------------------------------------------+ 1404 AUDIT_MAC_STATUS ^^^^^^^^^^^^^^^^^^^^^ diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst index 70b02f30013a..05301f03b717 100644 --- a/Documentation/admin-guide/README.rst +++ b/Documentation/admin-guide/README.rst @@ -259,7 +259,7 @@ Configuring the kernel Compiling the kernel -------------------- - - Make sure you have at least gcc 5.1 available. + - Make sure you have at least gcc 8.1 available. For more information, refer to :ref:`Documentation/process/changes.rst <changes>`. - Do a ``make`` to create a compressed kernel image. It is also possible to do diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index 9bdb30901a93..3e273c1bb749 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -317,6 +317,26 @@ a single line of text and contains the following stats separated by whitespace: Optional Feature ================ +IDLE pages tracking +------------------- + +zram has built-in support for idle pages tracking (that is, allocated but +not used pages). This feature is useful for e.g. zram writeback and +recompression. In order to mark pages as idle, execute the following command:: + + echo all > /sys/block/zramX/idle + +This will mark all allocated zram pages as idle. The idle mark will be +removed only when the page (block) is accessed (e.g. overwritten or freed). +Additionally, when CONFIG_ZRAM_TRACK_ENTRY_ACTIME is enabled, pages can be +marked as idle based on how many seconds have passed since the last access to +a particular zram page:: + + echo 86400 > /sys/block/zramX/idle + +In this example, all pages which haven't been accessed in more than 86400 +seconds (one day) will be marked idle. + writeback --------- @@ -331,24 +351,7 @@ If admin wants to use incompressible page writeback, they could do it via:: echo huge > /sys/block/zramX/writeback -To use idle page writeback, first, user need to declare zram pages -as idle:: - - echo all > /sys/block/zramX/idle - -From now on, any pages on zram are idle pages. The idle mark -will be removed until someone requests access of the block. -IOW, unless there is access request, those pages are still idle pages. -Additionally, when CONFIG_ZRAM_TRACK_ENTRY_ACTIME is enabled pages can be -marked as idle based on how long (in seconds) it's been since they were -last accessed:: - - echo 86400 > /sys/block/zramX/idle - -In this example all pages which haven't been accessed in more than 86400 -seconds (one day) will be marked idle. - -Admin can request writeback of those idle pages at right timing via:: +Admin can request writeback of idle pages at right timing via:: echo idle > /sys/block/zramX/writeback @@ -369,6 +372,23 @@ they could write a page index into the interface:: echo "page_index=1251" > /sys/block/zramX/writeback +In Linux 6.16 this interface underwent some rework. First, the interface +now supports `key=value` format for all of its parameters (`type=huge_idle`, +etc.) Second, the support for `page_indexes` was introduced, which specify +`LOW-HIGH` range (or ranges) of pages to be written-back. This reduces the +number of syscalls, but more importantly this enables optimal post-processing +target selection strategy. Usage example:: + + echo "type=idle" > /sys/block/zramX/writeback + echo "page_indexes=1-100 page_indexes=200-300" > \ + /sys/block/zramX/writeback + +We also now permit multiple page_index params per call and a mix of +single pages and page ranges:: + + echo page_index=42 page_index=99 page_indexes=100-200 \ + page_indexes=500-700 > /sys/block/zramX/writeback + If there are lots of write IO with flash device, potentially, it has flash wearout problem so that admin needs to design write limitation to guarantee storage health for entire product life. @@ -482,8 +502,6 @@ attempt to recompress::: echo "type=huge_idle max_pages=42" > /sys/block/zramX/recompress -Recompression of idle pages requires memory tracking. - During re-compression for every page, that matches re-compression criteria, ZRAM iterates the list of registered alternative compression algorithms in order of their priorities. ZRAM stops either when re-compression was diff --git a/Documentation/admin-guide/cgroup-v1/cgroups.rst b/Documentation/admin-guide/cgroup-v1/cgroups.rst index a3e2edb3d274..463f98453323 100644 --- a/Documentation/admin-guide/cgroup-v1/cgroups.rst +++ b/Documentation/admin-guide/cgroup-v1/cgroups.rst @@ -13,7 +13,7 @@ Portions Copyright (c) 2004-2006 Silicon Graphics, Inc. Modified by Paul Jackson <pj@sgi.com> -Modified by Christoph Lameter <cl@linux.com> +Modified by Christoph Lameter <cl@gentwo.org> .. CONTENTS: diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst index f401af5e2f09..c7909e5ac136 100644 --- a/Documentation/admin-guide/cgroup-v1/cpusets.rst +++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst @@ -10,7 +10,7 @@ Written by Simon.Derr@bull.net - Portions Copyright (c) 2004-2006 Silicon Graphics, Inc. - Modified by Paul Jackson <pj@sgi.com> -- Modified by Christoph Lameter <cl@linux.com> +- Modified by Christoph Lameter <cl@gentwo.org> - Modified by Paul Menage <menage@google.com> - Modified by Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 1edc26622594..bd98ea3175ec 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1334,6 +1334,18 @@ PAGE_SIZE multiple when read back. monitors the limited cgroup to alleviate heavy reclaim pressure. + If memory.high is opened with O_NONBLOCK then the synchronous + reclaim is bypassed. This is useful for admin processes that + need to dynamically adjust the job's memory limits without + expending their own CPU resources on memory reclamation. The + job will trigger the reclaim and/or get throttled on its + next charge request. + + Please note that with O_NONBLOCK, there is a chance that the + target memory cgroup may take indefinite amount of time to + reduce usage below the limit due to delayed charge request or + busy-hitting its memory to slow down reclaim. + memory.max A read-write single value file which exists on non-root cgroups. The default is "max". @@ -1351,6 +1363,18 @@ PAGE_SIZE multiple when read back. Caller could retry them differently, return into userspace as -ENOMEM or silently ignore in cases like disk readahead. + If memory.max is opened with O_NONBLOCK, then the synchronous + reclaim and oom-kill are bypassed. This is useful for admin + processes that need to dynamically adjust the job's memory limits + without expending their own CPU resources on memory reclamation. + The job will trigger the reclaim and/or oom-kill on its next + charge request. + + Please note that with O_NONBLOCK, there is a chance that the + target memory cgroup may take indefinite amount of time to + reduce usage below the limit due to delayed charge request or + busy-hitting its memory to slow down reclaim. + memory.reclaim A write-only nested-keyed file which exists for all cgroups. @@ -1383,6 +1407,9 @@ The following nested keys are defined. same semantics as vm.swappiness applied to memcg reclaim with all the existing limitations and potential future extensions. + The valid range for swappiness is [0-200, max], setting + swappiness=max exclusively reclaims anonymous memory. + memory.peak A read-write single value file which exists on non-root cgroups. diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 1f7f14c6e184..20fabdf6567e 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -547,6 +547,38 @@ from within add_taint() whenever the value set in this bitmask matches with the bit flag being set by add_taint(). This will cause a kdump to occur at the add_taint()->panic() call. +Write the dump file to encrypted disk volume +============================================ + +CONFIG_CRASH_DM_CRYPT can be enabled to support saving the dump file to an +encrypted disk volume (only x86_64 supported for now). User space can interact +with /sys/kernel/config/crash_dm_crypt_keys for setup, + +1. Tell the first kernel what logon keys are needed to unlock the disk volumes, + # Add key #1 + mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720 + # Add key #1's description + echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 1 + + # Add key #2 in the same way + + # how many keys do we have now? + cat /sys/kernel/config/crash_dm_crypt_keys/count + 2 + + # To support CPU/memory hot-plugging, re-use keys already saved to reserved + # memory + echo true > /sys/kernel/config/crash_dm_crypt_key/reuse + +2. Load the dump-capture kernel + +3. After the dump-capture kerne get booted, restore the keys to user keyring + echo yes > /sys/kernel/crash_dm_crypt_keys/restore + Contact ======= diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst index 0f714fc945ac..8cf4614385b7 100644 --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst @@ -331,8 +331,8 @@ PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_slab|PG_hwpoision|PG_head_mask|P Page attributes. These flags are used to filter various unnecessary for dumping pages. -PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline) ------------------------------------------------------------------------------ +PAGE_BUDDY_MAPCOUNT_VALUE(~PG_buddy)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_offline)|PAGE_OFFLINE_MAPCOUNT_VALUE(~PG_unaccepted) +------------------------------------------------------------------------------------------------------------------------- More page attributes. These flags are used to filter various unnecessary for dumping pages. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ea81784be981..a3ea40b22fb9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2749,6 +2749,31 @@ kgdbwait [KGDB,EARLY] Stop kernel execution and enter the kernel debugger at the earliest opportunity. + kho= [KEXEC,EARLY] + Format: { "0" | "1" | "off" | "on" | "y" | "n" } + Enables or disables Kexec HandOver. + "0" | "off" | "n" - kexec handover is disabled + "1" | "on" | "y" - kexec handover is enabled + + kho_scratch= [KEXEC,EARLY] + Format: ll[KMG],mm[KMG],nn[KMG] | nn% + Defines the size of the KHO scratch region. The KHO + scratch regions are physically contiguous memory + ranges that can only be used for non-kernel + allocations. That way, even when memory is heavily + fragmented with handed over memory, the kexeced + kernel will always have enough contiguous ranges to + bootstrap itself. + + It is possible to specify the exact amount of + memory in the form of "ll[KMG],mm[KMG],nn[KMG]" + where the first parameter defines the size of a low + memory scratch area, the second parameter defines + the size of a global scratch area and the third + parameter defines the size of additional per-node + scratch areas. The form "nn%" defines scale factor + (in percents) of memory that was used during boot. + kmac= [MIPS] Korina ethernet MAC address. Configure the RouterBoard 532 series on-chip Ethernet adapter MAC address. diff --git a/Documentation/admin-guide/laptops/alienware-wmi.rst b/Documentation/admin-guide/laptops/alienware-wmi.rst new file mode 100644 index 000000000000..27a32a8057da --- /dev/null +++ b/Documentation/admin-guide/laptops/alienware-wmi.rst @@ -0,0 +1,127 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +==================== +Alienware WMI Driver +==================== + +Kurt Borja <kuurtb@gmail.com> + +This is a driver for the "WMAX" WMI device, which is found in most Dell gaming +laptops and controls various special features. + +Before the launch of M-Series laptops (~2018), the "WMAX" device controlled +basic RGB lighting, deep sleep mode, HDMI mode and amplifier status. + +Later, this device was completely repurpused. Now it mostly deals with thermal +profiles, sensor monitoring and overclocking. This interface is named "AWCC" and +is known to be used by the AWCC OEM application to control these features. + +The alienware-wmi driver controls both interfaces. + +AWCC Interface +============== + +WMI device documentation: Documentation/wmi/devices/alienware-wmi.rst + +Supported devices +----------------- + +- Alienware M-Series laptops +- Alienware X-Series laptops +- Alienware Aurora Desktops +- Dell G-Series laptops + +If you believe your device supports the AWCC interface and you don't have any of +the features described in this document, try the following alienware-wmi module +parameters: + +- ``force_platform_profile=1``: Forces probing for platform profile support +- ``force_hwmon=1``: Forces probing for HWMON support + +If the module loads successfully with these parameters, consider submitting a +patch adding your model to the ``awcc_dmi_table`` located in +``drivers/platform/x86/dell/alienware-wmi-wmax.c`` or contacting the maintainer +for further guidance. + +Status +------ + +The following features are currently supported: + +- :ref:`Platform Profile <platform-profile>`: + + - Thermal profile control + + - G-Mode toggling + +- :ref:`HWMON <hwmon>`: + + - Sensor monitoring + + - Manual fan control + +.. _platform-profile: + +Platform Profile +---------------- + +The AWCC interface exposes various firmware defined thermal profiles. These are +exposed to user-space through the Platform Profile class interface. Refer to +:ref:`sysfs-class-platform-profile <abi_file_testing_sysfs_class_platform_profile>` +for more information. + +The name of the platform-profile class device exported by this driver is +"alienware-wmi" and it's path can be found with: + +:: + + grep -l "alienware-wmi" /sys/class/platform-profile/platform-profile-*/name | sed 's|/[^/]*$||' + +If the device supports G-Mode, it is also toggled when selecting the +``performance`` profile. + +.. note:: + You may set the ``force_gmode`` module parameter to always try to toggle this + feature, without checking if your model supports it. + +.. _hwmon: + +HWMON +----- + +The AWCC interface also supports sensor monitoring and manual fan control. Both +of these features are exposed to user-space through the HWMON interface. + +The name of the hwmon class device exported by this driver is "alienware_wmi" +and it's path can be found with: + +:: + + grep -l "alienware_wmi" /sys/class/hwmon/hwmon*/name | sed 's|/[^/]*$||' + +Sensor monitoring is done through the standard HWMON interface. Refer to +:ref:`sysfs-class-hwmon <abi_file_testing_sysfs_class_hwmon>` for more +information. + +Manual fan control on the other hand, is not exposed directly by the AWCC +interface. Instead it let's us control a fan `boost` value. This `boost` value +has the following aproximate behavior over the fan pwm: + +:: + + pwm = pwm_base + (fan_boost / 255) * (pwm_max - pwm_base) + +Due to the above behavior, the fan `boost` control is exposed to user-space +through the following, custom hwmon sysfs attribute: + +=============================== ======= ======================================= +Name Perm Description +=============================== ======= ======================================= +fan[1-4]_boost RW Fan boost value. + + Integer value between 0 and 255 +=============================== ======= ======================================= + +.. note:: + In some devices, manual fan control only works reliably if the ``custom`` + platform profile is selected. diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst index e71c8984c23e..db842b629303 100644 --- a/Documentation/admin-guide/laptops/index.rst +++ b/Documentation/admin-guide/laptops/index.rst @@ -7,6 +7,7 @@ Laptop Drivers .. toctree:: :maxdepth: 1 + alienware-wmi asus-laptop disk-shock-protection laptop-mode diff --git a/Documentation/admin-guide/mm/damon/index.rst b/Documentation/admin-guide/mm/damon/index.rst index 33d37bb2fb4e..bc7e976120e0 100644 --- a/Documentation/admin-guide/mm/damon/index.rst +++ b/Documentation/admin-guide/mm/damon/index.rst @@ -1,12 +1,11 @@ .. SPDX-License-Identifier: GPL-2.0 -========================== -DAMON: Data Access MONitor -========================== +================================================================ +DAMON: Data Access MONitoring and Access-aware System Operations +================================================================ -:doc:`DAMON </mm/damon/index>` allows light-weight data access monitoring. -Using DAMON, users can analyze the memory access patterns of their systems and -optimize those. +:doc:`DAMON </mm/damon/index>` is a Linux kernel subsystem for efficient data +access monitoring and access-aware system operations. .. toctree:: :maxdepth: 2 diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index ced2013db3df..d960aba72b82 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -81,7 +81,7 @@ comma (","). │ │ │ │ │ │ │ :ref:`quotas <sysfs_quotas>`/ms,bytes,reset_interval_ms,effective_bytes │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil │ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals - │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value + │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid │ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,target_idx,min,max @@ -390,11 +390,11 @@ number (``N``) to the file creates the number of child directories named ``0`` to ``N-1``. Each directory represents each goal and current achievement. Among the multiple feedback, the best one is used. -Each goal directory contains three files, namely ``target_metric``, -``target_value`` and ``current_value``. Users can set and get the three -parameters for the quota auto-tuning goals that specified on the :ref:`design -doc <damon_design_damos_quotas_auto_tuning>` by writing to and reading from each -of the files. Note that users should further write +Each goal directory contains four files, namely ``target_metric``, +``target_value``, ``current_value`` and ``nid``. Users can set and get the +four parameters for the quota auto-tuning goals that specified on the +:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and +reading from each of the files. Note that users should further write ``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond directory <sysfs_kdamond>` to pass the feedback to DAMON. diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst index 8b35795b664b..2d2f6c222308 100644 --- a/Documentation/admin-guide/mm/index.rst +++ b/Documentation/admin-guide/mm/index.rst @@ -42,3 +42,4 @@ the Linux memory management. transhuge userfaultfd zswap + kho diff --git a/Documentation/admin-guide/mm/kho.rst b/Documentation/admin-guide/mm/kho.rst new file mode 100644 index 000000000000..6dc18ed4b886 --- /dev/null +++ b/Documentation/admin-guide/mm/kho.rst @@ -0,0 +1,115 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +==================== +Kexec Handover Usage +==================== + +Kexec HandOver (KHO) is a mechanism that allows Linux to preserve memory +regions, which could contain serialized system states, across kexec. + +This document expects that you are familiar with the base KHO +:ref:`concepts <kho-concepts>`. If you have not read +them yet, please do so now. + +Prerequisites +============= + +KHO is available when the kernel is compiled with ``CONFIG_KEXEC_HANDOVER`` +set to y. Every KHO producer may have its own config option that you +need to enable if you would like to preserve their respective state across +kexec. + +To use KHO, please boot the kernel with the ``kho=on`` command line +parameter. You may use ``kho_scratch`` parameter to define size of the +scratch regions. For example ``kho_scratch=16M,512M,256M`` will reserve a +16 MiB low memory scratch area, a 512 MiB global scratch region, and 256 MiB +per NUMA node scratch regions on boot. + +Perform a KHO kexec +=================== + +First, before you perform a KHO kexec, you need to move the system into +the :ref:`KHO finalization phase <kho-finalization-phase>` :: + + $ echo 1 > /sys/kernel/debug/kho/out/finalize + +After this command, the KHO FDT is available in +``/sys/kernel/debug/kho/out/fdt``. Other subsystems may also register +their own preserved sub FDTs under +``/sys/kernel/debug/kho/out/sub_fdts/``. + +Next, load the target payload and kexec into it. It is important that you +use the ``-s`` parameter to use the in-kernel kexec file loader, as user +space kexec tooling currently has no support for KHO with the user space +based file loader :: + + # kexec -l /path/to/bzImage --initrd /path/to/initrd -s + # kexec -e + +The new kernel will boot up and contain some of the previous kernel's state. + +For example, if you used ``reserve_mem`` command line parameter to create +an early memory reservation, the new kernel will have that memory at the +same physical address as the old kernel. + +Abort a KHO exec +================ + +You can move the system out of KHO finalization phase again by calling :: + + $ echo 0 > /sys/kernel/debug/kho/out/active + +After this command, the KHO FDT is no longer available in +``/sys/kernel/debug/kho/out/fdt``. + +debugfs Interfaces +================== + +Currently KHO creates the following debugfs interfaces. Notice that these +interfaces may change in the future. They will be moved to sysfs once KHO is +stabilized. + +``/sys/kernel/debug/kho/out/finalize`` + Kexec HandOver (KHO) allows Linux to transition the state of + compatible drivers into the next kexec'ed kernel. To do so, + device drivers will instruct KHO to preserve memory regions, + which could contain serialized kernel state. + While the state is serialized, they are unable to perform + any modifications to state that was serialized, such as + handed over memory allocations. + + When this file contains "1", the system is in the transition + state. When contains "0", it is not. To switch between the + two states, echo the respective number into this file. + +``/sys/kernel/debug/kho/out/fdt`` + When KHO state tree is finalized, the kernel exposes the + flattened device tree blob that carries its current KHO + state in this file. Kexec user space tooling can use this + as input file for the KHO payload image. + +``/sys/kernel/debug/kho/out/scratch_len`` + Lengths of KHO scratch regions, which are physically contiguous + memory regions that will always stay available for future kexec + allocations. Kexec user space tools can use this file to determine + where it should place its payload images. + +``/sys/kernel/debug/kho/out/scratch_phys`` + Physical locations of KHO scratch regions. Kexec user space tools + can use this file in conjunction to scratch_phys to determine where + it should place its payload images. + +``/sys/kernel/debug/kho/out/sub_fdts/`` + In the KHO finalization phase, KHO producers register their own + FDT blob under this directory. + +``/sys/kernel/debug/kho/in/fdt`` + When the kernel was booted with Kexec HandOver (KHO), + the state tree that carries metadata about the previous + kernel's state is in this file in the format of flattened + device tree. This file may disappear when all consumers of + it finished to interpret their metadata. + +``/sys/kernel/debug/kho/in/sub_fdts/`` + Similar to ``kho/out/sub_fdts/``, but contains sub FDT blobs + of KHO producers passed from the old kernel. diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst index 33e068830497..9cb54b4ff5d9 100644 --- a/Documentation/admin-guide/mm/multigen_lru.rst +++ b/Documentation/admin-guide/mm/multigen_lru.rst @@ -151,8 +151,9 @@ generations less than or equal to ``min_gen_nr``. ``min_gen_nr`` should be less than ``max_gen_nr-1``, since ``max_gen_nr`` and ``max_gen_nr-1`` are not fully aged (equivalent to the active list) and therefore cannot be evicted. ``swappiness`` -overrides the default value in ``/proc/sys/vm/swappiness``. -``nr_to_reclaim`` limits the number of pages to evict. +overrides the default value in ``/proc/sys/vm/swappiness`` and the valid +range is [0-200, max], with max being exclusively used for the reclamation +of anonymous memory. ``nr_to_reclaim`` limits the number of pages to evict. A typical use case is that a job scheduler runs this command before it tries to land a new job on a server. If it fails to materialize enough diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst index afce291649dd..e60e9211fd9b 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -250,6 +250,7 @@ Following flags about pages are currently supported: - ``PAGE_IS_PFNZERO`` - Page has zero PFN - ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed - ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty +- ``PAGE_IS_GUARD`` - Page is a part of a guard region The ``struct pm_scan_arg`` is used as the argument of the IOCTL. diff --git a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst index 5151ec312dc0..d367ba4d744a 100644 --- a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst +++ b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst @@ -91,12 +91,22 @@ Attributes in each directory: ``domain_id`` This attribute is used to get the power domain id of this instance. +``die_id`` + This attribute is used to get the Linux die id of this instance. + This attribute is only present for domains with core agents and + when the CPUID leaf 0x1f presents die ID. + ``fabric_cluster_id`` This attribute is used to get the fabric cluster id of this instance. ``package_id`` This attribute is used to get the package id of this instance. +``agent_types`` + This attribute displays all the hardware agents present within the + domain. Each agent has the capability to control one or more hardware + subsystems, which include: core, cache, memory, and I/O. + The other attributes are same as presented at package_*_die_* level. In most of current use cases, the "max_freq_khz" and "min_freq_khz" diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index d385985b305f..9bef46151d53 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -132,6 +132,12 @@ to latency spikes in unsuspecting applications. The kernel employs various heuristics to avoid wasting CPU cycles if it detects that proactive compaction is not being effective. +Setting the value above 80 will, in addition to lowering the acceptable level +of fragmentation, make the compaction code more sensitive to increases in +fragmentation, i.e. compaction will trigger more often, but reduce +fragmentation by a smaller amount. +This makes the fragmentation level more stable over time. + Be careful when setting it to extreme values like 100, as that may cause excessive background compaction activity. |