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authorLinus Torvalds <torvalds@linux-foundation.org>2022-05-26 22:32:41 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-05-26 22:32:41 +0300
commit98931dd95fd489fcbfa97da563505a6f071d7c77 (patch)
tree44683fc4a92efa614acdca2742a7ff19d26da1e3 /Documentation/admin-guide
parentdf202b452fe6c6d6f1351bad485e2367ef1e644e (diff)
parentf403f22f8ccb12860b2b62fec3173c6ccd45938b (diff)
downloadlinux-98931dd95fd489fcbfa97da563505a6f071d7c77.tar.xz
Merge tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton: "Almost all of MM here. A few things are still getting finished off, reviewed, etc. - Yang Shi has improved the behaviour of khugepaged collapsing of readonly file-backed transparent hugepages. - Johannes Weiner has arranged for zswap memory use to be tracked and managed on a per-cgroup basis. - Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for runtime enablement of the recent huge page vmemmap optimization feature. - Baolin Wang contributes a series to fix some issues around hugetlb pagetable invalidation. - Zhenwei Pi has fixed some interactions between hwpoisoned pages and virtualization. - Tong Tiangen has enabled the use of the presently x86-only page_table_check debugging feature on arm64 and riscv. - David Vernet has done some fixup work on the memcg selftests. - Peter Xu has taught userfaultfd to handle write protection faults against shmem- and hugetlbfs-backed files. - More DAMON development from SeongJae Park - adding online tuning of the feature and support for monitoring of fixed virtual address ranges. Also easier discovery of which monitoring operations are available. - Nadav Amit has done some optimization of TLB flushing during mprotect(). - Neil Brown continues to labor away at improving our swap-over-NFS support. - David Hildenbrand has some fixes to anon page COWing versus get_user_pages(). - Peng Liu fixed some errors in the core hugetlb code. - Joao Martins has reduced the amount of memory consumed by device-dax's compound devmaps. - Some cleanups of the arch-specific pagemap code from Anshuman Khandual. - Muchun Song has found and fixed some errors in the TLB flushing of transparent hugepages. - Roman Gushchin has done more work on the memcg selftests. ... and, of course, many smaller fixes and cleanups. Notably, the customary million cleanup serieses from Miaohe Lin" * tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (381 commits) mm: kfence: use PAGE_ALIGNED helper selftests: vm: add the "settings" file with timeout variable selftests: vm: add "test_hmm.sh" to TEST_FILES selftests: vm: check numa_available() before operating "merge_across_nodes" in ksm_tests selftests: vm: add migration to the .gitignore selftests/vm/pkeys: fix typo in comment ksm: fix typo in comment selftests: vm: add process_mrelease tests Revert "mm/vmscan: never demote for memcg reclaim" mm/kfence: print disabling or re-enabling message include/trace/events/percpu.h: cleanup for "percpu: improve percpu_alloc_percpu event trace" include/trace/events/mmflags.h: cleanup for "tracing: incorrect gfp_t conversion" mm: fix a potential infinite loop in start_isolate_page_range() MAINTAINERS: add Muchun as co-maintainer for HugeTLB zram: fix Kconfig dependency warning mm/shmem: fix shmem folio swapoff hang cgroup: fix an error handling path in alloc_pagecache_max_30M() mm: damon: use HPAGE_PMD_SIZE tracing: incorrect isolate_mote_t cast in mm_vmscan_lru_isolate nodemask.h: fix compilation error with GCC12 ...
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/blockdev/zram.rst5
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst49
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt10
-rw-r--r--Documentation/admin-guide/mm/damon/reclaim.rst11
-rw-r--r--Documentation/admin-guide/mm/damon/usage.rst41
-rw-r--r--Documentation/admin-guide/mm/hugetlbpage.rst2
-rw-r--r--Documentation/admin-guide/mm/ksm.rst18
-rw-r--r--Documentation/admin-guide/sysctl/vm.rst48
8 files changed, 165 insertions, 19 deletions
diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index 54fe63745ed8..c73b16930449 100644
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -343,6 +343,11 @@ Admin can request writeback of those idle pages at right timing via::
With the command, zram will writeback idle pages from memory to the storage.
+Additionally, if a user choose to writeback only huge and idle pages
+this can be accomplished with::
+
+ echo huge_idle > /sys/block/zramX/writeback
+
If an admin wants to write a specific page in zram device to the backing device,
they could write a page index into the interface.
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 38aa01939e1e..176298f2f4de 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1208,6 +1208,34 @@ PAGE_SIZE multiple when read back.
high limit is used and monitored properly, this limit's
utility is limited to providing the final safety net.
+ memory.reclaim
+ A write-only nested-keyed file which exists for all cgroups.
+
+ This is a simple interface to trigger memory reclaim in the
+ target cgroup.
+
+ This file accepts a single key, the number of bytes to reclaim.
+ No nested keys are currently supported.
+
+ Example::
+
+ echo "1G" > memory.reclaim
+
+ The interface can be later extended with nested keys to
+ configure the reclaim behavior. For example, specify the
+ type of memory to reclaim from (anon, file, ..).
+
+ Please note that the kernel can over or under reclaim from
+ the target cgroup. If less bytes are reclaimed than the
+ specified amount, -EAGAIN is returned.
+
+ memory.peak
+ A read-only single value file which exists on non-root
+ cgroups.
+
+ The max memory usage recorded for the cgroup and its
+ descendants since the creation of the cgroup.
+
memory.oom.group
A read-write single value file which exists on non-root
cgroups. The default value is "0".
@@ -1326,6 +1354,12 @@ PAGE_SIZE multiple when read back.
Amount of cached filesystem data that is swap-backed,
such as tmpfs, shm segments, shared anonymous mmap()s
+ zswap
+ Amount of memory consumed by the zswap compression backend.
+
+ zswapped
+ Amount of application memory swapped out to zswap.
+
file_mapped
Amount of cached filesystem data mapped with mmap()
@@ -1516,6 +1550,21 @@ PAGE_SIZE multiple when read back.
higher than the limit for an extended period of time. This
reduces the impact on the workload and memory management.
+ memory.zswap.current
+ A read-only single value file which exists on non-root
+ cgroups.
+
+ The total amount of memory consumed by the zswap compression
+ backend.
+
+ memory.zswap.max
+ A read-write single value file which exists on non-root
+ cgroups. The default is "max".
+
+ Zswap usage hard limit. If a cgroup's zswap pool reaches this
+ limit, it will refuse to take any more stores before existing
+ entries fault back in or are written out to disk.
+
memory.pressure
A read-only nested-keyed file.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a9066cfb85a0..32073f873662 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1705,16 +1705,16 @@
boot-time allocation of gigantic hugepages is skipped.
hugetlb_free_vmemmap=
- [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+ [KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
enabled.
Allows heavy hugetlb users to free up some more
memory (7 * PAGE_SIZE for each 2MB hugetlb page).
- Format: { on | off (default) }
+ Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) }
- on: enable the feature
- off: disable the feature
+ [oO][Nn]/Y/y/1: enable the feature
+ [oO][Ff]/N/n/0: disable the feature
- Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y,
+ Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y,
the default is on.
This is not compatible with memory_hotplug.memmap_on_memory.
diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
index 0af51a9705b1..46306f1f34b1 100644
--- a/Documentation/admin-guide/mm/damon/reclaim.rst
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -66,6 +66,17 @@ Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could do
no real monitoring and reclamation due to the watermarks-based activation
condition. Refer to below descriptions for the watermarks parameter for this.
+commit_inputs
+-------------
+
+Make DAMON_RECLAIM reads the input parameters again, except ``enabled``.
+
+Input parameters that updated while DAMON_RECLAIM is running are not applied
+by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values
+of parametrs except ``enabled`` again. Once the re-reading is done, this
+parameter is set as ``N``. If invalid parameters are found while the
+re-reading, DAMON_RECLAIM will be disabled.
+
min_age
-------
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index 592ea9a50881..1bb7b72414b2 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -68,7 +68,7 @@ comma (","). ::
│ kdamonds/nr_kdamonds
│ │ 0/state,pid
│ │ │ contexts/nr_contexts
- │ │ │ │ 0/operations
+ │ │ │ │ 0/avail_operations,operations
│ │ │ │ │ monitoring_attrs/
│ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
│ │ │ │ │ │ nr_regions/min,max
@@ -121,10 +121,11 @@ In each kdamond directory, two files (``state`` and ``pid``) and one directory
Reading ``state`` returns ``on`` if the kdamond is currently running, or
``off`` if it is not running. Writing ``on`` or ``off`` makes the kdamond be
-in the state. Writing ``update_schemes_stats`` to ``state`` file updates the
-contents of stats files for each DAMON-based operation scheme of the kdamond.
-For details of the stats, please refer to :ref:`stats section
-<sysfs_schemes_stats>`.
+in the state. Writing ``commit`` to the ``state`` file makes kdamond reads the
+user inputs in the sysfs files except ``state`` file again. Writing
+``update_schemes_stats`` to ``state`` file updates the contents of stats files
+for each DAMON-based operation scheme of the kdamond. For details of the
+stats, please refer to :ref:`stats section <sysfs_schemes_stats>`.
If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread.
@@ -143,17 +144,28 @@ be written to the file.
contexts/<N>/
-------------
-In each context directory, one file (``operations``) and three directories
-(``monitoring_attrs``, ``targets``, and ``schemes``) exist.
+In each context directory, two files (``avail_operations`` and ``operations``)
+and three directories (``monitoring_attrs``, ``targets``, and ``schemes``)
+exist.
DAMON supports multiple types of monitoring operations, including those for
-virtual address space and the physical address space. You can set and get what
-type of monitoring operations DAMON will use for the context by writing one of
-below keywords to, and reading from the file.
+virtual address space and the physical address space. You can get the list of
+available monitoring operations set on the currently running kernel by reading
+``avail_operations`` file. Based on the kernel configuration, the file will
+list some or all of below keywords.
- vaddr: Monitor virtual address spaces of specific processes
+ - fvaddr: Monitor fixed virtual address ranges
- paddr: Monitor the physical address space of the system
+Please refer to :ref:`regions sysfs directory <sysfs_regions>` for detailed
+differences between the operations sets in terms of the monitoring target
+regions.
+
+You can set and get what type of monitoring operations DAMON will use for the
+context by writing one of the keywords listed in ``avail_operations`` file and
+reading from the ``operations`` file.
+
contexts/<N>/monitoring_attrs/
------------------------------
@@ -192,6 +204,8 @@ If you wrote ``vaddr`` to the ``contexts/<N>/operations``, each target should
be a process. You can specify the process to DAMON by writing the pid of the
process to the ``pid_target`` file.
+.. _sysfs_regions:
+
targets/<N>/regions
-------------------
@@ -202,9 +216,10 @@ can be covered. However, users could want to set the initial monitoring region
to specific address ranges.
In contrast, DAMON do not automatically sets and updates the monitoring target
-regions when ``paddr`` monitoring operations set is being used (``paddr`` is
-written to the ``contexts/<N>/operations``). Therefore, users should set the
-monitoring target regions by themselves in the case.
+regions when ``fvaddr`` or ``paddr`` monitoring operations sets are being used
+(``fvaddr`` or ``paddr`` have written to the ``contexts/<N>/operations``).
+Therefore, users should set the monitoring target regions by themselves in the
+cases.
For such cases, users can explicitly set the initial monitoring target regions
as they want, by writing proper values to the files under this directory.
diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
index 0166f9de3428..a90330d0a837 100644
--- a/Documentation/admin-guide/mm/hugetlbpage.rst
+++ b/Documentation/admin-guide/mm/hugetlbpage.rst
@@ -164,7 +164,7 @@ default_hugepagesz
will all result in 256 2M huge pages being allocated. Valid default
huge page size is architecture dependent.
hugetlb_free_vmemmap
- When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing
+ When CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is set, this enables optimizing
unused vmemmap pages associated with each HugeTLB page.
When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
index 97d816791aca..b244f0202a03 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -184,6 +184,24 @@ The maximum possible ``pages_sharing/pages_shared`` ratio is limited by the
``max_page_sharing`` tunable. To increase the ratio ``max_page_sharing`` must
be increased accordingly.
+Monitoring KSM events
+=====================
+
+There are some counters in /proc/vmstat that may be used to monitor KSM events.
+KSM might help save memory, it's a tradeoff by may suffering delay on KSM COW
+or on swapping in copy. Those events could help users evaluate whether or how
+to use KSM. For example, if cow_ksm increases too fast, user may decrease the
+range of madvise(, , MADV_MERGEABLE).
+
+cow_ksm
+ is incremented every time a KSM page triggers copy on write (COW)
+ when users try to write to a KSM page, we have to make a copy.
+
+ksm_swpin_copy
+ is incremented every time a KSM page is copied when swapping in
+ note that KSM page might be copied when swapping in because do_swap_page()
+ cannot do all the locking needed to reconstitute a cross-anon_vma KSM page.
+
--
Izik Eidus,
Hugh Dickins, 17 Nov 2009
diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
index f4804ce37c58..5c9aa171a0d3 100644
--- a/Documentation/admin-guide/sysctl/vm.rst
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -62,6 +62,7 @@ Currently, these files are in /proc/sys/vm:
- overcommit_memory
- overcommit_ratio
- page-cluster
+- page_lock_unfairness
- panic_on_oom
- percpu_pagelist_high_fraction
- stat_interval
@@ -561,6 +562,45 @@ Change the minimum size of the hugepage pool.
See Documentation/admin-guide/mm/hugetlbpage.rst
+hugetlb_optimize_vmemmap
+========================
+
+This knob is not available when memory_hotplug.memmap_on_memory (kernel parameter)
+is configured or the size of 'struct page' (a structure defined in
+include/linux/mm_types.h) is not power of two (an unusual system config could
+result in this).
+
+Enable (set to 1) or disable (set to 0) the feature of optimizing vmemmap pages
+associated with each HugeTLB page.
+
+Once enabled, the vmemmap pages of subsequent allocation of HugeTLB pages from
+buddy allocator will be optimized (7 pages per 2MB HugeTLB page and 4095 pages
+per 1GB HugeTLB page), whereas already allocated HugeTLB pages will not be
+optimized. When those optimized HugeTLB pages are freed from the HugeTLB pool
+to the buddy allocator, the vmemmap pages representing that range needs to be
+remapped again and the vmemmap pages discarded earlier need to be rellocated
+again. If your use case is that HugeTLB pages are allocated 'on the fly' (e.g.
+never explicitly allocating HugeTLB pages with 'nr_hugepages' but only set
+'nr_overcommit_hugepages', those overcommitted HugeTLB pages are allocated 'on
+the fly') instead of being pulled from the HugeTLB pool, you should weigh the
+benefits of memory savings against the more overhead (~2x slower than before)
+of allocation or freeing HugeTLB pages between the HugeTLB pool and the buddy
+allocator. Another behavior to note is that if the system is under heavy memory
+pressure, it could prevent the user from freeing HugeTLB pages from the HugeTLB
+pool to the buddy allocator since the allocation of vmemmap pages could be
+failed, you have to retry later if your system encounter this situation.
+
+Once disabled, the vmemmap pages of subsequent allocation of HugeTLB pages from
+buddy allocator will not be optimized meaning the extra overhead at allocation
+time from buddy allocator disappears, whereas already optimized HugeTLB pages
+will not be affected. If you want to make sure there are no optimized HugeTLB
+pages, you can set "nr_hugepages" to 0 first and then disable this. Note that
+writing 0 to nr_hugepages will make any "in use" HugeTLB pages become surplus
+pages. So, those surplus pages are still optimized until they are no longer
+in use. You would need to wait for those surplus pages to be released before
+there are no optimized pages in the system.
+
+
nr_hugepages_mempolicy
======================
@@ -754,6 +794,14 @@ extra faults and I/O delays for following faults if they would have been part of
that consecutive pages readahead would have brought in.
+page_lock_unfairness
+====================
+
+This value determines the number of times that the page lock can be
+stolen from under a waiter. After the lock is stolen the number of times
+specified in this file (default is 5), the "fair lock handoff" semantics
+will apply, and the waiter will only be awakened if the lock can be taken.
+
panic_on_oom
============