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
  ...

Author: torvalds

Documentation/ABI/testing/sysfs-kernel-mm-damon

@@ -23,9 +23,10 @@ Date:		Mar 2022
 Contact:	SeongJae Park <[email protected]>
 Description:	Writing 'on' or 'off' to this file makes the kdamond starts or
 		stops, respectively.  Reading the file returns the keywords
-		based on the current status.  Writing 'update_schemes_stats' to
-		the file updates contents of schemes stats files of the
-		kdamond.
+		based on the current status.  Writing 'commit' to this file
+		makes the kdamond reads the user inputs in the sysfs files
+		except 'state' again.  Writing 'update_schemes_stats' to the
+		file updates contents of schemes stats files of the kdamond.
 
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/pid
 Date:		Mar 2022
@@ -40,14 +41,24 @@ Description:	Writing a number 'N' to this file creates the number of
 		directories for controlling each DAMON context named '0' to
 		'N-1' under the contexts/ directory.
 
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/avail_operations
+Date:		Apr 2022
+Contact:	SeongJae Park <[email protected]>
+Description:	Reading this file returns the available monitoring operations
+		sets on the currently running kernel.
+
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/operations
 Date:		Mar 2022
 Contact:	SeongJae Park <[email protected]>
 Description:	Writing a keyword for a monitoring operations set ('vaddr' for
-		virtual address spaces monitoring, and 'paddr' for the physical
-		address space monitoring) to this file makes the context to use
-		the operations set.  Reading the file returns the keyword for
-		the operations set the context is set to use.
+		virtual address spaces monitoring, 'fvaddr' for fixed virtual
+		address ranges monitoring, and 'paddr' for the physical address
+		space monitoring) to this file makes the context to use the
+		operations set.  Reading the file returns the keyword for the
+		operations set the context is set to use.
+
+		Note that only the operations sets that listed in
+		'avail_operations' file are valid inputs.
 
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/monitoring_attrs/intervals/sample_us
 Date:		Mar 2022

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.
 

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.
 

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.

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
 -------
 

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.

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``

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

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
 ============