linux.git/Documentation/mm, branch v6.17

Merge tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-07-31T21:57:54+00:00

Pull MM updates from Andrew Morton:
 "As usual, many cleanups. The below blurbiage describes 42 patchsets.
  21 of those are partially or fully cleanup work. "cleans up",
  "cleanup", "maintainability", "rationalizes", etc.

  I never knew the MM code was so dirty.

  "mm: ksm: prevent KSM from breaking merging of new VMAs" (Lorenzo Stoakes)
     addresses an issue with KSM's PR_SET_MEMORY_MERGE mode: newly
     mapped VMAs were not eligible for merging with existing adjacent
     VMAs.

  "mm/damon: introduce DAMON_STAT for simple and practical access monitoring" (SeongJae Park)
     adds a new kernel module which simplifies the setup and usage of
     DAMON in production environments.

  "stop passing a writeback_control to swap/shmem writeout" (Christoph Hellwig)
     is a cleanup to the writeback code which removes a couple of
     pointers from struct writeback_control.

  "drivers/base/node.c: optimization and cleanups" (Donet Tom)
     contains largely uncorrelated cleanups to the NUMA node setup and
     management code.

  "mm: userfaultfd: assorted fixes and cleanups" (Tal Zussman)
     does some maintenance work on the userfaultfd code.

  "Readahead tweaks for larger folios" (Ryan Roberts)
     implements some tuneups for pagecache readahead when it is reading
     into order>0 folios.

  "selftests/mm: Tweaks to the cow test" (Mark Brown)
     provides some cleanups and consistency improvements to the
     selftests code.

  "Optimize mremap() for large folios" (Dev Jain)
     does that. A 37% reduction in execution time was measured in a
     memset+mremap+munmap microbenchmark.

  "Remove zero_user()" (Matthew Wilcox)
     expunges zero_user() in favor of the more modern memzero_page().

  "mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes" (David Hildenbrand)
     addresses some warts which David noticed in the huge page code.
     These were not known to be causing any issues at this time.

  "mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD" (SeongJae Park)
     provides some cleanup and consolidation work in DAMON.

  "use vm_flags_t consistently" (Lorenzo Stoakes)
     uses vm_flags_t in places where we were inappropriately using other
     types.

  "mm/memfd: Reserve hugetlb folios before allocation" (Vivek Kasireddy)
     increases the reliability of large page allocation in the memfd
     code.

  "mm: Remove pXX_devmap page table bit and pfn_t type" (Alistair Popple)
     removes several now-unneeded PFN_* flags.

  "mm/damon: decouple sysfs from core" (SeongJae Park)
     implememnts some cleanup and maintainability work in the DAMON
     sysfs layer.

  "madvise cleanup" (Lorenzo Stoakes)
     does quite a lot of cleanup/maintenance work in the madvise() code.

  "madvise anon_name cleanups" (Vlastimil Babka)
     provides additional cleanups on top or Lorenzo's effort.

  "Implement numa node notifier" (Oscar Salvador)
     creates a standalone notifier for NUMA node memory state changes.
     Previously these were lumped under the more general memory
     on/offline notifier.

  "Make MIGRATE_ISOLATE a standalone bit" (Zi Yan)
     cleans up the pageblock isolation code and fixes a potential issue
     which doesn't seem to cause any problems in practice.

  "selftests/damon: add python and drgn based DAMON sysfs functionality tests" (SeongJae Park)
     adds additional drgn- and python-based DAMON selftests which are
     more comprehensive than the existing selftest suite.

  "Misc rework on hugetlb faulting path" (Oscar Salvador)
     fixes a rather obscure deadlock in the hugetlb fault code and
     follows that fix with a series of cleanups.

  "cma: factor out allocation logic from __cma_declare_contiguous_nid" (Mike Rapoport)
     rationalizes and cleans up the highmem-specific code in the CMA
     allocator.

  "mm/migration: rework movable_ops page migration (part 1)" (David Hildenbrand)
     provides cleanups and future-preparedness to the migration code.

  "mm/damon: add trace events for auto-tuned monitoring intervals and DAMOS quota" (SeongJae Park)
     adds some tracepoints to some DAMON auto-tuning code.

  "mm/damon: fix misc bugs in DAMON modules" (SeongJae Park)
     does that.

  "mm/damon: misc cleanups" (SeongJae Park)
     also does what it claims.

  "mm: folio_pte_batch() improvements" (David Hildenbrand)
     cleans up the large folio PTE batching code.

  "mm/damon/vaddr: Allow interleaving in migrate_{hot,cold} actions" (SeongJae Park)
     facilitates dynamic alteration of DAMON's inter-node allocation
     policy.

  "Remove unmap_and_put_page()" (Vishal Moola)
     provides a couple of page->folio conversions.

  "mm: per-node proactive reclaim" (Davidlohr Bueso)
     implements a per-node control of proactive reclaim - beyond the
     current memcg-based implementation.

  "mm/damon: remove damon_callback" (SeongJae Park)
     replaces the damon_callback interface with a more general and
     powerful damon_call()+damos_walk() interface.

  "mm/mremap: permit mremap() move of multiple VMAs" (Lorenzo Stoakes)
     implements a number of mremap cleanups (of course) in preparation
     for adding new mremap() functionality: newly permit the remapping
     of multiple VMAs when the user is specifying MREMAP_FIXED. It still
     excludes some specialized situations where this cannot be performed
     reliably.

  "drop hugetlb_free_pgd_range()" (Anthony Yznaga)
     switches some sparc hugetlb code over to the generic version and
     removes the thus-unneeded hugetlb_free_pgd_range().

  "mm/damon/sysfs: support periodic and automated stats update" (SeongJae Park)
     augments the present userspace-requested update of DAMON sysfs
     monitoring files. Automatic update is now provided, along with a
     tunable to control the update interval.

  "Some randome fixes and cleanups to swapfile" (Kemeng Shi)
     does what is claims.

  "mm: introduce snapshot_page" (Luiz Capitulino and David Hildenbrand)
     provides (and uses) a means by which debug-style functions can grab
     a copy of a pageframe and inspect it locklessly without tripping
     over the races inherent in operating on the live pageframe
     directly.

  "use per-vma locks for /proc/pid/maps reads" (Suren Baghdasaryan)
     addresses the large contention issues which can be triggered by
     reads from that procfs file. Latencies are reduced by more than
     half in some situations. The series also introduces several new
     selftests for the /proc/pid/maps interface.

  "__folio_split() clean up" (Zi Yan)
     cleans up __folio_split()!

  "Optimize mprotect() for large folios" (Dev Jain)
     provides some quite large (>3x) speedups to mprotect() when dealing
     with large folios.

  "selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup" (wang lian)
     does some cleanup work in the selftests code.

  "tools/testing: expand mremap testing" (Lorenzo Stoakes)
     extends the mremap() selftest in several ways, including adding
     more checking of Lorenzo's recently added "permit mremap() move of
     multiple VMAs" feature.

  "selftests/damon/sysfs.py: test all parameters" (SeongJae Park)
     extends the DAMON sysfs interface selftest so that it tests all
     possible user-requested parameters. Rather than the present minimal
     subset"

* tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (370 commits)
  MAINTAINERS: add missing headers to mempory policy & migration section
  MAINTAINERS: add missing file to cgroup section
  MAINTAINERS: add MM MISC section, add missing files to MISC and CORE
  MAINTAINERS: add missing zsmalloc file
  MAINTAINERS: add missing files to page alloc section
  MAINTAINERS: add missing shrinker files
  MAINTAINERS: move memremap.[ch] to hotplug section
  MAINTAINERS: add missing mm_slot.h file THP section
  MAINTAINERS: add missing interval_tree.c to memory mapping section
  MAINTAINERS: add missing percpu-internal.h file to per-cpu section
  mm/page_alloc: remove trace_mm_alloc_contig_migrate_range_info()
  selftests/damon: introduce _common.sh to host shared function
  selftests/damon/sysfs.py: test runtime reduction of DAMON parameters
  selftests/damon/sysfs.py: test non-default parameters runtime commit
  selftests/damon/sysfs.py: generalize DAMON context commit assertion
  selftests/damon/sysfs.py: generalize monitoring attributes commit assertion
  selftests/damon/sysfs.py: generalize DAMOS schemes commit assertion
  selftests/damon/sysfs.py: test DAMOS filters commitment
  selftests/damon/sysfs.py: generalize DAMOS scheme commit assertion
  selftests/damon/sysfs.py: test DAMOS destinations commitment
  ...

Docs/mm/damon/design: document vaddr support for migrate_{hot,cold}

2025-07-20T01:59:50+00:00

Document that the migrate_{hot,cold} schemes can be used by the vaddr
operations set.

Link: https://lkml.kernel.org/r/20250709005952.17776-11-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda 
Signed-off-by: Ravi Shankar Jonnalagadda 
Signed-off-by: Bijan Tabatabai 
Reviewed-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton

Docs/mm/damon/maintainer-profile: update for mm-new tree

2025-07-20T01:59:44+00:00

Recently a new mm tree for new patches, namely mm-new, has been added. 
Update DAMON maintainer's profile doc for DAMON patches life cycle, which
depend on those of mm trees.

Link: https://lkml.kernel.org/r/20250705175000.56259-7-sj@kernel.org
Signed-off-by: SeongJae Park 
Signed-off-by: Andrew Morton

docs/mm: convert from "Non-LRU page migration" to "movable_ops page migration"

2025-07-13T23:38:32+00:00

Let's bring the docs up-to-date.

Link: https://lkml.kernel.org/r/20250704102524.326966-28-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Zi Yan 
Reviewed-by: Lorenzo Stoakes 
Reviewed-by: Harry Yoo 
Cc: Alistair Popple 
Cc: Al Viro 
Cc: Arnd Bergmann 
Cc: Brendan Jackman 
Cc: Byungchul Park 
Cc: Chengming Zhou 
Cc: Christian Brauner 
Cc: Christophe Leroy 
Cc: Eugenio Pé rez 
Cc: Greg Kroah-Hartman 
Cc: Gregory Price 
Cc: "Huang, Ying" 
Cc: Jan Kara 
Cc: Jason Gunthorpe 
Cc: Jason Wang 
Cc: Jerrin Shaji George 
Cc: Johannes Weiner 
Cc: John Hubbard 
Cc: Jonathan Corbet 
Cc: Joshua Hahn 
Cc: Liam Howlett 
Cc: Madhavan Srinivasan 
Cc: Mathew Brost 
Cc: Matthew Wilcox (Oracle) 
Cc: Miaohe Lin 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Minchan Kim 
Cc: Naoya Horiguchi 
Cc: Nicholas Piggin 
Cc: Oscar Salvador 
Cc: Peter Xu 
Cc: Qi Zheng 
Cc: Rakie Kim 
Cc: Rik van Riel 
Cc: Sergey Senozhatsky 
Cc: Shakeel Butt 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Xuan Zhuo 
Cc: xu xin 
Signed-off-by: Andrew Morton

mm/debug_vm_pgtable: use a swp_entry_t input value for swap tests

2025-07-13T23:38:21+00:00

The various __pte/pmd_to_swp_entry and __swp_entry_to_pte/pmd helper
functions are expected to operate on swap PTE/PMD entries, not on present
and mapped entries.

Reflect this in the swap tests by using a swp_entry_t as input value, and
convert it to a swap PTE/PMD for testing, similar to how it is already
done in pte_swap_exclusive_tests().  Move the swap entry creation from
there to init_args() and store it in args, so it can also be used in other
functions.

The pte/pmd_swap_tests() are also changed to compare entries instead of
pfn values, again similar to pte_swap_exclusive_tests().  pte/pmd_pfn()
helpers are also not expected to operate on swap PTE/PMD entries at all.

Also update documentation, to reflect that the helpers operate on swap
PTE/PMD entries and not present and mapped entries, and use correct names,
i.e.  __swp_to_pte/pmd_entry -> __swp_entry_to_pte/pmd.

For consistency, also change pte/pmd_swap_soft_dirty_tests() to use
args->swp_entry instead of a present and mapped PTE/PMD.

Link: https://lore.kernel.org/all/20250623184321.927418-1-gerald.schaefer@linux.ibm.com
Link: https://lkml.kernel.org/r/20250630164726.930405-1-gerald.schaefer@linux.ibm.com
Signed-off-by: Gerald Schaefer 
Acked-by: David Hildenbrand 
Reviewed-by: Anshuman Khandual 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mm/page_alloc: pageblock flags functions clean up

2025-07-13T23:38:17+00:00

Patch series "Make MIGRATE_ISOLATE a standalone bit", v10.

This patchset moves MIGRATE_ISOLATE to a standalone bit to avoid being
overwritten during pageblock isolation process.  Currently,
MIGRATE_ISOLATE is part of enum migratetype (in include/linux/mmzone.h),
thus, setting a pageblock to MIGRATE_ISOLATE overwrites its original
migratetype.  This causes pageblock migratetype loss during
alloc_contig_range() and memory offline, especially when the process fails
due to a failed pageblock isolation and the code tries to undo the
finished pageblock isolations.

In terms of performance for changing pageblock types, no performance
change is observed:

1. I used perf to collect stats of offlining and onlining all memory
   of a 40GB VM 10 times and see that get_pfnblock_flags_mask() and
   set_pfnblock_flags_mask() take about 0.12% and 0.02% of the whole
   process respectively with and without this patchset across 3 runs.

2. I used perf to collect stats of dd from /dev/random to a 40GB tmpfs
   file and find get_pfnblock_flags_mask() takes about 0.05% of the
   process with and without this patchset across 3 runs.


This patch (of 6):

No functional change is intended.

1. Add __NR_PAGEBLOCK_BITS for the number of pageblock flag bits and use
   roundup_pow_of_two(__NR_PAGEBLOCK_BITS) as NR_PAGEBLOCK_BITS to take
   right amount of bits for pageblock flags.
2. Rename PB_migrate_skip to PB_compact_skip.
3. Add {get,set,clear}_pfnblock_bit() to operate one a standalone bit,
   like PB_compact_skip.
3. Make {get,set}_pfnblock_flags_mask() internal functions and use
   {get,set}_pfnblock_migratetype() for pageblock migratetype operations.
4. Move pageblock flags common code to get_pfnblock_bitmap_bitidx().
3. Use MIGRATETYPE_MASK to get the migratetype of a pageblock from its
   flags.
4. Use PB_migrate_end in the definition of MIGRATETYPE_MASK instead of
   PB_migrate_bits.
5. Add a comment on is_migrate_cma_folio() to prevent one from changing it
   to use get_pageblock_migratetype() and causing issues.

Link: https://lkml.kernel.org/r/20250617021115.2331563-1-ziy@nvidia.com
Link: https://lkml.kernel.org/r/20250617021115.2331563-2-ziy@nvidia.com
Signed-off-by: Zi Yan 
Reviewed-by: Vlastimil Babka 
Acked-by: David Hildenbrand 
Cc: Baolin Wang 
Cc: Brendan Jackman 
Cc: Johannes Weiner 
Cc: Kirill A. Shuemov 
Cc: Mel Gorman 
Cc: Michal Hocko 
Cc: Oscar Salvador 
Cc: Richard Chang 
Cc: Suren Baghdasaryan 
Signed-off-by: Andrew Morton

mm: remove devmap related functions and page table bits

2025-07-10T05:42:18+00:00

Now that DAX and all other reference counts to ZONE_DEVICE pages are
managed normally there is no need for the special devmap PTE/PMD/PUD page
table bits.  So drop all references to these, freeing up a software
defined page table bit on architectures supporting it.

Link: https://lkml.kernel.org/r/6389398c32cc9daa3dfcaa9f79c7972525d310ce.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple 
Acked-by: Will Deacon  # arm64
Acked-by: David Hildenbrand 
Suggested-by: Chunyan Zhang 
Reviewed-by: Björn Töpel 
Reviewed-by: Jason Gunthorpe 
Cc: Balbir Singh 
Cc: Björn Töpel 
Cc: Christoph Hellwig 
Cc: Dan Williams 
Cc: Deepak Gupta 
Cc: Gerald Schaefer 
Cc: Inki Dae 
Cc: John Groves 
Cc: John Hubbard 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

docs/mm: expand vma doc to highlight pte freeing, non-vma traversal

2025-07-10T05:41:52+00:00

The process addresses documentation already contains a great deal of
information about mmap/VMA locking and page table traversal and
manipulation.

However it waves it hands about non-VMA traversal.  Add a section for this
and explain the caveats around this kind of traversal.

Additionally, commit 6375e95f381e ("mm: pgtable: reclaim empty PTE page in
madvise(MADV_DONTNEED)") caused zapping to also free empty PTE page
tables.  Highlight this.

Link: https://lkml.kernel.org/r/20250604180308.137116-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: Bagas Sanjaya 
Cc: Jann Horn 
Cc: Jonathan Corbet 
Cc: Liam Howlett 
Cc: Qi Zheng 
Cc: Shakeel Butt 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

doc: Add slab internal kernel-doc

2025-06-18T11:06:26+00:00

We don't have much real internal documentation to extract yet, but
let's make sure that what we do have is available.

Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: Harry Yoo 
Link: https://patch.msgid.link/20250611155916.2579160-7-willy@infradead.org
Signed-off-by: Vlastimil Babka

doc: Move SLUB documentation to the admin guide

2025-06-18T11:06:26+00:00

This section is supposed to be for internal documentation, while the
document is advice for sysadmins.  Move it to the appropriate place.

Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: Harry Yoo 
Link: https://patch.msgid.link/20250611155916.2579160-2-willy@infradead.org
Signed-off-by: Vlastimil Babka