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Author SHA1 Message Date
SeongJae Park
6a4b3551ba Docs/damon: update titles and brief introductions to explain DAMOS 
DAMON was initially developed only for data access monitoring, and then
extended for not only access monitoring but also access-aware system
operations (DAMOS).  But the documents have old titles and brief
introductions for only the monitoring part.  Update the titles and the
brief introductions to explain DAMOS part together.

Link: https://lkml.kernel.org/r/20250513002715.40126-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-22 14:55:38 -07:00
Thushara.M.S
5ec56c1cb6 docs/mm/damon/design: fix spelling mistake 
The word accuracy was misspelled as "accruracy".

Signed-off-by: Thushara.M.S <thusharms@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-12 23:50:49 -07:00
SeongJae Park
b3b95a3594 Docs/mm/damon/design: document node_mem_{used,free}_bp 
Add description of DAMOS quota goal metrics for NUMA node utilization on
the DAMON deesign document.

Link: https://lkml.kernel.org/r/20250420194030.75838-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-05-12 23:50:30 -07:00
Linus Torvalds
eb0ece1602 - The 6 patch series "Enable strict percpu address space checks" from 
Uros Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.
 
   This has caused a small amount of fallout - two or three issues were
   reported.  In all cases the calling code was founf to be incorrect.
 
 - The 4 patch series "Some cleanup for memcg" from Chen Ridong
   implements some relatively monir cleanups for the memcontrol code.
 
 - The 17 patch series "mm: fixes for device-exclusive entries (hmm)"
   from David Hildenbrand fixes a boatload of issues which David found then
   using device-exclusive PTE entries when THP is enabled.  More work is
   needed, but this makes thins better - our own HMM selftests now succeed.
 
 - The 2 patch series "mm: zswap: remove z3fold and zbud" from Yosry
   Ahmed remove the z3fold and zbud implementations.  They have been
   deprecated for half a year and nobody has complained.
 
 - The 5 patch series "mm: further simplify VMA merge operation" from
   Lorenzo Stoakes implements numerous simplifications in this area.  No
   runtime effects are anticipated.
 
 - The 4 patch series "mm/madvise: remove redundant mmap_lock operations
   from process_madvise()" from SeongJae Park rationalizes the locking in
   the madvise() implementation.  Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.
 
 - The 12 patch series "Tiny cleanup and improvements about SWAP code"
   from Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.
 
 - The 2 patch series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak user-visible
   output.
 
 - The 2 patch series "mm/damon/paddr: fix large folios access and
   schemes handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.
 
 - The 3 patch series "mm/damon/core: fix wrong and/or useless
   damos_walk() behaviors" from SeongJae Park fixes a few issues with the
   accuracy of kdamond's walking of DAMON regions.
 
 - The 3 patch series "expose mapping wrprotect, fix fb_defio use" from
   Lorenzo Stoakes changes the interaction between framebuffer deferred-io
   and core MM.  No functional changes are anticipated - this is
   preparatory work for the future removal of page structure fields.
 
 - The 4 patch series "mm/damon: add support for hugepage_size DAMOS
   filter" from Usama Arif adds a DAMOS filter which permits the filtering
   by huge page sizes.
 
 - The 4 patch series "mm: permit guard regions for file-backed/shmem
   mappings" from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state.  The feature now covers shmem and
   file-backed mappings.
 
 - The 4 patch series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping for
   pte-mapped large folios.
 
 - The 18 patch series "reimplement per-vma lock as a refcount" from
   Suren Baghdasaryan puts the vm_lock back into the vma.  Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy.  This patchset provides small (0-10%) improvements on one
   microbenchmark.
 
 - The 5 patch series "Docs/mm/damon: misc DAMOS filters documentation
   fixes and improves" from SeongJae Park does some maintenance work on the
   DAMON docs.
 
 - The 27 patch series "hugetlb/CMA improvements for large systems" from
   Frank van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.
 
 - The 2 patch series "mm/damon: introduce DAMOS filter type for unmapped
   pages" from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.
 
 - The 19 patch series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.
 
 - The 12 patch series "selftests/mm: Some cleanups from trying to run
   them" from Brendan Jackman fixes a pile of unrelated issues which
   Brendan encountered while runnimg our selftests.
 
 - The 2 patch series "fs/proc/task_mmu: add guard region bit to pagemap"
   from Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.
 
 - The 7 patch series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply wasn't
   being effective.
 
 - The 5 patch series "mm: cleanups for device-exclusive entries (hmm)"
   from David Hildenbrand implements a number of unrelated cleanups in this
   code.
 
 - The 5 patch series "mm: Rework generic PTDUMP configs" from Anshuman
   Khandual implements a number of preparatoty cleanups to the
   GENERIC_PTDUMP Kconfig logic.
 
 - The 8 patch series "mm/damon: auto-tune aggregation interval" from
   SeongJae Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.
 
 - The 5 patch series "Fix lazy mmu mode" from Ryan Roberts fixes some
   issues in powerpc, sparc and x86 lazy MMU implementations.  Ryan did
   this in preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.
 
 - The 2 patch series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the code
   easier to follow.
 
 - The 3 patch series "page_counter cleanup and size reduction" from
   Shakeel Butt cleans up the page_counter code and fixes a size increase
   which we accidentally added late last year.
 
 - The 3 patch series "Add a command line option that enables control of
   how many threads should be used to allocate huge pages" from Thomas
   Prescher does that.  It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.
 
 - The 3 patch series "Fix calculations in trace_balance_dirty_pages()
   for cgwb" from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.
 
 - The 9 patch series "mm/damon: make allow filters after reject filters
   useful and intuitive" from SeongJae Park improves the handling of allow
   and reject filters.  Behaviour is made more consistent and the
   documention is updated accordingly.
 
 - The 5 patch series "Switch zswap to object read/write APIs" from Yosry
   Ahmed updates zswap to the new object read/write APIs and thus permits
   the removal of some legacy code from zpool and zsmalloc.
 
 - The 6 patch series "Some trivial cleanups for shmem" from Baolin Wang
   does as it claims.
 
 - The 20 patch series "fs/dax: Fix ZONE_DEVICE page reference counts"
   from Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.
 
 - The 4 patch series "refactor mremap and fix bug" from Lorenzo Stoakes
   is a preparatoty refactoring and cleanup of the mremap() code.
 
 - The 20 patch series "mm: MM owner tracking for large folios (!hugetlb)
   + CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.
 
 - The 8 patch series "mm/damon: add sysfs dirs for managing DAMOS
   filters based on handling layers" from SeongJae Park adds a couple of
   new sysfs directories to ease the management of DAMON/DAMOS filters.
 
 - The 13 patch series "arch, mm: reduce code duplication in mem_init()"
   from Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.
 
 - The 13 patch series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.
 
 - The 3 patch series "mm: page_ext: Introduce new iteration API" from
   Luiz Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.
 
 - The 8 patch series "Buddy allocator like (or non-uniform) folio split"
   from Zi Yan reworks the code to split a folio into smaller folios.  The
   main benefit is lessened memory consumption: fewer post-split folios are
   generated.
 
 - The 2 patch series "Minimize xa_node allocation during xarry split"
   from Zi Yan reduces the number of xarray xa_nodes which are generated
   during an xarray split.
 
 - The 2 patch series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.
 
 - The 3 patch series "Add tracepoints for lowmem reserves, watermarks
   and totalreserve_pages" from Martin Liu adds some more tracepoints to
   the page allocator code.
 
 - The 4 patch series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which SeongJae
   observed during his earlier madvise work.
 
 - The 3 patch series "mm/hwpoison: Fix regressions in memory failure
   handling" from Shuai Xue addresses two quite serious regressions which
   Shuai has observed in the memory-failure implementation.
 
 - The 5 patch series "mm: reliable huge page allocator" from Johannes
   Weiner makes huge page allocations cheaper and more reliable by reducing
   fragmentation.
 
 - The 5 patch series "Minor memcg cleanups & prep for memdescs" from
   Matthew Wilcox is preparatory work for the future implementation of
   memdescs.
 
 - The 4 patch series "track memory used by balloon drivers" from Nico
   Pache introduces a way to track memory used by our various balloon
   drivers.
 
 - The 2 patch series "mm/damon: introduce DAMOS filter type for active
   pages" from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.
 
 - The 2 patch series "Adding Proactive Memory Reclaim Statistics" from
   Hao Jia separates the proactive reclaim statistics from the direct
   reclaim statistics.
 
 - The 2 patch series "mm/vmscan: don't try to reclaim hwpoison folio"
   from Jinjiang Tu fixes our handling of hwpoisoned pages within the
   reclaim code.
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Merge tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - The series "Enable strict percpu address space checks" from Uros
   Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.

   This has caused a small amount of fallout - two or three issues were
   reported. In all cases the calling code was found to be incorrect.

 - The series "Some cleanup for memcg" from Chen Ridong implements some
   relatively monir cleanups for the memcontrol code.

 - The series "mm: fixes for device-exclusive entries (hmm)" from David
   Hildenbrand fixes a boatload of issues which David found then using
   device-exclusive PTE entries when THP is enabled. More work is
   needed, but this makes thins better - our own HMM selftests now
   succeed.

 - The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed
   remove the z3fold and zbud implementations. They have been deprecated
   for half a year and nobody has complained.

 - The series "mm: further simplify VMA merge operation" from Lorenzo
   Stoakes implements numerous simplifications in this area. No runtime
   effects are anticipated.

 - The series "mm/madvise: remove redundant mmap_lock operations from
   process_madvise()" from SeongJae Park rationalizes the locking in the
   madvise() implementation. Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.

 - The series "Tiny cleanup and improvements about SWAP code" from
   Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.

 - The series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak
   user-visible output.

 - The series "mm/damon/paddr: fix large folios access and schemes
   handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.

 - The series "mm/damon/core: fix wrong and/or useless damos_walk()
   behaviors" from SeongJae Park fixes a few issues with the accuracy of
   kdamond's walking of DAMON regions.

 - The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo
   Stoakes changes the interaction between framebuffer deferred-io and
   core MM. No functional changes are anticipated - this is preparatory
   work for the future removal of page structure fields.

 - The series "mm/damon: add support for hugepage_size DAMOS filter"
   from Usama Arif adds a DAMOS filter which permits the filtering by
   huge page sizes.

 - The series "mm: permit guard regions for file-backed/shmem mappings"
   from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state. The feature now covers shmem and
   file-backed mappings.

 - The series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping
   for pte-mapped large folios.

 - The series "reimplement per-vma lock as a refcount" from Suren
   Baghdasaryan puts the vm_lock back into the vma. Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy. This patchset provides small (0-10%) improvements on one
   microbenchmark.

 - The series "Docs/mm/damon: misc DAMOS filters documentation fixes and
   improves" from SeongJae Park does some maintenance work on the DAMON
   docs.

 - The series "hugetlb/CMA improvements for large systems" from Frank
   van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.

 - The series "mm/damon: introduce DAMOS filter type for unmapped pages"
   from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.

 - The series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.

 - The series "selftests/mm: Some cleanups from trying to run them" from
   Brendan Jackman fixes a pile of unrelated issues which Brendan
   encountered while runnimg our selftests.

 - The series "fs/proc/task_mmu: add guard region bit to pagemap" from
   Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.

 - The series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply
   wasn't being effective.

 - The series "mm: cleanups for device-exclusive entries (hmm)" from
   David Hildenbrand implements a number of unrelated cleanups in this
   code.

 - The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual
   implements a number of preparatoty cleanups to the GENERIC_PTDUMP
   Kconfig logic.

 - The series "mm/damon: auto-tune aggregation interval" from SeongJae
   Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.

 - The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in
   powerpc, sparc and x86 lazy MMU implementations. Ryan did this in
   preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.

 - The series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the
   code easier to follow.

 - The series "page_counter cleanup and size reduction" from Shakeel
   Butt cleans up the page_counter code and fixes a size increase which
   we accidentally added late last year.

 - The series "Add a command line option that enables control of how
   many threads should be used to allocate huge pages" from Thomas
   Prescher does that. It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.

 - The series "Fix calculations in trace_balance_dirty_pages() for cgwb"
   from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.

 - The series "mm/damon: make allow filters after reject filters useful
   and intuitive" from SeongJae Park improves the handling of allow and
   reject filters. Behaviour is made more consistent and the documention
   is updated accordingly.

 - The series "Switch zswap to object read/write APIs" from Yosry Ahmed
   updates zswap to the new object read/write APIs and thus permits the
   removal of some legacy code from zpool and zsmalloc.

 - The series "Some trivial cleanups for shmem" from Baolin Wang does as
   it claims.

 - The series "fs/dax: Fix ZONE_DEVICE page reference counts" from
   Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.

 - The series "refactor mremap and fix bug" from Lorenzo Stoakes is a
   preparatoty refactoring and cleanup of the mremap() code.

 - The series "mm: MM owner tracking for large folios (!hugetlb) +
   CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.

 - The series "mm/damon: add sysfs dirs for managing DAMOS filters based
   on handling layers" from SeongJae Park adds a couple of new sysfs
   directories to ease the management of DAMON/DAMOS filters.

 - The series "arch, mm: reduce code duplication in mem_init()" from
   Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.

 - The series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.

 - The series "mm: page_ext: Introduce new iteration API" from Luiz
   Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.

 - The series "Buddy allocator like (or non-uniform) folio split" from
   Zi Yan reworks the code to split a folio into smaller folios. The
   main benefit is lessened memory consumption: fewer post-split folios
   are generated.

 - The series "Minimize xa_node allocation during xarry split" from Zi
   Yan reduces the number of xarray xa_nodes which are generated during
   an xarray split.

 - The series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.

 - The series "Add tracepoints for lowmem reserves, watermarks and
   totalreserve_pages" from Martin Liu adds some more tracepoints to the
   page allocator code.

 - The series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which
   SeongJae observed during his earlier madvise work.

 - The series "mm/hwpoison: Fix regressions in memory failure handling"
   from Shuai Xue addresses two quite serious regressions which Shuai
   has observed in the memory-failure implementation.

 - The series "mm: reliable huge page allocator" from Johannes Weiner
   makes huge page allocations cheaper and more reliable by reducing
   fragmentation.

 - The series "Minor memcg cleanups & prep for memdescs" from Matthew
   Wilcox is preparatory work for the future implementation of memdescs.

 - The series "track memory used by balloon drivers" from Nico Pache
   introduces a way to track memory used by our various balloon drivers.

 - The series "mm/damon: introduce DAMOS filter type for active pages"
   from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.

 - The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia
   separates the proactive reclaim statistics from the direct reclaim
   statistics.

 - The series "mm/vmscan: don't try to reclaim hwpoison folio" from
   Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim
   code.

* tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits)
  mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex()
  x86/mm: restore early initialization of high_memory for 32-bits
  mm/vmscan: don't try to reclaim hwpoison folio
  mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper
  cgroup: docs: add pswpin and pswpout items in cgroup v2 doc
  mm: vmscan: split proactive reclaim statistics from direct reclaim statistics
  selftests/mm: speed up split_huge_page_test
  selftests/mm: uffd-unit-tests support for hugepages > 2M
  docs/mm/damon/design: document active DAMOS filter type
  mm/damon: implement a new DAMOS filter type for active pages
  fs/dax: don't disassociate zero page entries
  MM documentation: add "Unaccepted" meminfo entry
  selftests/mm: add commentary about 9pfs bugs
  fork: use __vmalloc_node() for stack allocation
  docs/mm: Physical Memory: Populate the "Zones" section
  xen: balloon: update the NR_BALLOON_PAGES state
  hv_balloon: update the NR_BALLOON_PAGES state
  balloon_compaction: update the NR_BALLOON_PAGES state
  meminfo: add a per node counter for balloon drivers
  mm: remove references to folio in __memcg_kmem_uncharge_page()
  ...
 2025-04-01 09:29:18 -07:00
Nhat Pham
af96c610c6 docs/mm/damon/design: document active DAMOS filter type 
Document availability and meaning of "active" DAMOS filter type on design
document.  Since introduction of the type requires no additional user ABI,
usage and ABI document need no update.

Link: https://lkml.kernel.org/r/20250318183029.2062917-3-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: SeongJae Park <sj@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-21 22:03:15 -07:00
Jiwen Qi
9f171d94be docs/mm: Physical Memory: Populate the "Zones" section 
Briefly describe what zones are and the fields of struct zone.

Link: https://lkml.kernel.org/r/20250315211317.27612-1-jiwen7.qi@gmail.com
Signed-off-by: Jiwen Qi <jiwen7.qi@gmail.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-21 22:03:14 -07:00
David Hildenbrand
749492229e mm: stop maintaining the per-page mapcount of large folios (CONFIG_NO_PAGE_MAPCOUNT) 
Everything is in place to stop using the per-page mapcounts in large
folios: the mapcount of tail pages will always be logically 0 (-1 value),
just like it currently is for hugetlb folios already, and the page
mapcount of the head page is either 0 (-1 value) or contains a page type
(e.g., hugetlb).

Maintaining _nr_pages_mapped without per-page mapcounts is impossible, so
that one also has to go with CONFIG_NO_PAGE_MAPCOUNT.

There are two remaining implications:

(1) Per-node, per-cgroup and per-lruvec stats of "NR_ANON_MAPPED"
    ("mapped anonymous memory") and "NR_FILE_MAPPED"
    ("mapped file memory"):

    As soon as any page of the folio is mapped -- folio_mapped() -- we
    now account the complete folio as mapped. Once the last page is
    unmapped -- !folio_mapped() -- we account the complete folio as
    unmapped.

    This implies that ...

    * "AnonPages" and "Mapped" in /proc/meminfo and
      /sys/devices/system/node/*/meminfo
    * cgroup v2: "anon" and "file_mapped" in "memory.stat" and
      "memory.numa_stat"
    * cgroup v1: "rss" and "mapped_file" in "memory.stat" and
      "memory.numa_stat

    ... can now appear higher than before. But note that these folios do
    consume that memory, simply not all pages are actually currently
    mapped.

    It's worth nothing that other accounting in the kernel (esp. cgroup
    charging on allocation) is not affected by this change.

    [why oh why is "anon" called "rss" in cgroup v1]

 (2) Detecting partial mappings

     Detecting whether anon THPs are partially mapped gets a bit more
     unreliable. As long as a single MM maps such a large folio
     ("exclusively mapped"), we can reliably detect it. Especially before
     fork() / after a short-lived child process quit, we will detect
     partial mappings reliably, which is the common case.

     In essence, if the average per-page mapcount in an anon THP is < 1,
     we know for sure that we have a partial mapping.

     However, as soon as multiple MMs are involved, we might miss detecting
     partial mappings: this might be relevant with long-lived child
     processes. If we have a fully-mapped anon folio before fork(), once
     our child processes and our parent all unmap (zap/COW) the same pages
     (but not the complete folio), we might not detect the partial mapping.
     However, once the child processes quit we would detect the partial
     mapping.

     How relevant this case is in practice remains to be seen.
     Swapout/migration will likely mitigate this.

     In the future, RMAP walkers could check for that for that case
     (e.g., when collecting access bits during reclaim) and simply flag
     them for deferred-splitting.

Link: https://lkml.kernel.org/r/20250303163014.1128035-21-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andy Lutomirks^H^Hski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michal Koutn <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: tejun heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 22:06:48 -07:00
David Hildenbrand
6af8cb80d3 mm/rmap: basic MM owner tracking for large folios (!hugetlb) 
For small folios, we traditionally use the mapcount to decide whether it
was "certainly mapped exclusively" by a single MM (mapcount == 1) or
whether it "maybe mapped shared" by multiple MMs (mapcount > 1).  For
PMD-sized folios that were PMD-mapped, we were able to use a similar
mechanism (single PMD mapping), but for PTE-mapped folios and in the
future folios that span multiple PMDs, this does not work.

So we need a different mechanism to handle large folios.  Let's add a new
mechanism to detect whether a large folio is "certainly mapped
exclusively", or whether it is "maybe mapped shared".

We'll use this information next to optimize CoW reuse for PTE-mapped
anonymous THP, and to convert folio_likely_mapped_shared() to
folio_maybe_mapped_shared(), independent of per-page mapcounts.

For each large folio, we'll have two slots, whereby a slot stores:
 (1) an MM id: unique id assigned to each MM
 (2) a per-MM mapcount

If a slot is unoccupied, it can be taken by the next MM that maps folio
page.

In addition, we'll remember the current state -- "mapped exclusively" vs. 
"maybe mapped shared" -- and use a bit spinlock to sync on updates and to
reduce the total number of atomic accesses on updates.  In the future, it
might be possible to squeeze a proper spinlock into "struct folio".  For
now, keep it simple, as we require the whole thing with THP only, that is
incompatible with RT.

As we have to squeeze this information into the "struct folio" of even
folios of order-1 (2 pages), and we generally want to reduce the required
metadata, we'll assign each MM a unique ID that can fit into an int.  In
total, we can squeeze everything into 4x int (2x long) on 64bit.

32bit support is a bit challenging, because we only have 2x long == 2x int
in order-1 folios.  But we can make it work for now, because we neither
expect many MMs nor very large folios on 32bit.

We will reliably detect folios as "mapped exclusively" vs.  "mapped
shared" as long as only two MMs map pages of a folio at one point in time
-- for example with fork() and short-lived child processes, or with apps
that hand over state from one instance to another.

As soon as three MMs are involved at the same time, we might detect "maybe
mapped shared" although the folio is "mapped exclusively".

Example 1:

(1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0
(2) App2 faults in a folio page -> Tracked as MM1
(4) App1 unmaps all folio pages

 -> We will detect "mapped exclusively".

Example 2:

(1) App1 faults in a (shmem/file-backed) folio page -> Tracked as MM0
(2) App2 faults in a folio page -> Tracked as MM1
(3) App3 faults in a folio page -> No slot available, tracked as "unknown"
(4) App1 and App2 unmap all folio pages

 -> We will detect "maybe mapped shared".

Make use of __always_inline to keep possible performance degradation when
(un)mapping large folios to a minimum.

Note: by squeezing the two flags into the "unsigned long" that stores the
MM ids, we can use non-atomic __bit_spin_unlock() and non-atomic
setting/clearing of the "maybe mapped shared" bit, effectively not adding
any new atomics on the hot path when updating the large mapcount + new
metadata, which further helps reduce the runtime overhead in
micro-benchmarks.

Link: https://lkml.kernel.org/r/20250303163014.1128035-13-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andy Lutomirks^H^Hski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michal Koutn <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: tejun heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 22:06:46 -07:00
Yosry Ahmed
07864f1a57 mm: zsmalloc: remove object mapping APIs and per-CPU map areas 
zs_map_object() and zs_unmap_object() are no longer used, remove them. 
Since these are the only users of per-CPU mapping_areas, remove them and
the associated CPU hotplug callbacks too.

[yosry.ahmed@linux.dev: update the docs]
  Link: https://lkml.kernel.org/r/Z8ier-ZZp8T6MOTH@google.com
Link: https://lkml.kernel.org/r/20250305061134.4105762-5-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 00:05:41 -07:00
SeongJae Park
9ea705a54b Docs/mm/damon/design: update for changed filter-default behavior 
Update the design documentation for changed DAMOS filters default
allowance behaviors.

Link: https://lkml.kernel.org/r/20250304211913.53574-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 00:05:39 -07:00
SeongJae Park
b243d666d1 Docs/admin-guide/mm/damon/usage: add intervals_goal directory on the hierarchy 
Document DAMON sysfs interface usage for DAMON sampling and aggregation
intervals auto-tuning.

Link: https://lkml.kernel.org/r/20250303221726.484227-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 00:05:34 -07:00
SeongJae Park
af03edb521 Docs/mm/damon/design: document for intervals auto-tuning 
Document the design of DAMON sampling and aggregation intervals
auto-tuning.

[sj@kernel.org: fix a typo on 'intervals auto-tuning' section]
  Link: https://lkml.kernel.org/r/20250305182744.56125-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250303221726.484227-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-17 00:05:33 -07:00
SeongJae Park
375c28a0df Docs/mm/damon/design: document unmapped DAMOS filter type 
Document availability and meaning of unmapped DAMOS filter type on design
document.  Since introduction of the type requires no additional user ABI,
usage and ABI document need no update.

Link: https://lkml.kernel.org/r/20250219220146.133650-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:32 -07:00
SeongJae Park
edab6ffd79 Docs/mm/damon/design: categorize DAMOS filter types based on handling layer 
On what DAMON layer a DAMOS filter is handled is important to expect in
what order filters will be evaluated.  Re-organize the DAMOS filter types
list on the design doc to categorize types based on the handling layer, to
let users more easily understand the handling order.

Link: https://lkml.kernel.org/r/20250218223708.53437-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:24 -07:00
SeongJae Park
4a4d8e7925 Docs/mm/damon/design: clarify handling layer based filters evaluation sequence 
If an element of memory matches a DAMOS filter, filters that installed
after that get no chance to make any effect to the element.  Hence in what
order DAMOS filters are handled is important, if both allow filters and
reject filters are used together.

The ordering is affected by both the installation order and which layter
the filters are handled.  The design document is not clearly documenting
the latter part.  Clarify it on the design doc.

Link: https://lkml.kernel.org/r/20250218223708.53437-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:24 -07:00
SeongJae Park
0f28583b28 Docs/damon: move DAMOS filter type names and meaning to design doc 
DAMON sysfs usage doc is describing DAMOS filter type names and their
meanings in short.  The design doc is providing the short meaning and
detailed descriptions, too.  This is unnecessary duplicates and confuses
where to document new DAMOS filter types and features.  Move the details
from usage to design doc.

Link: https://lkml.kernel.org/r/20250218223708.53437-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:24 -07:00
SeongJae Park
e52a942b47 Docs/mm/damon/design: document hugepage_size filter 
'hugepage_size' DAMOS filter type is not documented on the design doc.
Add a description of the type.

Link: https://lkml.kernel.org/r/20250218223708.53437-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:24 -07:00
SeongJae Park
381ff0341a Docs/mm/damon/design: fix typo on DAMOS filters usage doc link 
Patch series "Docs/mm/damon: misc DAMOS filters documentation fixes and
improves".

Fix and improve DAMOS filters documentation by fixing a copy-paste typo,
adding hugepage_size filter documentation on design doc, moving logic
details from usage to design, clarify DAMOS filters handling sequence
based on handling layer, and re-organizing the filters type list for
easier understanding of the handling sequence.


This patch (of 5):

The link from DAMOS filters design doc to usage doc has a typo calling
filters as watermarks.  Fix it.

Link: https://lkml.kernel.org/r/20250218223708.53437-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250218223708.53437-2-sj@kernel.org
Fixes: d31f5626a0 ("Docs/mm/damon/design: add links to sections of DAMON sysfs interface usage doc")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:23 -07:00
Suchit K
8e4909d693 Documentation/mm: fix spelling mistake 
The word watermark was misspelled as "watemark".

Link: https://lkml.kernel.org/r/CAO9wTFhe4sf1eVVgijt2cdLPPsUHBj7B=HN-380_JSpve5KbvQ@mail.gmail.com
Signed-off-by: Suchit <suchitkarunakaran@gmail.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:23 -07:00
Marcelo Moreira
fcd807a03b Docs/mm/damon: fix spelling and grammar in monitoring_intervals_tuning_example.rst 
This patch fixes some spelling and grammar mistakes in the documentation,
improving the readability.

- multipled  -> multiplied
- idential   -> identical
- minuts     -> minutes
- efficieny  -> efficiency

Link: https://lkml.kernel.org/r/20250217215512.12833-1-marcelomoreira1905@gmail.com
Signed-off-by: Marcelo Moreira <marcelomoreira1905@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Shuah khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:22 -07:00
Suren Baghdasaryan
795f29616e docs/mm: document latest changes to vm_lock 
Change the documentation to reflect that vm_lock is integrated into vma
and replaced with vm_refcnt.  Document newly introduced
vma_start_read_locked{_nested} functions.

Link: https://lkml.kernel.org/r/20250213224655.1680278-19-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:21 -07:00
Yosry Ahmed
58ba73e521 mm: z3fold: remove z3fold 
Patch series "mm: zswap: remove z3fold and zbud", v2.

After 2 cycles of deprecating z3fold, remove it as well as zbud (rationale
in specific patches).


This patch (of 2):

Z3fold has been marked as deprecated for 2 cycles and no one complained,
as expected.  As there are no known users, remove the code now.

Link: https://lkml.kernel.org/r/20250129180633.3501650-1-yosry.ahmed@linux.dev
Link: https://lkml.kernel.org/r/20250129180633.3501650-2-yosry.ahmed@linux.dev
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:06:01 -07:00
David Hildenbrand
599b684a78 mm/rmap: convert make_device_exclusive_range() to make_device_exclusive() 
The single "real" user in the tree of make_device_exclusive_range() always
requests making only a single address exclusive.  The current
implementation is hard to fix for properly supporting anonymous THP /
large folios and for avoiding messing with rmap walks in weird ways.

So let's always process a single address/page and return folio + page to
minimize page -> folio lookups.  This is a preparation for further
changes.

Reject any non-anonymous or hugetlb folios early, directly after GUP.

While at it, extend the documentation of make_device_exclusive() to
clarify some things.

Link: https://lkml.kernel.org/r/20250210193801.781278-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Tested-by: Alistair Popple <apopple@nvidia.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Lyude <lyude@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yanteng Si <si.yanteng@linux.dev>
Cc: Barry Song <v-songbaohua@oppo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-03-16 22:05:57 -07:00
I Hsin Cheng
a9fe4f04da mm: pgtable: Fix grammar error 
Fix "due high contention" to "due to high contention".

Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250204093326.206007-1-richard120310@gmail.com
 2025-02-04 09:40:14 -07:00
Linus Torvalds
9c5968db9e The various patchsets are summarized below. Plus of course many 
indivudual patches which are described in their changelogs.
 
 - "Allocate and free frozen pages" from Matthew Wilcox reorganizes the
   page allocator so we end up with the ability to allocate and free
   zero-refcount pages.  So that callers (ie, slab) can avoid a refcount
   inc & dec.
 
 - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to use
   large folios other than PMD-sized ones.
 
 - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance and
   fixes for this small built-in kernel selftest.
 
 - "mas_anode_descend() related cleanup" from Wei Yang tidies up part of
   the mapletree code.
 
 - "mm: fix format issues and param types" from Keren Sun implements a
   few minor code cleanups.
 
 - "simplify split calculation" from Wei Yang provides a few fixes and a
   test for the mapletree code.
 
 - "mm/vma: make more mmap logic userland testable" from Lorenzo Stoakes
   continues the work of moving vma-related code into the (relatively) new
   mm/vma.c.
 
 - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
   Hildenbrand cleans up and rationalizes handling of gfp flags in the page
   allocator.
 
 - "readahead: Reintroduce fix for improper RA window sizing" from Jan
   Kara is a second attempt at fixing a readahead window sizing issue.  It
   should reduce the amount of unnecessary reading.
 
 - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
   addresses an issue where "huge" amounts of pte pagetables are
   accumulated
   (https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/).
   Qi's series addresses this windup by synchronously freeing PTE memory
   within the context of madvise(MADV_DONTNEED).
 
 - "selftest/mm: Remove warnings found by adding compiler flags" from
   Muhammad Usama Anjum fixes some build warnings in the selftests code
   when optional compiler warnings are enabled.
 
 - "mm: don't use __GFP_HARDWALL when migrating remote pages" from David
   Hildenbrand tightens the allocator's observance of __GFP_HARDWALL.
 
 - "pkeys kselftests improvements" from Kevin Brodsky implements various
   fixes and cleanups in the MM selftests code, mainly pertaining to the
   pkeys tests.
 
 - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
   estimate application working set size.
 
 - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
   provides some cleanups to memcg's hugetlb charging logic.
 
 - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
   removes the global swap cgroup lock.  A speedup of 10% for a tmpfs-based
   kernel build was demonstrated.
 
 - "zram: split page type read/write handling" from Sergey Senozhatsky
   has several fixes and cleaups for zram in the area of zram_write_page().
   A watchdog softlockup warning was eliminated.
 
 - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin Brodsky
   cleans up the pagetable destructor implementations.  A rare
   use-after-free race is fixed.
 
 - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
   simplifies and cleans up the debugging code in the VMA merging logic.
 
 - "Account page tables at all levels" from Kevin Brodsky cleans up and
   regularizes the pagetable ctor/dtor handling.  This results in
   improvements in accounting accuracy.
 
 - "mm/damon: replace most damon_callback usages in sysfs with new core
   functions" from SeongJae Park cleans up and generalizes DAMON's sysfs
   file interface logic.
 
 - "mm/damon: enable page level properties based monitoring" from
   SeongJae Park increases the amount of information which is presented in
   response to DAMOS actions.
 
 - "mm/damon: remove DAMON debugfs interface" from SeongJae Park removes
   DAMON's long-deprecated debugfs interfaces.  Thus the migration to sysfs
   is completed.
 
 - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from Peter
   Xu cleans up and generalizes the hugetlb reservation accounting.
 
 - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
   removes a never-used feature of the alloc_pages_bulk() interface.
 
 - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
   extends DAMOS filters to support not only exclusion (rejecting), but
   also inclusion (allowing) behavior.
 
 - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
   "introduces a new memory descriptor for zswap.zpool that currently
   overlaps with struct page for now.  This is part of the effort to reduce
   the size of struct page and to enable dynamic allocation of memory
   descriptors."
 
 - "mm, swap: rework of swap allocator locks" from Kairui Song redoes and
   simplifies the swap allocator locking.  A speedup of 400% was
   demonstrated for one workload.  As was a 35% reduction for kernel build
   time with swap-on-zram.
 
 - "mm: update mips to use do_mmap(), make mmap_region() internal" from
   Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
   mmap_region() can be made MM-internal.
 
 - "mm/mglru: performance optimizations" from Yu Zhao fixes a few MGLRU
   regressions and otherwise improves MGLRU performance.
 
 - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae Park
   updates DAMON documentation.
 
 - "Cleanup for memfd_create()" from Isaac Manjarres does that thing.
 
 - "mm: hugetlb+THP folio and migration cleanups" from David Hildenbrand
   provides various cleanups in the areas of hugetlb folios, THP folios and
   migration.
 
 - "Uncached buffered IO" from Jens Axboe implements the new
   RWF_DONTCACHE flag which provides synchronous dropbehind for pagecache
   reading and writing.  To permite userspace to address issues with
   massive buildup of useless pagecache when reading/writing fast devices.
 
 - "selftests/mm: virtual_address_range: Reduce memory" from Thomas
   Weißschuh fixes and optimizes some of the MM selftests.
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Merge tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "The various patchsets are summarized below. Plus of course many
  indivudual patches which are described in their changelogs.

   - "Allocate and free frozen pages" from Matthew Wilcox reorganizes
     the page allocator so we end up with the ability to allocate and
     free zero-refcount pages. So that callers (ie, slab) can avoid a
     refcount inc & dec

   - "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
     use large folios other than PMD-sized ones

   - "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
     and fixes for this small built-in kernel selftest

   - "mas_anode_descend() related cleanup" from Wei Yang tidies up part
     of the mapletree code

   - "mm: fix format issues and param types" from Keren Sun implements a
     few minor code cleanups

   - "simplify split calculation" from Wei Yang provides a few fixes and
     a test for the mapletree code

   - "mm/vma: make more mmap logic userland testable" from Lorenzo
     Stoakes continues the work of moving vma-related code into the
     (relatively) new mm/vma.c

   - "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
     Hildenbrand cleans up and rationalizes handling of gfp flags in the
     page allocator

   - "readahead: Reintroduce fix for improper RA window sizing" from Jan
     Kara is a second attempt at fixing a readahead window sizing issue.
     It should reduce the amount of unnecessary reading

   - "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
     addresses an issue where "huge" amounts of pte pagetables are
     accumulated:

       https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/

     Qi's series addresses this windup by synchronously freeing PTE
     memory within the context of madvise(MADV_DONTNEED)

   - "selftest/mm: Remove warnings found by adding compiler flags" from
     Muhammad Usama Anjum fixes some build warnings in the selftests
     code when optional compiler warnings are enabled

   - "mm: don't use __GFP_HARDWALL when migrating remote pages" from
     David Hildenbrand tightens the allocator's observance of
     __GFP_HARDWALL

   - "pkeys kselftests improvements" from Kevin Brodsky implements
     various fixes and cleanups in the MM selftests code, mainly
     pertaining to the pkeys tests

   - "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
     estimate application working set size

   - "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
     provides some cleanups to memcg's hugetlb charging logic

   - "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
     removes the global swap cgroup lock. A speedup of 10% for a
     tmpfs-based kernel build was demonstrated

   - "zram: split page type read/write handling" from Sergey Senozhatsky
     has several fixes and cleaups for zram in the area of
     zram_write_page(). A watchdog softlockup warning was eliminated

   - "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
     Brodsky cleans up the pagetable destructor implementations. A rare
     use-after-free race is fixed

   - "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
     simplifies and cleans up the debugging code in the VMA merging
     logic

   - "Account page tables at all levels" from Kevin Brodsky cleans up
     and regularizes the pagetable ctor/dtor handling. This results in
     improvements in accounting accuracy

   - "mm/damon: replace most damon_callback usages in sysfs with new
     core functions" from SeongJae Park cleans up and generalizes
     DAMON's sysfs file interface logic

   - "mm/damon: enable page level properties based monitoring" from
     SeongJae Park increases the amount of information which is
     presented in response to DAMOS actions

   - "mm/damon: remove DAMON debugfs interface" from SeongJae Park
     removes DAMON's long-deprecated debugfs interfaces. Thus the
     migration to sysfs is completed

   - "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
     Peter Xu cleans up and generalizes the hugetlb reservation
     accounting

   - "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
     removes a never-used feature of the alloc_pages_bulk() interface

   - "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
     extends DAMOS filters to support not only exclusion (rejecting),
     but also inclusion (allowing) behavior

   - "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
     introduces a new memory descriptor for zswap.zpool that currently
     overlaps with struct page for now. This is part of the effort to
     reduce the size of struct page and to enable dynamic allocation of
     memory descriptors

   - "mm, swap: rework of swap allocator locks" from Kairui Song redoes
     and simplifies the swap allocator locking. A speedup of 400% was
     demonstrated for one workload. As was a 35% reduction for kernel
     build time with swap-on-zram

   - "mm: update mips to use do_mmap(), make mmap_region() internal"
     from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
     mmap_region() can be made MM-internal

   - "mm/mglru: performance optimizations" from Yu Zhao fixes a few
     MGLRU regressions and otherwise improves MGLRU performance

   - "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
     Park updates DAMON documentation

   - "Cleanup for memfd_create()" from Isaac Manjarres does that thing

   - "mm: hugetlb+THP folio and migration cleanups" from David
     Hildenbrand provides various cleanups in the areas of hugetlb
     folios, THP folios and migration

   - "Uncached buffered IO" from Jens Axboe implements the new
     RWF_DONTCACHE flag which provides synchronous dropbehind for
     pagecache reading and writing. To permite userspace to address
     issues with massive buildup of useless pagecache when
     reading/writing fast devices

   - "selftests/mm: virtual_address_range: Reduce memory" from Thomas
     Weißschuh fixes and optimizes some of the MM selftests"

* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
  mm/compaction: fix UBSAN shift-out-of-bounds warning
  s390/mm: add missing ctor/dtor on page table upgrade
  kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
  tools: add VM_WARN_ON_VMG definition
  mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
  seqlock: add missing parameter documentation for raw_seqcount_try_begin()
  mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
  mm/page_alloc: remove the incorrect and misleading comment
  zram: remove zcomp_stream_put() from write_incompressible_page()
  mm: separate move/undo parts from migrate_pages_batch()
  mm/kfence: use str_write_read() helper in get_access_type()
  selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
  kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
  selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
  selftests/mm: vm_util: split up /proc/self/smaps parsing
  selftests/mm: virtual_address_range: unmap chunks after validation
  selftests/mm: virtual_address_range: mmap() without PROT_WRITE
  selftests/memfd/memfd_test: fix possible NULL pointer dereference
  mm: add FGP_DONTCACHE folio creation flag
  mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
  ...
 2025-01-26 18:36:23 -08:00
SeongJae Park
a96f9e2773 Docs/mm/damon: add an example monitoring intervals tuning 
Add a DAMON monitoring intervals tuning example that contains output from
a demonstration of the guide on a real server workload system.  The
example with real world numbers will help users better understanding the
guide instructions and what outputs they can expect and verify.  Those
will again help finding the rooms for improvements on the guide.

Link: https://lkml.kernel.org/r/20250110185232.54907-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:39 -08:00
SeongJae Park
82047ae184 Docs/mm/damon/design: add monitoring parameters tuning guide 
Patch series "Docs/mm/damon: add tuning guide and misc updates".

Add DAMON monitoring parameters tuning guide (patches 1 and 2), with misc
documentation fixes (patch 3), updates (patch 4) and clarifications (patch
5).


This patch (of 5):

DAMON monitoring parameters including sampling and aggregation intervals
should be tuned for given workloads.  However, the fact is not explicitly
documented.  Also there is no official guide to help the tuning.  This
apparently confused a number of people[1] at best, or made people forgive
DAMON without tuning.  Add a guide on the design document.

[1] https://lore.kernel.org/20241202175459.2005526-1-sj@kernel.org

Link: https://lkml.kernel.org/r/20250110185232.54907-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250110185232.54907-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:39 -08:00
SeongJae Park
f477b9b409 Docs/mm/damon/design: document allow/reject DAMOS filter behaviors 
Update DAMOS filters design document to describe the allow/reject behavior
of filters.

Link: https://lkml.kernel.org/r/20250109175126.57878-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:32 -08:00
SeongJae Park
550b7af318 Docs/mm/damon/design: update for removal of DAMON debugfs interface 
It's time to remove DAMON debugfs interface, which has deprecated long
before in February 2023.  Read the cover letter of this patch series for
more details.

Update DAMON design documentation to stop mentioning about the interface,
to avoid unnecessary confuses.

Link: https://lkml.kernel.org/r/20250106191941.107070-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:29 -08:00
SeongJae Park
156845977b Docs/mm/damon/design: document per-region sz_filter_passed stat 
Update 'Regions Walking' section of design document for the newly added
per-region operations set handling DAMOS filters-passed bytes.

Link: https://lkml.kernel.org/r/20250106193401.109161-15-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:28 -08:00
SeongJae Park
0f0a0bfd07 Docs/mm/damon/design: document sz_ops_filter_passed 
Document the new per-scheme accumulated stat for total bytes that passed
the operations set layer-handled DAMOS filters on the design document.

Link: https://lkml.kernel.org/r/20250106193401.109161-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:27 -08:00
SeongJae Park
fc4e40937d Docs/admin-guide/mm/damon/usage: link damos stat design doc 
DAMON sysfs usage document focuses on usage, rather than the detail of the
stat metric itself.  Add a link to the design document on DAMOS stat usage
section.

Link: https://lkml.kernel.org/r/20250106193401.109161-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
SeongJae Park
10418f263a Docs/mm/damon/design: add 'statistics' section 
DAMOS stats are important feature for tuning of DAMOS-based access-aware
system operation, and efficient access pattern monitoring.  But not well
documented on the design document.  Add a section on the document.

Link: https://lkml.kernel.org/r/20250106193401.109161-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
SeongJae Park
cce0b334c3 Docs/mm/damon/design: document DAMOS regions walking 
DAMOS' regions walking is a feature for efficiently retrieving monitoring
results or DAMOS-internal behavior.  It can be useful for multiple
purposes including investigations and tuning.  Add a section for it on the
design document.

Link: https://lkml.kernel.org/r/20250103174400.54890-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:26 -08:00
Qi Zheng
db6b435d73 mm: pgtable: introduce pagetable_dtor() 
The pagetable_p*_dtor() are exactly the same except for the handling of
ptlock.  If we make ptlock_free() handle the case where ptdesc->ptl is
NULL and remove VM_BUG_ON_PAGE() from pmd_ptlock_free(), we can unify
pagetable_p*_dtor() into one function.  Let's introduce pagetable_dtor()
to do this.

Later, pagetable_dtor() will be moved to tlb_remove_ptdesc(), so that
ptlock and page table pages can be freed together (regardless of whether
RCU is used).  This prevents the use-after-free problem where the ptlock
is freed immediately but the page table pages is freed later via RCU.

Link: https://lkml.kernel.org/r/47f44fff9dc68d9d9e9a0d6c036df275f820598a.1736317725.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>	[s390]
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-25 20:22:22 -08:00
Linus Torvalds
d0f93ac2c3 Documentation changes this time around include: 
- Quite a bit of Chinese and Spanish translation work.
 
 - Clarifying that Git commit IDs >12chars are OK
 
 - A new nvme-multipath document
 
 - A reorganization of the admin-guide top-level page to make it readable
 
 - Clarification of the role of Acked-by and maintainer discretion on their
   acceptance.
 
 - Some reorganization of debugging-oriented docs.
 
 ...and typo fixes, documentation updates, etc. as usual.
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Merge tag 'docs-6.14' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:

 - Quite a bit of Chinese and Spanish translation work

 - Clarifying that Git commit IDs >12chars are OK

 - A new nvme-multipath document

 - A reorganization of the admin-guide top-level page to make it
   readable

 - Clarification of the role of Acked-by and maintainer discretion on
   their acceptance

 - Some reorganization of debugging-oriented docs

... and typo fixes, documentation updates, etc as usual

* tag 'docs-6.14' of git://git.lwn.net/linux: (50 commits)
  Documentation: Fix x86_64 UEFI outdated references to elilo
  Documentation/sysctl: Add timer_migration to kernel.rst
  docs/mm: Physical memory: Remove zone_t
  docs: submitting-patches: clarify that signers may use their discretion on tags
  docs: submitting-patches: clarify difference between Acked-by and Reviewed-by
  docs: submitting-patches: clarify Acked-by and introduce "# Suffix"
  Documentation: bug-hunting.rst: remove odd contact information
  docs/zh_CN: Add sak index Chinese translation
  doc: module: DEFAULT_SYMBOL_NAMESPACE must be defined before #includes
  doc: module: Fix documented type of namespace
  Documentation/kernel-parameters: Fix a reference to vga-softcursor.rst
  docs/zh_CN: Add landlock index Chinese translation
  Documentation: Fix typo localmodonfig -> localmodconfig
  overlayfs.rst: Fix and improve grammar
  docs/zh_CN: Add siphash index Chinese translation
  docs/zh_CN: Add security IMA-templates Chinese translation
  docs/zh_CN: Add security digsig Chinese translation
  Align git commit ID abbreviation guidelines and checks
  docs: process: submitting-patches: split canonical patch format section
  docs/zh_CN: Add security lsm Chinese translation
  ...
 2025-01-21 18:00:00 -08:00
I Hsin Cheng
b6cdff984c docs/mm: Physical memory: Remove zone_t 
"zone_t" doesn't exist in current code base anymore, remove the
description of it.

Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250115070355.41769-1-richard120310@gmail.com
 2025-01-16 11:16:47 -07:00
Qi Zheng
6c18ec9af8 mm: khugepaged: recheck pmd state in retract_page_tables() 
Patch series "synchronously scan and reclaim empty user PTE pages", v4.

Previously, we tried to use a completely asynchronous method to reclaim
empty user PTE pages [1].  After discussing with David Hildenbrand, we
decided to implement synchronous reclaimation in the case of
madvise(MADV_DONTNEED) as the first step.

So this series aims to synchronously free the empty PTE pages in
madvise(MADV_DONTNEED) case.  We will detect and free empty PTE pages in
zap_pte_range(), and will add zap_details.reclaim_pt to exclude cases
other than madvise(MADV_DONTNEED).

In zap_pte_range(), mmu_gather is used to perform batch tlb flushing and
page freeing operations.  Therefore, if we want to free the empty PTE page
in this path, the most natural way is to add it to mmu_gather as well. 
Now, if CONFIG_MMU_GATHER_RCU_TABLE_FREE is selected, mmu_gather will free
page table pages by semi RCU:

 - batch table freeing: asynchronous free by RCU
 - single table freeing: IPI + synchronous free

But this is not enough to free the empty PTE page table pages in paths
other that munmap and exit_mmap path, because IPI cannot be synchronized
with rcu_read_lock() in pte_offset_map{_lock}().  So we should let single
table also be freed by RCU like batch table freeing.

As a first step, we supported this feature on x86_64 and selectd the newly
introduced CONFIG_ARCH_SUPPORTS_PT_RECLAIM.

For other cases such as madvise(MADV_FREE), consider scanning and freeing
empty PTE pages asynchronously in the future.

Note: issues related to TLB flushing are not new to this series and are tracked
      in the separate RFC patch [3]. And more context please refer to this
      thread [4].

[1]. https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
[2]. https://lore.kernel.org/lkml/cover.1727332572.git.zhengqi.arch@bytedance.com/
[3]. https://lore.kernel.org/lkml/20240815120715.14516-1-zhengqi.arch@bytedance.com/
[4]. https://lore.kernel.org/lkml/6f38cb19-9847-4f70-bbe7-06881bb016be@bytedance.com/


This patch (of 11):

In retract_page_tables(), the lock of new_folio is still held, we will be
blocked in the page fault path, which prevents the pte entries from being
set again.  So even though the old empty PTE page may be concurrently
freed and a new PTE page is filled into the pmd entry, it is still empty
and can be removed.

So just refactor the retract_page_tables() a little bit and recheck the
pmd state after holding the pmd lock.

Link: https://lkml.kernel.org/r/cover.1733305182.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/70a51804cd19d44ccaf031825d9fb6eaf92f2bad.1733305182.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Suggested-by: Jann Horn <jannh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-01-13 22:40:46 -08:00
Lorenzo Stoakes
dbf8be8218 docs/mm: add VMA locks documentation 
Locking around VMAs is complicated and confusing.  While we have a number
of disparate comments scattered around the place, we seem to be reaching a
level of complexity that justifies a serious effort at clearly documenting
how locks are expected to be used when it comes to interacting with
mm_struct and vm_area_struct objects.

This is especially pertinent as regards the efforts to find sensible
abstractions for these fundamental objects in kernel rust code whose
compiler strictly requires some means of expressing these rules (and
through this expression, self-document these requirements as well as
enforce them).

The document limits scope to mmap and VMA locks and those that are
immediately adjacent and relevant to them - so additionally covers page
table locking as this is so very closely tied to VMA operations (and
relies upon us handling these correctly).

The document tries to cover some of the nastier and more confusing edge
cases and concerns especially around lock ordering and page table
teardown.

The document is split between generally useful information for users of mm
interfaces, and separately a section intended for mm kernel developers
providing a discussion around internal implementation details.

[lorenzo.stoakes@oracle.com: v3]
  Link: https://lkml.kernel.org/r/20241114205402.859737-1-lorenzo.stoakes@oracle.com
[lorenzo.stoakes@oracle.com: docs/mm: minor corrections]
  Link: https://lkml.kernel.org/r/d3de735a-25ae-4eb2-866c-a9624fe6f795@lucifer.local
[jannh@google.com: docs/mm: add more warnings around page table access]
  Link: https://lkml.kernel.org/r/20241118-vma-docs-addition1-onv3-v2-1-c9d5395b72ee@google.com
Link: https://lkml.kernel.org/r/20241108135708.48567-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Jann Horn <jannh@google.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-12-18 19:04:41 -08:00
Linus Torvalds
e06635e26c slab updates for 6.13 
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Merge tag 'slab-for-6.13-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab updates from Vlastimil Babka:

 - Add new slab_strict_numa boot parameter to enforce per-object memory
   policies on top of slab folio policies, for systems where saving cost
   of remote accesses is more important than minimizing slab allocation
   overhead (Christoph Lameter)

 - Fix for freeptr_offset alignment check being too strict for m68k
   (Geert Uytterhoeven)

 - krealloc() fixes for not violating __GFP_ZERO guarantees on
   krealloc() when slub_debug (redzone and object tracking) is enabled
   (Feng Tang)

 - Fix a memory leak in case sysfs registration fails for a slab cache,
   and also no longer fail to create the cache in that case (Hyeonggon
   Yoo)

 - Fix handling of detected consistency problems (due to buggy slab
   user) with slub_debug enabled, so that it does not cause further list
   corruption bugs (yuan.gao)

 - Code cleanup and kerneldocs polishing (Zhen Lei, Vlastimil Babka)

* tag 'slab-for-6.13-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  slab: Fix too strict alignment check in create_cache()
  mm/slab: Allow cache creation to proceed even if sysfs registration fails
  mm/slub: Avoid list corruption when removing a slab from the full list
  mm/slub, kunit: Add testcase for krealloc redzone and zeroing
  mm/slub: Improve redzone check and zeroing for krealloc()
  mm/slub: Consider kfence case for get_orig_size()
  SLUB: Add support for per object memory policies
  mm, slab: add kerneldocs for common SLAB_ flags
  mm/slab: remove duplicate check in create_cache()
  mm/slub: Move krealloc() and related code to slub.c
  mm/kasan: Don't store metadata inside kmalloc object when slub_debug_orig_size is on
 2024-11-25 16:51:24 -08:00
Linus Torvalds
5c00ff742b - The series "zram: optimal post-processing target selection" from 
Sergey Senozhatsky improves zram's post-processing selection algorithm.
   This leads to improved memory savings.
 
 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
 
 	- "refine mas_mab_cp()"
 	- "Reduce the space to be cleared for maple_big_node"
 	- "maple_tree: simplify mas_push_node()"
 	- "Following cleanup after introduce mas_wr_store_type()"
 	- "refine storing null"
 
 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.
 
 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping code.
 
 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of shadow
   entries.
 
 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.
 
 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in the
   hugetlb code.
 
 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page into
   small pages.  Instead we replace the whole thing with a THP.  More
   consistent cleaner and potentiall saves a large number of pagefaults.
 
 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.
 
 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to do.
 
 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio size
   rather than as individual pages.  A 20% speedup was observed.
 
 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting.
 
 - The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt
   removes the long-deprecated memcgv2 charge moving feature.
 
 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.
 
 - The series "x86/module: use large ROX pages for text allocations" from
   Mike Rapoport teaches x86 to use large pages for read-only-execute
   module text.
 
 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.
 
 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/.  A slow march towards shrinking
   struct page.
 
 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.
 
 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression.  It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.
 
 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests
   over to the KUnit framework.
 
 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a single
   VMA, rather than requiring that multiple VMAs be created for this.
   Improved efficiencies for userspace memory allocators are expected.
 
 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.
 
 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.
 
 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP from
   the kernel boot command line.
 
 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.
 
 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep is
   enabled.
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Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - The series "zram: optimal post-processing target selection" from
   Sergey Senozhatsky improves zram's post-processing selection
   algorithm. This leads to improved memory savings.

 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
	- "refine mas_mab_cp()"
	- "Reduce the space to be cleared for maple_big_node"
	- "maple_tree: simplify mas_push_node()"
	- "Following cleanup after introduce mas_wr_store_type()"
	- "refine storing null"

 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.

 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping
   code.

 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of
   shadow entries.

 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.

 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in
   the hugetlb code.

 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page
   into small pages. Instead we replace the whole thing with a THP. More
   consistent cleaner and potentiall saves a large number of pagefaults.

 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.

 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to
   do.

 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio
   size rather than as individual pages. A 20% speedup was observed.

 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
   splitting.

 - The series "memcg-v1: fully deprecate charge moving" from Shakeel
   Butt removes the long-deprecated memcgv2 charge moving feature.

 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.

 - The series "x86/module: use large ROX pages for text allocations"
   from Mike Rapoport teaches x86 to use large pages for
   read-only-execute module text.

 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.

 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/. A slow march towards shrinking
   struct page.

 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.

 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression. It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.

 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
   tests over to the KUnit framework.

 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a
   single VMA, rather than requiring that multiple VMAs be created for
   this. Improved efficiencies for userspace memory allocators are
   expected.

 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.

 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.

 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP
   from the kernel boot command line.

 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.

 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep
   is enabled.

* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
  cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
  mm/kfence: add a new kunit test test_use_after_free_read_nofault()
  zram: fix NULL pointer in comp_algorithm_show()
  memcg/hugetlb: add hugeTLB counters to memcg
  vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
  mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
  zram: ZRAM_DEF_COMP should depend on ZRAM
  MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
  Docs/mm/damon: recommend academic papers to read and/or cite
  mm: define general function pXd_init()
  kmemleak: iommu/iova: fix transient kmemleak false positive
  mm/list_lru: simplify the list_lru walk callback function
  mm/list_lru: split the lock to per-cgroup scope
  mm/list_lru: simplify reparenting and initial allocation
  mm/list_lru: code clean up for reparenting
  mm/list_lru: don't export list_lru_add
  mm/list_lru: don't pass unnecessary key parameters
  kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
  kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
  kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
  ...
 2024-11-23 09:58:07 -08:00
Linus Torvalds
c3cda60e83 Another moderately busy cycle in docsland: 
- Work on Chinese translations has picked up again.  Happily, they are
   maintaining the existing translations and not just adding new ones.
 
 - Some maintenance of the Japanese and Italian translations as well.
 
 - The removal of the venerable "dontdiff" file.  It has long outlived its
   usefulness and contained entries ("parse.*") that would actively mask
   actual source change.
 
 - The addition of enforcement information to the code-of-conduct
   documentation.
 
 Along with some build-system fixes and a lot of typo and language fixes.
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Merge tag 'docs-6.13' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "Another moderately busy cycle in docsland:

   - Work on Chinese translations has picked up again. Happily, they are
     maintaining the existing translations and not just adding new ones.

   - Some maintenance of the Japanese and Italian translations as well.

   - The removal of the venerable "dontdiff" file. It has long outlived
     its usefulness and contained entries ("parse.*") that would
     actively mask actual source change.

   - The addition of enforcement information to the code-of-conduct
     documentation.

  Along with some build-system fixes and a lot of typo and language
  fixes"

* tag 'docs-6.13' of git://git.lwn.net/linux: (52 commits)
  Documentation/CoC: spell out enforcement for unacceptable behaviors
  docs: fix typos and whitespace in Documentation/process/backporting.rst
  docs/zh_CN: fix one sentence in llvm.rst
  docs: bug-bisect: add a note about bisecting -next
  docs/zh_CN: add the translation of kbuild/llvm.rst
  Documentation: Fix incorrect paths/magic in magic numbers rst
  Documentation/maintainer-tip: Fix typos
  Documentation: Improve crash_kexec_post_notifiers description
  Docs/zh_CN: Translate physical_memory.rst to Simplified Chinese
  Documentation: admin: reorganize kernel-parameters intro
  docs/zh_CN: update the translation of process/programming-language.rst
  docs/zh_CN: update the translation of mm/page_owner.rst
  docs/zh_CN: update the translation of mm/page_table_check.rst
  docs/zh_CN: update the translation of mm/overcommit-accounting.rst
  docs/zh_CN: update the translation of mm/admon/faq.rst
  docs/zh_CN: update the translation of mm/active_mm.rst
  docs/zh_CN: update the translation of mm/hmm.rst
  docs: remove Documentation/dontdiff
  docs/zh_CN: Add a entry in Chinese glossary
  Docs/zh_CN: Fix the pfn calculation error in page_tables.rst
  ...
 2024-11-20 09:16:45 -08:00
SeongJae Park
e191759091 Docs/mm/damon: recommend academic papers to read and/or cite 
Kernel documentation is the most up-to-date and recommended resource for
DAMON.  It doesn't cover non-kernel part of the entire project[1], though.
Also it is not optimum for formal long-term citations.  Depending on
cases, DAMON academic papers[2,3] could be better to be read and cited. 
However, there is no clear guidance for those.  Add a paragraph for DAMON
academic papers on the kernel documentation for DAMON.

[1] https://damonitor.github.io
[2] https://dl.acm.org/doi/abs/10.1145/3366626.3368125
[3] https://dl.acm.org/doi/abs/10.1145/3502181.353146

Link: https://lkml.kernel.org/r/20241101203557.55210-1-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-11-11 17:22:27 -08:00
Suren Baghdasaryan
4835f747d3 alloc_tag: support for page allocation tag compression 
Implement support for storing page allocation tag references directly in
the page flags instead of page extensions.  sysctl.vm.mem_profiling boot
parameter it extended to provide a way for a user to request this mode. 
Enabling compression eliminates memory overhead caused by page_ext and
results in better performance for page allocations.  However this mode
will not work if the number of available page flag bits is insufficient to
address all kernel allocations.  Such condition can happen during boot or
when loading a module.  If this condition is detected, memory allocation
profiling gets disabled with an appropriate warning.  By default
compression mode is disabled.

Link: https://lkml.kernel.org/r/20241023170759.999909-7-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xiongwei Song <xiongwei.song@windriver.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-11-07 14:25:16 -08:00
Qi Zheng
583e66debd mm: pgtable: remove pte_offset_map_nolock() 
Now no users are using the pte_offset_map_nolock(), remove it.

Link: https://lkml.kernel.org/r/d04f9bbbcde048fb6ffa6f2bdbc6f9b22d5286f9.1727332572.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-11-05 16:56:29 -08:00
Qi Zheng
66efef9b1a mm: pgtable: introduce pte_offset_map_{ro|rw}_nolock() 
Patch series "introduce pte_offset_map_{ro|rw}_nolock()", v5.

As proposed by David Hildenbrand [1], this series introduces the following
two new helper functions to replace pte_offset_map_nolock().

1. pte_offset_map_ro_nolock()
2. pte_offset_map_rw_nolock()

As the name suggests, pte_offset_map_ro_nolock() is used for read-only
case.  In this case, only read-only operations will be performed on PTE
page after the PTL is held.  The RCU lock in pte_offset_map_nolock() will
ensure that the PTE page will not be freed, and there is no need to worry
about whether the pmd entry is modified.  Therefore
pte_offset_map_ro_nolock() is just a renamed version of
pte_offset_map_nolock().

pte_offset_map_rw_nolock() is used for may-write case.  In this case, the
pte or pmd entry may be modified after the PTL is held, so we need to
ensure that the pmd entry has not been modified concurrently.  So in
addition to the name change, it also outputs the pmdval when successful. 
The users should make sure the page table is stable like checking
pte_same() or checking pmd_same() by using the output pmdval before
performing the write operations.

This series will convert all pte_offset_map_nolock() into the above two
helper functions one by one, and finally completely delete it.

This also a preparation for reclaiming the empty user PTE page table
pages.


This patch (of 13):

Currently, the usage of pte_offset_map_nolock() can be divided into the
following two cases:

1) After acquiring PTL, only read-only operations are performed on the PTE
   page. In this case, the RCU lock in pte_offset_map_nolock() will ensure
   that the PTE page will not be freed, and there is no need to worry
   about whether the pmd entry is modified.

2) After acquiring PTL, the pte or pmd entries may be modified. At this
   time, we need to ensure that the pmd entry has not been modified
   concurrently.

To more clearing distinguish between these two cases, this commit
introduces two new helper functions to replace pte_offset_map_nolock(). 
For 1), just rename it to pte_offset_map_ro_nolock().  For 2), in addition
to changing the name to pte_offset_map_rw_nolock(), it also outputs the
pmdval when successful.  It is applicable for may-write cases where any
modification operations to the page table may happen after the
corresponding spinlock is held afterwards.  But the users should make sure
the page table is stable like checking pte_same() or checking pmd_same()
by using the output pmdval before performing the write operations.

Note: "RO" / "RW" expresses the intended semantics, not that the *kmap*
will be read-only/read-write protected.

Subsequent commits will convert pte_offset_map_nolock() into the above
two functions one by one, and finally completely delete it.

Link: https://lkml.kernel.org/r/cover.1727332572.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/5aeecfa131600a454b1f3a038a1a54282ca3b856.1727332572.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-11-05 16:56:26 -08:00
Christoph Lameter
f7c80fad6c SLUB: Add support for per object memory policies 
The old SLAB allocator used to support memory policies on a per
allocation bases. In SLUB the memory policies are applied on a
per page frame / folio bases. Doing so avoids having to check memory
policies in critical code paths for kmalloc and friends.

This worked on general well on Intel/AMD/PowerPC because the
interconnect technology is mature and can minimize the latencies
through intelligent caching even if a small object is not
placed optimally.

However, on ARM we have an emergence of new NUMA interconnect
technology based more on embedded devices. Caching of remote content
can currently be ineffective using the standard building blocks / mesh
available on that platform. Such architectures benefit if each slab
object is individually placed according to memory policies
and other restrictions.

This patch adds another kernel parameter

    slab_strict_numa

If that is set then a static branch is activated that will cause
the hotpaths of the allocator to evaluate the current memory
allocation policy. Each object will be properly placed by
paying the price of extra processing and SLUB will no longer
defer to the page allocator to apply memory policies at the
folio level.

This patch improves performance of memcached running
on Ampere Altra 2P system (ARM Neoverse N1 processor)
by 3.6% due to accurate placement of small kernel objects.

Tested-by: Huang Shijie <shijie@os.amperecomputing.com>
Signed-off-by: Christoph Lameter (Ampere) <cl@gentwo.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
 2024-10-29 10:43:53 +01:00
SeongJae Park
f4050ccab7 Docs/damon/maintainer-profile: update deprecated awslabs GitHub URLs 
DAMON GitHub repos have moved from awslabs GitHub org to damonitor org[1].
Following the change, URLs on documents are also updated[2].  However,
commit 2e9b3d6e2e ("Docs/damon/maintainer-profile: add links in place"),
which was added just after the update, was using the deprecated GitHub
URLs.  Update those to use damonitor GitHub URLs instead.

[1] https://lore.kernel.org/20240813232158.83903-1-sj@kernel.org
[2] https://lore.kernel.org/20240826015741.80707-2-sj@kernel.org

Link: https://lkml.kernel.org/r/20241011170154.70651-3-sj@kernel.org
Fixes: 2e9b3d6e2e ("Docs/damon/maintainer-profile: add links in place")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-10-17 00:28:09 -07:00
SeongJae Park
46e10f644a Docs/damon/maintainer-profile: add missing '_' suffixes for external web links 
Patch series "Docs/damon/maintainer-profile: a couple of minor hotfixes".

DAMON maintainer-profile.rst file patches[1] that were merged into the
v6.12-rc1 have a couple of minor mistakes.  Fix those.

[1] https://lore.kernel.org/20240826015741.80707-1-sj@kernel.org


This patch (of 2):

Links to external web pages on DAMON's maintainer-profile.rst are missing
'_' suffixes.  As a result, rendered document is having only verbose URLs
that cannot be clicked.  Fix those.

Also, update the link texts for git trees to contain the names of the
trees, for better readability and avoiding below Sphinx warning.

    maintainer-profile.rst:4: WARNING: Duplicate explicit target name: "tree".

Link: https://lkml.kernel.org/r/20241011170154.70651-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20241011170154.70651-2-sj@kernel.org
Fixes: 2e9b3d6e2e ("Docs/damon/maintainer-profile: add links in place")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-10-17 00:28:09 -07:00
Pengyu Zhang
6a32c8dfec Docs/mm: Fix a mistake for pfn in page_tables.rst 
The documentation incorrectly calculate the pfn value as 0x3fffff,
which should be 0x3ffff instead. It is obtained by right-shifting
0xffffc000 by 14 bits.

This patch corrects the value to prevent any potential confusion
for developers referencing this document.

Signed-off-by: Pengyu Zhang <zpenya1314@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241009144135.12453-1-zpenya1314@gmail.com
 2024-10-14 10:16:16 -06:00