linux.git/include/linux/huge_mm.h, branch v7.3-rc2

mm/huge_memory: fold split_folio_to_list_to_order() into split_folio_to_order()

2026-08-07T01:57:16+00:00

split_folio_to_list_to_order() had no direct callers; its only user was
split_folio_to_order(), which always passed a NULL list.  Fold it into
split_folio_to_order() and call split_huge_page_to_list_to_order()
directly.

No functional change.

Link: https://lore.kernel.org/20260716100345.473473-3-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau (Meta) 
Acked-by: Usama Arif 
Reviewed-by: Lorenzo Stoakes (ARM) 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand (Arm) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Nico Pache 
Cc: Ryan Roberts 
Signed-off-by: Andrew Morton

mm/huge_memory: remove unused can_split_folio()

2026-08-07T01:57:15+00:00

Patch series "mm/huge_memory: drop dead split helper variants".

Two trivial cleanups in the folio split API, found while auditing the
split helpers for the inode UAF fix [1]:

 - can_split_folio() is dead: only the !THP stub remains, no definition
   under CONFIG_TRANSPARENT_HUGEPAGE and no callers. Leftover from an
   earlier cleanup.

 - split_folio_to_list_to_order() has no direct callers; its only user
   is split_folio_to_order(), which always passes a NULL list. Fold it.

No functional change.


This patch (of 2):

can_split_folio() has no callers and no definition under
CONFIG_TRANSPARENT_HUGEPAGE; only the !THP stub remains, left behind by an
earlier cleanup.  Remove it.

No functional change.

Link: https://lore.kernel.org/20260716100345.473473-1-kirill@shutemov.name
Link: https://lore.kernel.org/20260716100345.473473-2-kirill@shutemov.name
Link: https://lore.kernel.org/linux-mm/aldjhtfVByHDQXe6@thinkstation [1]
Link: https://lore.kernel.org/linux-mm/20260714122344.351895-1-kirill@shutemov.name [2]
Signed-off-by: Kiryl Shutsemau (Meta) 
Acked-by: Usama Arif 
Reviewed-by: Lorenzo Stoakes (ARM) 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand (Arm) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Dev Jain 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Nico Pache 
Cc: Ryan Roberts 
Signed-off-by: Andrew Morton

mm: introduce pud_is_huge() helper

2026-08-07T01:57:14+00:00

Patch series "mm: mincore: misc cleanups", v3.

This series cleans up and simplifies the mincore.  Most importantly, it
removes the historical special behavior that always reports VM_PFNMAP
pages as non-resident.


This patch (of 6):

Introduce the pud_is_huge() helper function to check whether a PUD is a
huge PUD or a software leaf entry.  Note that, unlike PMD, PUD currently
does not support transparent migration entries or device private entries. 
However, the function still includes `!pud_none()` branches to accommodate
potential future implementations.

Link: https://lore.kernel.org/20260717091347.1144789-1-wangkefeng.wang@huawei.com
Link: https://lore.kernel.org/20260717091347.1144789-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Acked-by: David Hildenbrand (Arm) 
Cc: Jann Horn 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Pedro Falcato 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

mm: convert __get_unmapped_area() to use vma_flags_t

2026-08-07T01:57:01+00:00

Update __get_unmapped_area() to be parameterised by vma_flags_t rather
than vm_flags_t as part of the effort to move VMA flags from a system word
to a bitmap.

We cascade the changes up to arch_get_unmapped_area_topdown() and
arch_get_unmapped_area(), where, for now, we use vma_flags_to_legacy() in
order to propagate the VMA flags.

No functional change intended.

Link: https://lore.kernel.org/20260711-b4-vma-flags-mm-v2-3-0fa2357d5431@kernel.org
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: Lance Yang 
Reviewed-by: Zi Yan 
Reviewed-by: Vlastimil Babka (SUSE) 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Christian Brauner 
Cc: Dave Airlie 
Cc: David Hildenbrand 
Cc: Dev Jain 
Cc: Jani Nikula 
Cc: Jan Kara 
Cc: Jann Horn 
Cc: Mike Rapoport 
Cc: Muchun Song 
Cc: Nico Pache 
Cc: Oscar Salvador 
Cc: Pedro Falcato 
Cc: Suren Baghdasaryan 
Cc: Thomas Zimmermann 
Signed-off-by: Andrew Morton

mm/vma: use vma_start_pgoff(), linear_page_index() in mm code

2026-08-05T02:19:00+00:00

There are many instances in which linear_page_index() (as well as
linear_page_delta()) is open-coded, which is confusing and inconsistent.

Additionally, vma->vm_pgoff doesn't necessarily make it clear that this is
the page offset of the start of the VMA range.

Doing so also aids greppability.

So use vma_start_pgoff() in favour of directly accessing vma->vm_pgoff, and
linear_page_index() where we can.

This also lays the ground for future changes which will add an anonymous
page offset in order to be able to index MAP_PRIVATE-file backed anon
folios in terms of their virtual page offset.

No functional change intended.

Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-18-2a5aa403d977@kernel.org
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: Gregory Price 
Reviewed-by: SJ Park 
Reviewed-by: Pedro Falcato 
Reviewed-by: Vlastimil Babka (SUSE) 
Cc: Ackerley Tng 
Cc: David Hildenbrand (Arm) 
Cc: Kai Huang 
Cc: Marek Szyprowski 
Cc: Thomas Zimmermann 
Cc: Liam R. Howlett (Oracle) 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP

2026-08-05T02:18:38+00:00

Wire the fault side of read-write protection tracking and turn the
userspace interface on.

An RWP-protected PTE is PAGE_NONE with the uffd bit set.  The PROT_NONE
triggers a fault on any access; the uffd bit distinguishes it from plain
mprotect(PROT_NONE) or NUMA hinting.

Fault dispatch, per level:

  PTE     handle_pte_fault()    -> do_uffd_rwp()
  PMD     __handle_mm_fault()   -> do_huge_pmd_uffd_rwp()
  hugetlb hugetlb_fault()       -> hugetlb_handle_userfault()

The RWP branches gate on userfaultfd_pte_rwp() /
userfaultfd_huge_pmd_rwp() (VM_UFFD_RWP plus the uffd bit) and fall
through to do_numa_page() / do_huge_pmd_numa_page() otherwise.  Each
delivers a UFFD_PAGEFAULT_FLAG_RWP message through handle_userfault(); the
handler resolves it with UFFDIO_RWPROTECT clearing MODE_RWP.

userfaultfd_must_wait() and userfaultfd_huge_must_wait() add matching
protnone+uffd waiters so sync-mode fault handlers block correctly.

Expose the UAPI:

  UFFDIO_REGISTER_MODE_RWP   -> UFFD_API_REGISTER_MODES
  UFFD_FEATURE_RWP           -> UFFD_API_FEATURES
  _UFFDIO_RWPROTECT          -> UFFD_API_RANGE_IOCTLS
                                UFFD_API_RANGE_IOCTLS_BASIC

UFFD_FEATURE_RWP is masked out at UFFDIO_API time when PROT_NONE is not
available or VM_UFFD_RWP aliases VM_NONE (32-bit), so userspace never sees
an advertised-but-broken feature.

Works on anonymous, shmem, and hugetlb memory.

Link: https://lore.kernel.org/20260708111417.173443-11-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau 
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) 
Cc: Andrea Arcangeli 
Cc: David Hildenbrand 
Cc: James Houghton 
Cc: Jonathan Corbet 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Paolo Bonzini 
Cc: Peter Xu 
Cc: Sean Christopherson 
Cc: SeongJae Park 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES

2026-07-31T02:40:25+00:00

CONFIG_ARCH_ENABLE_THP_MIGRATION gates PMD-level migration entries. 
PMD-level device-private entries use the same migration mechanism and
therefore require the same architecture support.

Upcoming PMD-level swap entries can use the same PMD softleaf helpers
without depending on page migration, so rename the architecture gate to
CONFIG_ARCH_HAS_PMD_SOFTLEAVES.  This describes the PMD entry capability
rather than one current user of it.

This is a pure rename: the set of selecting architectures (x86, arm64,
s390, riscv, loongarch, and powerpc on PPC_BOOK3S_64) and the gating
semantics are unchanged.

No functional change intended.

Link: https://lore.kernel.org/20260706114320.1643046-7-usama.arif@linux.dev
Signed-off-by: Usama Arif 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand (Arm) 
Cc: Alexandre Ghiti 
Cc: Baolin Wang 
Cc: Baoquan He 
Cc: Barry Song 
Cc: Chris Li 
Cc: Dev Jain 
Cc: "Huang, Ying" 
Cc: Johannes Weiner 
Cc: Kairui Song 
Cc: Kemeng Shi 
Cc: Kiryl Shutsemau 
Cc: Lance Yang 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox (Oracle) 
Cc: Nhat Pham 
Cc: Nico Pache 
Cc: Rik van Riel 
Cc: Ryan Roberts 
Cc: Shakeel Butt 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

mm/truncate: use folio_split() in truncate_inode_partial_folio()

2026-06-21T18:37:16+00:00

After READ_ONLY_THP_FOR_FS is removed, FS either supports large folio or
not.  folio_split() can be used on a FS with large folio support without
worrying about getting a THP on a FS without large folio support.

When READ_ONLY_THP_FOR_FS was present, a PMD large pagecache folio can
appear in a FS without large folio support after khugepaged or
madvise(MADV_COLLAPSE) creates it.  During truncate_inode_partial_folio(),
such a PMD large pagecache folio is split and if the FS does not support
large folio, it needs to be split to order-0 ones and could not be split
non uniformly to ones with various orders.  try_folio_split_to_order() was
added to handle this situation by checking folio_check_splittable(...,
SPLIT_TYPE_NON_UNIFORM) to detect if the large folio is created due to
READ_ONLY_THP_FOR_FS and the FS does not support large folio.  Now
READ_ONLY_THP_FOR_FS is removed, all large pagecache folios are created
with FSes supporting large folio, this function is no longer needed and
all large pagecache folios can be split non uniformly.

Link: https://lore.kernel.org/20260517135416.1434539-10-ziy@nvidia.com
Signed-off-by: Zi Yan 
Reviewed-by: Lance Yang 
Acked-by: David Hildenbrand (Arm) 
Cc: Al Viro 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Chris Mason 
Cc: Christian Brauner 
Cc: David Sterba 
Cc: Dev Jain 
Cc: Jan Kara 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Nico Pache 
Cc: Ryan Roberts 
Cc: Shuah Khan 
Cc: Song Liu 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

mm/khugepaged: add per-order mTHP collapse failure statistics

2026-06-21T18:31:31+00:00

Add three new mTHP statistics to track collapse failures for different
orders when encountering swap PTEs, excessive none PTEs, and shared PTEs:

- collapse_exceed_swap_pte: Increment when mTHP collapse fails due to
	encountering a swap PTE.

- collapse_exceed_none_pte: Counts when mTHP collapse fails due to
  	exceeding the none PTE threshold for the given order

- collapse_exceed_shared_pte: Counts when mTHP collapse fails due to
	encountering a shared PTE.

These statistics complement the existing THP_SCAN_EXCEED_* events by
providing per-order granularity for mTHP collapse attempts.  The stats are
exposed via sysfs under
`/sys/kernel/mm/transparent_hugepage/hugepages-*/stats/` for each
supported hugepage size.

As we currently do not support collapsing mTHPs that contain a swap or
shared entry, those statistics keep track of how often we are encountering
failed mTHP collapses due to these restrictions.

We will add support for mTHP collapse for anonymous pages next; lets also
track when this happens at the PMD level within the per-mTHP stats.

Link: https://lore.kernel.org/20260605161422.213817-9-npache@redhat.com
Signed-off-by: Nico Pache 
Reviewed-by: Lorenzo Stoakes 
Acked-by: David Hildenbrand (Arm) 
Reviewed-by: Lance Yang 
Cc: Alistair Popple 
Cc: Andrea Arcangeli 
Cc: Anshuman Khandual 
Cc: Bagas Sanjaya 
Cc: Baolin Wang 
Cc: Barry Song 
Cc: Brendan Jackman 
Cc: Byungchul Park 
Cc: Catalin Marinas 
Cc: David Rientjes 
Cc: Dev Jain 
Cc: Gregory Price 
Cc: "Huang, Ying" 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: Jann Horn 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Joshua Hahn 
Cc: Kefeng Wang 
Cc: Liam R. Howlett 
Cc: "Masami Hiramatsu (Google)" 
Cc: Mathieu Desnoyers 
Cc: Matthew Brost 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Nanyong Sun 
Cc: Pedro Falcato 
Cc: Peter Xu 
Cc: Rafael Aquini 
Cc: Rakie Kim 
Cc: Randy Dunlap 
Cc: Ryan Roberts 
Cc: Shivank Garg 
Cc: Steven Rostedt 
Cc: Suren Baghdasaryan 
Cc: Takashi Iwai (SUSE) 
Cc: Thomas Hellström 
Cc: Usama Arif 
Cc: Usama Arif 
Cc: Vishal Moola (Oracle) 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Will Deacon 
Cc: Yang Shi 
Cc: Zach O'Keefe 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

mm/khugepaged: generalize alloc_charge_folio()

2026-06-21T18:31:29+00:00

Pass order to alloc_charge_folio() and update mTHP statistics.

Link: https://lore.kernel.org/20260605161422.213817-3-npache@redhat.com
Signed-off-by: Dev Jain 
Co-developed-by: Nico Pache 
Signed-off-by: Nico Pache 
Reviewed-by: Wei Yang 
Reviewed-by: Lance Yang 
Reviewed-by: Baolin Wang 
Reviewed-by: Lorenzo Stoakes 
Reviewed-by: Zi Yan 
Acked-by: Usama Arif 
Acked-by: David Hildenbrand (Arm) 
Cc: Alistair Popple 
Cc: Andrea Arcangeli 
Cc: Anshuman Khandual 
Cc: Bagas Sanjaya 
Cc: Barry Song 
Cc: Brendan Jackman 
Cc: Byungchul Park 
Cc: Catalin Marinas 
Cc: David Rientjes 
Cc: Gregory Price 
Cc: "Huang, Ying" 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: Jann Horn 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Joshua Hahn 
Cc: Kefeng Wang 
Cc: Liam R. Howlett 
Cc: "Masami Hiramatsu (Google)" 
Cc: Mathieu Desnoyers 
Cc: Matthew Brost 
Cc: Matthew Wilcox (Oracle) 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Nanyong Sun 
Cc: Pedro Falcato 
Cc: Peter Xu 
Cc: Rafael Aquini 
Cc: Rakie Kim 
Cc: Randy Dunlap 
Cc: Ryan Roberts 
Cc: Shivank Garg 
Cc: Steven Rostedt 
Cc: Suren Baghdasaryan 
Cc: Takashi Iwai (SUSE) 
Cc: Thomas Hellström 
Cc: Usama Arif 
Cc: Vishal Moola (Oracle) 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Cc: Yang Shi 
Cc: Zach O'Keefe 
Signed-off-by: Andrew Morton