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Author SHA1 Message Date
Lorenzo Stoakes (ARM)
5f653f8b7a mm/migrate: calculate large folio page index using PFN 
Rather than having to figure out the page index to use using
linear_page_index(), calculate it using PFN.

This is a more natural fit as the linear page index is immaterial to
determining the folio page index.

Derive the page index from the offset between migration entry PFN and
folio PFN - pvmw.pfn (set via DEFINE_FOLIO_VMA_WALK() which uses
folio_pfn() to obtain it).

Additionally remove a not so useful comment and clean the code layout up.

No functional change intended.

Link: https://lore.kernel.org/20260813-b4-scalable-cow-virt-pgoff-v5-13-c21581c0c3c8@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price (Meta) <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang Ray <Ray.Huang@amd.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-24 18:42:53 -07:00
Lorenzo Stoakes (ARM)
8e658ecc3b mm/huge_memory: update remove_migration_pmd() to accept a folio 
This function does not need to accept a page and requiring it to is
unnecessary and misleading.

make_[writable, readable]_device_private_entry() must be passed a
PMD-aligned PFN as they immediately used to obtain a softleaf PMD entry
and the same argument applies to folio_add_[anon, file]_rmap_pmd().

While we are here, update a VM_BUG_ON() to a VM_WARN_ON_ONCE().

No functional change intended.

Link: https://lore.kernel.org/20260813-b4-scalable-cow-virt-pgoff-v5-12-c21581c0c3c8@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price (Meta) <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang Ray <Ray.Huang@amd.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-24 18:42:52 -07:00
Breno Leitao
efe8f86c09 mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch() 
migrate_pages_batch() unmaps each folio before moving it, and every
unmap runs the mmu_notifier invalidate callbacks.  On KVM hosts
try_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() ->
tdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps
the CPU busy for a long time.

The loop already calls cond_resched(), but on PREEMPTION kernels that is
a no-op, and involuntary preemption is not a Tasks-RCU quiescent state.

A long batch therefore never reports a quiescent state, and the
migrating task (e.g. kcompactd) becomes a Tasks-RCU holdout, stalling the
Tasks-RCU grace period for minutes, which is common at Meta fleet:

  INFO: rcu_tasks detected stalls on tasks:
  0000000055349ecc: .. nvcsw: 1157401/1157401 holdout: 1 idle_cpu: -1/56 task:kcompactd0      state:R  running task
  Call Trace:
   tdp_mmu_zap_leafs
   tdp_mmu_next_root
   gfn_to_pfn_cache_invalidate_start
   kvm_mmu_notifier_invalidate_range_start
   __mmu_notifier_invalidate_range_start
   try_to_migrate_one
   try_to_migrate
   migrate_pages_batch
   migrate_pages
   compact_zone
   compact_node
   kcompactd
   kthread

Use cond_resched_tasks_rcu_qs() so a quiescent state is reported even
when cond_resched() does nothing.

This has also been discussed at [1]

Link: https://lore.kernel.org/20260727-kcompact-v1-1-bdfefddd6874@debian.org
Link: https://lore.kernel.org/all/amdWVTs0WKOxguxP@gmail.com/ [1]
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-06 18:57:25 -07:00
Kiryl Shutsemau (Meta)
763f43865f mm: preserve RWP marker across PTE rewrites 
The uffd PTE bit must survive any kernel path that rewrites a PTE on a
VM_UFFD_RWP VMA, otherwise the marker that carries PAGE_NONE semantics is
silently dropped and the next access leaks past RWP tracking.  Wire the
preservation through every path that rewrites a VM_UFFD_RWP PTE.

Swap and device-exclusive: do_swap_page(), restore_exclusive_pte(), and
unuse_pte() (swapoff()) re-apply PAGE_NONE when the swap PTE carries the
uffd bit and the VMA has VM_UFFD_RWP.

Migration: remove_migration_pte() and remove_migration_pmd() do the same
after the migration entry is replaced with a real PTE/PMD.

Fork: __copy_present_ptes(), copy_present_page(), copy_nonpresent_pte(),
copy_huge_pmd(), copy_huge_non_present_pmd(), and
copy_hugetlb_page_range() keep the uffd bit on the child when the
destination VMA has VM_UFFD_RWP, matching the existing VM_UFFD_WP
handling.  Add VM_UFFD_RWP to VM_COPY_ON_FORK so the flag itself
propagates.

mprotect(): change_pte_range() and change_huge_pmd() restore PAGE_NONE
after pte_modify()/pmd_modify() have recomputed the base protection from a
(possibly user-changed) vm_page_prot.  pte_modify() preserves _PAGE_UFFD,
so the bit stays; we just have to force PAGE_NONE back on top.

Link: https://lore.kernel.org/20260708111417.173443-8-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:37 -07:00
Kiryl Shutsemau (Meta)
c0ffe79eed mm: rename uffd-wp PTE accessors to uffd 
Userfaultfd RWP will reuse the uffd-wp PTE bit to mark access-tracking
PTEs, alongside the write-protected ones it already marks.  The bit's
meaning now depends on the VMA flag (WP or RWP), not on its name.

Rename the kernel-internal names that describe the bit:

  - pte/pmd/huge_pte accessors (and swap variants)
  - pgtable_supports_uffd() capability query
  - SCAN_PTE_UFFD khugepaged enum

The ftrace string emitted by mm_khugepaged_scan_pmd for this enum is
kept as "pte_uffd_wp" so existing trace-based tooling keeps matching.

Pure mechanical rename -- no behavior change.

Link: https://lore.kernel.org/20260708111417.173443-4-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:36 -07:00
Andrew Morton
330f108fd3 Merge branch 'mm-hotfixes-stable' into mm-stable in order to pick up 
vmscan.c changes which are required by "memcg: bail out proactive reclaim
when memcg is dying".
 2026-08-04 19:15:12 -07:00
Dev Jain
ac1ec50d71 mm/migrate: use huge_ptep_get() in remove_migration_pte() 
remove_migration_pte() converts migration entries back to present PTEs
after folio migration completes.  For hugetlb folios,
page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in
pvmw.pte, but the code reads it with ptep_get().

On arches which provide their own huge_ptep_get() to dereference a huge
pte pointer, accessing via ptep_get() would cause pte_pfn(),
pte_present() etc to misbehave.

It is not clear whether this has a trivially visible effect to userspace.

Use huge_ptep_get() to dereference a huge pte pointer.

Link: https://lore.kernel.org/20260703114202.365553-5-dev.jain@arm.com
Fixes: 290408d4a2 ("hugetlb: hugepage migration core")
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Jun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-30 19:40:45 -07:00
Brendan Jackman
d0850de699 mm: split out internal page_alloc.h 
internal.h is a bit bloated, seems like time for a page_alloc.h.

Where it wasn't obvious, the heuristic for deciding what goes into this
new header was "does it support/correspond to a definition in
mm/page_alloc.c?"

Only need to include it from ~20 .c files out of ~150 so this does seem
like a genuine reduction in scopes, which is nice. And there's no
circular internal.h<->page_alloc.h dependency, so it seems worthwhile to
split this up before that inevitably emerges!

Link: https://lore.kernel.org/20260703-alloc-trylock-v5-4-c87b714e19d3@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Suggested-by: "David Hildenbrand (Arm)" <david@kernel.org>
Link: https://lore.kernel.org/all/41e92bab-6882-401a-8de9-154adbdcfb36@kernel.org/
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-30 19:40:41 -07:00
Usama Arif
d547b10017 mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES 
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 <usama.arif@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-30 19:40:25 -07:00
Shivank Garg
3dd5a633a0 mm/migrate: use migrate_info field instead of private 
Add an unsigned long migrate_info member to the struct folio union and use
it to store migration state (anon_vma pointer and FOLIO_WAS_* markers)
instead of using folio->private.  While at it, switch to bitwise OR.

No functional change.

[rdunlap@infradead.org: add missing kernel-doc for @migrate_info]
  Link: https://lore.kernel.org/20260717022146.1290242-1-rdunlap@infradead.org
Link: https://lore.kernel.org/20260701-migrate-cleanups-prep-v2-3-d9e8f17130b1@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Huang Ying <ying.huang@linux.alibaba.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: SJ Park <sj@kernel.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-28 21:11:53 -07:00
Shivank Garg
8d76257715 mm/migrate: fix stale list name in migrate_folios_move() comment 
The return-value description in migrate_folios_move() still refers to
unmap_folios, but that list no longer exists.  Update this name to
src_folios.

Link: https://lore.kernel.org/20260701-migrate-cleanups-prep-v2-2-d9e8f17130b1@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-28 21:11:53 -07:00
Shivank Garg
9aaf5aa244 mm/migrate: rename page to folio leftovers 
Patch series "mm/migrate: preparatory cleanups for batch copy and
offload", v2.

This is a small set of mm/migrate cleanups split out of the batch-copy and
offload RFC [1], so they can be reviewed and merged independently ahead of
that larger series.

No functional change intended.


This patch (of 3):

Rename migrate_folio_undo_src()'s page_was_mapped parameter to was_mapped,
unmap_and_move_huge_page() to unmap_and_move_hugetlb_folio(), its
page_was_mapped variable to was_mapped and fix stale "page" wording in its
comments.

Also fix migrate_folio() kerneldoc to say "folio" instead of "page".

Link: https://lore.kernel.org/20260701-migrate-cleanups-prep-v2-0-d9e8f17130b1@amd.com
Link: https://lore.kernel.org/20260701-migrate-cleanups-prep-v2-1-d9e8f17130b1@amd.com
Link: https://lore.kernel.org/all/20260428155043.39251-2-shivankg@amd.com [1]
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: Dev Jain <dev.jain@arm.com>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-28 21:11:53 -07:00
Ye Liu
c95dc0a84b mm: use enum migrate_reason instead of int for migration reason parameters 
Replace all 'int reason' function parameters that carry migrate_reason
values with the proper 'enum migrate_reason' type.  This makes the intent
explicit and leverages compiler type checking.  The affected subsystems
are:

  - page_owner: __folio_set_owner_migrate_reason(),
                folio_set_owner_migrate_reason()
  - migrate: migrate_pages(), migrate_pages_sync(),
             migrate_pages_batch(), migrate_folios_move(),
             migrate_hugetlbs(), unmap_and_move_huge_page()
  - hugetlb: move_hugetlb_state(), htlb_allow_alloc_fallback()
  - trace: mm_migrate_pages and mm_migrate_pages_start events

The 'short last_migrate_reason' struct field and internal helper parameter
in page_owner are intentionally left as 'short' since they store per-page
metadata where size matters.

No functional change.

Link: https://lore.kernel.org/20260714015117.78351-4-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-28 21:11:50 -07:00
Nico Pache
d09a8fd521 mm/migrate: exclude hugetlb folios from MTHP_STAT_NR_ANON accounting 
__folio_migrate_mapping() increments MTHP_STAT_NR_ANON for the destination
folio when `folio_test_anon(folio) && folio_test_large(folio)` is true. 
However, hugetlb folios satisfy both conditions despite having a
completely separate accounting system — they use hugetlb_add_anon_rmap()
which does not touch mTHP stats, and their free path also bypasses the
mTHP decrement in __free_pages_prepare().

This causes MTHP_STAT_NR_ANON to be incremented on each hugetlb migration
without a corresponding decrement, permanently inflating the nr_anon
counter.

Add a !folio_test_hugetlb() check to __folio_migrate_mapping() so that
only actual mTHP folios are counted.

Link: https://lore.kernel.org/20260717064502.1980173-3-npache@redhat.com
Fixes: 5d65c8d758 ("mm: count the number of anonymous THPs per size")
Co-developed-by: David Hildenbrand <david@kernel.org>
Signed-off-by: David Hildenbrand <david@kernel.org>
Signed-off-by: Nico Pache <npache@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-07-28 17:37:31 -07:00
Oleg Nesterov
13f77972b9 mm/migrate: find_mm_struct: fix race between security checks and suid exec 
The target task can execute a setuid binary between ptrace_may_access()
and get_task_mm().  Protect this critical section with exec_update_lock.

I don't think cpuset_mems_allowed(task) should be called under
exec_update_lock, but this patch just tries to add the minimal fix.

Perhaps we can later add a common helper which can be used by
find_mm_struct() and kernel_migrate_pages().

Link: https://lore.kernel.org/ahWxQ3JxdR5ff2qf@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-06-04 14:45:08 -07:00
Matthew Wilcox (Oracle)
088a2353d7 mm: remove mentions of PageWriteback 
Update two comments to refer to writeback in general instead of the
specific flag.  Convert the large comment in memory.c to be entirely
folio-based.

Link: https://lore.kernel.org/20260526195650.353196-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-06-04 14:45:07 -07:00
Shivank Garg
d94d0f9c15 mm/migrate: rename PAGE_ migration flags to FOLIO_ 
These flags only track folio-specific state during migration and are not
used for movable_ops pages.  Rename the enum values and the old_page_state
variable to match.

No functional change.

Link: https://lore.kernel.org/20260324190706.964555-4-shivankg@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: David Hildenbrand <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Huang Ying <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-05-28 21:05:00 -07:00
Muchun Song
5305089080 mm: migrate: prevent memory cgroup release in folio_migrate_mapping() 
In the near future, a folio will no longer pin its corresponding memory
cgroup.  To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.

In __folio_migrate_mapping(), the rcu read lock is employed to safeguard
against the release of the memory cgroup in folio_migrate_mapping().

This serves as a preparatory measure for the reparenting of the LRU pages.

Link: https://lore.kernel.org/0f156c2f1188f256855617953f8305f43e066065.1772711148.git.zhengqi.arch@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yosry Ahmed <yosry@kernel.org>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-04-18 00:10:45 -07:00
Lance Yang
3bac011689 mm: fix deferred split queue races during migration 
migrate_folio_move() records the deferred split queue state from src and
replays it on dst.  Replaying it after remove_migration_ptes(src, dst, 0)
makes dst visible before it is requeued, so a concurrent rmap-removal path
can mark dst partially mapped and trip the WARN in deferred_split_folio().

Move the requeue before remove_migration_ptes() so dst is back on the
deferred split queue before it becomes visible again.

Because migration still holds dst locked at that point, teach
deferred_split_scan() to requeue a folio when folio_trylock() fails. 
Otherwise a fully mapped underused folio can be dequeued by the shrinker
and silently lost from split_queue.

[ziy@nvidia.com: move the comment]
  Link: https://lkml.kernel.org/r/FB71A764-0F10-4E5A-B4A0-BA4C7F138408@nvidia.com
Link: https://syzkaller.appspot.com/bug?extid=a7067a757858ac8eb085
Link: https://lkml.kernel.org/r/20260401131032.13011-1-lance.yang@linux.dev
Fixes: 8a8ca142a488 ("mm: migrate: requeue destination folio on deferred split queue")
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: syzbot+a7067a757858ac8eb085@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-mm/69ccb65b.050a0220.183828.003a.GAE@google.com/
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-04-05 13:53:47 -07:00
David Hildenbrand (Arm)
6ebf98d71f mm: introduce CONFIG_NUMA_MIGRATION and simplify CONFIG_MIGRATION 
CONFIG_MEMORY_HOTREMOVE, CONFIG_COMPACTION and CONFIG_CMA all select
CONFIG_MIGRATION, because they require it to work (users).

Only CONFIG_NUMA_BALANCING and CONFIG_BALLOON_MIGRATION depend on
CONFIG_MIGRATION.  CONFIG_BALLOON_MIGRATION is not an actual user, but an
implementation of migration support, so the dependency is correct
(CONFIG_BALLOON_MIGRATION does not make any sense without
CONFIG_MIGRATION).

However, kconfig-language.rst clearly states "In general use select only
for non-visible symbols".  So far CONFIG_MIGRATION is user-visible ... 
and the dependencies rather confusing.

The whole reason why CONFIG_MIGRATION is user-visible is because of
CONFIG_NUMA: some users might want CONFIG_NUMA but not page migration
support.

Let's clean all that up by introducing a dedicated CONFIG_NUMA_MIGRATION
config option for that purpose only.  Make CONFIG_NUMA_BALANCING that so
far depended on CONFIG_NUMA && CONFIG_MIGRATION to depend on
CONFIG_MIGRATION instead.  CONFIG_NUMA_MIGRATION will depend on
CONFIG_NUMA && CONFIG_MMU.

CONFIG_NUMA_MIGRATION is user-visible and will default to "y".  We use
that default so new configs will automatically enable it, just like it was
the case with CONFIG_MIGRATION.  The downside is that some configs that
used to have CONFIG_MIGRATION=n might get it re-enabled by
CONFIG_NUMA_MIGRATION=y, which shouldn't be a problem.

CONFIG_MIGRATION is now a non-visible config option.  Any code that select
CONFIG_MIGRATION (as before) must depend directly or indirectly on
CONFIG_MMU.

CONFIG_NUMA_MIGRATION is responsible for any NUMA migration code, which is
mempolicy migration code, memory-tiering code, and move_pages() code in
migrate.c.  CONFIG_NUMA_BALANCING uses its functionality.

Note that this implies that with CONFIG_NUMA_MIGRATION=n, move_pages()
will not be available even though CONFIG_MIGRATION=y, which is an expected
change.

In migrate.c, we can remove the CONFIG_NUMA check as both
CONFIG_NUMA_MIGRATION and CONFIG_NUMA_BALANCING depend on it.

With this change, CONFIG_MIGRATION is an internal config, all users of
migration selects CONFIG_MIGRATION, and only CONFIG_BALLOON_MIGRATION
depends on it.

Link: https://lkml.kernel.org/r/20260319-config_migration-v1-2-42270124966f@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-04-05 13:53:33 -07:00
Usama Arif
a2e0c0668a mm: migrate: requeue destination folio on deferred split queue 
During folio migration, __folio_migrate_mapping() removes the source folio
from the deferred split queue, but the destination folio is never
re-queued.  This causes underutilized THPs to escape the shrinker after
NUMA migration, since they silently drop off the deferred split list.

Fix this by recording whether the source folio was on the deferred split
queue and its partially mapped state before move_to_new_folio() unqueues
it, and re-queuing the destination folio after a successful migration if
it was.

By the time migrate_folio_move() runs, partially mapped folios without a
pin have already been split by migrate_pages_batch().  So only two cases
remain on the deferred list at this point:
  1. Partially mapped folios with a pin (split failed).
  2. Fully mapped but potentially underused folios.  The recorded
     partially_mapped state is forwarded to deferred_split_folio() so that
     the destination folio is correctly re-queued in both cases.

Because THPs are removed from the deferred_list, THP shinker cannot
split the underutilized THPs in time.  As a result, users will show
less free memory than before.  

Link: https://lkml.kernel.org/r/20260312104723.1351321-1-usama.arif@linux.dev
Fixes: dafff3f4c8 ("mm: split underused THPs")
Signed-off-by: Usama Arif <usama.arif@linux.dev>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-04-05 13:53:27 -07:00
Mike Rapoport (Microsoft)
9a1d0c738b mm: rename my_zero_pfn() to zero_pfn() 
my_zero_pfn() is a silly name.

Rename zero_pfn variable to zero_page_pfn and my_zero_pfn() function to
zero_pfn().

While on it, move extern declarations of zero_page_pfn outside the
functions that use it and add a comment about what ZERO_PAGE is.

Link: https://lkml.kernel.org/r/20260211103141.3215197-3-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-04-05 13:53:01 -07:00
Thomas Hellström
b570f37a2c
mm: Fix a hmm_range_fault() livelock / starvation problem 
If hmm_range_fault() fails a folio_trylock() in do_swap_page,
trying to acquire the lock of a device-private folio for migration,
to ram, the function will spin until it succeeds grabbing the lock.

However, if the process holding the lock is depending on a work
item to be completed, which is scheduled on the same CPU as the
spinning hmm_range_fault(), that work item might be starved and
we end up in a livelock / starvation situation which is never
resolved.

This can happen, for example if the process holding the
device-private folio lock is stuck in
   migrate_device_unmap()->lru_add_drain_all()
sinc lru_add_drain_all() requires a short work-item
to be run on all online cpus to complete.

A prerequisite for this to happen is:
a) Both zone device and system memory folios are considered in
   migrate_device_unmap(), so that there is a reason to call
   lru_add_drain_all() for a system memory folio while a
   folio lock is held on a zone device folio.
b) The zone device folio has an initial mapcount > 1 which causes
   at least one migration PTE entry insertion to be deferred to
   try_to_migrate(), which can happen after the call to
   lru_add_drain_all().
c) No or voluntary only preemption.

This all seems pretty unlikely to happen, but indeed is hit by
the "xe_exec_system_allocator" igt test.

Resolve this by waiting for the folio to be unlocked if the
folio_trylock() fails in do_swap_page().

Rename migration_entry_wait_on_locked() to
softleaf_entry_wait_unlock() and update its documentation to
indicate the new use-case.

Future code improvements might consider moving
the lru_add_drain_all() call in migrate_device_unmap() to be
called *after* all pages have migration entries inserted.
That would eliminate also b) above.

v2:
- Instead of a cond_resched() in hmm_range_fault(),
  eliminate the problem by waiting for the folio to be unlocked
  in do_swap_page() (Alistair Popple, Andrew Morton)
v3:
- Add a stub migration_entry_wait_on_locked() for the
  !CONFIG_MIGRATION case. (Kernel Test Robot)
v4:
- Rename migrate_entry_wait_on_locked() to
  softleaf_entry_wait_on_locked() and update docs (Alistair Popple)
v5:
- Add a WARN_ON_ONCE() for the !CONFIG_MIGRATION
  version of softleaf_entry_wait_on_locked().
- Modify wording around function names in the commit message
  (Andrew Morton)

Suggested-by: Alistair Popple <apopple@nvidia.com>
Fixes: 1afaeb8293 ("mm/migrate: Trylock device page in do_swap_page")
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: linux-mm@kvack.org
Cc: <dri-devel@lists.freedesktop.org>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.15+
Reviewed-by: John Hubbard <jhubbard@nvidia.com> #v3
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://patch.msgid.link/20260210115653.92413-1-thomas.hellstrom@linux.intel.com
(cherry picked from commit a69d1ab971)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
 2026-03-02 11:51:51 -05:00
David Hildenbrand (Red Hat)
cd8e95d80b mm: rename CONFIG_BALLOON_COMPACTION to CONFIG_BALLOON_MIGRATION 
While compaction depends on migration, the other direction is not the
case.  So let's make it clearer that this is all about migration of
balloon pages.

Adjust all comments/docs in the core to talk about "migration" instead of
"compaction".

While at it add some "/* CONFIG_BALLOON_MIGRATION */".

Link: https://lkml.kernel.org/r/20260119230133.3551867-23-david@kernel.org
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pérez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-01-31 14:22:36 -08:00
Matthew Wilcox (Oracle)
832d95b531 migrate: replace RMP_ flags with TTU_ flags 
Instead of translating between RMP_ and TTU_ flags, remove the RMP_ flags
and just use the TTU_ flag space; there's plenty available.

Possibly we should rename these to RMAP_ flags, and maybe even pass them
in through rmap_walk_arg, but that can be done later.

Link: https://lkml.kernel.org/r/20260109041345.3863089-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-01-26 20:02:33 -08:00
Matthew Wilcox (Oracle)
b7880cb166 migrate: correct lock ordering for hugetlb file folios 
Syzbot has found a deadlock (analyzed by Lance Yang):

1) Task (5749): Holds folio_lock, then tries to acquire i_mmap_rwsem(read lock).
2) Task (5754): Holds i_mmap_rwsem(write lock), then tries to acquire
folio_lock.

migrate_pages()
  -> migrate_hugetlbs()
    -> unmap_and_move_huge_page()     <- Takes folio_lock!
      -> remove_migration_ptes()
        -> __rmap_walk_file()
          -> i_mmap_lock_read()       <- Waits for i_mmap_rwsem(read lock)!

hugetlbfs_fallocate()
  -> hugetlbfs_punch_hole()           <- Takes i_mmap_rwsem(write lock)!
    -> hugetlbfs_zero_partial_page()
     -> filemap_lock_hugetlb_folio()
      -> filemap_lock_folio()
        -> __filemap_get_folio        <- Waits for folio_lock!

The migration path is the one taking locks in the wrong order according to
the documentation at the top of mm/rmap.c.  So expand the scope of the
existing i_mmap_lock to cover the calls to remove_migration_ptes() too.

This is (mostly) how it used to be after commit c0d0381ade.  That was
removed by 336bf30eb7 for both file & anon hugetlb pages when it should
only have been removed for anon hugetlb pages.

Link: https://lkml.kernel.org/r/20260109041345.3863089-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Fixes: 336bf30eb7 ("hugetlbfs: fix anon huge page migration race")
Reported-by: syzbot+2d9c96466c978346b55f@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/68e9715a.050a0220.1186a4.000d.GAE@google.com
Debugged-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-01-19 12:30:01 -08:00
Shakeel Butt
5b3eb779a2 memcg: remove __mod_lruvec_state 
__mod_lruvec_state() is already safe against irqs, so there is no need to
have a separate interface (i.e.  mod_lruvec_state) which wraps calls to it
with irq disabling and reenabling.  Let's rename __mod_lruvec_state() to
mod_lruvec_state().

Link: https://lkml.kernel.org/r/20251110232008.1352063-4-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:54 -08:00
Lorenzo Stoakes
a3a3e215c9 mm: replace remaining pte_to_swp_entry() with softleaf_from_pte() 
There are straggler invocations of pte_to_swp_entry() lying around,
replace all of these with the software leaf entry equivalent -
softleaf_from_pte().

With those removed, eliminate pte_to_swp_entry() altogether.

No functional change intended.

Link: https://lkml.kernel.org/r/d8ee5ccefe4c42d7c4fe1a2e46f285ac40421cd3.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:52 -08:00
Lorenzo Stoakes
93976a2034 mm: eliminate further swapops predicates 
Having converted so much of the code base to software leaf entries, we can
mop up some remaining cases.

We replace is_pfn_swap_entry(), pfn_swap_entry_to_page(),
is_writable_device_private_entry(), is_device_exclusive_entry(),
is_migration_entry(), is_writable_migration_entry(),
is_readable_migration_entry(), swp_offset_pfn() and pfn_swap_entry_folio()
with softleaf equivalents.

No functional change intended.

Link: https://lkml.kernel.org/r/956bc9c031604811c0070d2f4bf2f1373f230213.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:52 -08:00
Lorenzo Stoakes
03bfbc3ad6 mm: remove is_hugetlb_entry_[migration, hwpoisoned]() 
We do not need to have explicit helper functions for these, it adds a
level of confusion and indirection when we can simply use software leaf
entry logic here instead and spell out the special huge_pte_none() case we
must consider.

No functional change intended.

Link: https://lkml.kernel.org/r/0e92d6924d3de88cd014ce1c53e20edc08fc152e.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:51 -08:00
Lorenzo Stoakes
0ac881efe1 mm: replace pmd_to_swp_entry() with softleaf_from_pmd() 
Introduce softleaf_from_pmd() to do the equivalent operation for PMDs that
softleaf_from_pte() fulfils, and cascade changes through code base
accordingly, introducing helpers as necessary.

We are then able to eliminate pmd_to_swp_entry(),
is_pmd_migration_entry(), is_pmd_device_private_entry() and
is_pmd_non_present_folio_entry().

This further establishes the use of leaf operations throughout the code
base and further establishes the foundations for eliminating
is_swap_pmd().

No functional change intended.

[lorenzo.stoakes@oracle.com: check writable, not readable/writable, per Vlastimil]
  Link: https://lkml.kernel.org/r/cd97b6ec-00f9-45a4-9ae0-8f009c212a94@lucifer.local
Link: https://lkml.kernel.org/r/3fb431699639ded8fdc63d2210aa77a38c8891f1.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: SeongJae Park <sj@kernel.org>\
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:51 -08:00
Lorenzo Stoakes
fb888710e2 mm: avoid unnecessary uses of is_swap_pte() 
There's an established convention in the kernel that we treat PTEs as
containing swap entries (and the unfortunately named non-swap swap
entries) should they be neither empty (i.e.  pte_none() evaluating true)
nor present (i.e.  pte_present() evaluating true).

However, there is some inconsistency in how this is applied, as we also
have the is_swap_pte() helper which explicitly performs this check:

	/* check whether a pte points to a swap entry */
	static inline int is_swap_pte(pte_t pte)
	{
		return !pte_none(pte) && !pte_present(pte);
	}

As this represents a predicate, and it's logical to assume that in order
to establish that a PTE entry can correctly be manipulated as a
swap/non-swap entry, this predicate seems as if it must first be checked.

But we instead, we far more often utilise the established convention of
checking pte_none() / pte_present() before operating on entries as if they
were swap/non-swap.

This patch works towards correcting this inconsistency by removing all
uses of is_swap_pte() where we are already in a position where we perform
pte_none()/pte_present() checks anyway or otherwise it is clearly logical
to do so.

We also take advantage of the fact that pte_swp_uffd_wp() is only set on
swap entries.

Additionally, update comments referencing to is_swap_pte() and
non_swap_entry().

No functional change intended.

Link: https://lkml.kernel.org/r/17fd6d7f46a846517fd455fadd640af47fcd7c55.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:50 -08:00
Balbir Singh
1462872900 mm/huge_memory: implement device-private THP splitting 
Add support for splitting device-private THP folios, enabling fallback
to smaller page sizes when large page allocation or migration fails.

Key changes:
- split_huge_pmd(): Handle device-private PMD entries during splitting
- Preserve RMAP_EXCLUSIVE semantics for anonymous exclusive folios
- Skip RMP_USE_SHARED_ZEROPAGE for device-private entries as they
  don't support shared zero page semantics

Link: https://lkml.kernel.org/r/20251001065707.920170-6-balbirs@nvidia.com
Signed-off-by: Balbir Singh <balbirs@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Mika Penttilä <mpenttil@redhat.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-24 15:08:48 -08:00
Matthew Wilcox (Oracle)
c537f0dd30 migrate: optimise alloc_migration_target() 
Extract the zone number directly from the folio instead of using the
folio's zone number to look up the zone and asking the zone what its
number is.

[ziy@nvidia.com: fix folio_zonenum() return type]
  Link: https://lkml.kernel.org/r/26E8FF35-503E-4F14-98F7-7B4FA25FBD37@nvidia.com
Link: https://lkml.kernel.org/r/20251106201452.2292631-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-20 13:43:57 -08:00
Kairui Song
ab61de9b78 mm/migrate, swap: drop usage of folio_index 
This helper was used when swap cache was mixed with page cache.  Now they
are completely separate from each other, access to the swap cache is all
wrapped by the swap_cache_* helpers, which expect the folio's swap entry
as a parameter.

This helper is no longer used, remove the last redundant user and drop it.

Link: https://lkml.kernel.org/r/20251024-swap-clean-after-swap-table-p1-v2-4-a709469052e7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-16 17:28:20 -08:00
Qiuxu Zhuo
841a8bfcba mm: prevent poison consumption when splitting THP 
When performing memory error injection on a THP (Transparent Huge Page)
mapped to userspace on an x86 server, the kernel panics with the following
trace.  The expected behavior is to terminate the affected process instead
of panicking the kernel, as the x86 Machine Check code can recover from an
in-userspace #MC.

  mce: [Hardware Error]: CPU 0: Machine Check Exception: f Bank 3: bd80000000070134
  mce: [Hardware Error]: RIP 10:<ffffffff8372f8bc> {memchr_inv+0x4c/0xf0}
  mce: [Hardware Error]: TSC afff7bbff88a ADDR 1d301b000 MISC 80 PPIN 1e741e77539027db
  mce: [Hardware Error]: PROCESSOR 0:d06d0 TIME 1758093249 SOCKET 0 APIC 0 microcode 80000320
  mce: [Hardware Error]: Run the above through 'mcelog --ascii'
  mce: [Hardware Error]: Machine check: Data load in unrecoverable area of kernel
  Kernel panic - not syncing: Fatal local machine check

The root cause of this panic is that handling a memory failure triggered
by an in-userspace #MC necessitates splitting the THP.  The splitting
process employs a mechanism, implemented in
try_to_map_unused_to_zeropage(), which reads the pages in the THP to
identify zero-filled pages.  However, reading the pages in the THP results
in a second in-kernel #MC, occurring before the initial memory_failure()
completes, ultimately leading to a kernel panic.  See the kernel panic
call trace on the two #MCs.

  First Machine Check occurs // [1]
    memory_failure()         // [2]
      try_to_split_thp_page()
        split_huge_page()
          split_huge_page_to_list_to_order()
            __folio_split()  // [3]
              remap_page()
                remove_migration_ptes()
                  remove_migration_pte()
                    try_to_map_unused_to_zeropage()  // [4]
                      memchr_inv()                   // [5]
                        Second Machine Check occurs  // [6]
                          Kernel panic

[1] Triggered by accessing a hardware-poisoned THP in userspace, which is
    typically recoverable by terminating the affected process.

[2] Call folio_set_has_hwpoisoned() before try_to_split_thp_page().

[3] Pass the RMP_USE_SHARED_ZEROPAGE remap flag to remap_page().

[4] Try to map the unused THP to zeropage.

[5] Re-access pages in the hw-poisoned THP in the kernel.

[6] Triggered in-kernel, leading to a panic kernel.

In Step[2], memory_failure() sets the poisoned flag on the page in the THP
by TestSetPageHWPoison() before calling try_to_split_thp_page().

As suggested by David Hildenbrand, fix this panic by not accessing to the
poisoned page in the THP during zeropage identification, while continuing
to scan unaffected pages in the THP for possible zeropage mapping.  This
prevents a second in-kernel #MC that would cause kernel panic in Step[4].

Thanks to Andrew Zaborowski for his initial work on fixing this issue.

Link: https://lkml.kernel.org/r/20251015064926.1887643-1-qiuxu.zhuo@intel.com
Link: https://lkml.kernel.org/r/20251011075520.320862-1-qiuxu.zhuo@intel.com
Fixes: b1f202060a ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Reported-by: Farrah Chen <farrah.chen@intel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Farrah Chen <farrah.chen@intel.com>
Tested-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Acked-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-10-15 13:24:34 -07:00
Lance Yang
9658d698a8 mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage 
When splitting an mTHP and replacing a zero-filled subpage with the shared
zeropage, try_to_map_unused_to_zeropage() currently drops several
important PTE bits.

For userspace tools like CRIU, which rely on the soft-dirty mechanism for
incremental snapshots, losing the soft-dirty bit means modified pages are
missed, leading to inconsistent memory state after restore.

As pointed out by David, the more critical uffd-wp bit is also dropped. 
This breaks the userfaultfd write-protection mechanism, causing writes to
be silently missed by monitoring applications, which can lead to data
corruption.

Preserve both the soft-dirty and uffd-wp bits from the old PTE when
creating the new zeropage mapping to ensure they are correctly tracked.

Link: https://lkml.kernel.org/r/20250930081040.80926-1-lance.yang@linux.dev
Fixes: b1f202060a ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-10-07 14:01:11 -07:00
Lance Yang
1ce6473d17 mm/thp: fix MTE tag mismatch when replacing zero-filled subpages 
When both THP and MTE are enabled, splitting a THP and replacing its
zero-filled subpages with the shared zeropage can cause MTE tag mismatch
faults in userspace.

Remapping zero-filled subpages to the shared zeropage is unsafe, as the
zeropage has a fixed tag of zero, which may not match the tag expected by
the userspace pointer.

KSM already avoids this problem by using memcmp_pages(), which on arm64
intentionally reports MTE-tagged pages as non-identical to prevent unsafe
merging.

As suggested by David[1], this patch adopts the same pattern, replacing the
memchr_inv() byte-level check with a call to pages_identical(). This
leverages existing architecture-specific logic to determine if a page is
truly identical to the shared zeropage.

Having both the THP shrinker and KSM rely on pages_identical() makes the
design more future-proof, IMO. Instead of handling quirks in generic code,
we just let the architecture decide what makes two pages identical.

[1] https://lore.kernel.org/all/ca2106a3-4bb2-4457-81af-301fd99fbef4@redhat.com

Link: https://lkml.kernel.org/r/20250922021458.68123-1-lance.yang@linux.dev
Fixes: b1f202060a ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Reported-by: Qun-wei Lin <Qun-wei.Lin@mediatek.com>
Closes: https://lore.kernel.org/all/a7944523fcc3634607691c35311a5d59d1a3f8d4.camel@mediatek.com
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: andrew.yang <andrew.yang@mediatek.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Samuel Holland <samuel.holland@sifive.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-10-07 14:01:11 -07:00
Kairui Song
8578e0c00d mm, swap: use the swap table for the swap cache and switch API 
Introduce basic swap table infrastructures, which are now just a
fixed-sized flat array inside each swap cluster, with access wrappers.

Each cluster contains a swap table of 512 entries.  Each table entry is an
opaque atomic long.  It could be in 3 types: a shadow type (XA_VALUE), a
folio type (pointer), or NULL.

In this first step, it only supports storing a folio or shadow, and it is
a drop-in replacement for the current swap cache.  Convert all swap cache
users to use the new sets of APIs.  Chris Li has been suggesting using a
new infrastructure for swap cache for better performance, and that idea
combined well with the swap table as the new backing structure.  Now the
lock contention range is reduced to 2M clusters, which is much smaller
than the 64M address_space.  And we can also drop the multiple
address_space design.

All the internal works are done with swap_cache_get_* helpers.  Swap cache
lookup is still lock-less like before, and the helper's contexts are same
with original swap cache helpers.  They still require a pin on the swap
device to prevent the backing data from being freed.

Swap cache updates are now protected by the swap cluster lock instead of
the XArray lock.  This is mostly handled internally, but new
__swap_cache_* helpers require the caller to lock the cluster.  So, a few
new cluster access and locking helpers are also introduced.

A fully cluster-based unified swap table can be implemented on top of this
to take care of all count tracking and synchronization work, with dynamic
allocation.  It should reduce the memory usage while making the
performance even better.

Link: https://lkml.kernel.org/r/20250916160100.31545-12-ryncsn@gmail.com
Co-developed-by: Chris Li <chrisl@kernel.org>
Signed-off-by: Chris Li <chrisl@kernel.org>
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-21 14:22:24 -07:00
Kairui Song
094dc8b059 mm, swap: wrap swap cache replacement with a helper 
There are currently three swap cache users that are trying to replace an
existing folio with a new one: huge memory splitting, migration, and shmem
replacement.  What they are doing is quite similar.

Introduce a common helper for this.  In later commits, this can be easily
switched to use the swap table by updating this helper.

The newly added helper also makes the swap cache API better defined, and
make debugging easier by adding a few more debug checks.

Migration and shmem replace are meant to clone the folio, including
content, swap entry value, and flags.  And splitting will adjust each sub
folio's swap entry according to order, which could be non-uniform in the
future.  So document it clearly that it's the caller's responsibility to
set up the new folio's swap entries and flags before calling the helper. 
The helper will just follow the new folio's entry value.

This also prepares for replacing high-order folios in the swap cache. 
Currently, only splitting to order 0 is allowed for swap cache folios. 
Using the new helper, we can handle high-order folio splitting better.

Link: https://lkml.kernel.org/r/20250916160100.31545-11-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Chris Li <chrisl@kernel.org>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-21 14:22:24 -07:00
David Hildenbrand
fb49a4425c treewide: remove MIGRATEPAGE_SUCCESS 
At this point MIGRATEPAGE_SUCCESS is misnamed for all folio users,
and now that we remove MIGRATEPAGE_UNMAP, it's really the only "success"
return value that the code uses and expects.

Let's just get rid of MIGRATEPAGE_SUCCESS completely and just use "0"
for success.

Link: https://lkml.kernel.org/r/20250811143949.1117439-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>			[mm]
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>	[jfs]
Acked-by: David Sterba <dsterba@suse.com>		[btrfs]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Byungchul Park <byungchul@sk.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:50 -07:00
David Hildenbrand
95c2908f1a mm/migrate: remove MIGRATEPAGE_UNMAP 
migrate_folio_unmap() is the only user of MIGRATEPAGE_UNMAP.  We want to
remove MIGRATEPAGE_* completely.

It's rather weird to have a generic MIGRATEPAGE_UNMAP, documented to be
returned from address-space callbacks, when it's only used for an internal
helper.

Let's start by having only a single "success" return value for
migrate_folio_unmap() -- 0 -- by moving the "folio was already freed"
check into the single caller.

There is a remaining comment for PG_isolated, which we renamed to
PG_movable_ops_isolated recently and forgot to update.

While we might still run into that case with zsmalloc, it's something we
want to get rid of soon.  So let's just focus that optimization on real
folios only for now by excluding movable_ops pages.  Note that concurrent
freeing can happen at any time and this "already freed" check is not
relevant for correctness.

[david@redhat.com: no need to pass "reason" to migrate_folio_unmap(), per Lance]
  Link: https://lkml.kernel.org/r/3bb725f8-28d7-4aa2-b75f-af40d5cab280@redhat.com
Link: https://lkml.kernel.org/r/20250811143949.1117439-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-09-13 16:54:50 -07:00
Huacai Chen
053c8ebe74 mm/migrate: fix NULL movable_ops if CONFIG_ZSMALLOC=m 
After commit 84caf98838 ("mm: stop storing migration_ops in
page->mapping") we get such an error message if CONFIG_ZSMALLOC=m:

 WARNING: CPU: 3 PID: 42 at mm/migrate.c:142 isolate_movable_ops_page+0xa8/0x1c0
 CPU: 3 UID: 0 PID: 42 Comm: kcompactd0 Not tainted 6.16.0-rc5+ #2133 PREEMPT
 pc 9000000000540bd8 ra 9000000000540b84 tp 9000000100420000 sp 9000000100423a60
 a0 9000000100193a80 a1 000000000000000c a2 000000000000001b a3 ffffffffffffffff
 a4 ffffffffffffffff a5 0000000000000267 a6 0000000000000000 a7 9000000100423ae0
 t0 00000000000000f1 t1 00000000000000f6 t2 0000000000000000 t3 0000000000000001
 t4 ffffff00010eb834 t5 0000000000000040 t6 900000010c89d380 t7 90000000023fcc70
 t8 0000000000000018 u0 0000000000000000 s9 ffffff00010eb800 s0 ffffff00010eb800
 s1 000000000000000c s2 0000000000043ae0 s3 0000800000000000 s4 900000000219cc40
 s5 0000000000000000 s6 ffffff00010eb800 s7 0000000000000001 s8 90000000025b4000
    ra: 9000000000540b84 isolate_movable_ops_page+0x54/0x1c0
   ERA: 9000000000540bd8 isolate_movable_ops_page+0xa8/0x1c0
  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
  PRMD: 00000004 (PPLV0 +PIE -PWE)
  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
  ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)
 ESTAT: 000c0000 [BRK] (IS= ECode=12 EsubCode=0)
  PRID: 0014c010 (Loongson-64bit, Loongson-3A5000)
 CPU: 3 UID: 0 PID: 42 Comm: kcompactd0 Not tainted 6.16.0-rc5+ #2133 PREEMPT
 Stack : 90000000021fd000 0000000000000000 9000000000247720 9000000100420000
         90000001004236a0 90000001004236a8 0000000000000000 90000001004237e8
         90000001004237e0 90000001004237e0 9000000100423550 0000000000000001
         0000000000000001 90000001004236a8 725a84864a19e2d9 90000000023fcc58
         9000000100420000 90000000024c6848 9000000002416848 0000000000000001
         0000000000000000 000000000000000a 0000000007fe0000 ffffff00010eb800
         0000000000000000 90000000021fd000 0000000000000000 900000000205cf30
         000000000000008e 0000000000000009 ffffff00010eb800 0000000000000001
         90000000025b4000 0000000000000000 900000000024773c 00007ffff103d748
         00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d
         ...
 Call Trace:
 [<900000000024773c>] show_stack+0x5c/0x190
 [<90000000002415e0>] dump_stack_lvl+0x70/0x9c
 [<90000000004abe6c>] isolate_migratepages_block+0x3bc/0x16e0
 [<90000000004af408>] compact_zone+0x558/0x1000
 [<90000000004b0068>] compact_node+0xa8/0x1e0
 [<90000000004b0aa4>] kcompactd+0x394/0x410
 [<90000000002b3c98>] kthread+0x128/0x140
 [<9000000001779148>] ret_from_kernel_thread+0x28/0xc0
 [<9000000000245528>] ret_from_kernel_thread_asm+0x10/0x88

The reason is that defined(CONFIG_ZSMALLOC) evaluates to 1 only when
CONFIG_ZSMALLOC=y, we should use IS_ENABLED(CONFIG_ZSMALLOC) instead.  But
when I use IS_ENABLED(CONFIG_ZSMALLOC), page_movable_ops() cannot access
zsmalloc_mops because zsmalloc_mops is in a module.

To solve this problem, we define a set_movable_ops() interface to register
and unregister offline_movable_ops / zsmalloc_movable_ops in mm/migrate.c,
and call them at mm/balloon_compaction.c & mm/zsmalloc.c.  Since
offline_movable_ops / zsmalloc_movable_ops are always accessible, all
#ifdef / #endif are removed in page_movable_ops().

Link: https://lkml.kernel.org/r/20250817151759.2525174-1-chenhuacai@loongson.cn
Fixes: 84caf98838 ("mm: stop storing migration_ops in page->mapping")
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-08-19 16:35:57 -07:00
Sidhartha Kumar
9989db9f23 mm/page_owner: convert set_page_owner_migrate_reason() to folios 
Both callers of set_page_owner_migrate_reason() use folios.  Convert the
function to take a folio directly and move the &folio->page conversion
inside __set_page_owner_migrate_reason().

Link: https://lkml.kernel.org/r/20250711145910.90135-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-19 18:59:57 -07:00
Wei Yang
7765794810 mm/migrate: remove the -EEXIST conversion for move_pages() 
The -EEXIST conversion is introduced in commit 65462462ff ("mm/gup:
follow_pfn_pte(): -EEXIST cleanup"), since follow_page() may call
follow_pfn_pte() which may return -EEXIST.

But after commit 7dff875c94 ("mm/migrate: convert
add_page_for_migration() from follow_page() to folio_walk"), it use
folio_walk instead.  This limit the error code and won't return -EEXIST.

Remove the error code conversion here.

Link: https://lkml.kernel.org/r/20250707065711.18056-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-19 18:59:45 -07:00
David Hildenbrand
92f091769f mm: rename PG_isolated to PG_movable_ops_isolated 
Let's rename the flag to make it clearer where it applies (not folios
...).

While at it, define the flag only with CONFIG_MIGRATION.

Link: https://lkml.kernel.org/r/20250704102524.326966-22-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-13 16:38:30 -07:00
David Hildenbrand
84caf98838 mm: stop storing migration_ops in page->mapping 
...  instead, look them up statically based on the page type.  Maybe in
the future we want a registration interface?  At least for now, it can be
easily handled using the two page types that actually support page
migration.

The remaining usage of page->mapping is to flag such pages as actually
being movable (having movable_ops), which we will change next.

Link: https://lkml.kernel.org/r/20250704102524.326966-20-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-13 16:38:29 -07:00
David Hildenbrand
457d7b3adb mm: remove __folio_test_movable() 
Convert to page_has_movable_ops().  While at it, cleanup relevant code a
bit.

The data_race() in migrate_folio_unmap() is questionable: we already hold
a page reference, and concurrent modifications can no longer happen (iow:
__ClearPageMovable() no longer exists).  Drop it for now, we'll rework
page_has_movable_ops() soon either way to no longer rely on page->mapping.

Wherever we cast from folio to page now is a clear sign that this code has
to be decoupled.

Link: https://lkml.kernel.org/r/20250704102524.326966-19-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-13 16:38:29 -07:00
David Hildenbrand
d4fb4587bd mm: rename __PageMovable() to page_has_movable_ops() 
Let's make it clearer that we are talking about movable_ops pages.

While at it, convert a VM_BUG_ON to a VM_WARN_ON_ONCE_PAGE.

Link: https://lkml.kernel.org/r/20250704102524.326966-17-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-13 16:38:29 -07:00
David Hildenbrand
22d103aef0 mm/migration: remove PageMovable() 
Previously, if __ClearPageMovable() were invoked on a page, this would
cause __PageMovable() to return false, but due to the continued existence
of page movable ops, PageMovable() would have returned true.

With __ClearPageMovable() gone, the two are exactly equivalent.

So we can replace PageMovable() checks by __PageMovable().  In fact,
__PageMovable() cannot change until a page is freed, so we can turn some
PageMovable() into sanity checks for __PageMovable().

Link: https://lkml.kernel.org/r/20250704102524.326966-16-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-07-13 16:38:28 -07:00