kernel/git/stable/linux.git/mm/Kconfig, branch master

mm/Kconfig: make MEMORY_FAILURE select MIGRATION

2026-08-25T01:43:24+00:00

For embedded devices, lacking support for NUMA, memory hotplug/hotremove, CMA and huge pages is a quite common scenario. In this scenario, the demand for contiguous physical memory allocation is very low. To reduce the kernel image size, some devices disable the compaction. However, their SoCs do support DDR ECC, meaning that memory-failure may be needed. Migration is very useful for soft_offline_page() in memory-failure, which may be triggered by correctable memory errors. Most anonymous and file-mapped faulty pages can be migrated to other healthy pages. Currently, MEMORY_FAILURE does not explicitly select MIGRATION. When COMPACTION, MEMORY_HOTREMOVE, NUMA_MIGRATION and CMA are all disabled, MEMORY_FAILURE can be enabled, but MIGRATION cannot be selected. Make MEMORY_FAILURE select MIGRATION to handle this situation. Link: https://lore.kernel.org/20260813134916.292733-1-xieyuanbin1@huawei.com Signed-off-by: Xie Yuanbin Suggested-by: Mike Rapoport Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Mike Rapoport (Microsoft) Acked-by: Zi Yan Acked-by: David Hildenbrand (Arm) Acked-by: Miaohe Lin Cc: Alistair Popple Cc: "Borislav Petkov (AMD)" Cc: Byungchul Park Cc: David Hildenbrand Cc: Gregory Price Cc: "Huang, Ying" Cc: Joshua Hahn Cc: Liam R. Howlett Cc: liaohua Cc: "Luck, Tony" Cc: Matthew Brost Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Rakie Kim Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Yuanbin Xie Signed-off-by: Andrew Morton

drivers/base, mm: move arch_numa.c to mm/

2026-08-25T01:43:10+00:00

arch_numa.c implements boot time discovery and initialization of NUMA topology on architectures that select GENERIC_ARCH_NUMA (currently arm64 and riscv). Since this is step in the initialization of the memory management subsystem, it's logical to have arch_numa.c in mm/ alongside numa.c, numa_memblks.c and numa_emulation.c. Move arch_numa.c to mm/ and add its F: entry to "MEMBLOCK AND MEMORY MANAGEMENT INITIALIZATION" in MAINTAINERS. Link: https://lore.kernel.org/20260806-arch-numa-v1-1-968ec128121e@kernel.org Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Greg Kroah-Hartman Acked-by: Lorenzo Stoakes (ARM) Acked-by: Vlastimil Babka (SUSE) Acked-by: David Hildenbrand (Arm) Acked-by: Danilo Krummrich Cc: Albert Ou Cc: Alexandre Ghiti Cc: Catalin Marinas Cc: Liam R. Howlett Cc: Michal Hocko Cc: Palmer Dabbelt Cc: "Rafael J. Wysocki" Cc: Suren Baghdasaryan Cc: Will Deacon Signed-off-by: Andrew Morton

mm/Kconfig: make FLATMEM depend on !NUMA

2026-08-25T01:43:03+00:00

Patch series "mm/page_ext: remove pgdat_page_ext_init()", v2. pgdat_page_ext_init() has no effect on FLATMEM. The pgdat is always the zero-initialized contig_page_data, because no architecture supports FLATMEM + NUMA. That constraint is only implicit in the arch Kconfig files. So patch 1 makes it explicit in mm/Kconfig, and patch 2 removes pgdat_page_ext_init(). No functional change. This patch (of 2): FLATMEM + NUMA is not supported by any architecture and fails to build. The constraint is only implicit in the arch Kconfig files. So make it explicit in mm/Kconfig. No functional change. Link: https://lore.kernel.org/20260804151145.3419768-1-ekffu200098@gmail.com Link: https://lore.kernel.org/20260804151145.3419768-2-ekffu200098@gmail.com Signed-off-by: Sang-Heon Jeon Suggested-by: Zi Yan Acked-by: Zi Yan Acked-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/kconfig: drop redundant dependency wrappers

2026-08-25T01:42:49+00:00

Some mm Kconfig entries repeat dependencies that are already expressed by their surrounding blocks or menus. The zsmalloc allocator options menu already depends on ZSMALLOC, so the outer if ZSMALLOC block does not add any extra constraint. MEMORY_HOTREMOVE and MHP_MEMMAP_ON_MEMORY are both inside the if MEMORY_HOTPLUG block, so their local depends on MEMORY_HOTPLUG entries are redundant. PTE_MARKER_UFFD_WP is the only entry under if USERFAULTFD. Move the USERFAULTFD dependency into the symbol itself and combine it with the architecture support dependency. This keeps the same visibility and defaults while avoiding duplicate dependency expressions. Link: https://lore.kernel.org/20260712093326.8313-1-kaitao.cheng@linux.dev Signed-off-by: Kaitao Cheng Suggested-by: Julian Braha Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) Cc: Liam R. Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/kconfig: drop redundant memory hotplug dependencies

2026-08-25T01:42:49+00:00

MHP_MEMMAP_ON_MEMORY is defined inside the MEMORY_HOTPLUG block, and MEMORY_HOTPLUG already depends on SPARSEMEM_VMEMMAP. Keep the explicit MEMORY_HOTPLUG dependency for local readability, but drop the redundant SPARSEMEM_VMEMMAP dependency. ZONE_DEVICE depends on MEMORY_HOTREMOVE, which depends on MEMORY_HOTPLUG. MEMORY_HOTPLUG in turn depends on SPARSEMEM_VMEMMAP. Drop the direct MEMORY_HOTPLUG and SPARSEMEM_VMEMMAP dependencies from ZONE_DEVICE. This does not change the set of valid configurations. Link: https://lore.kernel.org/20260707090331.52971-1-kaitao.cheng@linux.dev Signed-off-by: Kaitao Cheng Acked-by: David Hildenbrand (Arm) Acked-by: Muchun Song Reviewed-by: Lorenzo Stoakes Cc: Liam R. Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/hmm: make CONFIG_HMM_MIRROR select CONFIG_MMU_NOTIFIER

2026-08-05T02:18:53+00:00

hmm doesn't currently build well with MMU_NOTIFIER=n: With microblaze https://download.01.org/0day-ci/archive/20260702/202607021433.DYT5fDqE-lkp@intel.com/config (CONFIG_MMU_NOTIFIER=n): mm/hmm.c: In function 'hmm_range_fault_unlocked_timeout': mm/hmm.c:804:25: error: implicit declaration of function 'mmu_interval_read_begin'; did you mean 'mmu_interval_check_retry'? [-Wimplicit-function-declaration] 804 | mmu_interval_read_begin(range->notifier); | ^~~~~~~~~~~~~~~~~~~~~~~ | mmu_interval_check_retry Quoting Stanislav: : Documentation/mm/hmm.rst explicitly states: : : "Address space mirroring's main objective is to allow duplication of a : range of CPU page table into a device page table; HMM helps keep both : synchronized. A device driver that wants to mirror a process address : space must start with the registration of a mmu_interval_notifier" : : I think making CONFIG_HMM_MIRROR dependent on the CONFIG_MMU_NOTIFIER : is the right thing to do. So select MMU_NOTIFIER if hmm.c is to be compiled. Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Stanislav Kinsburskii Signed-off-by: Andrew Morton

mm/bootmem_info: remove CONFIG_HAVE_BOOTMEM_INFO_NODE

2026-08-05T02:18:42+00:00

The whole infrastructure is unused now. Let's remove the config option along with mm/bootmem_info. + include/linux/bootmem_info.h. Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-10-4afc76c73d61@kernel.org Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Muchun Song Reviewed-by: Dave Hansen Cc: Alexander Gordeev Cc: Andy Lutomirski Cc: "Borislav Petkov (AMD)" Cc: Brendan Jackman Cc: Brendan Jackman Cc: Christian Borntraeger Cc: Gerald Schaefer Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Peter Zijlstra Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton

x86/mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE

2026-08-05T02:18:42+00:00

CONFIG_HAVE_BOOTMEM_INFO_NODE now essentially doesn't do anything. So let's remove support for CONFIG_HAVE_BOOTMEM_INFO_NODE. Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-7-4afc76c73d61@kernel.org Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Dave Hansen Cc: Alexander Gordeev Cc: Andy Lutomirski Cc: "Borislav Petkov (AMD)" Cc: Brendan Jackman Cc: Brendan Jackman Cc: Christian Borntraeger Cc: Gerald Schaefer Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Muchun Song Cc: Oscar Salvador Cc: Peter Zijlstra Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton

userfaultfd: add UFFDIO_REGISTER_MODE_RWP and UFFDIO_RWPROTECT plumbing

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

Add the userspace interface for read-write protection tracking: - UFFDIO_REGISTER_MODE_RWP register a range for RWP tracking - UFFD_FEATURE_RWP capability bit - UFFDIO_RWPROTECT install / remove RWP on a range Introduce CONFIG_USERFAULTFD_RWP, auto-selected on 64-bit kernels with ARCH_HAS_PTE_PROTNONE and HAVE_ARCH_USERFAULTFD_WP. The symbol gates VM_UFFD_RWP (previously aliased to VM_NONE) and the smaps/trace-flag hooks added in the preparatory patches; without it the UAPI bits added here have nothing to drive and would be unreachable. Registration sets VM_UFFD_RWP on the VMA. Combining MODE_WP with MODE_RWP is rejected because both modes claim the uffd PTE bit. UFFDIO_RWPROTECT is the bidirectional counterpart of UFFDIO_WRITEPROTECT: - MODE_RWP change_protection() with MM_CP_UFFD_RWP installs PAGE_NONE and sets the uffd bit on present PTEs - !MODE_RWP change_protection() with MM_CP_UFFD_RWP_RESOLVE restores vma->vm_page_prot and clears the bit userfaultfd_clear_vma() runs the same resolve pass on unregister so RWP state cannot outlive the uffd. Re-registering a range must not drop a mode that installs per-PTE markers (WP or RWP); doing so returns -EBUSY. This also closes a pre-existing window where re-registering without MODE_WP would strand uffd-wp markers: before, those caused extra write-faults but were otherwise benign; with RWP preservation in place, a subsequent mprotect() on a VM_UFFD_RWP VMA would silently promote the stale markers to RWP. The feature is not yet advertised. UFFDIO_REGISTER_MODE_RWP, UFFD_FEATURE_RWP, and _UFFDIO_RWPROTECT are intentionally absent from UFFD_API_REGISTER_MODES, UFFD_API_FEATURES, and UFFD_API_RANGE_IOCTLS, so UFFDIO_API masks them out and the register-mode validator rejects the bit. The follow-up patch adds fault dispatch and exposes the UAPI. Link: https://lore.kernel.org/20260708111417.173443-10-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau Assisted-by: Claude:claude-opus-4-6 Reviewed-by: Mike Rapoport (Microsoft) Cc: Andrea Arcangeli Cc: David Hildenbrand Cc: James Houghton Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Paolo Bonzini Cc: Peter Xu Cc: Sean Christopherson Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton

mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES

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

CONFIG_ARCH_ENABLE_THP_MIGRATION gates PMD-level migration entries. PMD-level device-private entries use the same migration mechanism and therefore require the same architecture support. Upcoming PMD-level swap entries can use the same PMD softleaf helpers without depending on page migration, so rename the architecture gate to CONFIG_ARCH_HAS_PMD_SOFTLEAVES. This describes the PMD entry capability rather than one current user of it. This is a pure rename: the set of selecting architectures (x86, arm64, s390, riscv, loongarch, and powerpc on PPC_BOOK3S_64) and the gating semantics are unchanged. No functional change intended. Link: https://lore.kernel.org/20260706114320.1643046-7-usama.arif@linux.dev Signed-off-by: Usama Arif Reviewed-by: Zi Yan Acked-by: David Hildenbrand (Arm) Cc: Alexandre Ghiti Cc: Baolin Wang Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: Dev Jain Cc: "Huang, Ying" Cc: Johannes Weiner Cc: Kairui Song Cc: Kemeng Shi Cc: Kiryl Shutsemau Cc: Lance Yang Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Nhat Pham Cc: Nico Pache Cc: Rik van Riel Cc: Ryan Roberts Cc: Shakeel Butt Cc: Vlastimil Babka Signed-off-by: Andrew Morton