kernel/linux.git/include/linux/memremap.h, branch v6.19.11

mm/zone_device: reinitialize large zone device private folios

2026-01-27T03:03:48+00:00

Reinitialize metadata for large zone device private folios in zone_device_page_init prior to creating a higher-order zone device private folio. This step is necessary when the folio's order changes dynamically between zone_device_page_init calls to avoid building a corrupt folio. As part of the metadata reinitialization, the dev_pagemap must be passed in from the caller because the pgmap stored in the folio page may have been overwritten with a compound head. Without this fix, individual pages could have invalid pgmap fields and flags (with PG_locked being notably problematic) due to prior different order allocations, which can, and will, result in kernel crashes. Link: https://lkml.kernel.org/r/20260116111325.1736137-2-francois.dugast@intel.com Fixes: d245f9b4ab80 ("mm/zone_device: support large zone device private folios") Signed-off-by: Matthew Brost Signed-off-by: Francois Dugast Acked-by: Felix Kuehling Reviewed-by: Balbir Singh Acked-by: Vlastimil Babka Cc: Zi Yan Cc: Alistair Popple Cc: Madhavan Srinivasan Cc: Nicholas Piggin Cc: Michael Ellerman Cc: "Christophe Leroy (CS GROUP)" Cc: Alex Deucher Cc: "Christian König" Cc: David Airlie Cc: Simona Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Hildenbrand Cc: Oscar Salvador Cc: Andrew Morton Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Lorenzo Stoakes Cc: Liam R. Howlett Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2025-12-03-21-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-12-05T21:52:43+00:00

Pull MM updates from Andrew Morton: "__vmalloc()/kvmalloc() and no-block support" (Uladzislau Rezki) Rework the vmalloc() code to support non-blocking allocations (GFP_ATOIC, GFP_NOWAIT) "ksm: fix exec/fork inheritance" (xu xin) Fix a rare case where the KSM MMF_VM_MERGE_ANY prctl state is not inherited across fork/exec "mm/zswap: misc cleanup of code and documentations" (SeongJae Park) Some light maintenance work on the zswap code "mm/page_owner: add debugfs files 'show_handles' and 'show_stacks_handles'" (Mauricio Faria de Oliveira) Enhance the /sys/kernel/debug/page_owner debug feature by adding unique identifiers to differentiate the various stack traces so that userspace monitoring tools can better match stack traces over time "mm/page_alloc: pcp->batch cleanups" (Joshua Hahn) Minor alterations to the page allocator's per-cpu-pages feature "Improve UFFDIO_MOVE scalability by removing anon_vma lock" (Lokesh Gidra) Address a scalability issue in userfaultfd's UFFDIO_MOVE operation "kasan: cleanups for kasan_enabled() checks" (Sabyrzhan Tasbolatov) "drivers/base/node: fold node register and unregister functions" (Donet Tom) Clean up the NUMA node handling code a little "mm: some optimizations for prot numa" (Kefeng Wang) Cleanups and small optimizations to the NUMA allocation hinting code "mm/page_alloc: Batch callers of free_pcppages_bulk" (Joshua Hahn) Address long lock hold times at boot on large machines. These were causing (harmless) softlockup warnings "optimize the logic for handling dirty file folios during reclaim" (Baolin Wang) Remove some now-unnecessary work from page reclaim "mm/damon: allow DAMOS auto-tuned for per-memcg per-node memory usage" (SeongJae Park) Enhance the DAMOS auto-tuning feature "mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON_RECLAIM" (Quanmin Yan) Fix DAMON_LRU_SORT and DAMON_RECLAIM with certain userspace configuration "expand mmap_prepare functionality, port more users" (Lorenzo Stoakes) Enhance the new(ish) file_operations.mmap_prepare() method and port additional callsites from the old ->mmap() over to ->mmap_prepare() "Fix stale IOTLB entries for kernel address space" (Lu Baolu) Fix a bug (and possible security issue on non-x86) in the IOMMU code. In some situations the IOMMU could be left hanging onto a stale kernel pagetable entry "mm/huge_memory: cleanup __split_unmapped_folio()" (Wei Yang) Clean up and optimize the folio splitting code "mm, swap: misc cleanup and bugfix" (Kairui Song) Some cleanups and a minor fix in the swap discard code "mm/damon: misc documentation fixups" (SeongJae Park) "mm/damon: support pin-point targets removal" (SeongJae Park) Permit userspace to remove a specific monitoring target in the middle of the current targets list "mm: MISC follow-up patches for linux/pgalloc.h" (Harry Yoo) A couple of cleanups related to mm header file inclusion "mm/swapfile.c: select swap devices of default priority round robin" (Baoquan He) improve the selection of swap devices for NUMA machines "mm: Convert memory block states (MEM_*) macros to enums" (Israel Batista) Change the memory block labels from macros to enums so they will appear in kernel debug info "ksm: perform a range-walk to jump over holes in break_ksm" (Pedro Demarchi Gomes) Address an inefficiency when KSM unmerges an address range "mm/damon/tests: fix memory bugs in kunit tests" (SeongJae Park) Fix leaks and unhandled malloc() failures in DAMON userspace unit tests "some cleanups for pageout()" (Baolin Wang) Clean up a couple of minor things in the page scanner's writeback-for-eviction code "mm/hugetlb: refactor sysfs/sysctl interfaces" (Hui Zhu) Move hugetlb's sysfs/sysctl handling code into a new file "introduce VM_MAYBE_GUARD and make it sticky" (Lorenzo Stoakes) Make the VMA guard regions available in /proc/pid/smaps and improves the mergeability of guarded VMAs "mm: perform guard region install/remove under VMA lock" (Lorenzo Stoakes) Reduce mmap lock contention for callers performing VMA guard region operations "vma_start_write_killable" (Matthew Wilcox) Start work on permitting applications to be killed when they are waiting on a read_lock on the VMA lock "mm/damon/tests: add more tests for online parameters commit" (SeongJae Park) Add additional userspace testing of DAMON's "commit" feature "mm/damon: misc cleanups" (SeongJae Park) "make VM_SOFTDIRTY a sticky VMA flag" (Lorenzo Stoakes) Address the possible loss of a VMA's VM_SOFTDIRTY flag when that VMA is merged with another "mm: support device-private THP" (Balbir Singh) Introduce support for Transparent Huge Page (THP) migration in zone device-private memory "Optimize folio split in memory failure" (Zi Yan) "mm/huge_memory: Define split_type and consolidate split support checks" (Wei Yang) Some more cleanups in the folio splitting code "mm: remove is_swap_[pte, pmd]() + non-swap entries, introduce leaf entries" (Lorenzo Stoakes) Clean up our handling of pagetable leaf entries by introducing the concept of 'software leaf entries', of type softleaf_t "reparent the THP split queue" (Muchun Song) Reparent the THP split queue to its parent memcg. This is in preparation for addressing the long-standing "dying memcg" problem, wherein dead memcg's linger for too long, consuming memory resources "unify PMD scan results and remove redundant cleanup" (Wei Yang) A little cleanup in the hugepage collapse code "zram: introduce writeback bio batching" (Sergey Senozhatsky) Improve zram writeback efficiency by introducing batched bio writeback support "memcg: cleanup the memcg stats interfaces" (Shakeel Butt) Clean up our handling of the interrupt safety of some memcg stats "make vmalloc gfp flags usage more apparent" (Vishal Moola) Clean up vmalloc's handling of incoming GFP flags "mm: Add soft-dirty and uffd-wp support for RISC-V" (Chunyan Zhang) Teach soft dirty and userfaultfd write protect tracking to use RISC-V's Svrsw60t59b extension "mm: swap: small fixes and comment cleanups" (Youngjun Park) Fix a small bug and clean up some of the swap code "initial work on making VMA flags a bitmap" (Lorenzo Stoakes) Start work on converting the vma struct's flags to a bitmap, so we stop running out of them, especially on 32-bit "mm/swapfile: fix and cleanup swap list iterations" (Youngjun Park) Address a possible bug in the swap discard code and clean things up a little [ This merge also reverts commit ebb9aeb980e5 ("vfio/nvgrace-gpu: register device memory for poison handling") because it looks broken to me, I've asked for clarification - Linus ] * tag 'mm-stable-2025-12-03-21-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits) mm: fix vma_start_write_killable() signal handling mm/swapfile: use plist_for_each_entry in __folio_throttle_swaprate mm/swapfile: fix list iteration when next node is removed during discard fs/proc/task_mmu.c: fix make_uffd_wp_huge_pte() huge pte handling mm/kfence: add reboot notifier to disable KFENCE on shutdown memcg: remove inc/dec_lruvec_kmem_state helpers selftests/mm/uffd: initialize char variable to Null mm: fix DEBUG_RODATA_TEST indentation in Kconfig mm: introduce VMA flags bitmap type tools/testing/vma: eliminate dependency on vma->__vm_flags mm: simplify and rename mm flags function for clarity mm: declare VMA flags by bit zram: fix a spelling mistake mm/page_alloc: optimize lowmem_reserve max lookup using its semantic monotonicity mm/vmscan: skip increasing kswapd_failures when reclaim was boosted pagemap: update BUDDY flag documentation mm: swap: remove scan_swap_map_slots() references from comments mm: swap: change swap_alloc_slow() to void mm, swap: remove redundant comment for read_swap_cache_async mm, swap: use SWP_SOLIDSTATE to determine if swap is rotational ...

mm/memremap: add driver callback support for folio splitting

2025-11-24T23:08:48+00:00

When a zone device page is split (via huge pmd folio split). The driver callback for folio_split is invoked to let the device driver know that the folio size has been split into a smaller order. Provide a default implementation for drivers that do not provide this callback that copies the pgmap and mapping fields for the split folios. Update the HMM test driver to handle the split. Link: https://lkml.kernel.org/r/20251001065707.920170-11-balbirs@nvidia.com Signed-off-by: Balbir Singh Cc: David Hildenbrand Cc: Zi Yan Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Oscar Salvador Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: "Liam R. Howlett" Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Airlie Cc: Simona Vetter Cc: Ralph Campbell Cc: Mika Penttilä Cc: Matthew Brost Cc: Francois Dugast Signed-off-by: Andrew Morton

lib/test_hmm: add zone device private THP test infrastructure

2025-11-24T23:08:48+00:00

Enhance the hmm test driver (lib/test_hmm) with support for THP pages. A new pool of free_folios() has now been added to the dmirror device, which can be allocated when a request for a THP zone device private page is made. Add compound page awareness to the allocation function during normal migration and fault based migration. These routines also copy folio_nr_pages() when moving data between system memory and device memory. args.src and args.dst used to hold migration entries are now dynamically allocated (as they need to hold HPAGE_PMD_NR entries or more). Split and migrate support will be added in future patches in this series. Link: https://lkml.kernel.org/r/20251001065707.920170-10-balbirs@nvidia.com Signed-off-by: Balbir Singh Cc: David Hildenbrand Cc: Zi Yan Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Oscar Salvador Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: "Liam R. Howlett" Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Airlie Cc: Simona Vetter Cc: Ralph Campbell Cc: Mika Penttilä Cc: Matthew Brost Cc: Francois Dugast Signed-off-by: Andrew Morton

mm/zone_device: rename page_free callback to folio_free

2025-11-24T23:08:47+00:00

Change page_free to folio_free to make the folio support for zone device-private more consistent. The PCI P2PDMA callback has also been updated and changed to folio_free() as a result. For drivers that do not support folios (yet), the folio is converted back into page via &folio->page and the page is used as is, in the current callback implementation. Link: https://lkml.kernel.org/r/20251001065707.920170-3-balbirs@nvidia.com Signed-off-by: Balbir Singh Cc: David Hildenbrand Cc: Zi Yan Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Oscar Salvador Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: "Liam R. Howlett" Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Airlie Cc: Simona Vetter Cc: Ralph Campbell Cc: Mika Penttilä Cc: Matthew Brost Cc: Francois Dugast Cc: Madhavan Srinivasan Cc: Christophe Leroy Cc: Felix Kuehling Cc: Alex Deucher Cc: "Christian König" Signed-off-by: Andrew Morton

mm/zone_device: support large zone device private folios

2025-11-24T23:08:47+00:00

Patch series "mm: support device-private THP", v7. This patch series introduces support for Transparent Huge Page (THP) migration in zone device-private memory. The implementation enables efficient migration of large folios between system memory and device-private memory Background Current zone device-private memory implementation only supports PAGE_SIZE granularity, leading to: - Increased TLB pressure - Inefficient migration between CPU and device memory This series extends the existing zone device-private infrastructure to support THP, leading to: - Reduced page table overhead - Improved memory bandwidth utilization - Seamless fallback to base pages when needed In my local testing (using lib/test_hmm) and a throughput test, the series shows a 350% improvement in data transfer throughput and a 80% improvement in latency These patches build on the earlier posts by Ralph Campbell [1] Two new flags are added in vma_migration to select and mark compound pages. migrate_vma_setup(), migrate_vma_pages() and migrate_vma_finalize() support migration of these pages when MIGRATE_VMA_SELECT_COMPOUND is passed in as arguments. The series also adds zone device awareness to (m)THP pages along with fault handling of large zone device private pages. page vma walk and the rmap code is also zone device aware. Support has also been added for folios that might need to be split in the middle of migration (when the src and dst do not agree on MIGRATE_PFN_COMPOUND), that occurs when src side of the migration can migrate large pages, but the destination has not been able to allocate large pages. The code supported and used folio_split() when migrating THP pages, this is used when MIGRATE_VMA_SELECT_COMPOUND is not passed as an argument to migrate_vma_setup(). The test infrastructure lib/test_hmm.c has been enhanced to support THP migration. A new ioctl to emulate failure of large page allocations has been added to test the folio split code path. hmm-tests.c has new test cases for huge page migration and to test the folio split path. A new throughput test has been added as well. The nouveau dmem code has been enhanced to use the new THP migration capability. mTHP support: The patches hard code, HPAGE_PMD_NR in a few places, but the code has been kept generic to support various order sizes. With additional refactoring of the code support of different order sizes should be possible. The future plan is to post enhancements to support mTHP with a rough design as follows: 1. Add the notion of allowable thp orders to the HMM based test driver 2. For non PMD based THP paths in migrate_device.c, check to see if a suitable order is found and supported by the driver 3. Iterate across orders to check the highest supported order for migration 4. Migrate and finalize The mTHP patches can be built on top of this series, the key design elements that need to be worked out are infrastructure and driver support for multiple ordered pages and their migration. HMM support for large folios was added in 10b9feee2d0d ("mm/hmm: populate PFNs from PMD swap entry"). This patch (of 16) Add routines to support allocation of large order zone device folios and helper functions for zone device folios, to check if a folio is device private and helpers for setting zone device data. When large folios are used, the existing page_free() callback in pgmap is called when the folio is freed, this is true for both PAGE_SIZE and higher order pages. Zone device private large folios do not support deferred split and scan like normal THP folios. Link: https://lkml.kernel.org/r/20251001065707.920170-1-balbirs@nvidia.com Link: https://lkml.kernel.org/r/20251001065707.920170-2-balbirs@nvidia.com Link: https://lore.kernel.org/linux-mm/20201106005147.20113-1-rcampbell@nvidia.com/ [1] Signed-off-by: Balbir Singh Cc: David Hildenbrand Cc: Zi Yan Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Oscar Salvador Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: "Liam R. Howlett" Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Airlie Cc: Simona Vetter Cc: Ralph Campbell Cc: Mika Penttilä Cc: Matthew Brost Cc: Francois Dugast Cc: Madhavan Srinivasan Cc: Christophe Leroy Cc: Felix Kuehling Cc: Alex Deucher Cc: "Christian König" Signed-off-by: Andrew Morton

mm/memory_hotplug: Remove MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers

2025-10-14T12:24:53+00:00

MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers were introduced to prepare the transition of memory to and from a physically accessible state. This enhancement was crucial for implementing the "memmap on memory" feature for s390. With introduction of dynamic (de)configuration of hotpluggable memory, memory can be brought to accessible state before add_memory(). Memory can be brought to inaccessible state before remove_memory(). Hence, there is no need of MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers anymore. This basically reverts commit c5f1e2d18909 ("mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers") Additionally, apply minor adjustments to the function parameters of move_pfn_range_to_zone() and mhp_supports_memmap_on_memory() to ensure compatibility with the latest branch. Acked-by: David Hildenbrand Signed-off-by: Sumanth Korikkar Signed-off-by: Heiko Carstens

mm/memremap: remove unused get_dev_pagemap() parameter

2025-09-21T21:22:21+00:00

GUP no longer uses get_dev_pagemap(). As it was the only user of the get_dev_pagemap() pgmap caching feature it can be removed. Link: https://lkml.kernel.org/r/20250903225926.34702-2-apopple@nvidia.com Signed-off-by: Alistair Popple Acked-by: David Hildenbrand Reviewed-by: Jason Gunthorpe Reviewed-by: Dan Williams Cc: John Hubbard Cc: Oscar Salvador Cc: Peter Xu Signed-off-by: Andrew Morton

mm: add folio_is_pci_p2pdma()

2025-09-13T23:55:10+00:00

Reimplement is_pci_p2pdma_page() in terms of folio_is_pci_p2pdma(). Moves the page_folio() call from inside page_pgmap() to is_pci_p2pdma_page(). This removes a page_folio() call from try_grab_folio() which already has a folio and can pass it in. Link: https://lkml.kernel.org/r/20250805172307.1302730-12-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Shakeel Butt Cc: Zi Yan Signed-off-by: Andrew Morton

mm: reimplement folio_is_fsdax()

2025-09-13T23:55:09+00:00

For callers of folio_is_fsdax(), we save a folio->page->folio conversion. Callers of is_fsdax_page() simply move the conversion of page->folio from the implementation of page_pgmap() to is_fsdax_page(). Link: https://lkml.kernel.org/r/20250805172307.1302730-11-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Zi Yan Cc: Shakeel Butt Signed-off-by: Andrew Morton