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linux/mm
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David Hildenbrand (Arm) 89e69c7d18 mm/memory_hotplug: fix possible race in scan_movable_pages() 
Patch series "mm: memory hot(un)plug and SPARSEMEM cleanups", v2.

Some cleanups around memory hot(un)plug and SPARSEMEM.  In essence, we can
limit CONFIG_MEMORY_HOTPLUG to CONFIG_SPARSEMEM_VMEMMAP, remove some dead
code, and move all the hotplug bits over to mm/sparse-vmemmap.c.

Some further/related cleanups around other unnecessary code (memory hole
handling and complicated usemap allocation).

I have some further sparse.c cleanups lying around, and I'm planning on
getting rid of bootmem_info.c entirely.


This patch (of 15):

If a hugetlb folio gets freed while we are in scan_movable_pages(),
folio_nr_pages() could return 0, resulting in or'ing "0 - 1 = -1" to the
PFN, resulting in PFN = -1.  We're not holding any locks or references
that would prevent that.

for_each_valid_pfn() would then search for the next valid PFN, and could
return a PFN that is outside of the range of the original requested range.
do_migrate_page() would then try to migrate quite a big range, which is
certainly undesirable.

To fix it, simply test for valid folio_nr_pages() values.  While at it, as
PageHuge() really just does a page_folio() internally, we can just use
folio_test_hugetlb() on the folio directly.

scan_movable_pages() is expected to be fast, and we try to avoid taking
locks or grabbing references.  We cannot use folio_try_get() as that does
not work for free hugetlb folios.  We could grab the hugetlb_lock, but
that just adds complexity.

The race is unlikely to trigger in practice, so we won't be CCing stable.

Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-0-096addc8800d@kernel.org
Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-1-096addc8800d@kernel.org
Fixes: 16540dae95 ("mm/hugetlb: mm/memory_hotplug: use a folio in scan_movable_pages()")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
History 2026-04-05 13:53:31 -07:00
..
damon mm/damon/lru_sort: respect addr_unit on default monitoring region setup 2026-04-05 13:53:29 -07:00
kasan kasan: fix bug type classification for SW_TAGS mode 2026-04-05 13:53:18 -07:00
kfence kfence: add kfence.fault parameter 2026-04-05 13:53:06 -07:00
kmsan Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
tests sparc/mm: export symbols for lazy_mmu_mode KUnit tests 2026-01-31 14:22:40 -08:00
backing-dev.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
balloon.c mm: rename CONFIG_BALLOON_COMPACTION to CONFIG_BALLOON_MIGRATION 2026-01-31 14:22:36 -08:00
bootmem_info.c mm/sparse: allow for alternate vmemmap section init at boot 2025-03-16 22:06:27 -07:00
bpf_memcontrol.c bpf: Revert "bpf: drop KF_ACQUIRE flag on BPF kfunc bpf_get_root_mem_cgroup()" 2026-01-21 09:38:16 -08:00
cma.c mm/cma: move put_page_testzero() out of VM_WARN_ON in cma_release() 2026-03-04 09:44:22 -08:00
cma.h mm: cma: set early_pfn and bitmap as a union in cma_memrange 2025-05-22 14:55:36 -07:00
cma_debug.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
cma_sysfs.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
compaction.c mm/compaction: fix low_pfn advance on isolating hugetlb 2025-09-28 11:51:29 -07:00
debug.c mm: constify __dump_folio() arguments 2025-11-20 13:43:57 -08:00
debug_page_alloc.c mm/debug_page_alloc: improve error message for invalid guardpage minorder 2025-05-12 23:50:38 -07:00
debug_page_ref.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
debug_vm_pgtable.c mm/debug_vm_pgtable: replace WRITE_ONCE() with pxd_clear() 2026-04-05 13:53:11 -07:00
dmapool.c docs: dma-api: replace consistent with coherent 2025-07-01 13:25:36 -06:00
dmapool_test.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
early_ioremap.c mm/early_ioremap: clean up the use of WARN() for debugging 2026-01-26 20:02:26 -08:00
execmem.c mm: remove PMD alignment constraint in execmem_vmalloc() 2025-09-28 11:51:31 -07:00
fadvise.c mm/fadvise: validate offset in generic_fadvise 2026-04-05 13:52:53 -07:00
fail_page_alloc.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
failslab.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
filemap.c folio_batch: rename pagevec.h to folio_batch.h 2026-04-05 13:53:07 -07:00
folio-compat.c mm: add SPDX id lines to some mm source files 2026-02-06 15:47:16 -08:00
gup.c folio_batch: rename pagevec.h to folio_batch.h 2026-04-05 13:53:07 -07:00
gup_test.c mm: add SPDX id lines to some mm source files 2026-02-06 15:47:16 -08:00
gup_test.h mm/gup_test: start/stop/read functionality for PIN LONGTERM test 2022-11-08 17:37:15 -08:00
highmem.c mm/highmem: fix __kmap_to_page() build error 2026-01-31 14:22:38 -08:00
hmm.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
huge_memory.c mm: introduce is_pmd_order helper 2026-04-05 13:53:29 -07:00
hugetlb.c mm: move vma_mmu_pagesize() from hugetlb to vma.c 2026-04-05 13:53:23 -07:00
hugetlb_cgroup.c Convert 'alloc_flex' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
hugetlb_cma.c mm: hugetlb_cma: mark hugetlb_cma{_only} as __ro_after_init 2026-01-31 14:22:43 -08:00
hugetlb_cma.h mm: hugetlb: allocate frozen pages for gigantic allocation 2026-01-26 20:02:28 -08:00
hugetlb_internal.h mm/hugetlb: extract sysctl into hugetlb_sysctl.c 2025-11-20 13:43:57 -08:00
hugetlb_sysctl.c mm, hugetlb: implement movable_gigantic_pages sysctl 2026-01-20 19:24:50 -08:00
hugetlb_sysfs.c mm/hugetlb: extract sysfs into hugetlb_sysfs.c 2025-11-20 13:43:57 -08:00
hugetlb_vmemmap.c mm/hugetlb: remove hugetlb_optimize_vmemmap_key static key 2026-04-05 13:53:09 -07:00
hugetlb_vmemmap.h mm/hugetlb: do pre-HVO for bootmem allocated pages 2025-03-16 22:06:29 -07:00
hwpoison-inject.c mm/hwpoison: decouple hwpoison_filter from mm/memory-failure.c 2025-09-21 14:22:21 -07:00
init-mm.c mm: rename cpu_bitmap field to flexible_array 2026-01-19 12:30:00 -08:00
internal.h mm: abstract reading sysctl_max_map_count, and READ_ONCE() 2026-04-05 13:53:28 -07:00
interval_tree.c mm/memory: simplify calculation in unmap_mapping_range_tree() 2026-04-05 13:53:13 -07:00
ioremap.c mm/ioremap: pass pgprot_t to ioremap_prot() instead of unsigned long 2025-03-16 22:06:23 -07:00
Kconfig mm.git review status for linus..mm-stable 2026-02-12 11:32:37 -08:00
Kconfig.debug mm: fix DEBUG_RODATA_TEST indentation in Kconfig 2025-11-29 10:41:09 -08:00
khugepaged.c mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() 2026-04-05 13:53:30 -07:00
kmemleak.c mm/kmemleak: use PF_KTHREAD flag to detect kernel threads 2026-04-05 13:53:02 -07:00
ksm.c ksm: initialize the addr only once in rmap_walk_ksm 2026-04-05 13:52:35 -07:00
list_lru.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
maccess.c mm: unexport globally copy_to_kernel_nofault 2025-07-09 22:42:22 -07:00
madvise.c mm: rename zap_page_range_single() to zap_vma_range() 2026-04-05 13:53:15 -07:00
Makefile mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
mapping_dirty_helpers.c mm/dirty: replace READ_ONCE() with pudp_get() 2025-11-16 17:27:58 -08:00
memblock.c memblock: updates for 7.0-rc1 2026-02-14 12:39:34 -08:00
memcontrol-v1.c memcg: consolidate private id refcount get/put helpers 2026-04-05 13:53:00 -07:00
memcontrol-v1.h memcg: consolidate private id refcount get/put helpers 2026-04-05 13:53:00 -07:00
memcontrol.c mm: memcg: separate slab stat accounting from objcg charge cache 2026-04-05 13:53:17 -07:00
memfd.c memfd: export memfd_{add,get}_seals() 2026-04-05 13:53:00 -07:00
memfd_luo.c mm: memfd_luo: preserve file seals 2026-04-05 13:53:00 -07:00
memory-failure.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
memory-tiers.c Convert more 'alloc_obj' cases to default GFP_KERNEL arguments 2026-02-21 20:03:00 -08:00
memory.c mm: introduce is_pmd_order helper 2026-04-05 13:53:29 -07:00
memory_hotplug.c mm/memory_hotplug: fix possible race in scan_movable_pages() 2026-04-05 13:53:31 -07:00
mempolicy.c mm: introduce is_pmd_order helper 2026-04-05 13:53:29 -07:00
mempool.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
memremap.c mm/zone_device: reinitialize large zone device private folios 2026-01-26 19:03:48 -08:00
memtest.c mm/memtest: add underflow detection for size calculation 2026-01-09 11:53:51 +02:00
migrate.c mm: migrate: requeue destination folio on deferred split queue 2026-04-05 13:53:27 -07:00
migrate_device.c mm/migrate_device: document folio_get requirement before frozen PMD split 2026-04-05 13:53:19 -07:00
mincore.c mm: replace remaining pte_to_swp_entry() with softleaf_from_pte() 2025-11-24 15:08:52 -08:00
mlock.c mm: prevent droppable mappings from being locked 2026-04-05 13:53:25 -07:00
mm_init.c mm: change the interface of prep_compound_tail() 2026-04-05 13:53:07 -07:00
mm_slot.h mm: introduce common struct mm_slot 2022-10-03 14:02:43 -07:00
mmap.c mm: abstract reading sysctl_max_map_count, and READ_ONCE() 2026-04-05 13:53:28 -07:00
mmap_lock.c mm/vma: improve and document __is_vma_write_locked() 2026-01-31 14:22:51 -08:00
mmu_gather.c mm/mmu_gather: replace IPI with synchronize_rcu() when batch allocation fails 2026-04-05 13:53:05 -07:00
mmu_notifier.c mm/mmu_notifiers: use hlist_for_each_entry_srcu() for SRCU list traversal 2026-04-05 13:53:02 -07:00
mmzone.c mm: introduce memdesc_flags_t 2025-09-13 16:55:07 -07:00
mprotect.c mm/pkeys: remove unused tsk parameter from arch_set_user_pkey_access() 2026-04-05 13:52:57 -07:00
mremap.c mm/khugepaged: rename hpage_collapse_* to collapse_* 2026-04-05 13:53:30 -07:00
mseal.c mm: fix minor spelling mistakes in comments 2026-01-20 19:24:48 -08:00
msync.c mm/msync: use vma_find() instead of vma linked list 2022-09-26 19:46:25 -07:00
nommu.c mm: abstract reading sysctl_max_map_count, and READ_ONCE() 2026-04-05 13:53:28 -07:00
numa.c mm/numa: remove unnecessary local variable in alloc_node_data() 2025-05-12 23:50:38 -07:00
numa_emulation.c mm: numa,memblock: Use SZ_1M macro to denote bytes to MB conversion 2025-08-20 16:31:23 +03:00
numa_memblks.c memblock: numa_memblks: fix detection of NUMA node for CXL windows 2026-02-21 09:58:22 -08:00
oom_kill.c mm/oom_kill.c: simpilfy rcu call with guard(rcu) 2026-04-05 13:53:17 -07:00
page-writeback.c mm: rename zap_vma_pages() to zap_vma() 2026-04-05 13:53:14 -07:00
page_alloc.c mm: introduce is_pmd_order helper 2026-04-05 13:53:29 -07:00
page_counter.c page_counter: track failcnt only for legacy cgroups 2025-03-17 00:05:35 -07:00
page_ext.c mm/page_ext: Add page_ext_get_from_phys() 2026-01-21 12:51:48 +01:00
page_frag_cache.c mm/page_alloc: export free_frozen_pages() instead of free_unref_page() 2025-01-13 22:40:31 -08:00
page_idle.c mm/page_idle.c: remove redundant mmu notifier in aging code 2026-04-05 13:53:02 -07:00
page_io.c mm: fix minor spelling mistakes in comments 2026-01-20 19:24:48 -08:00
page_isolation.c mm: page_isolation: introduce page_is_unmovable() 2026-01-31 14:22:42 -08:00
page_owner.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
page_poison.c mm/page_poison: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:50 -08:00
page_reporting.c mm/page_reporting: change page_reporting_order to PAGE_REPORTING_ORDER_UNSPECIFIED 2026-04-05 13:53:17 -07:00
page_reporting.h mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
page_table_check.c mm: provide address parameter to p{te,md,ud}_user_accessible_page() 2026-01-26 20:02:35 -08:00
page_vma_mapped.c mm: centralize+fix comments about compound_mapcount() in new sync_with_folio_pmd_zap() 2026-04-05 13:53:03 -07:00
pagewalk.c mm/pagewalk: drop FW_MIGRATION 2026-04-05 13:53:10 -07:00
percpu-internal.h mm: remove CONFIG_MEMCG_KMEM 2024-07-10 12:14:54 -07:00
percpu-km.c mm/mm/percpu-km: drop nth_page() usage within single allocation 2025-09-21 14:22:04 -07:00
percpu-stats.c mm: remove outdated filename comment in percpu-stats.c 2025-07-13 16:38:23 -07:00
percpu-vm.c kmsan: remove hard-coded GFP_KERNEL flags 2025-11-16 17:27:54 -08:00
percpu.c percpu: add double free check to pcpu_free_area() 2026-01-31 14:22:52 -08:00
pgalloc-track.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgtable-generic.c compiler-context-analysis: Remove __cond_lock() function-like helper 2026-01-05 16:43:33 +01:00
process_vm_access.c mm: refactor mm_access() to not return NULL 2024-11-05 16:56:23 -08:00
ptdump.c mm/ptdump: replace READ_ONCE() with standard page table accessors 2025-11-16 17:27:52 -08:00
readahead.c mm.git review status for linus..mm-stable 2026-02-12 11:32:37 -08:00
rmap.c mm: support batched checking of the young flag for MGLRU 2026-04-05 13:53:16 -07:00
rodata_test.c mm/rodata_test: verify test data is unchanged, rather than non-zero 2025-01-13 22:40:38 -08:00
secretmem.c mm: rename VMA flag helpers to be more readable 2026-04-05 13:53:18 -07:00
shmem.c mm: introduce is_pmd_order helper 2026-04-05 13:53:29 -07:00
shmem_quota.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
show_mem.c mm/vmscan: add tracepoint and reason for kswapd_failures reset 2026-01-31 14:22:38 -08:00
shrinker.c mm: do not allocate shrinker info with cgroup.memory=nokmem 2026-04-05 13:53:05 -07:00
shrinker_debug.c memcg: rename mem_cgroup_ino() to mem_cgroup_id() 2026-01-26 20:02:25 -08:00
shuffle.c mm/shuffle: convert module_param_call to module_param_cb 2022-10-03 14:03:07 -07:00
shuffle.h mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
slab.h mm/slab: use compound_head() in page_slab() 2026-04-05 13:53:10 -07:00
slab_common.c Merge branch 'slab/for-7.0/sheaves' into slab/for-next 2026-02-10 09:10:00 +01:00
slub.c slab: fix memory leak when refill_sheaf() fails 2026-03-11 17:55:26 +01:00
sparse-vmemmap.c mm/hugetlb: remove fake head pages 2026-04-05 13:53:09 -07:00
sparse.c mm/sparse: check memmap alignment for compound_info_has_mask() 2026-04-05 13:53:08 -07:00
swap.c folio_batch: rename PAGEVEC_SIZE to FOLIO_BATCH_SIZE 2026-04-05 13:53:07 -07:00
swap.h mm, swap: no need to clear the shadow explicitly 2026-04-05 13:52:59 -07:00
swap_cgroup.c mm: swap_cgroup: remove double initialization of locals 2025-03-17 22:06:58 -07:00
swap_state.c folio_batch: rename PAGEVEC_SIZE to FOLIO_BATCH_SIZE 2026-04-05 13:53:07 -07:00
swap_table.h mm, swap: use the swap table to track the swap count 2026-04-05 13:52:59 -07:00
swapfile.c mm/swapfile: remove duplicate include of swap_table.h 2026-04-05 13:53:31 -07:00
truncate.c folio_batch: rename PAGEVEC_SIZE to FOLIO_BATCH_SIZE 2026-04-05 13:53:07 -07:00
usercopy.c usercopy: Remove folio references from check_heap_object() 2025-11-13 11:01:08 +01:00
userfaultfd.c mm/userfaultfd: fix hugetlb fault mutex hash calculation 2026-04-05 13:53:29 -07:00
util.c mm: rework compound_head() for power-of-2 sizeof(struct page) 2026-04-05 13:53:08 -07:00
vma.c mm: abstract reading sysctl_max_map_count, and READ_ONCE() 2026-04-05 13:53:28 -07:00
vma.h mm: make vm_area_desc utilise vma_flags_t only 2026-02-12 15:42:59 -08:00
vma_exec.c mm: softdirty: add pgtable_supports_soft_dirty() 2025-11-24 15:08:54 -08:00
vma_init.c Summary of significant series in this pull request: 2025-10-02 18:18:33 -07:00
vma_internal.h mm: relocate the page table ceiling and floor definitions 2026-02-12 15:42:53 -08:00
vmalloc.c vmalloc: support __GFP_RETRY_MAYFAIL and __GFP_NORETRY 2026-04-05 13:53:12 -07:00
vmpressure.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
vmscan.c mm/vmscan: fix unintended mtc->nmask mutation in alloc_demote_folio() 2026-04-05 13:53:18 -07:00
vmstat.c mm: vmalloc: streamline vmalloc memory accounting 2026-04-05 13:53:04 -07:00
workingset.c mm/workingset: leave highest bits empty for anon shadow 2026-04-05 13:52:58 -07:00
zpdesc.h mm: zpdesc: minor naming and comment corrections 2025-09-21 14:21:59 -07:00
zsmalloc.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
zswap.c mm/zswap: remove SWP_SYNCHRONOUS_IO swapcache bypass workaround 2026-04-05 13:53:02 -07:00