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6251d650f4e71c07801015e460f930ccc034b652
linux/mm
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Hajime Tazaki 6251d650f4 mm: nommu: add sysctl_max_map_count() check for do_mmap() 
The sysctl variable vm.max_map_count (sysctl_max_map_count) is not exposed
under !MMU configurations, but its default value (DEFAULT_MAX_MAP_COUNT)
is still used as a allocation limit.  Currently, this limit is enforced
when a VMA entry is split into two chunks (split_vma()), but it is not
checked during initial allocation (do_mmap()).  As a result, if a user
requests a large number of memory allocations, the system will continue
allocating until it hits an Out-Of-Memory (OOM) condition.

This commit introduces a check at the beginning of do_mmap() in nommu.c to
prevent this situation.

This issue was detected using the Linux Test Project (LTP) test linked
below.

Link: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/munmap/munmap04.c
Link: https://lore.kernel.org/20260702012830.667205-1-thehajime@gmail.com
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-07-30 19:40:49 -07:00
..
damon
mm/damon/sysfs: remove region size validation
2026-07-30 19:40:48 -07:00
kasan
mm/kasan: remove redundant initialization for kasan_flag_write_only
2026-07-28 21:11:44 -07:00
kfence
Merge tag 'slab-for-7.2-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
2026-06-22 08:28:48 -07:00
kmsan
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
tests
sparc/mm: export symbols for lazy_mmu_mode KUnit tests
2026-01-31 14:22:40 -08:00
alloc_tag.c
mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG
2026-07-30 19:40:44 -07:00
backing-dev.c
mm: blk-cgroup: fix use-after-free in cgwb_release_workfn()
2026-04-18 23:24:27 -07:00
balloon.c
mm: rename CONFIG_BALLOON_COMPACTION to CONFIG_BALLOON_MIGRATION
2026-01-31 14:22:36 -08:00
bootmem_info.c
mm/bootmem_info: stop marking mem_section_usage as MIX_SECTION_INFO
2026-06-02 15:22:11 -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_debug.c
mm/cma_debug: fix invalid accesses for inactive CMA areas
2026-05-28 20:50:33 -07:00
cma_sysfs.c
mm/cma_sysfs: skip inactive CMA areas in sysfs
2026-06-03 16:25:49 -07:00
cma.c
mm/hugetlb_cma: validate hugetlb CMA range by zone at reserve time
2026-07-28 21:11:59 -07:00
cma.h
mm: cma: set early_pfn and bitmap as a union in cma_memrange
2025-05-22 14:55:36 -07:00
compaction.c
mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG
2026-07-30 19:40:44 -07:00
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
…
debug_vm_pgtable.c
mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES
2026-07-30 19:40:25 -07:00
debug.c
mm: constify __dump_folio() arguments
2025-11-20 13:43:57 -08:00
dmapool_test.c
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
2026-02-21 17:09:51 -08:00
dmapool.c
docs: dma-api: replace consistent with coherent
2025-07-01 13:25:36 -06:00
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/execmem: make the populate and alloc atomic
2026-04-05 13:53:34 -07:00
fadvise.c
mm/fadvise: validate offset in generic_fadvise
2026-04-05 13:52:53 -07:00
fail_page_alloc.c
…
failslab.c
…
filemap.c
mm: fix mapping_seek_hole_data() overflow on last page
2026-07-30 19:40:37 -07:00
folio-compat.c
mm: add SPDX id lines to some mm source files
2026-02-06 15:47:16 -08:00
gup_test.c
mm/gup_test: reject wrapped user ranges
2026-06-21 11:37:37 -07:00
gup_test.h
…
gup.c
mm/gup: cleanup pgtable entry accessors
2026-05-28 21:04:41 -07:00
highmem.c
mm/highmem: fix __kmap_to_page() build error
2026-01-31 14:22:38 -08:00
hmm.c
mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES
2026-07-30 19:40:25 -07:00
huge_memory.c
mm: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES
2026-07-30 19:40:25 -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: remove unused bootmem cma field
2026-07-28 21:12:00 -07:00
hugetlb_cma.h
mm/hugetlb: refactor early boot gigantic hugepage allocation
2026-07-28 21:11:59 -07:00
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: avoid unnecessary TLB flush for empty folio list in vmemmap optimize
2026-07-30 19:40:28 -07:00
hugetlb_vmemmap.h
mm/sparse-vmemmap: remove sparse_vmemmap_init_nid_late()
2026-07-28 21:12:00 -07:00
hugetlb.c
mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()
2026-07-30 19:40:41 -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
exec_state: relocate dumpable information
2026-05-26 11:02:01 +02:00
internal.h
mm: factor out can_spin_trylock()
2026-07-30 19:40:44 -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: rename ARCH_ENABLE_THP_MIGRATION to ARCH_HAS_PMD_SOFTLEAVES
2026-07-30 19:40:25 -07:00
Kconfig.debug
mm: move alloc tag to mm
2026-07-28 21:12:03 -07:00
khugepaged.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
kmemleak.c
mm/kmemleak: skip the remaining scan phases when interrupted
2026-07-28 21:12:01 -07:00
ksm.c
mm: remove PageTransCompound()
2026-07-28 21:11:47 -07:00
list_lru.c
Merge tag 'mm-stable-2026-06-18-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
2026-06-19 10:14:34 -07:00
maccess.c
mm: unexport globally copy_to_kernel_nofault
2025-07-09 22:42:22 -07:00
madvise.c
mm: cleanup clear_not_present_full_ptes() and rename to clear_non_present_ptes()
2026-07-28 21:12:10 -07:00
Makefile
mm: move alloc tag to mm
2026-07-28 21:12:03 -07:00
mapping_dirty_helpers.c
mm/dirty: replace READ_ONCE() with pudp_get()
2025-11-16 17:27:58 -08:00
memblock.c
kho: fix deferred initialization of scratch areas
2026-06-01 02:31:37 +03:00
memcontrol-v1.c
mm/vmpressure: move v1 userspace eventfd code into memcontrol-v1.c
2026-07-30 19:40:28 -07:00
memcontrol-v1.h
mm/memcontrol: remove unused for_each_mem_cgroup macro and cleanup
2026-07-28 21:11:43 -07:00
memcontrol.c
mm: memcg: reset oom_group in css_reset
2026-07-30 19:40:49 -07:00
memfd_luo.c
mm/memfd_luo: document preservation of file seals
2026-05-04 14:03:16 +00:00
memfd.c
memfd: deny writeable mappings when implying SEAL_WRITE
2026-05-21 19:06:11 -07:00
memory_hotplug.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
memory-failure.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
memory-tiers.c
mm: introduce CONFIG_NUMA_MIGRATION and simplify CONFIG_MIGRATION
2026-04-05 13:53:33 -07:00
memory.c
mm: extract mm_prepare_for_swap_entries() helper
2026-07-30 19:40:23 -07:00
mempolicy.c
mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()
2026-07-30 19:40:41 -07:00
mempool.c
mm: simplify the mempool_alloc_bulk API
2026-06-03 18:20:47 +02:00
memremap.c
mm/sparse-vmemmap: pass @pgmap argument to memory deactivation paths
2026-05-28 21:04:54 -07:00
memtest.c
mm/memtest: add underflow detection for size calculation
2026-01-09 11:53:51 +02:00
migrate_device.c
mm/migrate_device: pin large folios before splitting
2026-07-30 19:40:31 -07:00
migrate.c
mm/migrate: use huge_ptep_get() in remove_migration_pte()
2026-07-30 19:40:45 -07:00
mincore.c
mm: mincore: use walk_page_range_vma() in do_mincore()
2026-07-28 21:11:52 -07:00
mlock.c
mm: mlock: use walk_page_range_vma() in mlock_vma_pages_range()
2026-07-28 21:11:52 -07:00
mm_init.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
mm_slot.h
…
mmap_lock.c
mm/vma: improve and document __is_vma_write_locked()
2026-01-31 14:22:51 -08:00
mmap.c
mm: fix mmap errno value when MAP_DROPPABLE is not supported
2026-05-28 21:04:48 -07:00
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
Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
2026-04-15 12:59:16 -07:00
mmzone.c
mm: constify oom_control, scan_control, and alloc_context nodemask
2026-07-28 21:12:04 -07:00
mprotect.c
mm/mprotect: use huge_ptep_get() for hugetlb
2026-07-30 19:40:46 -07:00
mremap.c
mm: convert do_brk_flags() to use vma_flags_t
2026-04-05 13:53:40 -07:00
mseal.c
mm/mseal: use min/max in mseal_apply
2026-06-02 15:22:15 -07:00
msync.c
…
nommu.c
mm: nommu: add sysctl_max_map_count() check for do_mmap()
2026-07-30 19:40:49 -07:00
numa_emulation.c
mm/fake-numa: fix under-allocation detection in uniform split
2026-06-02 08:34:03 +03:00
numa_memblks.c
Merge tag 'fixes-2026-02-21' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
2026-02-21 09:58:22 -08:00
numa.c
mm/numa: remove unnecessary local variable in alloc_node_data()
2025-05-12 23:50:38 -07:00
oom_kill.c
mm/oom_kill.c: simpilfy rcu call with guard(rcu)
2026-04-05 13:53:17 -07:00
page_alloc.c
mm: factor out can_spin_trylock()
2026-07-30 19:40:44 -07:00
page_alloc.h
mm: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG
2026-07-30 19:40:44 -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: replace __GFP_NO_CODETAG with ALLOC_NO_CODETAG
2026-07-30 19:40:44 -07:00
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
Merge tag 'block-7.2-20260625' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux
2026-06-25 09:56:47 -07:00
page_isolation.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
page_owner.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
page_poison.c
…
page_reporting.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
page_reporting.h
…
page_table_check.c
mm/page_table_check: Pass mm_struct to pxx_user_accessible_page()
2026-03-13 00:07:47 +01:00
page_vma_mapped.c
mm/page_vma_mapped: use huge_ptep_get() for hugetlb
2026-07-30 19:40:45 -07:00
page-writeback.c
Merge tag 'vfs-7.2-rc1.writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
2026-06-15 03:30:45 +05:30
pagewalk.c
mm/pagewalk: fix race between concurrent split and refault
2026-04-05 13:53:37 -07:00
percpu-internal.h
mm/percpu-internal.h: optimise pcpu_chunk struct to save memory
2026-06-02 15:22:13 -07:00
percpu-km.c
mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()
2026-07-20 17:41:27 -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
mm/percpu: make cached pages lookup explicit
2026-07-28 21:11:47 -07:00
percpu.c
mm/percpu: avoid IO/FS reclaim in backing allocations
2026-07-28 21:11:47 -07:00
pgalloc-track.h
…
pgtable-generic.c
mm: change to return bool for pmdp_clear_flush_young()
2026-04-05 13:53:35 -07:00
process_vm_access.c
…
ptdump.c
mm/ptdump: replace READ_ONCE() with standard page table accessors
2025-11-16 17:27:52 -08:00
readahead.c
Revert "mm: limit filemap_fault readahead to VMA boundaries"
2026-06-21 11:37:38 -07:00
rmap.c
mm/rmap: use huge_ptep_get() in try_to_migrate_one()
2026-07-30 19:40:45 -07:00
rodata_test.c
…
secretmem.c
libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers
2026-06-04 10:10:49 +02:00
shmem_quota.c
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
2026-02-21 01:02:28 -08:00
shmem.c
mm/shmem: fix data-race in shmem_fault
2026-07-30 19:40:29 -07:00
show_mem.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
shrinker_debug.c
mm: shrinker: fix NULL pointer dereference in debugfs
2026-07-01 19:02:52 -07:00
shrinker.c
mm: shrinker: fix shrinker_info teardown race with expansion
2026-07-01 19:02:52 -07:00
shuffle.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
shuffle.h
…
slab_common.c
mm/slab: prevent unbounded recursion in free path with new kmalloc type
2026-07-14 17:22:40 +02:00
slab.h
mm: fix ASSERT_EXCLUSIVE_BITS by passing memdesc_flags_t by pointer
2026-07-30 19:40:31 -07:00
slub.c
mm: factor out can_spin_trylock()
2026-07-30 19:40:44 -07:00
sparse-vmemmap.c
mm/sparse-vmemmap: remove sparse_vmemmap_init_nid_late()
2026-07-28 21:12:00 -07:00
sparse.c
mm: fix ASSERT_EXCLUSIVE_BITS by passing memdesc_flags_t by pointer
2026-07-30 19:40:31 -07:00
swap_state.c
mm/swap_state: remove unnecessary lru_add_drain() from readahead
2026-07-28 21:12:04 -07:00
swap_table.h
mm, swap: merge zeromap into swap table
2026-06-02 15:22:23 -07:00
swap.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
swap.h
mm/swap: rename subpage->page in folio_dup_swap/folio_put_swap
2026-07-28 21:11:44 -07:00
swapfile.c
mm/swap: rename subpage->page in folio_dup_swap/folio_put_swap
2026-07-28 21:11:44 -07:00
truncate.c
mm/truncate: use folio_split() in truncate_inode_partial_folio()
2026-06-21 11:37:16 -07:00
usercopy.c
usercopy: Remove folio references from check_heap_object()
2025-11-13 11:01:08 +01:00
userfaultfd.c
userfaultfd: prevent registration of special VMAs
2026-07-09 15:48:53 -07:00
util.c
mm/util: don't read __page_2 for order-1 folios in snapshot_page()
2026-07-20 17:41:27 -07:00
vma_exec.c
mm: convert do_brk_flags() to use vma_flags_t
2026-04-05 13:53:40 -07:00
vma_init.c
Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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
vma.c
drivers/char/mem: eliminate unnecessary use of success_hook
2026-06-04 14:44:59 -07:00
vma.h
mm: allow handling of stacked mmap_prepare hooks in more drivers
2026-04-05 13:53:44 -07:00
vmalloc.c
mm/vmalloc: add alignment info in warning print as possible failure reason
2026-07-30 19:40:39 -07:00
vmpressure.c
mm/vmpressure: move v1 userspace eventfd code into memcontrol-v1.c
2026-07-30 19:40:28 -07:00
vmscan.c
mm: split out internal page_alloc.h
2026-07-30 19:40:41 -07:00
vmstat.c
mm: move some stuff to mm/page_alloc.h
2026-07-30 19:40:41 -07:00
workingset.c
mm/mglru: use folio_mark_accessed to replace folio_set_active
2026-06-04 14:45:02 -07:00
zpdesc.h
mm: zpdesc: minor naming and comment corrections
2025-09-21 14:21:59 -07:00
zsmalloc.c
mm/zsmalloc: document free_zspage helper variants
2026-07-28 21:12:03 -07:00
zswap.c
mm, swap: add support for stable large allocation in swap cache directly
2026-06-02 15:22:21 -07:00