kernel/linux.git/mm/mm_init.c, branch v6.6.149

mm/mm_init: fix pageblock migratetype for ZONE_DEVICE compound pages

2026-08-03T09:15:37+00:00

[ Upstream commit 94405c6136839f7c462249c8b4b957bcb9527a9d ] The memmap_init_zone_device() function only initializes the migratetype of the first pageblock of a compound page. If the compound page size exceeds pageblock_nr_pages (e.g., 1GB hugepages with 2MB pageblocks), subsequent pageblocks in the compound page remain uninitialized. Move the migratetype initialization out of __init_zone_device_page() and into a separate pageblock_migratetype_init_range() function. This iterates over the entire PFN range of the memory, ensuring that all pageblocks are correctly initialized. Also remove the stale confusing comment about MEMINIT_HOTPLUG above the migratetype setting since it is an obsolete relic from commit 966cf44f637e ("mm: defer ZONE_DEVICE page initialization to the point where we init pgmap") and no longer makes sense here. Link: https://lore.kernel.org/20260428081855.1249045-6-songmuchun@bytedance.com Fixes: c4386bd8ee3a ("mm/memremap: add ZONE_DEVICE support for compound pages") Signed-off-by: Muchun Song Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Oscar Salvador Acked-by: David Hildenbrand (Arm) Acked-by: Liam R. Howlett Cc: "Aneesh Kumar K.V" Cc: Joao Martins Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Nicholas Piggin Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm/mm_init: fix uninitialized struct pages for ZONE_DEVICE

2026-07-24T14:03:36+00:00

commit cd681403a87085562499d60325b7b45d3be11217 upstream. If DAX memory is hotplugged into an unoccupied subsection of an early section, section_activate() reuses the unoptimized boot memmap. However, compound_nr_pages() still assumes that vmemmap optimization is in effect and initializes only the reduced number of struct pages. As a result, the remaining tail struct pages are left uninitialized, which can later lead to unexpected behavior or crashes. Fix this by treating early sections as unoptimized when calculating how many struct pages to initialize. Link: https://lore.kernel.org/20260428081855.1249045-7-songmuchun@bytedance.com Fixes: 6fd3620b3428 ("mm/page_alloc: reuse tail struct pages for compound devmaps") Signed-off-by: Muchun Song Acked-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Acked-by: Liam R. Howlett Cc: "Aneesh Kumar K.V" Cc: Joao Martins Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/mm_init: fix hash table order logging in alloc_large_system_hash()

2025-11-24T09:30:07+00:00

commit 0d6c356dd6547adac2b06b461528e3573f52d953 upstream. When emitting the order of the allocation for a hash table, alloc_large_system_hash() unconditionally subtracts PAGE_SHIFT from log base 2 of the allocation size. This is not correct if the allocation size is smaller than a page, and yields a negative value for the order as seen below: TCP established hash table entries: 32 (order: -4, 256 bytes, linear) TCP bind hash table entries: 32 (order: -2, 1024 bytes, linear) Use get_order() to compute the order when emitting the hash table information to correctly handle cases where the allocation size is smaller than a page: TCP established hash table entries: 32 (order: 0, 256 bytes, linear) TCP bind hash table entries: 32 (order: 0, 1024 bytes, linear) Link: https://lkml.kernel.org/r/20251028191020.413002-1-isaacmanjarres@google.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Isaac J. Manjarres Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: David Hildenbrand Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

efi: disable mirror feature during crashkernel

2024-02-01T00:18:56+00:00

commit 7ea6ec4c25294e8bc8788148ef854df92ee8dc5e upstream. If the system has no mirrored memory or uses crashkernel.high while kernelcore=mirror is enabled on the command line then during crashkernel, there will be limited mirrored memory and this usually leads to OOM. To solve this problem, disable the mirror feature during crashkernel. Link: https://lkml.kernel.org/r/20240109041536.3903042-1-mawupeng1@huawei.com Signed-off-by: Ma Wupeng Acked-by: Mike Rapoport (IBM) Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/mm_init: use helper macro BITS_PER_LONG and BITS_PER_BYTE

2023-08-21T20:37:47+00:00

It's more readable to use helper macro BITS_PER_LONG and BITS_PER_BYTE. No functional change intended. Link: https://lkml.kernel.org/r/20230807023528.325191-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Reviewed-by: David Hildenbrand Reviewed-by: Mike Rapoport (IBM) Signed-off-by: Andrew Morton

mm: disable kernelcore=mirror when no mirror memory

2023-08-21T20:37:43+00:00

For system with kernelcore=mirror enabled while no mirrored memory is reported by efi. This could lead to kernel OOM during startup since all memory beside zone DMA are in the movable zone and this prevents the kernel to use it. Zone DMA/DMA32 initialization is independent of mirrored memory and their max pfn is set in zone_sizes_init(). Since kernel can fallback to zone DMA/DMA32 if there is no memory in zone Normal, these zones are seen as mirrored memory no mather their memory attributes are. To solve this problem, disable kernelcore=mirror when there is no real mirrored memory exists. Link: https://lkml.kernel.org/r/20230802072328.2107981-1-mawupeng1@huawei.com Signed-off-by: Ma Wupeng Suggested-by: Kefeng Wang Suggested-by: Mike Rapoport Reviewed-by: Mike Rapoport (IBM) Reviewed-by: Kefeng Wang Cc: Levi Yun Signed-off-by: Andrew Morton

mm: no need to export mm_kobj

2023-08-21T20:37:40+00:00

There are no modules using mm_kobj, so do not export it. Link: https://lkml.kernel.org/r/2023080436-algebra-cabana-417d@gregkh Signed-off-by: Greg Kroah-Hartman Reviewed-by: Mike Rapoport (IBM) Reviewed-by: Miaohe Lin Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton

mm/vmemmap: improve vmemmap_can_optimize and allow architectures to override

2023-08-18T17:12:53+00:00

dax vmemmap optimization requires a minimum of 2 PAGE_SIZE area within vmemmap such that tail page mapping can point to the second PAGE_SIZE area. Enforce that in vmemmap_can_optimize() function. Architectures like powerpc also want to enable vmemmap optimization conditionally (only with radix MMU translation). Hence allow architecture override. Link: https://lkml.kernel.org/r/20230724190759.483013-4-aneesh.kumar@linux.ibm.com Signed-off-by: Aneesh Kumar K.V Reviewed-by: Christophe Leroy Cc: Catalin Marinas Cc: Dan Williams Cc: Joao Martins Cc: Michael Ellerman Cc: Mike Kravetz Cc: Muchun Song Cc: Nicholas Piggin Cc: Oscar Salvador Cc: Will Deacon Signed-off-by: Andrew Morton

mm: kfence: allocate kfence_metadata at runtime

2023-08-18T17:12:39+00:00

kfence_metadata is currently a static array. For the purpose of allocating scalable __kfence_pool, we first change it to runtime allocation of metadata. Since the size of an object of kfence_metadata is 1160 bytes, we can save at least 72 pages (with default 256 objects) without enabling kfence. [akpm@linux-foundation.org: restore newline, per Marco] Link: https://lkml.kernel.org/r/20230718073019.52513-1-zhangpeng.00@bytedance.com Signed-off-by: Peng Zhang Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Muchun Song Signed-off-by: Andrew Morton

mm/mm_init.c: drop node_start_pfn from adjust_zone_range_for_zone_movable()

2023-08-18T17:12:37+00:00

node_start_pfn is not used in adjust_zone_range_for_zone_movable(), so it is pointless to waste a function argument. Drop the parameter. Link: https://lkml.kernel.org/r/20230717065811.1262-1-haifeng.xu@shopee.com Signed-off-by: Haifeng Xu Reviewed-by: David Hildenbrand Reviewed-by: Mike Rapoport (IBM) Reviewed-by: Anshuman Khandual Signed-off-by: Andrew Morton