Merge tag 'mm-hotfixes-stable-2025-11-10-19-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
"26 hotfixes. 22(!) are cc:stable, 22 are MM.

- add

Merge tag 'mm-hotfixes-stable-2025-11-10-19-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
"26 hotfixes. 22(!) are cc:stable, 22 are MM.

- address some Kexec Handover issues (Pasha Tatashin)

- fix handling of large folios which are mapped outside i_size (Kiryl
Shutsemau)

- fix some DAMON time issues on 32-bit machines (Quanmin Yan)

Plus the usual shower of singletons"

* tag 'mm-hotfixes-stable-2025-11-10-19-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (26 commits)
kho: warn and exit when unpreserved page wasn't preserved
kho: fix unpreservation of higher-order vmalloc preservations
kho: fix out-of-bounds access of vmalloc chunk
MAINTAINERS: add Chris and Kairui as the swap maintainer
mm/secretmem: fix use-after-free race in fault handler
mm/huge_memory: initialise the tags of the huge zero folio
nilfs2: avoid having an active sc_timer before freeing sci
scripts/decode_stacktrace.sh: fix build ID and PC source parsing
mm/damon/sysfs: change next_update_jiffies to a global variable
mm/damon/stat: change last_refresh_jiffies to a global variable
maple_tree: fix tracepoint string pointers
codetag: debug: handle existing CODETAG_EMPTY in mark_objexts_empty for slabobj_ext
mm/mremap: honour writable bit in mremap pte batching
gcov: add support for GCC 15
mm/mm_init: fix hash table order logging in alloc_large_system_hash()
mm/truncate: unmap large folio on split failure
mm/memory: do not populate page table entries beyond i_size
fs/proc: fix uaf in proc_readdir_de()
mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order
ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
...

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kho: warn and fail on metadata or preserved memory in scratch area

Patch series "KHO: kfence + KHO memory corruption fix", v3.

This series fixes a memory corruption bug in KHO that occurs when KFEN

kho: warn and fail on metadata or preserved memory in scratch area

Patch series "KHO: kfence + KHO memory corruption fix", v3.

This series fixes a memory corruption bug in KHO that occurs when KFENCE
is enabled.

The root cause is that KHO metadata, allocated via kzalloc(), can be
randomly serviced by kfence_alloc(). When a kernel boots via KHO, the
early memblock allocator is restricted to a "scratch area". This forces
the KFENCE pool to be allocated within this scratch area, creating a
conflict. If KHO metadata is subsequently placed in this pool, it gets
corrupted during the next kexec operation.

Google is using KHO and have had obscure crashes due to this memory
corruption, with stacks all over the place. I would prefer this fix to be
properly backported to stable so we can also automatically consume it once
we switch to the upstream KHO.

Patch 1/3 introduces a debug-only feature (CONFIG_KEXEC_HANDOVER_DEBUG)
that adds checks to detect and fail any operation that attempts to place
KHO metadata or preserved memory within the scratch area. This serves as
a validation and diagnostic tool to confirm the problem without affecting
production builds.

Patch 2/3 Increases bitmap to PAGE_SIZE, so buddy allocator can be used.

Patch 3/3 Provides the fix by modifying KHO to allocate its metadata
directly from the buddy allocator instead of slab. This bypasses the
KFENCE interception entirely.


This patch (of 3):

It is invalid for KHO metadata or preserved memory regions to be located
within the KHO scratch area, as this area is overwritten when the next
kernel is loaded, and used early in boot by the next kernel. This can
lead to memory corruption.

Add checks to kho_preserve_* and KHO's internal metadata allocators
(xa_load_or_alloc, new_chunk) to verify that the physical address of the
memory does not overlap with any defined scratch region. If an overlap is
detected, the operation will fail and a WARN_ON is triggered. To avoid
performance overhead in production kernels, these checks are enabled only
when CONFIG_KEXEC_HANDOVER_DEBUG is selected.

[rppt@kernel.org: fix KEXEC_HANDOVER_DEBUG Kconfig dependency]
Link: https://lkml.kernel.org/r/aQHUyyFtiNZhx8jo@kernel.org
[pasha.tatashin@soleen.com: build fix]
Link: https://lkml.kernel.org/r/CA+CK2bBnorfsTymKtv4rKvqGBHs=y=MjEMMRg_tE-RME6n-zUw@mail.gmail.com
Link: https://lkml.kernel.org/r/20251021000852.2924827-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20251021000852.2924827-2-pasha.tatashin@soleen.com
Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport <rppt@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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