linux-toradex.git/kernel/liveupdate, branch v6.19-rc2

mm: memfd_luo: add CONFIG_SHMEM dependency

2025-12-11T00:07:44+00:00

The new memfd code fails to link without SHMEM:

aarch64-linux-ld: mm/memfd_luo.o: in function `memfd_luo_retrieve_folios':
memfd_luo.c:(.text.memfd_luo_retrieve_folios+0xdc): undefined reference to `shmem_add_to_page_cache'
memfd_luo.c:(.text.memfd_luo_retrieve_folios+0x11c): undefined reference to `shmem_inode_acct_blocks'
memfd_luo.c:(.text.memfd_luo_retrieve_folios+0x134): undefined reference to `shmem_recalc_inode'

Add a Kconfig dependency to disallow that configuration.

Link: https://lkml.kernel.org/r/20251204100203.1034394-1-arnd@kernel.org
Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd")
Signed-off-by: Arnd Bergmann 
Reviewed-by: Pratyush Yadav 
Acked-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pasha Tatashin 
Signed-off-by: Andrew Morton

liveupdate: luo_core: fix redundant bound check in luo_ioctl()

2025-12-11T00:07:42+00:00

The kernel test robot reported a Smatch warning:
kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is
never less than zero.

This occurs because 'nr' is unsigned and LIVEUPDATE_CMD_BASE is currently
defined as 0, making the check (nr < LIVEUPDATE_CMD_BASE) always false.

Remove the explicit lower bound check.  The logic remains correct because
'nr' is unsigned; if nr is less than LIVEUPDATE_CMD_BASE, the expression
(nr - LIVEUPDATE_CMD_BASE) will wrap around to a large positive value. 
This will inevitably be larger than ARRAY_SIZE(luo_ioctl_ops) and be
caught by the upper bound check.

Link: https://lkml.kernel.org/r/20251130010919.1488230-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202511280300.6pvBmXUS-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) 
Cc: David Matlack 
Cc: Pratyush Yadav 
Signed-off-by: Andrew Morton

liveupdate: luo_file: don't use invalid list iterator

2025-12-11T00:07:41+00:00

If we exit a list_for_each_entry() without hitting a break then the list
iterator points to an offset from the list_head.  It's a non-NULL but
invalid pointer and dereferencing it isn't allowed.

Introduce a new "found" variable to test instead.

Link: https://lkml.kernel.org/r/aSlMc4SS09Re4_xn@stanley.mountain
Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Dan Carpenter 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pasha Tatashin 
Cc: Pratyush Yadav 
Signed-off-by: Andrew Morton

kho: fix restoring of contiguous ranges of order-0 pages

2025-11-27T22:24:44+00:00

When contiguous ranges of order-0 pages are restored, kho_restore_page()
calls prep_compound_page() with the first page in the range and order as
parameters and then kho_restore_pages() calls split_page() to make sure
all pages in the range are order-0.

However, since split_page() is not intended to split compound pages and
with VM_DEBUG enabled it will trigger a VM_BUG_ON_PAGE().

Update kho_restore_page() so that it will use prep_compound_page() when it
restores a folio and make sure it properly sets page count for both large
folios and ranges of order-0 pages.

Link: https://lkml.kernel.org/r/20251125110917.843744-3-rppt@kernel.org
Fixes: a667300bd53f ("kho: add support for preserving vmalloc allocations")
Signed-off-by: Mike Rapoport (Microsoft) 
Reported-by: Pratyush Yadav 
Cc: Alexander Graf 
Cc: Pasha Tatashin 
Signed-off-by: Andrew Morton

kho: kho_restore_vmalloc: fix initialization of pages array

2025-11-27T22:24:44+00:00

Patch series "kho: fixes for vmalloc restoration".

Pratyush reported off-list that when kho_restore_vmalloc() is used to
restore a vmalloc_huge() allocation it hits VM_BUG_ON() when we
reconstruct the struct pages in kho_restore_pages().

These patches fix the issue.


This patch (of 2):

In case a preserved vmalloc allocation was using huge pages, all pages in
the array of pages added to vm_struct during kho_restore_vmalloc() are
wrongly set to the same page.

Fix the indexing when assigning pages to that array.

Link: https://lkml.kernel.org/r/20251125110917.843744-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20251125110917.843744-2-rppt@kernel.org
Fixes: a667300bd53f ("kho: add support for preserving vmalloc allocations")
Signed-off-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav 
Cc: Alexander Graf 
Cc: Pasha Tatashin 
Signed-off-by: Andrew Morton

KHO: fix boot failure due to kmemleak access to non-PRESENT pages

2025-11-27T22:24:43+00:00

When booting with debug_pagealloc=on while having:
CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y
CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=n
the system fails to boot due to page faults during kmemleak scanning.

This occurs because:
With debug_pagealloc is enabled, __free_pages() invokes
debug_pagealloc_unmap_pages(), clearing the _PAGE_PRESENT bit for freed
pages in the kernel page table.  KHO scratch areas are allocated from
memblock and noted by kmemleak.  But these areas don't remain reserved but
released later to the page allocator using init_cma_reserved_pageblock(). 
This causes subsequent kmemleak scans access non-PRESENT pages, leading to
fatal page faults.

Mark scratch areas with kmemleak_ignore_phys() after they are allocated
from memblock to exclude them from kmemleak scanning before they are
released to buddy allocator to fix this.

[ran.xiaokai@zte.com.cn: add comment]
  Link: https://lkml.kernel.org/r/20251127122700.103927-1-ranxiaokai627@163.com
Link: https://lkml.kernel.org/r/20251122182929.92634-1-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai 
Reviewed-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav 
Cc: Alexander Graf 
Cc: Catalin Marinas 
Cc: Changyuan Lyu 
Cc: Pasha Tatashin 
Signed-off-by: Andrew Morton

kho: free chunks using free_page() instead of kfree()

2025-11-27T22:24:42+00:00

Before commit fa759cd75bce5 ("kho: allocate metadata directly from the
buddy allocator"), the chunks were allocated from the slab allocator using
kzalloc().  Those were rightly freed using kfree().

When the commit switched to using the buddy allocator directly, it missed
updating kho_mem_ser_free() to use free_page() instead of kfree().

Link: https://lkml.kernel.org/r/20251118182218.63044-1-pratyush@kernel.org
Fixes: fa759cd75bce5 ("kho: allocate metadata directly from the buddy allocator")
Signed-off-by: Pratyush Yadav 
Reviewed-by: Pasha Tatashin 
Reviewed-by: Mike Rapoport (Microsoft) 
Cc: Alexander Graf 
Cc: David Matlack 
Signed-off-by: Andrew Morton

liveupdate: luo_file: add private argument to store runtime state

2025-11-27T22:24:40+00:00

Currently file handlers only get the serialized_data field to store their
state.  This field has a pointer to the serialized state of the file, and
it becomes a part of LUO file's serialized state.

File handlers can also need some runtime state to track information that
shouldn't make it in the serialized data.

One such example is a vmalloc pointer.  While kho_preserve_vmalloc()
preserves the memory backing a vmalloc allocation, it does not store the
original vmap pointer, since that has no use being passed to the next
kernel.  The pointer is needed to free the memory in case the file is
unpreserved.

Provide a private field in struct luo_file and pass it to all the
callbacks.  The field's can be set by preserve, and must be freed by
unpreserve.

Link: https://lkml.kernel.org/r/20251125165850.3389713-14-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav 
Co-developed-by: Pasha Tatashin 
Signed-off-by: Pasha Tatashin 
Reviewed-by: Mike Rapoport (Microsoft) 
Tested-by: David Matlack 
Cc: Aleksander Lobakin 
Cc: Alexander Graf 
Cc: Alice Ryhl 
Cc: Andriy Shevchenko 
Cc: anish kumar 
Cc: Anna Schumaker 
Cc: Bartosz Golaszewski 
Cc: Bjorn Helgaas 
Cc: Borislav Betkov 
Cc: Chanwoo Choi 
Cc: Chen Ridong 
Cc: Chris Li 
Cc: Christian Brauner 
Cc: Daniel Wagner 
Cc: Danilo Krummrich 
Cc: Dan Williams 
Cc: David Hildenbrand 
Cc: David Jeffery 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Guixin Liu 
Cc: "H. Peter Anvin" 
Cc: Hugh Dickins 
Cc: Ilpo Järvinen 
Cc: Ingo Molnar 
Cc: Ira Weiny 
Cc: Jann Horn 
Cc: Jason Gunthorpe 
Cc: Jens Axboe 
Cc: Joanthan Cameron 
Cc: Joel Granados 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Lennart Poettering 
Cc: Leon Romanovsky 
Cc: Leon Romanovsky 
Cc: Lukas Wunner 
Cc: Marc Rutland 
Cc: Masahiro Yamada 
Cc: Matthew Maurer 
Cc: Miguel Ojeda 
Cc: Myugnjoo Ham 
Cc: Parav Pandit 
Cc: Pratyush Yadav 
Cc: Randy Dunlap 
Cc: Roman Gushchin 
Cc: Saeed Mahameed 
Cc: Samiullah Khawaja 
Cc: Song Liu 
Cc: Steven Rostedt 
Cc: Stuart Hayes 
Cc: Tejun Heo 
Cc: Thomas Gleinxer 
Cc: Thomas Weißschuh 
Cc: Vincent Guittot 
Cc: William Tu 
Cc: Yoann Congal 
Cc: Zhu Yanjun 
Cc: Zijun Hu 
Signed-off-by: Andrew Morton

liveupdate: luo_session: add ioctls for file preservation

2025-11-27T22:24:39+00:00

Introducing the userspace interface and internal logic required to manage
the lifecycle of file descriptors within a session.  Previously, a session
was merely a container; this change makes it a functional management unit.

The following capabilities are added:

A new set of ioctl commands are added, which operate on the file
descriptor returned by CREATE_SESSION. This allows userspace to:
- LIVEUPDATE_SESSION_PRESERVE_FD: Add a file descriptor to a session
  to be preserved across the live update.
- LIVEUPDATE_SESSION_RETRIEVE_FD: Retrieve a preserved file in the
  new kernel using its unique token.
- LIVEUPDATE_SESSION_FINISH: finish session

The session's .release handler is enhanced to be state-aware.  When a
session's file descriptor is closed, it correctly unpreserves the session
based on its current state before freeing all associated file resources.

Link: https://lkml.kernel.org/r/20251125165850.3389713-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin 
Reviewed-by: Pratyush Yadav 
Reviewed-by: Mike Rapoport (Microsoft) 
Tested-by: David Matlack 
Cc: Aleksander Lobakin 
Cc: Alexander Graf 
Cc: Alice Ryhl 
Cc: Andriy Shevchenko 
Cc: anish kumar 
Cc: Anna Schumaker 
Cc: Bartosz Golaszewski 
Cc: Bjorn Helgaas 
Cc: Borislav Betkov 
Cc: Chanwoo Choi 
Cc: Chen Ridong 
Cc: Chris Li 
Cc: Christian Brauner 
Cc: Daniel Wagner 
Cc: Danilo Krummrich 
Cc: Dan Williams 
Cc: David Hildenbrand 
Cc: David Jeffery 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Guixin Liu 
Cc: "H. Peter Anvin" 
Cc: Hugh Dickins 
Cc: Ilpo Järvinen 
Cc: Ingo Molnar 
Cc: Ira Weiny 
Cc: Jann Horn 
Cc: Jason Gunthorpe 
Cc: Jens Axboe 
Cc: Joanthan Cameron 
Cc: Joel Granados 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Lennart Poettering 
Cc: Leon Romanovsky 
Cc: Leon Romanovsky 
Cc: Lukas Wunner 
Cc: Marc Rutland 
Cc: Masahiro Yamada 
Cc: Matthew Maurer 
Cc: Miguel Ojeda 
Cc: Myugnjoo Ham 
Cc: Parav Pandit 
Cc: Pratyush Yadav 
Cc: Randy Dunlap 
Cc: Roman Gushchin 
Cc: Saeed Mahameed 
Cc: Samiullah Khawaja 
Cc: Song Liu 
Cc: Steven Rostedt 
Cc: Stuart Hayes 
Cc: Tejun Heo 
Cc: Thomas Gleinxer 
Cc: Thomas Weißschuh 
Cc: Vincent Guittot 
Cc: William Tu 
Cc: Yoann Congal 
Cc: Zhu Yanjun 
Cc: Zijun Hu 
Signed-off-by: Andrew Morton

liveupdate: luo_file: implement file systems callbacks

2025-11-27T22:24:38+00:00

This patch implements the core mechanism for managing preserved files
throughout the live update lifecycle.  It provides the logic to invoke the
file handler callbacks (preserve, unpreserve, freeze, unfreeze, retrieve,
and finish) at the appropriate stages.

During the reboot phase, luo_file_freeze() serializes the final metadata
for each file (handler compatible string, token, and data handle) into a
memory region preserved by KHO.  In the new kernel, luo_file_deserialize()
reconstructs the in-memory file list from this data, preparing the session
for retrieval.

Link: https://lkml.kernel.org/r/20251125165850.3389713-7-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin 
Reviewed-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav 
Tested-by: David Matlack 
Cc: Aleksander Lobakin 
Cc: Alexander Graf 
Cc: Alice Ryhl 
Cc: Andriy Shevchenko 
Cc: anish kumar 
Cc: Anna Schumaker 
Cc: Bartosz Golaszewski 
Cc: Bjorn Helgaas 
Cc: Borislav Betkov 
Cc: Chanwoo Choi 
Cc: Chen Ridong 
Cc: Chris Li 
Cc: Christian Brauner 
Cc: Daniel Wagner 
Cc: Danilo Krummrich 
Cc: Dan Williams 
Cc: David Hildenbrand 
Cc: David Jeffery 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Guixin Liu 
Cc: "H. Peter Anvin" 
Cc: Hugh Dickins 
Cc: Ilpo Järvinen 
Cc: Ingo Molnar 
Cc: Ira Weiny 
Cc: Jann Horn 
Cc: Jason Gunthorpe 
Cc: Jens Axboe 
Cc: Joanthan Cameron 
Cc: Joel Granados 
Cc: Johannes Weiner 
Cc: Jonathan Corbet 
Cc: Lennart Poettering 
Cc: Leon Romanovsky 
Cc: Leon Romanovsky 
Cc: Lukas Wunner 
Cc: Marc Rutland 
Cc: Masahiro Yamada 
Cc: Matthew Maurer 
Cc: Miguel Ojeda 
Cc: Myugnjoo Ham 
Cc: Parav Pandit 
Cc: Pratyush Yadav 
Cc: Randy Dunlap 
Cc: Roman Gushchin 
Cc: Saeed Mahameed 
Cc: Samiullah Khawaja 
Cc: Song Liu 
Cc: Steven Rostedt 
Cc: Stuart Hayes 
Cc: Tejun Heo 
Cc: Thomas Gleinxer 
Cc: Thomas Weißschuh 
Cc: Vincent Guittot 
Cc: William Tu 
Cc: Yoann Congal 
Cc: Zhu Yanjun 
Cc: Zijun Hu 
Signed-off-by: Andrew Morton