linux.git/kernel/liveupdate/luo_session.c, branch v7.3-rc2

Merge branch 'misc' into next

2026-08-04T07:51:49+00:00

liveupdate: reject nonzero reserved value for SESSION_FINISH

2026-07-25T12:26:30+00:00

The UAPI documents liveupdate_session_finish::reserved as requiring zero,
but luo_session_finish() currently ignores it and finishes the session.
Accepting nonzero values prevents the field from being safely repurposed
by a future extension.

Reject nonzero reserved values before changing session state, matching
LIVEUPDATE_SESSION_GET_NAME.

Fixes: 16cec0d26521 ("liveupdate: luo_session: add ioctls for file preservation")
Assisted-by: Codex:gpt-5.6-sol
Reviewed-by: Pratyush Yadav (Google) 
Signed-off-by: Jackie Liu 
Link: https://patch.msgid.link/20260716012607.22020-2-liu.yun@linux.dev
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: fix GET_NAME ioctl argument validation

2026-07-16T06:25:30+00:00

LIVEUPDATE_SESSION_GET_NAME was developed in the liveupdate/next branch
while the session type validation change was carried in liveupdate-fixes.
When the conflict between the two branches was resolved, the GET_NAME
operation descriptor picked up the structure and last member from
RETRIEVE_FD.

This makes both its known size and minimum size 16 bytes rather than 72.
A zero-initialized request still succeeds because luo_session_get_name()
writes the full name before luo_ucmd_respond() copies the full GET_NAME
response to userspace. However, copy_struct_from_user() treats the
output-only name field as unknown trailing data and rejects the request
with -E2BIG if any byte in that field is nonzero.

Use the GET_NAME structure and its name field in the descriptor.

Link: https://lore.kernel.org/all/ahWlYXNjGUbkKoHy@sirena.org.uk/
Assisted-by: Codex:gpt-5.6-sol
Reviewed-by: Pratyush Yadav (Google) 
Signed-off-by: Jackie Liu 
Link: https://patch.msgid.link/20260716012607.22020-1-liu.yun@linux.dev
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: Remove redundant INIT_LIST_HEAD in luo_session_alloc

2026-07-15T06:34:06+00:00

luo_session_alloc() calls INIT_LIST_HEAD(&session->file_set.files_list)
followed immediately by luo_file_set_init(), which also performs
INIT_LIST_HEAD() on the same list head. Remove the duplicate call.

Signed-off-by: Hongfu Li 
Reviewed-by: Pratyush Yadav 
Link: https://patch.msgid.link/20260714074056.95335-1-hongfu.li@linux.dev
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: Remove limit on the number of sessions

2026-06-03T18:15:46+00:00

Currently, the number of LUO sessions is limited by a fixed number of
pre-allocated pages for serialization (16 pages, allowing for ~819
sessions).

This limitation is problematic if LUO is used to support things such as
systemd file descriptor store, and would be used not just as VM memory
but to save other states on the machine.

Remove this limit by transitioning to a linked-block approach for
session metadata serialization. Instead of a single contiguous block,
session metadata is now stored in a chain of 16-page blocks. Each block
starts with a header containing the physical address of the next block
and the number of session entries in the current block.

Acked-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav (Google) 
Signed-off-by: Pasha Tatashin 
Link: https://patch.msgid.link/20260603154402.468928-10-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: defer session block allocation and physical address setting

2026-06-03T18:15:46+00:00

Currently, luo_session_setup_outgoing() allocates the session block and
sets its physical address in the header immediately. With upcoming
dynamic block-based session management, this makes the first block
different from the rest. Move the allocation to where it is first needed.

Acked-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav (Google) 
Signed-off-by: Pasha Tatashin 
Link: https://patch.msgid.link/20260603154402.468928-9-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: Extract luo_session_deserialize_one helper

2026-06-03T18:15:46+00:00

Extract the logic for deserializing single entries for sessions into
separate helper functions. In preparation to a linked-block
serialization for sessions.

This is a pure code movement, no other changes intended.

Acked-by: Mike Rapoport (Microsoft) 
Reviewed-by: Pratyush Yadav (Google) 
Signed-off-by: Pasha Tatashin 
Link: https://patch.msgid.link/20260603154402.468928-7-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: centralize state management into struct luo_ser

2026-06-03T18:15:45+00:00

Transition the LUO to ABI v2, which centralizes state management into a
single struct luo_ser header.

Previously, LUO state was spread across multiple FDT properties and
subnodes. ABI v2 simplifies this by placing all core state, including
the liveupdate number and physical addresses for sessions and FLB
headers into a centralized struct luo_ser.

Note that this change introduces a semantic difference: the sessions
and FLB serialization formats are no longer completely independent of
the core LUO. Their metadata (such as physical addresses for sessions
and FLB headers) is now coupled to and managed via the centralized
struct luo_ser.

Reviewed-by: Pratyush Yadav (Google) 
Acked-by: Mike Rapoport (Microsoft) 
Signed-off-by: Pasha Tatashin 
Link: https://patch.msgid.link/20260603154402.468928-4-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: avoid mixing cleanup guards with goto in luo_session_retrieve_fd

2026-06-03T18:15:45+00:00

Refactoring luo_session_retrieve_fd() to avoid mixing automated
cleanup-style guards with goto-based resource release, which is not
recommended under the Linux kernel coding style.

Reviewed-by: Pratyush Yadav (Google) 
Acked-by: Mike Rapoport (Microsoft) 
Signed-off-by: Pasha Tatashin 
Link: https://patch.msgid.link/20260603154402.468928-3-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)

liveupdate: block session mutations during reboot

2026-06-01T06:19:38+00:00

During the reboot() syscall, user processes may still be running
concurrently and attempting to mutate sessions (e.g., creating,
retrieving, or releasing sessions). To prevent this, introduce
luo_session_serialize_rwsem to synchronize mutations with the
serialization process.

All session mutation operations (create, retrieve, release, ioctl) take
the read lock. The serialization process (luo_session_serialize) takes
the write lock and holds it indefinitely on success. This effectively
freezes the LUO session subsystem during the transition to the new
kernel. If serialization fails, the lock is released to allow recovery.

Fixes: 0153094d03df ("liveupdate: luo_session: add sessions support")
Reported-by: Oskar Gerlicz Kowalczuk 
Acked-by: Mike Rapoport (Microsoft) 
Signed-off-by: Pasha Tatashin 
Reviewed-by: Pratyush Yadav (Google) 
Link: https://patch.msgid.link/20260527202737.1345192-4-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft)