Merge tag 'liveupdate-v7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux

d639d9fa · Linus Torvalds <[email protected]> · 2026-06-21 09:46:14 -07:00

Pull liveupdate updates from Mike Rapoport:
 "Kexec Handover (KHO):

   - make memory preservation compatible with deferred initialization
     of the memory map

  Live Update Orchestrator (LUO):

   - add LIVEUPDATE_SESSION_GET_NAME ioctl and parameter verification
     for LIVEUPDATE_IOCTL_CREATE_SESSION ioctl

   - documentation updates for liveupdate=on command line option,
     systemd support and the current compatibility status

   - remove the fixed limits on the number of files that can be
     preserved within a single session, and the total number of
     sessions managed by the LUO

  Misc fixes:

   - reference count incoming File-Lifecycle-Bound (FLB) data so
     it cannot be freed while a subsystem is still using it

   - fixes for a TOCTOU race in luo_session_retrieve(), a use-
     after-free in the file finish and unpreserve paths, concurrent
     session mutations during reboot and serialization on
     preserve_context kexec

   - make sure ioctls for incoming LUO sessions are blocked for
     outgoing sessions and vice versa

   - make sure KHO scratch size is always aligned by
     CMA_MIN_ALIGNMENT_BYTES

   - fix memblock tests build issue introduced by KHO changes"

* tag 'liveupdate-v7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux: (36 commits)
  liveupdate: Document that retrieve failure is permanent
  docs: memfd_preservation: fix rendering of ABI documentation
  selftests/liveupdate: Add stress-files kexec test
  selftests/liveupdate: Add stress-sessions kexec test
  selftests/liveupdate: Test session and file limit removal
  liveupdate: Remove limit on the number of files per session
  liveupdate: Remove limit on the number of sessions
  liveupdate: defer session block allocation and physical address setting
  kho: add support for linked-block serialization
  liveupdate: Extract luo_session_deserialize_one helper
  liveupdate: Extract luo_file_deserialize_one helper
  liveupdate: register luo_ser as KHO subtree
  liveupdate: centralize state management into struct luo_ser
  liveupdate: avoid mixing cleanup guards with goto in luo_session_retrieve_fd
  liveupdate: change file_set->count type to u64 for type safety
  liveupdate: Remove unused ser field from struct luo_session
  liveupdate: fix u-a-f in luo_file_unpreserve_files() and luo_file_finish()
  liveupdate: block session mutations during reboot
  liveupdate: fix TOCTOU race in luo_session_retrieve()
  liveupdate: skip serialization for context-preserving kexec
  ...

Commit: d639d9fa162aadec1ae9980c4dcf6e50bd2f8290
Parents: 1e762b53 · e98a9c61

Merge commit. Changes below are compared with the first parent: 1e762b53.

Changes

33 files changed · +1635 −584

File	Status	Add	Del	Content
Documentation/core-api/kho/abi.rst	modified	+5	−0	View file
Documentation/core-api/kho/index.rst	modified	+11	−0	View file
Documentation/mm/memfd_preservation.rst	modified	+1	−1	View file
Documentation/userspace-api/liveupdate.rst	modified	+31	−0	View file
MAINTAINERS	modified	+1	−0	View file
include/linux/kho/abi/block.h	added	+54	−0	View file
include/linux/kho/abi/kexec_handover.h	modified	+2	−2	View file
include/linux/kho/abi/luo.h	modified	+43	−105	View file
include/linux/kho_block.h	added	+106	−0	View file
include/linux/liveupdate.h	modified	+8	−1	View file
include/linux/memblock.h	modified	+19	−2	View file
include/uapi/linux/liveupdate.h	modified	+24	−1	View file
kernel/kexec_core.c	modified	+5	−3	View file
kernel/liveupdate/Kconfig	modified	+0	−2	View file
kernel/liveupdate/Makefile	modified	+1	−0	View file
kernel/liveupdate/kexec_handover.c	modified	+47	−37	View file
kernel/liveupdate/kho_block.c	added	+416	−0	View file
kernel/liveupdate/luo_core.c	modified	+48	−55	View file
kernel/liveupdate/luo_file.c	modified	+106	−104	View file
kernel/liveupdate/luo_flb.c	modified	+32	−80	View file
kernel/liveupdate/luo_internal.h	modified	+8	−10	View file
kernel/liveupdate/luo_session.c	modified	+202	−134	View file
lib/tests/liveupdate.c	modified	+3	−0	View file
mm/memblock.c	modified	+22	−34	View file
mm/mm_init.c	modified	+17	−13	View file
tools/testing/memblock/linux/mmzone.h	modified	+4	−0	View file
tools/testing/selftests/kho/vmtest.sh	modified	+4	−0	View file
tools/testing/selftests/liveupdate/Makefile	modified	+2	−0	View file
tools/testing/selftests/liveupdate/liveupdate.c	modified	+188	−0	View file
tools/testing/selftests/liveupdate/luo_stress_files.c	added	+97	−0	View file
tools/testing/selftests/liveupdate/luo_stress_sessions.c	added	+102	−0	View file
tools/testing/selftests/liveupdate/luo_test_utils.c	modified	+24	−0	View file
tools/testing/selftests/liveupdate/luo_test_utils.h	modified	+2	−0	View file

Only the first 600 diff lines are shown. Download the complete patch.

Documentation/core-api/kho/abi.rst

View file

diff --git a/Documentation/core-api/kho/abi.rst b/Documentation/core-api/kho/abi.rst
index 799d743..edeb5b3 100644
--- a/Documentation/core-api/kho/abi.rst
+++ b/Documentation/core-api/kho/abi.rst
@@ -28,6 +28,11 @@ KHO persistent memory tracker ABI
 .. kernel-doc:: include/linux/kho/abi/kexec_handover.h
   :doc: KHO persistent memory tracker
 
+KHO serialization block ABI
+===========================
+
+.. kernel-doc:: include/linux/kho/abi/block.h
+
 See Also
 ========
 

Documentation/core-api/kho/index.rst

View file

diff --git a/Documentation/core-api/kho/index.rst b/Documentation/core-api/kho/index.rst
index 0a2dee4..320914a 100644
--- a/Documentation/core-api/kho/index.rst
+++ b/Documentation/core-api/kho/index.rst
@@ -83,6 +83,17 @@ Public API
 .. kernel-doc:: kernel/liveupdate/kexec_handover.c
   :export:
 
+KHO Serialization Blocks API
+============================
+
+.. kernel-doc:: kernel/liveupdate/kho_block.c
+  :doc: KHO Serialization Blocks
+
+.. kernel-doc:: include/linux/kho_block.h
+
+.. kernel-doc:: kernel/liveupdate/kho_block.c
+  :internal:
+
 See Also
 ========
 

Documentation/mm/memfd_preservation.rst

View file

diff --git a/Documentation/mm/memfd_preservation.rst b/Documentation/mm/memfd_preservation.rst
index a8a5b47..c908a12 100644
--- a/Documentation/mm/memfd_preservation.rst
+++ b/Documentation/mm/memfd_preservation.rst
@@ -11,7 +11,7 @@ Memfd Preservation ABI
 ======================
 
 .. kernel-doc:: include/linux/kho/abi/memfd.h
-   :doc: DOC: memfd Live Update ABI
+   :doc: memfd Live Update ABI
 
 .. kernel-doc:: include/linux/kho/abi/memfd.h
    :internal:

Documentation/userspace-api/liveupdate.rst

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diff --git a/Documentation/userspace-api/liveupdate.rst b/Documentation/userspace-api/liveupdate.rst
index 41c0473..cdd7462 100644
--- a/Documentation/userspace-api/liveupdate.rst
+++ b/Documentation/userspace-api/liveupdate.rst
@@ -14,6 +14,37 @@ ioctl uAPI
 ===========
 .. kernel-doc:: include/uapi/linux/liveupdate.h
 
+Note on Compatibility
+=====================
+
+Note that the Live Update feature is still under development and subject to
+change, so compatibility is not guaranteed when kexec rebooting between
+different kernel versions. This is expected to change and stabilize in a future
+version.
+
+Userspace Integration
+=====================
+
+systemd (since version v261) uses LUO to preserve its per-service file
+descriptor store across a kexec-based live update. Services opt in by setting
+``FileDescriptorStoreMax=`` and ``FileDescriptorStorePreserve=`` in their unit,
+and push file descriptors with a name into the store via
+``sd_pid_notify_with_fds(... "FDSTORE=1\nFDNAME=foo")``.
+
+Services may also create their own LUO sessions (via ``/dev/liveupdate``) and
+push the resulting session fds into their file descriptor store like any other
+fd. systemd detects such session fds and handles them accordingly, and
+hands the re-retrieved session fd back to the service after kexec, using the
+existing file descriptor store service interface.
+
+For details, see:
+
+- `File Descriptor Store <https://systemd.io/FILE_DESCRIPTOR_STORE/>`_
+- `systemd.service(5) FileDescriptorStorePreserve=
+  <https://www.freedesktop.org/software/systemd/man/latest/systemd.service.html#FileDescriptorStorePreserve=>`_
+- `sd_pid_notify_with_fds(3)
+  <https://www.freedesktop.org/software/systemd/man/latest/sd_pid_notify_with_fds.html>`_
+
 See Also
 ========
 

MAINTAINERS

View file

diff --git a/MAINTAINERS b/MAINTAINERS
index d95d3ef..c97c254 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14301,6 +14301,7 @@ F:	Documentation/admin-guide/mm/kho.rst
 F:	Documentation/core-api/kho/*
 F:	include/linux/kexec_handover.h
 F:	include/linux/kho/
+F:	include/linux/kho_block.h
 F:	kernel/liveupdate/kexec_handover*
 F:	lib/test_kho.c
 F:	tools/testing/selftests/kho/

include/linux/kho/abi/block.h

View file

diff --git a/include/linux/kho/abi/block.h b/include/linux/kho/abi/block.h
new file mode 100644
index 0000000..d06d64b
--- /dev/null
+++ b/include/linux/kho/abi/block.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2026, Google LLC.
+ * Pasha Tatashin <[email protected]>
+ */
+
+/**
+ * DOC: KHO Serialization Blocks ABI
+ *
+ * Subsystems using the KHO Serialization Blocks framework rely on the stable
+ * Application Binary Interface defined below to pass serialized state from a
+ * pre-update kernel to a post-update kernel.
+ *
+ * This interface is a contract. Any modification to the structure fields,
+ * compatible strings, or the layout of the `__packed` serialization
+ * structures defined here constitutes a breaking change. Such changes require
+ * incrementing the version number in the `KHO_FDT_COMPATIBLE` string to
+ * prevent a new kernel from misinterpreting data from an old kernel.
+ *
+ * Changes are allowed provided the compatibility version is incremented;
+ * however, backward/forward compatibility is only guaranteed for kernels
+ * supporting the same ABI version.
+ */
+
+#ifndef _LINUX_KHO_ABI_BLOCK_H
+#define _LINUX_KHO_ABI_BLOCK_H
+
+#include <asm/page.h>
+#include <linux/types.h>
+
+/**
+ * KHO_BLOCK_SIZE - The size of each serialization block.
+ *
+ * This is defined as PAGE_SIZE. PAGE_SIZE is ABI compliant because live
+ * update between kernels with different page sizes is not supported by KHO.
+ */
+#define KHO_BLOCK_SIZE			PAGE_SIZE
+
+/**
+ * struct kho_block_header_ser - Header for the serialized data block.
+ * @next:  Physical address of the next struct kho_block_header_ser.
+ * @count: The number of entries that immediately follow this header in the
+ *         memory block.
+ *
+ * This structure is located at the beginning of a block of physical memory
+ * preserved across a kexec. It provides the necessary metadata to interpret
+ * the array of entries that follow.
+ */
+struct kho_block_header_ser {
+	u64 next;
+	u64 count;
+} __packed;
+
+#endif /* _LINUX_KHO_ABI_BLOCK_H */

include/linux/kho/abi/kexec_handover.h

View file

diff --git a/include/linux/kho/abi/kexec_handover.h b/include/linux/kho/abi/kexec_handover.h
index db9bda6..5e2eb85 100644
--- a/include/linux/kho/abi/kexec_handover.h
+++ b/include/linux/kho/abi/kexec_handover.h
@@ -64,7 +64,7 @@
  *   Root KHO Node (/):
  *     - compatible: "kho-v3"
  *
- *       Indentifies the overall KHO ABI version.
+ *       Identifies the overall KHO ABI version.
  *
  *     - preserved-memory-map: u64
  *
@@ -90,7 +90,7 @@
  */
 
 /* The compatible string for the KHO FDT root node. */
-#define KHO_FDT_COMPATIBLE "kho-v3"
+#define KHO_FDT_COMPATIBLE "kho-v4"
 
 /* The FDT property for the preserved memory map. */
 #define KHO_FDT_MEMORY_MAP_PROP_NAME "preserved-memory-map"

include/linux/kho/abi/luo.h

View file

diff --git a/include/linux/kho/abi/luo.h b/include/linux/kho/abi/luo.h
index 46750a0..288076d 100644
--- a/include/linux/kho/abi/luo.h
+++ b/include/linux/kho/abi/luo.h
@@ -10,11 +10,11 @@
  *
  * Live Update Orchestrator uses the stable Application Binary Interface
  * defined below to pass state from a pre-update kernel to a post-update
- * kernel. The ABI is built upon the Kexec HandOver framework and uses a
- * Flattened Device Tree to describe the preserved data.
+ * kernel. The ABI is built upon the Kexec HandOver framework and registers
+ * the central `struct luo_ser` via the KHO raw subtree API.
  *
- * This interface is a contract. Any modification to the FDT structure, node
- * properties, compatible strings, or the layout of the `__packed` serialization
+ * This interface is a contract. Any modification to the structure fields,
+ * compatible strings, or the layout of the `__packed` serialization
  * structures defined here constitutes a breaking change. Such changes require
  * incrementing the version number in the relevant `_COMPATIBLE` string to
  * prevent a new kernel from misinterpreting data from an old kernel.
@@ -23,68 +23,20 @@
  * however, backward/forward compatibility is only guaranteed for kernels
  * supporting the same ABI version.
  *
- * FDT Structure Overview:
+ * KHO Structure Overview:
  *   The entire LUO state is encapsulated within a single KHO entry named "LUO".
- *   This entry contains an FDT with the following layout:
- *
- *   .. code-block:: none
- *
- *     / {
- *         compatible = "luo-v1";
- *         liveupdate-number = <...>;
- *
- *         luo-session {
- *             compatible = "luo-session-v1";
- *             luo-session-header = <phys_addr_of_session_header_ser>;
- *         };
- *
- *         luo-flb {
- *             compatible = "luo-flb-v1";
- *             luo-flb-header = <phys_addr_of_flb_header_ser>;
- *         };
- *     };
- *
- * Main LUO Node (/):
- *
- *   - compatible: "luo-v1"
- *     Identifies the overall LUO ABI version.
- *   - liveupdate-number: u64
- *     A counter tracking the number of successful live updates performed.
- *
- * Session Node (luo-session):
- *   This node describes all preserved user-space sessions.
- *
- *   - compatible: "luo-session-v1"
- *     Identifies the session ABI version.
- *   - luo-session-header: u64
- *     The physical address of a `struct luo_session_header_ser`. This structure
- *     is the header for a contiguous block of memory containing an array of
- *     `struct luo_session_ser`, one for each preserved session.
- *
- * File-Lifecycle-Bound Node (luo-flb):
- *   This node describes all preserved global objects whose lifecycle is bound
- *   to that of the preserved files (e.g., shared IOMMU state).
- *
- *   - compatible: "luo-flb-v1"
- *     Identifies the FLB ABI version.
- *   - luo-flb-header: u64
- *     The physical address of a `struct luo_flb_header_ser`. This structure is
- *     the header for a contiguous block of memory containing an array of
- *     `struct luo_flb_ser`, one for each preserved global object.
+ *   This entry contains the `struct luo_ser` structure.
  *
  * Serialization Structures:
- *   The FDT properties point to memory regions containing arrays of simple,
- *   `__packed` structures. These structures contain the actual preserved state.
- *
- *   - struct luo_session_header_ser:
- *     Header for the session array. Contains the total page count of the
- *     preserved memory block and the number of `struct luo_session_ser`
- *     entries that follow.
+ *   - struct luo_ser:
+ *     The central ABI structure that contains the overall state of the LUO.
+ *     It includes the compatibility string, the liveupdate-number, and pointers
+ *     to sessions and FLBs.
  *
  *   - struct luo_session_ser:
  *     Metadata for a single session, including its name and a physical pointer
- *     to another preserved memory block containing an array of
- *     `struct luo_file_ser` for all files in that session.
+ *     to the first `struct kho_block_header_ser` for all files in that session.
+ *     Multiple blocks are linked via the `next` field in the header.
  *
  *   - struct luo_file_ser:
  *     Metadata for a single preserved file. Contains the `compatible` string to
@@ -105,17 +57,32 @@
 #ifndef _LINUX_KHO_ABI_LUO_H
 #define _LINUX_KHO_ABI_LUO_H
 
+#include <linux/align.h>
+#include <linux/kho/abi/block.h>
 #include <uapi/linux/liveupdate.h>
 
 /*
- * The LUO FDT hooks all LUO state for sessions, fds, etc.
- * In the root it also carries "liveupdate-number" 64-bit property that
- * corresponds to the number of live-updates performed on this machine.
+ * The LUO state is registered under this KHO entry name.
  */
-#define LUO_FDT_SIZE		PAGE_SIZE
-#define LUO_FDT_KHO_ENTRY_NAME	"LUO"
-#define LUO_FDT_COMPATIBLE	"luo-v1"
-#define LUO_FDT_LIVEUPDATE_NUM	"liveupdate-number"
+#define LUO_KHO_ENTRY_NAME	"LUO"
+#define LUO_ABI_COMPATIBLE	"luo-v5"
+#define LUO_ABI_COMPAT_LEN	ALIGN(sizeof(LUO_ABI_COMPATIBLE), 8)
+
+/**
+ * struct luo_ser - Centralized LUO ABI header.
+ * @compatible:     Compatibility string identifying the LUO ABI version.
+ * @liveupdate_num: A counter tracking the number of successful live updates.
+ * @sessions_pa:    Physical address of the first session block header.
+ * @flbs_pa:        Physical address of the FLB header.
+ *
+ * This structure is the root of all preserved LUO state.
+ */
+struct luo_ser {
+	char compatible[LUO_ABI_COMPAT_LEN];
+	u64 liveupdate_num;
+	u64 sessions_pa;
+	u64 flbs_pa;
+} __packed;
 
 #define LIVEUPDATE_HNDL_COMPAT_LENGTH	48
 
@@ -125,7 +92,7 @@
  * @data:        Private data
  * @token:       User provided token for this file
  *
- * If this structure is modified, LUO_SESSION_COMPATIBLE must be updated.
+ * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated.
  */
 struct luo_file_ser {
 	char compatible[LIVEUPDATE_HNDL_COMPAT_LENGTH];
@@ -135,9 +102,10 @@ struct luo_file_ser {
 
 /**
  * struct luo_file_set_ser - Represents the serialized metadata for file set
- * @files:   The physical address of a contiguous memory block that holds
- *           the serialized state of files (array of luo_file_ser) in this file
- *           set.
+ * @files:   The physical address of the first `struct kho_block_header_ser`.
+ *           This structure is the header for a block of memory containing
+ *           an array of `struct luo_file_ser` entries. Multiple blocks are
+ *           linked via the `next` field in the header.
  * @count:   The total number of files that were part of this session during
  *           serialization. Used for iteration and validation during
  *           restoration.
@@ -147,30 +115,6 @@ struct luo_file_set_ser {
 	u64 count;
 } __packed;
 
-/*
- * LUO FDT session node
- * LUO_FDT_SESSION_HEADER:  is a u64 physical address of struct
- *                          luo_session_header_ser
- */
-#define LUO_FDT_SESSION_NODE_NAME	"luo-session"
-#define LUO_FDT_SESSION_COMPATIBLE	"luo-session-v2"
-#define LUO_FDT_SESSION_HEADER		"luo-session-header"
-
-/**
- * struct luo_session_header_ser - Header for the serialized session data block.
- * @count: The number of `struct luo_session_ser` entries that immediately
- *         follow this header in the memory block.
- *
- * This structure is located at the beginning of a contiguous block of
- * physical memory preserved across the kexec. It provides the necessary
- * metadata to interpret the array of session entries that follow.
- *
- * If this structure is modified, `LUO_FDT_SESSION_COMPATIBLE` must be updated.
- */
-struct luo_session_header_ser {
-	u64 count;
-} __packed;
-
 /**
  * struct luo_session_ser - Represents the serialized metadata for a LUO session.
  * @name:         The unique name of the session, provided by the userspace at
@@ -182,7 +126,7 @@ struct luo_session_header_ser {
  * session) is created and passed to the new kernel, allowing it to reconstruct
  * the session context.
  *
- * If this structure is modified, `LUO_FDT_SESSION_COMPATIBLE` must be updated.
+ * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated.
  */
 struct luo_session_ser {
 	char name[LIVEUPDATE_SESSION_NAME_LENGTH];
@@ -192,10 +136,6 @@ struct luo_session_ser {
 /* The max size is set so it can be reliably used during in serialization */
 #define LIVEUPDATE_FLB_COMPAT_LENGTH	48
 
-#define LUO_FDT_FLB_NODE_NAME	"luo-flb"
-#define LUO_FDT_FLB_COMPATIBLE	"luo-flb-v1"
-#define LUO_FDT_FLB_HEADER	"luo-flb-header"
-
 /**
  * struct luo_flb_header_ser - Header for the serialized FLB data block.
  * @pgcnt: The total number of pages occupied by the entire preserved memory
@@ -205,11 +145,9 @@ struct luo_session_ser {
  *         in the memory block.
  *
  * This structure is located at the physical address specified by the
- * `LUO_FDT_FLB_HEADER` FDT property. It provides the new kernel with the
- * necessary information to find and iterate over the array of preserved
- * File-Lifecycle-Bound objects and to manage the underlying memory.
+ * flbs_pa in luo_ser.
  *
- * If this structure is modified, LUO_FDT_FLB_COMPATIBLE must be updated.
+ * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated.
  */
 struct luo_flb_header_ser {
 	u64 pgcnt;
@@ -231,7 +169,7 @@ struct luo_flb_header_ser {
  * passed to the new kernel. Each entry allows the LUO core to restore one
  * global, shared object.
  *
- * If this structure is modified, LUO_FDT_FLB_COMPATIBLE must be updated.
+ * If this structure is modified, `LUO_ABI_COMPATIBLE` must be updated.
  */
 struct luo_flb_ser {
 	char name[LIVEUPDATE_FLB_COMPAT_LENGTH];

include/linux/kho_block.h

View file

diff --git a/include/linux/kho_block.h b/include/linux/kho_block.h
new file mode 100644
index 0000000..93a7cc2
--- /dev/null
+++ b/include/linux/kho_block.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2026, Google LLC.
+ * Pasha Tatashin <[email protected]>
+ */
+
+#ifndef _LINUX_KHO_BLOCK_H
+#define _LINUX_KHO_BLOCK_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/kho/abi/block.h>
+
+/**
+ * struct kho_block - Internal representation of a serialization block.
+ * @list: List head for linking blocks in memory.
+ * @ser:  Pointer to the serialized header in preserved memory.
+ */
+struct kho_block {
+	struct list_head list;
+	struct kho_block_header_ser *ser;
+};
+
+/**
+ * struct kho_block_set - A set of blocks containing serialized entries of the same type.
+ * @blocks:          The list of serialization blocks (struct kho_block).
+ * @nblocks:         The number of allocated serialization blocks.
+ * @head_pa:         Physical address of the first block header.
+ * @entry_size:      The size of each entry in the blocks.
+ * @count_per_block: The maximum number of entries each block can hold.
+ * @incoming:        True if this block set was restored from the previous kernel.
+ *
+ * Note: Synchronization and locking are the responsibility of the caller.
+ * The block set structure itself is not internally synchronized.
+ */
+struct kho_block_set {
+	struct list_head blocks;
+	long nblocks;
+	u64 head_pa;
+	size_t entry_size;
+	u64 count_per_block;
+	bool incoming;
+};
+
+/**
+ * struct kho_block_set_it - Iterator for serializing entries into blocks.
+ * @bs:         The block set being iterated.
+ * @block:      The current block.
+ * @i:          The current entry index within @block.
+ */
+struct kho_block_set_it {
+	struct kho_block_set *bs;
+	struct kho_block *block;
+	u64 i;
+};
+
+/**
+ * KHO_BLOCK_SET_INIT - Initialize a static kho_block_set.
+ * @_name:       Name of the kho_block_set variable.
+ * @_entry_size: The size of each entry in the block set.
+ */
+#define KHO_BLOCK_SET_INIT(_name, _entry_size) {			\
+	.blocks = LIST_HEAD_INIT((_name).blocks),			\
+	.entry_size = _entry_size,					\
+	.count_per_block = (KHO_BLOCK_SIZE -				\
+			    sizeof(struct kho_block_header_ser)) /	\
+			   (_entry_size),				\
+}
+
+void kho_block_set_init(struct kho_block_set *bs, size_t entry_size);
+
+int kho_block_set_grow(struct kho_block_set *bs, u64 count);
+void kho_block_set_shrink(struct kho_block_set *bs, u64 count);
+
+int kho_block_set_restore(struct kho_block_set *bs, u64 head_pa);
+void kho_block_set_destroy(struct kho_block_set *bs);
+void kho_block_set_clear(struct kho_block_set *bs);
+
+/**
+ * kho_block_set_head_pa - Get the physical address of the first block header.
+ * @bs: The block set.
+ *
+ * Return: The physical address of the first block header, or 0 if empty.
+ */
+static inline u64 kho_block_set_head_pa(struct kho_block_set *bs)
+{
+	return bs->head_pa;
+}
+
+/**
+ * kho_block_set_is_empty - Check if the block set has no allocated blocks.
+ * @bs: The block set.
+ *
+ * Return: True if there are no blocks in the set, false otherwise.
+ */
+static inline bool kho_block_set_is_empty(struct kho_block_set *bs)
+{
+	return list_empty(&bs->blocks);
+}
+
+void kho_block_set_it_init(struct kho_block_set_it *it, struct kho_block_set *bs);
+void *kho_block_set_it_reserve_entry(struct kho_block_set_it *it);
+void *kho_block_set_it_read_entry(struct kho_block_set_it *it);
+void *kho_block_set_it_prev(struct kho_block_set_it *it);
+
+#endif /* _LINUX_KHO_BLOCK_H */

include/linux/liveupdate.h

View file

diff --git a/include/linux/liveupdate.h b/include/linux/liveupdate.h
index 30c5a39..88722e5 100644
--- a/include/linux/liveupdate.h
+++ b/include/linux/liveupdate.h
@@ -12,6 +12,7 @@
 #include <linux/kho/abi/luo.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/refcount.h>
 #include <linux/rwsem.h>
 #include <linux/types.h>
 #include <uapi/linux/liveupdate.h>
@@ -175,7 +176,7 @@ struct liveupdate_flb_ops {
  * @retrieved: True once the FLB's retrieve() callback has run.
  */
 struct luo_flb_private_state {
-	long count;
+	refcount_t count;
 	u64 data;
 	void *obj;
 	struct mutex lock;
@@ -239,6 +240,8 @@ void liveupdate_unregister_flb(struct liveupdate_file_handler *fh,
 			       struct liveupdate_flb *flb);
 
 int liveupdate_flb_get_incoming(struct liveupdate_flb *flb, void **objp);
+void liveupdate_flb_put_incoming(struct liveupdate_flb *flb);
+
 int liveupdate_flb_get_outgoing(struct liveupdate_flb *flb, void **objp);
 
 #else /* CONFIG_LIVEUPDATE */
@@ -279,6 +282,10 @@ static inline int liveupdate_flb_get_incoming(struct liveupdate_flb *flb,
 	return -EOPNOTSUPP;
 }
 
+static inline void liveupdate_flb_put_incoming(struct liveupdate_flb *flb)
+{
+}
+
 static inline int liveupdate_flb_get_outgoing(struct liveupdate_flb *flb,
 					      void **objp)
 {

include/linux/memblock.h

View file

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index b0f750d..5afcd99 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -613,11 +613,28 @@ static inline void memtest_report_meminfo(struct seq_file *m) { }
 #ifdef CONFIG_MEMBLOCK_KHO_SCRATCH
 void memblock_set_kho_scratch_only(void);
 void memblock_clear_kho_scratch_only(void);
-void memmap_init_kho_scratch_pages(void);
+bool memblock_is_kho_scratch_memory(phys_addr_t addr);
+
+static inline enum migratetype kho_scratch_migratetype(unsigned long pfn,
+						       enum migratetype mt)
+{
+	if (memblock_is_kho_scratch_memory(PFN_PHYS(pfn)))
+		return MIGRATE_CMA;
+	return mt;
+}
 #else
 static inline void memblock_set_kho_scratch_only(void) { }
 static inline void memblock_clear_kho_scratch_only(void) { }
-static inline void memmap_init_kho_scratch_pages(void) {}
+static inline bool memblock_is_kho_scratch_memory(phys_addr_t addr)
+{
+	return false;
+}