Merge tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - "panic: sys_info: Refactor and fix a potential issue" (Andy Shevchenko)
   fixes a build issue and does some cleanup in ib/sys_info.c

 - "Implement mul_u64_u64_div_u64_roundup()" (David Laight)
   enhances the 64-bit math code on behalf of a PWM driver and beefs up
   the test module for these library functions

 - "scripts/gdb/symbols: make BPF debug info available to GDB" (Ilya Leoshkevich)
   makes BPF symbol names, sizes, and line numbers available to the GDB
   debugger

 - "Enable hung_task and lockup cases to dump system info on demand" (Feng Tang)
   adds a sysctl which can be used to cause additional info dumping when
   the hung-task and lockup detectors fire

 - "lib/base64: add generic encoder/decoder, migrate users" (Kuan-Wei Chiu)
   adds a general base64 encoder/decoder to lib/ and migrates several
   users away from their private implementations

 - "rbree: inline rb_first() and rb_last()" (Eric Dumazet)
   makes TCP a little faster

 - "liveupdate: Rework KHO for in-kernel users" (Pasha Tatashin)
   reworks the KEXEC Handover interfaces in preparation for Live Update
   Orchestrator (LUO), and possibly for other future clients

 - "kho: simplify state machine and enable dynamic updates" (Pasha Tatashin)
   increases the flexibility of KEXEC Handover. Also preparation for LUO

 - "Live Update Orchestrator" (Pasha Tatashin)
   is a major new feature targeted at cloud environments. Quoting the
   cover letter:

      This series introduces the Live Update Orchestrator, a kernel
      subsystem designed to facilitate live kernel updates using a
      kexec-based reboot. This capability is critical for cloud
      environments, allowing hypervisors to be updated with minimal
      downtime for running virtual machines. LUO achieves this by
      preserving the state of selected resources, such as memory,
      devices and their dependencies, across the kernel transition.

      As a key feature, this series includes support for preserving
      memfd file descriptors, which allows critical in-memory data, such
      as guest RAM or any other large memory region, to be maintained in
      RAM across the kexec reboot.

   Mike Rappaport merits a mention here, for his extensive review and
   testing work.

 - "kexec: reorganize kexec and kdump sysfs" (Sourabh Jain)
   moves the kexec and kdump sysfs entries from /sys/kernel/ to
   /sys/kernel/kexec/ and adds back-compatibility symlinks which can
   hopefully be removed one day

 - "kho: fixes for vmalloc restoration" (Mike Rapoport)
   fixes a BUG which was being hit during KHO restoration of vmalloc()
   regions

* tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (139 commits)
  calibrate: update header inclusion
  Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()"
  vmcoreinfo: track and log recoverable hardware errors
  kho: fix restoring of contiguous ranges of order-0 pages
  kho: kho_restore_vmalloc: fix initialization of pages array
  MAINTAINERS: TPM DEVICE DRIVER: update the W-tag
  init: replace simple_strtoul with kstrtoul to improve lpj_setup
  KHO: fix boot failure due to kmemleak access to non-PRESENT pages
  Documentation/ABI: new kexec and kdump sysfs interface
  Documentation/ABI: mark old kexec sysfs deprecated
  kexec: move sysfs entries to /sys/kernel/kexec
  test_kho: always print restore status
  kho: free chunks using free_page() instead of kfree()
  selftests/liveupdate: add kexec test for multiple and empty sessions
  selftests/liveupdate: add simple kexec-based selftest for LUO
  selftests/liveupdate: add userspace API selftests
  docs: add documentation for memfd preservation via LUO
  mm: memfd_luo: allow preserving memfd
  liveupdate: luo_file: add private argument to store runtime state
  mm: shmem: export some functions to internal.h
  ...

1 files changed, 348 insertions, 0 deletions

diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
new file mode 100644
index 000000000000..c2878e3d5ef9
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/liveupdate.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+
+/*
+ * Selftests for the Live Update Orchestrator.
+ * This test suite verifies the functionality and behavior of the
+ * /dev/liveupdate character device and its session management capabilities.
+ *
+ * Tests include:
+ * - Device access: basic open/close, and enforcement of exclusive access.
+ * - Session management: creation of unique sessions, and duplicate name detection.
+ * - Resource preservation: successfully preserving individual and multiple memfds,
+ *   verifying contents remain accessible.
+ * - Complex multi-session scenarios involving mixed empty and populated files.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include <linux/liveupdate.h>
+
+#include "../kselftest.h"
+#include "../kselftest_harness.h"
+
+#define LIVEUPDATE_DEV "/dev/liveupdate"
+
+FIXTURE(liveupdate_device) {
+	int fd1;
+	int fd2;
+};
+
+FIXTURE_SETUP(liveupdate_device)
+{
+	self->fd1 = -1;
+	self->fd2 = -1;
+}
+
+FIXTURE_TEARDOWN(liveupdate_device)
+{
+	if (self->fd1 >= 0)
+		close(self->fd1);
+	if (self->fd2 >= 0)
+		close(self->fd2);
+}
+
+/*
+ * Test Case: Basic Open and Close
+ *
+ * Verifies that the /dev/liveupdate device can be opened and subsequently
+ * closed without errors. Skips if the device does not exist.
+ */
+TEST_F(liveupdate_device, basic_open_close)
+{
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist.", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+	ASSERT_EQ(close(self->fd1), 0);
+	self->fd1 = -1;
+}
+
+/*
+ * Test Case: Exclusive Open Enforcement
+ *
+ * Verifies that the /dev/liveupdate device can only be opened by one process
+ * at a time. It checks that a second attempt to open the device fails with
+ * the EBUSY error code.
+ */
+TEST_F(liveupdate_device, exclusive_open)
+{
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist.", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+	self->fd2 = open(LIVEUPDATE_DEV, O_RDWR);
+	EXPECT_LT(self->fd2, 0);
+	EXPECT_EQ(errno, EBUSY);
+}
+
+/* Helper function to create a LUO session via ioctl. */
+static int create_session(int lu_fd, const char *name)
+{
+	struct liveupdate_ioctl_create_session args = {};
+
+	args.size = sizeof(args);
+	strncpy((char *)args.name, name, sizeof(args.name) - 1);
+
+	if (ioctl(lu_fd, LIVEUPDATE_IOCTL_CREATE_SESSION, &args))
+		return -errno;
+
+	return args.fd;
+}
+
+/*
+ * Test Case: Create Duplicate Session
+ *
+ * Verifies that attempting to create two sessions with the same name fails
+ * on the second attempt with EEXIST.
+ */
+TEST_F(liveupdate_device, create_duplicate_session)
+{
+	int session_fd1, session_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "duplicate-session-test");
+	ASSERT_GE(session_fd1, 0);
+
+	session_fd2 = create_session(self->fd1, "duplicate-session-test");
+	EXPECT_LT(session_fd2, 0);
+	EXPECT_EQ(-session_fd2, EEXIST);
+
+	ASSERT_EQ(close(session_fd1), 0);
+}
+
+/*
+ * Test Case: Create Distinct Sessions
+ *
+ * Verifies that creating two sessions with different names succeeds.
+ */
+TEST_F(liveupdate_device, create_distinct_sessions)
+{
+	int session_fd1, session_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "distinct-session-1");
+	ASSERT_GE(session_fd1, 0);
+
+	session_fd2 = create_session(self->fd1, "distinct-session-2");
+	ASSERT_GE(session_fd2, 0);
+
+	ASSERT_EQ(close(session_fd1), 0);
+	ASSERT_EQ(close(session_fd2), 0);
+}
+
+static int preserve_fd(int session_fd, int fd_to_preserve, __u64 token)
+{
+	struct liveupdate_session_preserve_fd args = {};
+
+	args.size = sizeof(args);
+	args.fd = fd_to_preserve;
+	args.token = token;
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &args))
+		return -errno;
+
+	return 0;
+}
+
+/*
+ * Test Case: Preserve MemFD
+ *
+ * Verifies that a valid memfd can be successfully preserved in a session and
+ * that its contents remain intact after the preservation call.
+ */
+TEST_F(liveupdate_device, preserve_memfd)
+{
+	const char *test_str = "hello liveupdate";
+	char read_buf[64] = {};
+	int session_fd, mem_fd;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "preserve-memfd-test");
+	ASSERT_GE(session_fd, 0);
+
+	mem_fd = memfd_create("test-memfd", 0);
+	ASSERT_GE(mem_fd, 0);
+
+	ASSERT_EQ(write(mem_fd, test_str, strlen(test_str)), strlen(test_str));
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd, 0x1234), 0);
+	ASSERT_EQ(close(session_fd), 0);
+
+	ASSERT_EQ(lseek(mem_fd, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd, read_buf, sizeof(read_buf)), strlen(test_str));
+	ASSERT_STREQ(read_buf, test_str);
+	ASSERT_EQ(close(mem_fd), 0);
+}
+
+/*
+ * Test Case: Preserve Multiple MemFDs
+ *
+ * Verifies that multiple memfds can be preserved in a single session,
+ * each with a unique token, and that their contents remain distinct and
+ * correct after preservation.
+ */
+TEST_F(liveupdate_device, preserve_multiple_memfds)
+{
+	const char *test_str1 = "data for memfd one";
+	const char *test_str2 = "data for memfd two";
+	char read_buf[64] = {};
+	int session_fd, mem_fd1, mem_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "preserve-multi-memfd-test");
+	ASSERT_GE(session_fd, 0);
+
+	mem_fd1 = memfd_create("test-memfd-1", 0);
+	ASSERT_GE(mem_fd1, 0);
+	mem_fd2 = memfd_create("test-memfd-2", 0);
+	ASSERT_GE(mem_fd2, 0);
+
+	ASSERT_EQ(write(mem_fd1, test_str1, strlen(test_str1)), strlen(test_str1));
+	ASSERT_EQ(write(mem_fd2, test_str2, strlen(test_str2)), strlen(test_str2));
+
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd1, 0xAAAA), 0);
+	ASSERT_EQ(preserve_fd(session_fd, mem_fd2, 0xBBBB), 0);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd1, read_buf, sizeof(read_buf)), strlen(test_str1));
+	ASSERT_STREQ(read_buf, test_str1);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd2, read_buf, sizeof(read_buf)), strlen(test_str2));
+	ASSERT_STREQ(read_buf, test_str2);
+
+	ASSERT_EQ(close(mem_fd1), 0);
+	ASSERT_EQ(close(mem_fd2), 0);
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+/*
+ * Test Case: Preserve Complex Scenario
+ *
+ * Verifies a more complex scenario with multiple sessions and a mix of empty
+ * and non-empty memfds distributed across them.
+ */
+TEST_F(liveupdate_device, preserve_complex_scenario)
+{
+	const char *data1 = "data for session 1";
+	const char *data2 = "data for session 2";
+	char read_buf[64] = {};
+	int session_fd1, session_fd2;
+	int mem_fd_data1, mem_fd_empty1, mem_fd_data2, mem_fd_empty2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd1 = create_session(self->fd1, "complex-session-1");
+	ASSERT_GE(session_fd1, 0);
+	session_fd2 = create_session(self->fd1, "complex-session-2");
+	ASSERT_GE(session_fd2, 0);
+
+	mem_fd_data1 = memfd_create("data1", 0);
+	ASSERT_GE(mem_fd_data1, 0);
+	ASSERT_EQ(write(mem_fd_data1, data1, strlen(data1)), strlen(data1));
+
+	mem_fd_empty1 = memfd_create("empty1", 0);
+	ASSERT_GE(mem_fd_empty1, 0);
+
+	mem_fd_data2 = memfd_create("data2", 0);
+	ASSERT_GE(mem_fd_data2, 0);
+	ASSERT_EQ(write(mem_fd_data2, data2, strlen(data2)), strlen(data2));
+
+	mem_fd_empty2 = memfd_create("empty2", 0);
+	ASSERT_GE(mem_fd_empty2, 0);
+
+	ASSERT_EQ(preserve_fd(session_fd1, mem_fd_data1, 0x1111), 0);
+	ASSERT_EQ(preserve_fd(session_fd1, mem_fd_empty1, 0x2222), 0);
+	ASSERT_EQ(preserve_fd(session_fd2, mem_fd_data2, 0x3333), 0);
+	ASSERT_EQ(preserve_fd(session_fd2, mem_fd_empty2, 0x4444), 0);
+
+	ASSERT_EQ(lseek(mem_fd_data1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_data1, read_buf, sizeof(read_buf)), strlen(data1));
+	ASSERT_STREQ(read_buf, data1);
+
+	memset(read_buf, 0, sizeof(read_buf));
+	ASSERT_EQ(lseek(mem_fd_data2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_data2, read_buf, sizeof(read_buf)), strlen(data2));
+	ASSERT_STREQ(read_buf, data2);
+
+	ASSERT_EQ(lseek(mem_fd_empty1, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_empty1, read_buf, sizeof(read_buf)), 0);
+
+	ASSERT_EQ(lseek(mem_fd_empty2, 0, SEEK_SET), 0);
+	ASSERT_EQ(read(mem_fd_empty2, read_buf, sizeof(read_buf)), 0);
+
+	ASSERT_EQ(close(mem_fd_data1), 0);
+	ASSERT_EQ(close(mem_fd_empty1), 0);
+	ASSERT_EQ(close(mem_fd_data2), 0);
+	ASSERT_EQ(close(mem_fd_empty2), 0);
+	ASSERT_EQ(close(session_fd1), 0);
+	ASSERT_EQ(close(session_fd2), 0);
+}
+
+/*
+ * Test Case: Preserve Unsupported File Descriptor
+ *
+ * Verifies that attempting to preserve a file descriptor that does not have
+ * a registered Live Update handler fails gracefully.
+ * Uses /dev/null as a representative of a file type (character device)
+ * that is not supported by the orchestrator.
+ */
+TEST_F(liveupdate_device, preserve_unsupported_fd)
+{
+	int session_fd, unsupported_fd;
+	int ret;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, "unsupported-fd-test");
+	ASSERT_GE(session_fd, 0);
+
+	unsupported_fd = open("/dev/null", O_RDWR);
+	ASSERT_GE(unsupported_fd, 0);
+
+	ret = preserve_fd(session_fd, unsupported_fd, 0xDEAD);
+	EXPECT_EQ(ret, -ENOENT);
+
+	ASSERT_EQ(close(unsupported_fd), 0);
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+TEST_HARNESS_MAIN