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, 266 insertions, 0 deletions

diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.c b/tools/testing/selftests/liveupdate/luo_test_utils.c
new file mode 100644
index 000000000000..3c8721c505df
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_test_utils.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) 2025, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdarg.h>
+
+#include "luo_test_utils.h"
+
+int luo_open_device(void)
+{
+	return open(LUO_DEVICE, O_RDWR);
+}
+
+int luo_create_session(int luo_fd, const char *name)
+{
+	struct liveupdate_ioctl_create_session arg = { .size = sizeof(arg) };
+
+	snprintf((char *)arg.name, LIVEUPDATE_SESSION_NAME_LENGTH, "%.*s",
+		 LIVEUPDATE_SESSION_NAME_LENGTH - 1, name);
+
+	if (ioctl(luo_fd, LIVEUPDATE_IOCTL_CREATE_SESSION, &arg) < 0)
+		return -errno;
+
+	return arg.fd;
+}
+
+int luo_retrieve_session(int luo_fd, const char *name)
+{
+	struct liveupdate_ioctl_retrieve_session arg = { .size = sizeof(arg) };
+
+	snprintf((char *)arg.name, LIVEUPDATE_SESSION_NAME_LENGTH, "%.*s",
+		 LIVEUPDATE_SESSION_NAME_LENGTH - 1, name);
+
+	if (ioctl(luo_fd, LIVEUPDATE_IOCTL_RETRIEVE_SESSION, &arg) < 0)
+		return -errno;
+
+	return arg.fd;
+}
+
+int create_and_preserve_memfd(int session_fd, int token, const char *data)
+{
+	struct liveupdate_session_preserve_fd arg = { .size = sizeof(arg) };
+	long page_size = sysconf(_SC_PAGE_SIZE);
+	void *map = MAP_FAILED;
+	int mfd = -1, ret = -1;
+
+	mfd = memfd_create("test_mfd", 0);
+	if (mfd < 0)
+		return -errno;
+
+	if (ftruncate(mfd, page_size) != 0)
+		goto out;
+
+	map = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, mfd, 0);
+	if (map == MAP_FAILED)
+		goto out;
+
+	snprintf(map, page_size, "%s", data);
+	munmap(map, page_size);
+
+	arg.fd = mfd;
+	arg.token = token;
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &arg) < 0)
+		goto out;
+
+	ret = 0;
+out:
+	if (ret != 0 && errno != 0)
+		ret = -errno;
+	if (mfd >= 0)
+		close(mfd);
+	return ret;
+}
+
+int restore_and_verify_memfd(int session_fd, int token,
+			     const char *expected_data)
+{
+	struct liveupdate_session_retrieve_fd arg = { .size = sizeof(arg) };
+	long page_size = sysconf(_SC_PAGE_SIZE);
+	void *map = MAP_FAILED;
+	int mfd = -1, ret = -1;
+
+	arg.token = token;
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_RETRIEVE_FD, &arg) < 0)
+		return -errno;
+	mfd = arg.fd;
+
+	map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, mfd, 0);
+	if (map == MAP_FAILED)
+		goto out;
+
+	if (expected_data && strcmp(expected_data, map) != 0) {
+		ksft_print_msg("Data mismatch! Expected '%s', Got '%s'\n",
+			       expected_data, (char *)map);
+		ret = -EINVAL;
+		goto out_munmap;
+	}
+
+	ret = mfd;
+out_munmap:
+	munmap(map, page_size);
+out:
+	if (ret < 0 && errno != 0)
+		ret = -errno;
+	if (ret < 0 && mfd >= 0)
+		close(mfd);
+	return ret;
+}
+
+int luo_session_finish(int session_fd)
+{
+	struct liveupdate_session_finish arg = { .size = sizeof(arg) };
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_FINISH, &arg) < 0)
+		return -errno;
+
+	return 0;
+}
+
+void create_state_file(int luo_fd, const char *session_name, int token,
+		       int next_stage)
+{
+	char buf[32];
+	int state_session_fd;
+
+	state_session_fd = luo_create_session(luo_fd, session_name);
+	if (state_session_fd < 0)
+		fail_exit("luo_create_session for state tracking");
+
+	snprintf(buf, sizeof(buf), "%d", next_stage);
+	if (create_and_preserve_memfd(state_session_fd, token, buf) < 0)
+		fail_exit("create_and_preserve_memfd for state tracking");
+
+	/*
+	 * DO NOT close session FD, otherwise it is going to be unpreserved
+	 */
+}
+
+void restore_and_read_stage(int state_session_fd, int token, int *stage)
+{
+	char buf[32] = {0};
+	int mfd;
+
+	mfd = restore_and_verify_memfd(state_session_fd, token, NULL);
+	if (mfd < 0)
+		fail_exit("failed to restore state memfd");
+
+	if (read(mfd, buf, sizeof(buf) - 1) < 0)
+		fail_exit("failed to read state mfd");
+
+	*stage = atoi(buf);
+
+	close(mfd);
+}
+
+void daemonize_and_wait(void)
+{
+	pid_t pid;
+
+	ksft_print_msg("[STAGE 1] Forking persistent child to hold sessions...\n");
+
+	pid = fork();
+	if (pid < 0)
+		fail_exit("fork failed");
+
+	if (pid > 0) {
+		ksft_print_msg("[STAGE 1] Child PID: %d. Resources are pinned.\n", pid);
+		ksft_print_msg("[STAGE 1] You may now perform kexec reboot.\n");
+		exit(EXIT_SUCCESS);
+	}
+
+	/* Detach from terminal so closing the window doesn't kill us */
+	if (setsid() < 0)
+		fail_exit("setsid failed");
+
+	close(STDIN_FILENO);
+	close(STDOUT_FILENO);
+	close(STDERR_FILENO);
+
+	/* Change dir to root to avoid locking filesystems */
+	if (chdir("/") < 0)
+		exit(EXIT_FAILURE);
+
+	while (1)
+		sleep(60);
+}
+
+static int parse_stage_args(int argc, char *argv[])
+{
+	static struct option long_options[] = {
+		{"stage", required_argument, 0, 's'},
+		{0, 0, 0, 0}
+	};
+	int option_index = 0;
+	int stage = 1;
+	int opt;
+
+	optind = 1;
+	while ((opt = getopt_long(argc, argv, "s:", long_options, &option_index)) != -1) {
+		switch (opt) {
+		case 's':
+			stage = atoi(optarg);
+			if (stage != 1 && stage != 2)
+				fail_exit("Invalid stage argument");
+			break;
+		default:
+			fail_exit("Unknown argument");
+		}
+	}
+	return stage;
+}
+
+int luo_test(int argc, char *argv[],
+	     const char *state_session_name,
+	     luo_test_stage1_fn stage1,
+	     luo_test_stage2_fn stage2)
+{
+	int target_stage = parse_stage_args(argc, argv);
+	int luo_fd = luo_open_device();
+	int state_session_fd;
+	int detected_stage;
+
+	if (luo_fd < 0) {
+		ksft_exit_skip("Failed to open %s. Is the luo module loaded?\n",
+			       LUO_DEVICE);
+	}
+
+	state_session_fd = luo_retrieve_session(luo_fd, state_session_name);
+	if (state_session_fd == -ENOENT)
+		detected_stage = 1;
+	else if (state_session_fd >= 0)
+		detected_stage = 2;
+	else
+		fail_exit("Failed to check for state session");
+
+	if (target_stage != detected_stage) {
+		ksft_exit_fail_msg("Stage mismatch Requested --stage %d, but system is in stage %d.\n"
+				   "(State session %s: %s)\n",
+				   target_stage, detected_stage, state_session_name,
+				   (detected_stage == 2) ? "EXISTS" : "MISSING");
+	}
+
+	if (target_stage == 1)
+		stage1(luo_fd);
+	else
+		stage2(luo_fd, state_session_fd);
+
+	return 0;
+}