Merge tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - "ida: Remove the ida_simple_xxx() API" from Christophe Jaillet
   completes the removal of this legacy IDR API

 - "panic: introduce panic status function family" from Jinchao Wang
   provides a number of cleanups to the panic code and its various
   helpers, which were rather ad-hoc and scattered all over the place

 - "tools/delaytop: implement real-time keyboard interaction support"
   from Fan Yu adds a few nice user-facing usability changes to the
   delaytop monitoring tool

 - "efi: Fix EFI boot with kexec handover (KHO)" from Evangelos
   Petrongonas fixes a panic which was happening with the combination of
   EFI and KHO

 - "Squashfs: performance improvement and a sanity check" from Phillip
   Lougher teaches squashfs's lseek() about SEEK_DATA/SEEK_HOLE. A mere
   150x speedup was measured for a well-chosen microbenchmark

 - plus another 50-odd singleton patches all over the place

* tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (75 commits)
  Squashfs: reject negative file sizes in squashfs_read_inode()
  kallsyms: use kmalloc_array() instead of kmalloc()
  MAINTAINERS: update Sibi Sankar's email address
  Squashfs: add SEEK_DATA/SEEK_HOLE support
  Squashfs: add additional inode sanity checking
  lib/genalloc: fix device leak in of_gen_pool_get()
  panic: remove CONFIG_PANIC_ON_OOPS_VALUE
  ocfs2: fix double free in user_cluster_connect()
  checkpatch: suppress strscpy warnings for userspace tools
  cramfs: fix incorrect physical page address calculation
  kernel: prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit
  Squashfs: fix uninit-value in squashfs_get_parent
  kho: only fill kimage if KHO is finalized
  ocfs2: avoid extra calls to strlen() after ocfs2_sprintf_system_inode_name()
  kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths
  sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock
  coccinelle: platform_no_drv_owner: handle also built-in drivers
  coccinelle: of_table: handle SPI device ID tables
  lib/decompress: use designated initializers for struct compress_format
  efi: support booting with kexec handover (KHO)
  ...

kernel/Kconfig.kexec

@@ -148,6 +148,17 @@ config CRASH_DM_CRYPT_CONFIGS
 	  CRASH_DM_CRYPT cannot directly select CONFIGFS_FS, because that
 	  is required to be built-in.
 
+config CRASH_DUMP_KUNIT_TEST
+	tristate "Unit Tests for kernel crash dumps" if !KUNIT_ALL_TESTS
+	depends on CRASH_DUMP && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This option builds KUnit unit tests for kernel crash dumps. The unit
+	  tests will be used to verify the correctness of covered functions and
+	  also prevent any regression.
+
+	  If unsure, say N.
+
 config CRASH_HOTPLUG
 	bool "Update the crash elfcorehdr on system configuration changes"
 	default y

kernel/Makefile

@@ -78,6 +78,7 @@ obj-$(CONFIG_CRASH_RESERVE) += crash_reserve.o
 obj-$(CONFIG_KEXEC_CORE) += kexec_core.o
 obj-$(CONFIG_CRASH_DUMP) += crash_core.o
 obj-$(CONFIG_CRASH_DM_CRYPT) += crash_dump_dm_crypt.o
+obj-$(CONFIG_CRASH_DUMP_KUNIT_TEST) += crash_core_test.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
 obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o

kernel/crash_core.c

@@ -22,6 +22,7 @@
 #include <linux/btf.h>
 #include <linux/objtool.h>
 #include <linux/delay.h>
+#include <linux/panic.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -143,17 +144,7 @@ STACK_FRAME_NON_STANDARD(__crash_kexec);
 
 __bpf_kfunc void crash_kexec(struct pt_regs *regs)
 {
-	int old_cpu, this_cpu;
-
-	/*
-	 * Only one CPU is allowed to execute the crash_kexec() code as with
-	 * panic().  Otherwise parallel calls of panic() and crash_kexec()
-	 * may stop each other.  To exclude them, we use panic_cpu here too.
-	 */
-	old_cpu = PANIC_CPU_INVALID;
-	this_cpu = raw_smp_processor_id();
-
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
+	if (panic_try_start()) {
 		/* This is the 1st CPU which comes here, so go ahead. */
 		__crash_kexec(regs);
 
@@ -161,7 +152,7 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs)
 		 * Reset panic_cpu to allow another panic()/crash_kexec()
 		 * call.
 		 */
-		atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+		panic_reset();
 	}
 }
 
@@ -274,6 +265,20 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 	return 0;
 }
 
+/**
+ * crash_exclude_mem_range - exclude a mem range for existing ranges
+ * @mem: mem->range contains an array of ranges sorted in ascending order
+ * @mstart: the start of to-be-excluded range
+ * @mend: the start of to-be-excluded range
+ *
+ * If you are unsure if a range split will happen, to avoid function call
+ * failure because of -ENOMEM, always make sure
+ *    mem->max_nr_ranges == mem->nr_ranges + 1
+ * before calling the function each time.
+ *
+ * returns 0 if a memory range is excluded successfully
+ * return -ENOMEM if mem->ranges doesn't have space to hold split ranges
+ */
 int crash_exclude_mem_range(struct crash_mem *mem,
 			    unsigned long long mstart, unsigned long long mend)
 {
@@ -333,6 +338,7 @@ int crash_exclude_mem_range(struct crash_mem *mem,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(crash_exclude_mem_range);
 
 ssize_t crash_get_memory_size(void)
 {

kernel/crash_core_test.c

@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <kunit/test.h>
+#include <linux/crash_core.h> // For struct crash_mem and struct range if defined there
+
+// Helper to create and initialize crash_mem
+static struct crash_mem *create_crash_mem(struct kunit *test, unsigned int max_ranges,
+					  unsigned int nr_initial_ranges,
+					  const struct range *initial_ranges)
+{
+	struct crash_mem *mem;
+	size_t alloc_size;
+
+	// Check if max_ranges can even hold initial_ranges
+	if (max_ranges < nr_initial_ranges) {
+		kunit_err(test, "max_ranges (%u) < nr_initial_ranges (%u)\n",
+			  max_ranges, nr_initial_ranges);
+		return NULL;
+	}
+
+	alloc_size = sizeof(struct crash_mem) + (size_t)max_ranges * sizeof(struct range);
+	mem = kunit_kzalloc(test, alloc_size, GFP_KERNEL);
+	if (!mem) {
+		kunit_err(test, "Failed to allocate crash_mem\n");
+		return NULL;
+	}
+
+	mem->max_nr_ranges = max_ranges;
+	mem->nr_ranges = nr_initial_ranges;
+	if (initial_ranges && nr_initial_ranges > 0) {
+		memcpy(mem->ranges, initial_ranges,
+		       nr_initial_ranges * sizeof(struct range));
+	}
+
+	return mem;
+}
+
+// Helper to compare ranges for assertions
+static void assert_ranges_equal(struct kunit *test,
+				const struct range *actual_ranges,
+				unsigned int actual_nr_ranges,
+				const struct range *expected_ranges,
+				unsigned int expected_nr_ranges,
+				const char *case_name)
+{
+	unsigned int i;
+
+	KUNIT_ASSERT_EQ_MSG(test, expected_nr_ranges, actual_nr_ranges,
+			    "%s: Number of ranges mismatch.", case_name);
+
+	for (i = 0; i < expected_nr_ranges; i++) {
+		KUNIT_ASSERT_EQ_MSG(test, expected_ranges[i].start, actual_ranges[i].start,
+				    "%s: Range %u start mismatch.", case_name, i);
+		KUNIT_ASSERT_EQ_MSG(test, expected_ranges[i].end, actual_ranges[i].end,
+				    "%s: Range %u end mismatch.", case_name, i);
+	}
+}
+
+// Structure for test parameters
+struct exclude_test_param {
+	const char *description;
+	unsigned long long exclude_start;
+	unsigned long long exclude_end;
+	unsigned int initial_max_ranges;
+	const struct range *initial_ranges;
+	unsigned int initial_nr_ranges;
+	const struct range *expected_ranges;
+	unsigned int expected_nr_ranges;
+	int expected_ret;
+};
+
+static void run_exclude_test_case(struct kunit *test, const struct exclude_test_param *params)
+{
+	struct crash_mem *mem;
+	int ret;
+
+	kunit_info(test, "%s", params->description);
+
+	mem = create_crash_mem(test, params->initial_max_ranges,
+			       params->initial_nr_ranges, params->initial_ranges);
+	if (!mem)
+		return; // Error already logged by create_crash_mem or kunit_kzalloc
+
+	ret = crash_exclude_mem_range(mem, params->exclude_start, params->exclude_end);
+
+	KUNIT_ASSERT_EQ_MSG(test, params->expected_ret, ret,
+			    "%s: Return value mismatch.", params->description);
+
+	if (params->expected_ret == 0) {
+		assert_ranges_equal(test, mem->ranges, mem->nr_ranges,
+				    params->expected_ranges, params->expected_nr_ranges,
+				    params->description);
+	} else {
+		// If an error is expected, nr_ranges might still be relevant to check
+		// depending on the exact point of failure. For ENOMEM on split,
+		// nr_ranges shouldn't have changed.
+		KUNIT_ASSERT_EQ_MSG(test, params->initial_nr_ranges,
+				    mem->nr_ranges,
+				    "%s: Number of ranges mismatch on error.",
+				    params->description);
+	}
+}
+
+/*
+ * Test Strategy 1: One to-be-excluded range A and one existing range B.
+ *
+ * Exhaust all possibilities of the position of A regarding B.
+ */
+
+static const struct range single_range_b = { .start = 100, .end = 199 };
+
+static const struct exclude_test_param exclude_single_range_test_data[] = {
+	{
+		.description = "1.1: A is left of B, no overlap",
+		.exclude_start = 10, .exclude_end = 50,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.2: A's right boundary touches B's left boundary",
+		.exclude_start = 10, .exclude_end = 99,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.3: A overlaps B's left part",
+		.exclude_start = 50, .exclude_end = 149,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){{ .start = 150, .end = 199 }},
+		.expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.4: A is completely inside B",
+		.exclude_start = 120, .exclude_end = 179,
+		.initial_max_ranges = 2, // Needs space for split
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){
+			{ .start = 100, .end = 119 },
+			{ .start = 180, .end = 199 }
+		},
+		.expected_nr_ranges = 2,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.5: A overlaps B's right part",
+		.exclude_start = 150, .exclude_end = 249,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){{ .start = 100, .end = 149 }},
+		.expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.6: A's left boundary touches B's right boundary",
+		.exclude_start = 200, .exclude_end = 250,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.7: A is right of B, no overlap",
+		.exclude_start = 250, .exclude_end = 300,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.8: A completely covers B and extends beyond",
+		.exclude_start = 50, .exclude_end = 250,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = NULL, .expected_nr_ranges = 0,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.9: A covers B and extends to the left",
+		.exclude_start = 50, .exclude_end = 199, // A ends exactly where B ends
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = NULL, .expected_nr_ranges = 0,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.10: A covers B and extends to the right",
+		.exclude_start = 100, .exclude_end = 250, // A starts exactly where B starts
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = NULL, .expected_nr_ranges = 0,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.11: A is identical to B",
+		.exclude_start = 100, .exclude_end = 199,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = NULL, .expected_nr_ranges = 0,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.12: A is a point, left of B, no overlap",
+		.exclude_start = 10, .exclude_end = 10,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.13: A is a point, at start of B",
+		.exclude_start = 100, .exclude_end = 100,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){{ .start = 101, .end = 199 }},
+		.expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.14: A is a point, in middle of B (causes split)",
+		.exclude_start = 150, .exclude_end = 150,
+		.initial_max_ranges = 2, // Needs space for split
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){
+			{ .start = 100, .end = 149 },
+			{ .start = 151, .end = 199 }
+		},
+		.expected_nr_ranges = 2,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.15: A is a point, at end of B",
+		.exclude_start = 199, .exclude_end = 199,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = (const struct range[]){{ .start = 100, .end = 198 }},
+		.expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	{
+		.description = "1.16: A is a point, right of B, no overlap",
+		.exclude_start = 250, .exclude_end = 250,
+		.initial_max_ranges = 1,
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = &single_range_b, .expected_nr_ranges = 1,
+		.expected_ret = 0,
+	},
+	// ENOMEM case for single range split
+	{
+		.description = "1.17: A completely inside B (split), no space (ENOMEM)",
+		.exclude_start = 120, .exclude_end = 179,
+		.initial_max_ranges = 1, // Not enough for split
+		.initial_ranges = &single_range_b, .initial_nr_ranges = 1,
+		.expected_ranges = NULL, // Not checked on error by assert_ranges_equal for content
+		.expected_nr_ranges = 1, // Should remain unchanged
+		.expected_ret = -ENOMEM,
+	},
+};
+
+
+static void exclude_single_range_test(struct kunit *test)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(exclude_single_range_test_data); i++) {
+		kunit_log(KERN_INFO, test, "Running: %s", exclude_single_range_test_data[i].description);
+		run_exclude_test_case(test, &exclude_single_range_test_data[i]);
+		// KUnit will stop on first KUNIT_ASSERT failure within run_exclude_test_case
+	}
+}
+
+/*
+ * Test Strategy 2: Regression test.
+ */
+
+static const struct exclude_test_param exclude_range_regression_test_data[] = {
+	// Test data from commit a2e9a95d2190
+	{
+		.description = "2.1: exclude low 1M",
+		.exclude_start = 0, .exclude_end = (1 << 20) - 1,
+		.initial_max_ranges = 3,
+		.initial_ranges = (const struct range[]){
+			{ .start = 0, .end = 0x3efff },
+			{ .start = 0x3f000, .end = 0x3ffff },
+			{ .start = 0x40000, .end = 0x9ffff }
+		},
+		.initial_nr_ranges = 3,
+		.expected_nr_ranges = 0,
+		.expected_ret = 0,
+	},
+	// Test data from https://lore.kernel.org/all/ZXrY7QbXAlxydsSC@MiWiFi-R3L-srv/T/#u
+	{
+		.description = "2.2: when range out of bound",
+		.exclude_start = 100, .exclude_end = 200,
+		.initial_max_ranges = 3,
+		.initial_ranges = (const struct range[]){
+			{ .start = 1, .end = 299 },
+			{ .start = 401, .end = 1000 },
+			{ .start = 1001, .end = 2000 }
+		},
+		.initial_nr_ranges = 3,
+		.expected_ranges = NULL, // Not checked on error by assert_ranges_equal for content
+		.expected_nr_ranges = 3, // Should remain unchanged
+		.expected_ret = -ENOMEM
+	},
+
+};
+
+
+static void exclude_range_regression_test(struct kunit *test)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(exclude_range_regression_test_data); i++) {
+		kunit_log(KERN_INFO, test, "Running: %s", exclude_range_regression_test_data[i].description);
+		run_exclude_test_case(test, &exclude_range_regression_test_data[i]);
+		// KUnit will stop on first KUNIT_ASSERT failure within run_exclude_test_case
+	}
+}
+
+/*
+ * KUnit Test Suite
+ */
+static struct kunit_case crash_exclude_mem_range_test_cases[] = {
+	KUNIT_CASE(exclude_single_range_test),
+	KUNIT_CASE(exclude_range_regression_test),
+	{}
+};
+
+static struct kunit_suite crash_exclude_mem_range_suite = {
+	.name = "crash_exclude_mem_range_tests",
+	.test_cases = crash_exclude_mem_range_test_cases,
+	// .init and .exit can be NULL if not needed globally for the suite
+};
+
+kunit_test_suite(crash_exclude_mem_range_suite);
+
+MODULE_DESCRIPTION("crash dump KUnit test suite");
+MODULE_LICENSE("GPL");

kernel/fork.c

@@ -2132,9 +2132,7 @@ __latent_entropy struct task_struct *copy_process(
 
 	p->pagefault_disabled = 0;
 
-#ifdef CONFIG_LOCKDEP
 	lockdep_init_task(p);
-#endif
 
 	p->blocked_on = NULL; /* not blocked yet */
 
@@ -2547,11 +2545,9 @@ struct task_struct * __init fork_idle(int cpu)
 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
 {
 	unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
-				CLONE_IO;
+			      CLONE_IO|CLONE_VM|CLONE_UNTRACED;
 	struct kernel_clone_args args = {
-		.flags		= ((lower_32_bits(flags) | CLONE_VM |
-				    CLONE_UNTRACED) & ~CSIGNAL),
-		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
+		.flags		= flags,
 		.fn		= fn,
 		.fn_arg		= arg,
 		.io_thread	= 1,
@@ -2663,9 +2659,8 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
 		    unsigned long flags)
 {
 	struct kernel_clone_args args = {
-		.flags		= ((lower_32_bits(flags) | CLONE_VM |
-				    CLONE_UNTRACED) & ~CSIGNAL),
-		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
+		.flags		= ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL),
+		.exit_signal	= (flags & CSIGNAL),
 		.fn		= fn,
 		.fn_arg		= arg,
 		.name		= name,
@@ -2681,9 +2676,8 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
 pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
 {
 	struct kernel_clone_args args = {
-		.flags		= ((lower_32_bits(flags) | CLONE_VM |
-				    CLONE_UNTRACED) & ~CSIGNAL),
-		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
+		.flags		= ((flags | CLONE_VM | CLONE_UNTRACED) & ~CSIGNAL),
+		.exit_signal	= (flags & CSIGNAL),
 		.fn		= fn,
 		.fn_arg		= arg,
 	};

kernel/hung_task.c

@@ -95,9 +95,41 @@ static struct notifier_block panic_block = {
 	.notifier_call = hung_task_panic,
 };
 
+static bool task_is_hung(struct task_struct *t, unsigned long timeout)
+{
+	unsigned long switch_count = t->nvcsw + t->nivcsw;
+	unsigned int state = READ_ONCE(t->__state);
+
+	/*
+	 * skip the TASK_KILLABLE tasks -- these can be killed
+	 * skip the TASK_IDLE tasks -- those are genuinely idle
+	 * skip the TASK_FROZEN task -- it reasonably stops scheduling by freezer
+	 */
+	if (!(state & TASK_UNINTERRUPTIBLE) ||
+	    (state & (TASK_WAKEKILL | TASK_NOLOAD | TASK_FROZEN)))
+		return false;
+
+	/*
+	 * When a freshly created task is scheduled once, changes its state to
+	 * TASK_UNINTERRUPTIBLE without having ever been switched out once, it
+	 * musn't be checked.
+	 */
+	if (unlikely(!switch_count))
+		return false;
+
+	if (switch_count != t->last_switch_count) {
+		t->last_switch_count = switch_count;
+		t->last_switch_time = jiffies;
+		return false;
+	}
+	if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
+		return false;
+
+	return true;
+}
 
 #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
-static void debug_show_blocker(struct task_struct *task)
+static void debug_show_blocker(struct task_struct *task, unsigned long timeout)
 {
 	struct task_struct *g, *t;
 	unsigned long owner, blocker, blocker_type;
@@ -174,41 +206,21 @@ static void debug_show_blocker(struct task_struct *task)
 			       t->pid, rwsem_blocked_by);
 			break;
 		}
-		sched_show_task(t);
+		/* Avoid duplicated task dump, skip if the task is also hung. */
+		if (!task_is_hung(t, timeout))
+			sched_show_task(t);
 		return;
 	}
 }
 #else
-static inline void debug_show_blocker(struct task_struct *task)
+static inline void debug_show_blocker(struct task_struct *task, unsigned long timeout)
 {
 }
 #endif
 
 static void check_hung_task(struct task_struct *t, unsigned long timeout)
 {
-	unsigned long switch_count = t->nvcsw + t->nivcsw;
-
-	/*
-	 * Ensure the task is not frozen.
-	 * Also, skip vfork and any other user process that freezer should skip.
-	 */
-	if (unlikely(READ_ONCE(t->__state) & TASK_FROZEN))
-		return;
-
-	/*
-	 * When a freshly created task is scheduled once, changes its state to
-	 * TASK_UNINTERRUPTIBLE without having ever been switched out once, it
-	 * musn't be checked.
-	 */
-	if (unlikely(!switch_count))
-		return;
-
-	if (switch_count != t->last_switch_count) {
-		t->last_switch_count = switch_count;
-		t->last_switch_time = jiffies;
-		return;
-	}
-	if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
+	if (!task_is_hung(t, timeout))
 		return;
 
 	/*
@@ -243,7 +255,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 		pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
 			" disables this message.\n");
 		sched_show_task(t);
-		debug_show_blocker(t);
+		debug_show_blocker(t, timeout);
 		hung_task_show_lock = true;
 
 		if (sysctl_hung_task_all_cpu_backtrace)
@@ -299,7 +311,6 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 	hung_task_show_lock = false;
 	rcu_read_lock();
 	for_each_process_thread(g, t) {
-		unsigned int state;
 
 		if (!max_count--)
 			goto unlock;
@@ -308,15 +319,8 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 				goto unlock;
 			last_break = jiffies;
 		}
-		/*
-		 * skip the TASK_KILLABLE tasks -- these can be killed
-		 * skip the TASK_IDLE tasks -- those are genuinely idle
-		 */
-		state = READ_ONCE(t->__state);
-		if ((state & TASK_UNINTERRUPTIBLE) &&
-		    !(state & TASK_WAKEKILL) &&
-		    !(state & TASK_NOLOAD))
-			check_hung_task(t, timeout);
+
+		check_hung_task(t, timeout);
 	}
  unlock:
 	rcu_read_unlock();

kernel/kallsyms_selftest.c

@@ -264,7 +264,7 @@ static int test_kallsyms_basic_function(void)
 	char namebuf[KSYM_NAME_LEN];
 	struct test_stat *stat, *stat2;
 
-	stat = kmalloc(sizeof(*stat) * 2, GFP_KERNEL);
+	stat = kmalloc_array(2, sizeof(*stat), GFP_KERNEL);
 	if (!stat)
 		return -ENOMEM;
 	stat2 = stat + 1;

kernel/kcov.c

@@ -978,6 +978,15 @@ static void kcov_move_area(enum kcov_mode mode, void *dst_area,
 	memcpy(dst_entries, src_entries, bytes_to_move);
 	entries_moved = bytes_to_move >> entry_size_log;
 
+	/*
+	 * A write memory barrier is required here, to ensure
+	 * that the writes from the memcpy() are visible before
+	 * the count is updated. Without this, it is possible for
+	 * a user to observe a new count value but stale
+	 * coverage data.
+	 */
+	smp_wmb();
+
 	switch (mode) {
 	case KCOV_MODE_TRACE_PC:
 		WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved);

kernel/kexec_core.c

@@ -233,7 +233,6 @@ struct kimage *do_kimage_alloc_init(void)
 	if (!image)
 		return NULL;
 
-	image->head = 0;
 	image->entry = &image->head;
 	image->last_entry = &image->head;
 	image->control_page = ~0; /* By default this does not apply */

kernel/kexec_file.c

@@ -255,6 +255,7 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	}
 
 	image->no_cma = !!(flags & KEXEC_FILE_NO_CMA);
+	image->force_dtb = flags & KEXEC_FILE_FORCE_DTB;
 
 	if (cmdline_len) {
 		image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);

kernel/kexec_handover.c

@@ -987,6 +987,26 @@ static const void *kho_get_fdt(void)
 	return kho_in.fdt_phys ? phys_to_virt(kho_in.fdt_phys) : NULL;
 }
 
+/**
+ * is_kho_boot - check if current kernel was booted via KHO-enabled
+ * kexec
+ *
+ * This function checks if the current kernel was loaded through a kexec
+ * operation with KHO enabled, by verifying that a valid KHO FDT
+ * was passed.
+ *
+ * Note: This function returns reliable results only after
+ * kho_populate() has been called during early boot. Before that,
+ * it may return false even if KHO data is present.
+ *
+ * Return: true if booted via KHO-enabled kexec, false otherwise
+ */
+bool is_kho_boot(void)
+{
+	return !!kho_get_fdt();
+}
+EXPORT_SYMBOL_GPL(is_kho_boot);
+
 /**
  * kho_retrieve_subtree - retrieve a preserved sub FDT by its name.
  * @name: the name of the sub FDT passed to kho_add_subtree().
@@ -1269,7 +1289,7 @@ int kho_fill_kimage(struct kimage *image)
 	int err = 0;
 	struct kexec_buf scratch;
 
-	if (!kho_enable)
+	if (!kho_out.finalized)
 		return 0;
 
 	image->kho.fdt = page_to_phys(kho_out.ser.fdt);

kernel/panic.c

@@ -53,7 +53,7 @@ static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
 #define sysctl_oops_all_cpu_backtrace 0
 #endif /* CONFIG_SMP */
 
-int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
+int panic_on_oops = IS_ENABLED(CONFIG_PANIC_ON_OOPS);
 static unsigned long tainted_mask =
 	IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
 static int pause_on_oops;
@@ -67,6 +67,7 @@ static unsigned int warn_limit __read_mostly;
 static bool panic_console_replay;
 
 bool panic_triggering_all_cpu_backtrace;
+static bool panic_this_cpu_backtrace_printed;
 
 int panic_timeout = CONFIG_PANIC_TIMEOUT;
 EXPORT_SYMBOL_GPL(panic_timeout);
@@ -77,6 +78,11 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 
 EXPORT_SYMBOL(panic_notifier_list);
 
+static void panic_print_deprecated(void)
+{
+	pr_info_once("Kernel: The 'panic_print' parameter is now deprecated. Please use 'panic_sys_info' and 'panic_console_replay' instead.\n");
+}
+
 #ifdef CONFIG_SYSCTL
 
 /*
@@ -125,7 +131,7 @@ static int proc_taint(const struct ctl_table *table, int write,
 static int sysctl_panic_print_handler(const struct ctl_table *table, int write,
 			   void *buffer, size_t *lenp, loff_t *ppos)
 {
-	pr_info_once("Kernel: 'panic_print' sysctl interface will be obsoleted by both 'panic_sys_info' and 'panic_console_replay'\n");
+	panic_print_deprecated();
 	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 }
 
@@ -294,6 +300,59 @@ void __weak crash_smp_send_stop(void)
 
 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
 
+bool panic_try_start(void)
+{
+	int old_cpu, this_cpu;
+
+	/*
+	 * Only one CPU is allowed to execute the crash_kexec() code as with
+	 * panic().  Otherwise parallel calls of panic() and crash_kexec()
+	 * may stop each other.  To exclude them, we use panic_cpu here too.
+	 */
+	old_cpu = PANIC_CPU_INVALID;
+	this_cpu = raw_smp_processor_id();
+
+	return atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu);
+}
+EXPORT_SYMBOL(panic_try_start);
+
+void panic_reset(void)
+{
+	atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+}
+EXPORT_SYMBOL(panic_reset);
+
+bool panic_in_progress(void)
+{
+	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
+}
+EXPORT_SYMBOL(panic_in_progress);
+
+/* Return true if a panic is in progress on the current CPU. */
+bool panic_on_this_cpu(void)
+{
+	/*
+	 * We can use raw_smp_processor_id() here because it is impossible for
+	 * the task to be migrated to the panic_cpu, or away from it. If
+	 * panic_cpu has already been set, and we're not currently executing on
+	 * that CPU, then we never will be.
+	 */
+	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
+}
+EXPORT_SYMBOL(panic_on_this_cpu);
+
+/*
+ * Return true if a panic is in progress on a remote CPU.
+ *
+ * On true, the local CPU should immediately release any printing resources
+ * that may be needed by the panic CPU.
+ */
+bool panic_on_other_cpu(void)
+{
+	return (panic_in_progress() && !panic_on_this_cpu());
+}
+EXPORT_SYMBOL(panic_on_other_cpu);
+
 /*
  * A variant of panic() called from NMI context. We return if we've already
  * panicked on this CPU. If another CPU already panicked, loop in
@@ -302,15 +361,9 @@ atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
  */
 void nmi_panic(struct pt_regs *regs, const char *msg)
 {
-	int old_cpu, this_cpu;
-
-	old_cpu = PANIC_CPU_INVALID;
-	this_cpu = raw_smp_processor_id();
-
-	/* atomic_try_cmpxchg updates old_cpu on failure */
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
+	if (panic_try_start())
 		panic("%s", msg);
-	else if (old_cpu != this_cpu)
+	else if (panic_on_other_cpu())
 		nmi_panic_self_stop(regs);
 }
 EXPORT_SYMBOL(nmi_panic);
@@ -328,6 +381,19 @@ void check_panic_on_warn(const char *origin)
 		      origin, limit);
 }
 
+static void panic_trigger_all_cpu_backtrace(void)
+{
+	/* Temporary allow non-panic CPUs to write their backtraces. */
+	panic_triggering_all_cpu_backtrace = true;
+
+	if (panic_this_cpu_backtrace_printed)
+		trigger_allbutcpu_cpu_backtrace(raw_smp_processor_id());
+	else
+		trigger_all_cpu_backtrace();
+
+	panic_triggering_all_cpu_backtrace = false;
+}
+
 /*
  * Helper that triggers the NMI backtrace (if set in panic_print)
  * and then performs the secondary CPUs shutdown - we cannot have
@@ -335,12 +401,8 @@ void check_panic_on_warn(const char *origin)
  */
 static void panic_other_cpus_shutdown(bool crash_kexec)
 {
-	if (panic_print & SYS_INFO_ALL_CPU_BT) {
-		/* Temporary allow non-panic CPUs to write their backtraces. */
-		panic_triggering_all_cpu_backtrace = true;
-		trigger_all_cpu_backtrace();
-		panic_triggering_all_cpu_backtrace = false;
-	}
+	if (panic_print & SYS_INFO_ALL_CPU_BT)
+		panic_trigger_all_cpu_backtrace();
 
 	/*
 	 * Note that smp_send_stop() is the usual SMP shutdown function,
@@ -368,7 +430,6 @@ void vpanic(const char *fmt, va_list args)
 	static char buf[1024];
 	long i, i_next = 0, len;
 	int state = 0;
-	int old_cpu, this_cpu;
 	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
 
 	if (panic_on_warn) {
@@ -405,13 +466,10 @@ void vpanic(const char *fmt, va_list args)
 	 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
 	 * panic_cpu to this CPU.  In this case, this is also the 1st CPU.
 	 */
-	old_cpu = PANIC_CPU_INVALID;
-	this_cpu = raw_smp_processor_id();
-
 	/* atomic_try_cmpxchg updates old_cpu on failure */
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
+	if (panic_try_start()) {
 		/* go ahead */
-	} else if (old_cpu != this_cpu)
+	} else if (panic_on_other_cpu())
 		panic_smp_self_stop();
 
 	console_verbose();
@@ -422,13 +480,15 @@ void vpanic(const char *fmt, va_list args)
 		buf[len - 1] = '\0';
 
 	pr_emerg("Kernel panic - not syncing: %s\n", buf);
-#ifdef CONFIG_DEBUG_BUGVERBOSE
 	/*
 	 * Avoid nested stack-dumping if a panic occurs during oops processing
 	 */
-	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
+	if (test_taint(TAINT_DIE) || oops_in_progress > 1) {
+		panic_this_cpu_backtrace_printed = true;
+	} else if (IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE)) {
 		dump_stack();
-#endif
+		panic_this_cpu_backtrace_printed = true;
+	}
 
 	/*
 	 * If kgdb is enabled, give it a chance to run before we stop all
@@ -937,12 +997,29 @@ EXPORT_SYMBOL(__stack_chk_fail);
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
-core_param(panic_print, panic_print, ulong, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);
 core_param(panic_on_warn, panic_on_warn, int, 0644);
 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
 core_param(panic_console_replay, panic_console_replay, bool, 0644);
 
+static int panic_print_set(const char *val, const struct kernel_param *kp)
+{
+	panic_print_deprecated();
+	return  param_set_ulong(val, kp);
+}
+
+static int panic_print_get(char *val, const struct kernel_param *kp)
+{
+	panic_print_deprecated();
+	return  param_get_ulong(val, kp);
+}
+
+static const struct kernel_param_ops panic_print_ops = {
+	.set	= panic_print_set,
+	.get	= panic_print_get,
+};
+__core_param_cb(panic_print, &panic_print_ops, &panic_print, 0644);
+
 static int __init oops_setup(char *s)
 {
 	if (!s)

kernel/printk/internal.h

@@ -332,7 +332,6 @@ struct printk_message {
 	unsigned long		dropped;
 };
 
-bool other_cpu_in_panic(void);
 bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
 			     bool is_extended, bool may_supress);
 

kernel/printk/nbcon.c

@@ -12,6 +12,7 @@
 #include <linux/irqflags.h>
 #include <linux/kthread.h>
 #include <linux/minmax.h>
+#include <linux/panic.h>
 #include <linux/percpu.h>
 #include <linux/preempt.h>
 #include <linux/slab.h>
@@ -254,7 +255,7 @@ static int nbcon_context_try_acquire_direct(struct nbcon_context *ctxt,
 		 * opportunity to perform any necessary cleanup if they were
 		 * interrupted by the panic CPU while printing.
 		 */
-		if (other_cpu_in_panic() &&
+		if (panic_on_other_cpu() &&
 		    (!is_reacquire || cur->unsafe_takeover)) {
 			return -EPERM;
 		}
@@ -309,7 +310,7 @@ static bool nbcon_waiter_matches(struct nbcon_state *cur, int expected_prio)
 	 * Event #2 implies the new context is PANIC.
 	 * Event #3 occurs when panic() has flushed the console.
 	 * Event #4 occurs when a non-panic CPU reacquires.
-	 * Event #5 is not possible due to the other_cpu_in_panic() check
+	 * Event #5 is not possible due to the panic_on_other_cpu() check
 	 *          in nbcon_context_try_acquire_handover().
 	 */
 
@@ -348,7 +349,7 @@ static int nbcon_context_try_acquire_requested(struct nbcon_context *ctxt,
 	struct nbcon_state new;
 
 	/* Note that the caller must still remove the request! */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return -EPERM;
 
 	/*
@@ -446,7 +447,7 @@ static int nbcon_context_try_acquire_handover(struct nbcon_context *ctxt,
 	 * nbcon_waiter_matches(). In particular, the assumption that
 	 * lower priorities are ignored during panic.
 	 */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return -EPERM;
 
 	/* Handover is not possible on the same CPU. */
@@ -589,7 +590,6 @@ static struct printk_buffers panic_nbcon_pbufs;
  */
 static bool nbcon_context_try_acquire(struct nbcon_context *ctxt, bool is_reacquire)
 {
-	unsigned int cpu = smp_processor_id();
 	struct console *con = ctxt->console;
 	struct nbcon_state cur;
 	int err;
@@ -614,7 +614,7 @@ out:
 	/* Acquire succeeded. */
 
 	/* Assign the appropriate buffer for this context. */
-	if (atomic_read(&panic_cpu) == cpu)
+	if (panic_on_this_cpu())
 		ctxt->pbufs = &panic_nbcon_pbufs;
 	else
 		ctxt->pbufs = con->pbufs;
@@ -1394,7 +1394,7 @@ enum nbcon_prio nbcon_get_default_prio(void)
 {
 	unsigned int *cpu_emergency_nesting;
 
-	if (this_cpu_in_panic())
+	if (panic_on_this_cpu())
 		return NBCON_PRIO_PANIC;
 
 	cpu_emergency_nesting = nbcon_get_cpu_emergency_nesting();

kernel/printk/printk.c

@@ -48,6 +48,7 @@
 #include <linux/sched/clock.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
+#include <linux/panic.h>
 
 #include <linux/uaccess.h>
 #include <asm/sections.h>
@@ -345,34 +346,6 @@ static void __up_console_sem(unsigned long ip)
 }
 #define up_console_sem() __up_console_sem(_RET_IP_)
 
-static bool panic_in_progress(void)
-{
-	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
-}
-
-/* Return true if a panic is in progress on the current CPU. */
-bool this_cpu_in_panic(void)
-{
-	/*
-	 * We can use raw_smp_processor_id() here because it is impossible for
-	 * the task to be migrated to the panic_cpu, or away from it. If
-	 * panic_cpu has already been set, and we're not currently executing on
-	 * that CPU, then we never will be.
-	 */
-	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
-}
-
-/*
- * Return true if a panic is in progress on a remote CPU.
- *
- * On true, the local CPU should immediately release any printing resources
- * that may be needed by the panic CPU.
- */
-bool other_cpu_in_panic(void)
-{
-	return (panic_in_progress() && !this_cpu_in_panic());
-}
-
 /*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
@@ -2407,7 +2380,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 	 * non-panic CPUs are generating any messages, they will be
 	 * silently dropped.
 	 */
-	if (other_cpu_in_panic() &&
+	if (panic_on_other_cpu() &&
 	    !debug_non_panic_cpus &&
 	    !panic_triggering_all_cpu_backtrace)
 		return 0;
@@ -2843,7 +2816,7 @@ void console_lock(void)
 	might_sleep();
 
 	/* On panic, the console_lock must be left to the panic cpu. */
-	while (other_cpu_in_panic())
+	while (panic_on_other_cpu())
 		msleep(1000);
 
 	down_console_sem();
@@ -2863,7 +2836,7 @@ EXPORT_SYMBOL(console_lock);
 int console_trylock(void)
 {
 	/* On panic, the console_lock must be left to the panic cpu. */
-	if (other_cpu_in_panic())
+	if (panic_on_other_cpu())
 		return 0;
 	if (down_trylock_console_sem())
 		return 0;
@@ -3243,7 +3216,7 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
 			any_progress = true;
 
 			/* Allow panic_cpu to take over the consoles safely. */
-			if (other_cpu_in_panic())
+			if (panic_on_other_cpu())
 				goto abandon;
 
 			if (do_cond_resched)

kernel/printk/printk_ringbuffer.c

@@ -2143,7 +2143,7 @@ static bool _prb_read_valid(struct printk_ringbuffer *rb, u64 *seq,
 			 * But it would have the sequence number returned
 			 * by "prb_next_reserve_seq() - 1".
 			 */
-			if (this_cpu_in_panic() &&
+			if (panic_on_this_cpu() &&
 			    (!debug_non_panic_cpus || legacy_allow_panic_sync) &&
 			    ((*seq + 1) < prb_next_reserve_seq(rb))) {
 				(*seq)++;

kernel/sys.c

@@ -1734,6 +1734,7 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 	struct rlimit old, new;
 	struct task_struct *tsk;
 	unsigned int checkflags = 0;
+	bool need_tasklist;
 	int ret;
 
 	if (old_rlim)
@@ -1760,8 +1761,25 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 	get_task_struct(tsk);
 	rcu_read_unlock();
 
-	ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
-			old_rlim ? &old : NULL);
+	need_tasklist = !same_thread_group(tsk, current);
+	if (need_tasklist) {
+		/*
+		 * Ensure we can't race with group exit or de_thread(),
+		 * so tsk->group_leader can't be freed or changed until
+		 * read_unlock(tasklist_lock) below.
+		 */
+		read_lock(&tasklist_lock);
+		if (!pid_alive(tsk))
+			ret = -ESRCH;
+	}
+
+	if (!ret) {
+		ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
+				old_rlim ? &old : NULL);
+	}
+
+	if (need_tasklist)
+		read_unlock(&tasklist_lock);
 
 	if (!ret && old_rlim) {
 		rlim_to_rlim64(&old, &old64);
@@ -2515,7 +2533,17 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			error = -EINVAL;
 			break;
 		}
+		/*
+		 * Ensure that either:
+		 *
+		 * 1. Subsequent getppid() calls reflect the parent process having died.
+		 * 2. forget_original_parent() will send the new me->pdeath_signal.
+		 *
+		 * Also prevent the read of me->pdeath_signal from being a data race.
+		 */
+		read_lock(&tasklist_lock);
 		me->pdeath_signal = arg2;
+		read_unlock(&tasklist_lock);
 		break;
 	case PR_GET_PDEATHSIG:
 		error = put_user(me->pdeath_signal, (int __user *)arg2);

kernel/watchdog.c

@@ -425,7 +425,11 @@ static DEFINE_PER_CPU(u8, cpustat_tail);
  */
 static u16 get_16bit_precision(u64 data_ns)
 {
-	return data_ns >> 24LL; /* 2^24ns ~= 16.8ms */
+	/*
+	 * 2^24ns ~= 16.8ms
+	 * Round to the nearest multiple of 16.8 milliseconds.
+	 */
+	return (data_ns + (1 << 23)) >> 24LL;
 }
 
 static void update_cpustat(void)
@@ -444,6 +448,14 @@ static void update_cpustat(void)
 		old_stat = __this_cpu_read(cpustat_old[i]);
 		new_stat = get_16bit_precision(cpustat[tracked_stats[i]]);
 		util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16);
+		/*
+		 * Since we use 16-bit precision, the raw data will undergo
+		 * integer division, which may sometimes result in data loss,
+		 * and then result might exceed 100%. To avoid confusion,
+		 * we enforce a 100% display cap when calculations exceed this threshold.
+		 */
+		if (util > 100)
+			util = 100;
 		__this_cpu_write(cpustat_util[tail][i], util);
 		__this_cpu_write(cpustat_old[i], new_stat);
 	}
@@ -455,17 +467,17 @@ static void print_cpustat(void)
 {
 	int i, group;
 	u8 tail = __this_cpu_read(cpustat_tail);
-	u64 sample_period_second = sample_period;
+	u64 sample_period_msecond = sample_period;
 
-	do_div(sample_period_second, NSEC_PER_SEC);
+	do_div(sample_period_msecond, NSEC_PER_MSEC);
 
 	/*
 	 * Outputting the "watchdog" prefix on every line is redundant and not
 	 * concise, and the original alarm information is sufficient for
 	 * positioning in logs, hence here printk() is used instead of pr_crit().
 	 */
-	printk(KERN_CRIT "CPU#%d Utilization every %llus during lockup:\n",
-	       smp_processor_id(), sample_period_second);
+	printk(KERN_CRIT "CPU#%d Utilization every %llums during lockup:\n",
+	       smp_processor_id(), sample_period_msecond);
 
 	for (i = 0; i < NUM_SAMPLE_PERIODS; i++) {
 		group = (tail + i) % NUM_SAMPLE_PERIODS;
@@ -740,6 +752,12 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 	if (!watchdog_enabled)
 		return HRTIMER_NORESTART;
 
+	/*
+	 * pass the buddy check if a panic is in process
+	 */
+	if (panic_in_progress())
+		return HRTIMER_NORESTART;
+
 	watchdog_hardlockup_kick();
 
 	/* kick the softlockup detector */

kernel/watchdog_perf.c

@@ -12,6 +12,7 @@
 
 #define pr_fmt(fmt) "NMI watchdog: " fmt
 
+#include <linux/panic.h>
 #include <linux/nmi.h>
 #include <linux/atomic.h>
 #include <linux/module.h>
@@ -108,6 +109,9 @@ static void watchdog_overflow_callback(struct perf_event *event,
 	/* Ensure the watchdog never gets throttled */
 	event->hw.interrupts = 0;
 
+	if (panic_in_progress())
+		return;
+
 	if (!watchdog_check_timestamp())
 		return;