change system file

hc

2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771

 kernel/kernel/panic.c
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@@ -31,6 +31,7 @@
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 #include <linux/bug.h>
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 #include <linux/ratelimit.h>
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 #include <linux/debugfs.h>
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+#include <linux/sysfs.h>
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 #include <asm/sections.h>
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 #define PANIC_TIMER_STEP 100
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@@ -41,7 +42,9 @@
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  * Should we dump all CPUs backtraces in an oops event?
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  * Defaults to 0, can be changed via sysctl.
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  */
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-unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
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+static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
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+#else
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+#define sysctl_oops_all_cpu_backtrace 0
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 #endif /* CONFIG_SMP */
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 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
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@@ -54,6 +57,7 @@
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 int panic_on_warn __read_mostly;
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 unsigned long panic_on_taint;
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 bool panic_on_taint_nousertaint = false;
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+static unsigned int warn_limit __read_mostly;
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 int panic_timeout = CONFIG_PANIC_TIMEOUT;
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 EXPORT_SYMBOL_GPL(panic_timeout);
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@@ -69,6 +73,56 @@
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 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
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 EXPORT_SYMBOL(panic_notifier_list);
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+
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+#ifdef CONFIG_SYSCTL
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+static struct ctl_table kern_panic_table[] = {
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+#ifdef CONFIG_SMP
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+	{
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+		.procname       = "oops_all_cpu_backtrace",
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+		.data           = &sysctl_oops_all_cpu_backtrace,
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+		.maxlen         = sizeof(int),
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+		.mode           = 0644,
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+		.proc_handler   = proc_dointvec_minmax,
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+		.extra1         = SYSCTL_ZERO,
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+		.extra2         = SYSCTL_ONE,
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+	},
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+#endif
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+	{
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+		.procname       = "warn_limit",
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+		.data           = &warn_limit,
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+		.maxlen         = sizeof(warn_limit),
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+		.mode           = 0644,
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+		.proc_handler   = proc_douintvec,
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+	},
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+	{ }
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+};
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+
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+static __init int kernel_panic_sysctls_init(void)
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+{
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+	register_sysctl_init("kernel", kern_panic_table);
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+	return 0;
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+}
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+late_initcall(kernel_panic_sysctls_init);
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+#endif
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+
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+static atomic_t warn_count = ATOMIC_INIT(0);
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+
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+#ifdef CONFIG_SYSFS
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+static ssize_t warn_count_show(struct kobject *kobj, struct kobj_attribute *attr,
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+			       char *page)
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+{
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+	return sysfs_emit(page, "%d\n", atomic_read(&warn_count));
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+}
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+
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+static struct kobj_attribute warn_count_attr = __ATTR_RO(warn_count);
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+
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+static __init int kernel_panic_sysfs_init(void)
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+{
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+	sysfs_add_file_to_group(kernel_kobj, &warn_count_attr.attr, NULL);
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+	return 0;
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+}
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+late_initcall(kernel_panic_sysfs_init);
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+#endif
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 static long no_blink(int state)
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 {
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@@ -166,6 +220,19 @@
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 		ftrace_dump(DUMP_ALL);
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 }
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222
 
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+void check_panic_on_warn(const char *origin)
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+{
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+	unsigned int limit;
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+
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+	if (panic_on_warn)
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+		panic("%s: panic_on_warn set ...\n", origin);
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+
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+	limit = READ_ONCE(warn_limit);
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+	if (atomic_inc_return(&warn_count) >= limit && limit)
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+		panic("%s: system warned too often (kernel.warn_limit is %d)",
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+		      origin, limit);
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+}
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+
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 /**
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  *	panic - halt the system
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  *	@fmt: The text string to print
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@@ -177,12 +244,21 @@
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 void panic(const char *fmt, ...)
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 {
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 	static char buf[1024];
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-	va_list args2;
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 	va_list args;
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 	long i, i_next = 0, len;
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 	int state = 0;
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 	int old_cpu, this_cpu;
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 	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
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+
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+	if (panic_on_warn) {
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+		/*
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+		 * This thread may hit another WARN() in the panic path.
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+		 * Resetting this prevents additional WARN() from panicking the
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+		 * system on this thread.  Other threads are blocked by the
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+		 * panic_mutex in panic().
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+		 */
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+		panic_on_warn = 0;
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+	}
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 	/*
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 	 * Disable local interrupts. This will prevent panic_smp_self_stop
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@@ -192,21 +268,6 @@
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 	 */
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 	local_irq_disable();
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 	preempt_disable_notrace();
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-
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-	console_verbose();
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-	pr_emerg("Kernel panic - not syncing:\n");
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-	va_start(args2, fmt);
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-	va_copy(args, args2);
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-	vprintk(fmt, args2);
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-	va_end(args2);
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-#ifdef CONFIG_DEBUG_BUGVERBOSE
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-	/*
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-	 * Avoid nested stack-dumping if a panic occurs during oops processing
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-	 */
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-	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
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-		dump_stack();
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-#endif
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-	pr_flush(1000, true);
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 	/*
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 	 * It's possible to come here directly from a panic-assertion and
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@@ -229,12 +290,23 @@
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 	if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
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 		panic_smp_self_stop();
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+	console_verbose();
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 	bust_spinlocks(1);
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+	va_start(args, fmt);
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 	len = vscnprintf(buf, sizeof(buf), fmt, args);
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 	va_end(args);
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 	if (len && buf[len - 1] == '\n')
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 		buf[len - 1] = '\0';
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+
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+	pr_emerg("Kernel panic - not syncing: %s\n", buf);
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+#ifdef CONFIG_DEBUG_BUGVERBOSE
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+	/*
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+	 * Avoid nested stack-dumping if a panic occurs during oops processing
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+	 */
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+	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
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+		dump_stack();
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+#endif
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 	/*
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 	 * If kgdb is enabled, give it a chance to run before we stop all
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@@ -252,6 +324,7 @@
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 	 * Bypass the panic_cpu check and call __crash_kexec directly.
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 	 */
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 	if (!_crash_kexec_post_notifiers) {
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+		printk_safe_flush_on_panic();
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 		__crash_kexec(NULL);
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 		/*
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@@ -275,6 +348,8 @@
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 	 */
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 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
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+	/* Call flush even twice. It tries harder with a single online CPU */
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+	printk_safe_flush_on_panic();
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 	kmsg_dump(KMSG_DUMP_PANIC);
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 	/*
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@@ -544,11 +619,9 @@
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619
 
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 static int init_oops_id(void)
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 {
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-#ifndef CONFIG_PREEMPT_RT
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 	if (!oops_id)
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 		get_random_bytes(&oops_id, sizeof(oops_id));
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 	else
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-#endif
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 		oops_id++;
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 	return 0;
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@@ -559,7 +632,6 @@
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 {
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 	init_oops_id();
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 	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
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-	pr_flush(1000, true);
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 }
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 /*
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@@ -599,16 +671,7 @@
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 	if (regs)
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 		show_regs(regs);
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673
 
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-	if (panic_on_warn) {
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-		/*
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-		 * This thread may hit another WARN() in the panic path.
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-		 * Resetting this prevents additional WARN() from panicking the
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-		 * system on this thread.  Other threads are blocked by the
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-		 * panic_mutex in panic().
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-		 */
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-		panic_on_warn = 0;
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-		panic("panic_on_warn set ...\n");
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-	}
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+	check_panic_on_warn("kernel");
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 	if (!regs)
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 		dump_stack();