From: Feng Tang Date: Thu, 13 Nov 2025 11:10:38 +0000 (+0800) Subject: watchdog: add sys_info sysctls to dump sys info on system lockup X-Git-Tag: v6.19-rc1~70^2~73 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9af76a78760717361cccc884dc649e30db61c8b;p=thirdparty%2Fkernel%2Flinux.git watchdog: add sys_info sysctls to dump sys info on system lockup When soft/hard lockup happens, developers may need different kinds of system information (call-stacks, memory info, locks, etc.) to help debugging. Add 'softlockup_sys_info' and 'hardlockup_sys_info' sysctl knobs to take human readable string like "tasks,mem,timers,locks,ftrace,...", and when system lockup happens, all requested information will be printed out. (refer kernel/sys_info.c for more details). Link: https://lkml.kernel.org/r/20251113111039.22701-4-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Reviewed-by: Petr Mladek Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Petr Mladek Cc: Steven Rostedt Signed-off-by: Andrew Morton --- diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 45b4408dad316..176520283f1a2 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -582,6 +582,11 @@ if leaking kernel pointer values to unprivileged users is a concern. When ``kptr_restrict`` is set to 2, kernel pointers printed using %pK will be replaced with 0s regardless of privileges. +softlockup_sys_info & hardlockup_sys_info +========================================= +A comma separated list of extra system information to be dumped when +soft/hard lockup is detected, for example, "tasks,mem,timers,locks,...". +Refer 'panic_sys_info' section below for more details. modprobe ======== diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 5b62d10027836..1f59b950c475f 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -65,6 +66,13 @@ int __read_mostly sysctl_hardlockup_all_cpu_backtrace; unsigned int __read_mostly hardlockup_panic = IS_ENABLED(CONFIG_BOOTPARAM_HARDLOCKUP_PANIC); +/* + * bitmasks to control what kinds of system info to be printed when + * hard lockup is detected, it could be task, memory, lock etc. + * Refer include/linux/sys_info.h for detailed bit definition. + */ +static unsigned long hardlockup_si_mask; + #ifdef CONFIG_SYSFS static unsigned int hardlockup_count; @@ -178,11 +186,15 @@ static void watchdog_hardlockup_kick(void) void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs) { + int hardlockup_all_cpu_backtrace; + if (per_cpu(watchdog_hardlockup_touched, cpu)) { per_cpu(watchdog_hardlockup_touched, cpu) = false; return; } + hardlockup_all_cpu_backtrace = (hardlockup_si_mask & SYS_INFO_ALL_BT) ? + 1 : sysctl_hardlockup_all_cpu_backtrace; /* * Check for a hardlockup by making sure the CPU's timer * interrupt is incrementing. The timer interrupt should have @@ -205,7 +217,7 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs) * Prevent multiple hard-lockup reports if one cpu is already * engaged in dumping all cpu back traces. */ - if (sysctl_hardlockup_all_cpu_backtrace) { + if (hardlockup_all_cpu_backtrace) { if (test_and_set_bit_lock(0, &hard_lockup_nmi_warn)) return; } @@ -234,12 +246,13 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs) trigger_single_cpu_backtrace(cpu); } - if (sysctl_hardlockup_all_cpu_backtrace) { + if (hardlockup_all_cpu_backtrace) { trigger_allbutcpu_cpu_backtrace(cpu); if (!hardlockup_panic) clear_bit_unlock(0, &hard_lockup_nmi_warn); } + sys_info(hardlockup_si_mask & ~SYS_INFO_ALL_BT); if (hardlockup_panic) nmi_panic(regs, "Hard LOCKUP"); @@ -330,6 +343,13 @@ static void lockup_detector_update_enable(void) int __read_mostly sysctl_softlockup_all_cpu_backtrace; #endif +/* + * bitmasks to control what kinds of system info to be printed when + * soft lockup is detected, it could be task, memory, lock etc. + * Refer include/linux/sys_info.h for detailed bit definition. + */ +static unsigned long softlockup_si_mask; + static struct cpumask watchdog_allowed_mask __read_mostly; /* Global variables, exported for sysctl */ @@ -746,7 +766,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) unsigned long touch_ts, period_ts, now; struct pt_regs *regs = get_irq_regs(); int duration; - int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; + int softlockup_all_cpu_backtrace; unsigned long flags; if (!watchdog_enabled) @@ -758,6 +778,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) if (panic_in_progress()) return HRTIMER_NORESTART; + softlockup_all_cpu_backtrace = (softlockup_si_mask & SYS_INFO_ALL_BT) ? + 1 : sysctl_softlockup_all_cpu_backtrace; + watchdog_hardlockup_kick(); /* kick the softlockup detector */ @@ -846,6 +869,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) } add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); + sys_info(softlockup_si_mask & ~SYS_INFO_ALL_BT); if (softlockup_panic) panic("softlockup: hung tasks"); } @@ -1197,6 +1221,13 @@ static const struct ctl_table watchdog_sysctls[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, + { + .procname = "softlockup_sys_info", + .data = &softlockup_si_mask, + .maxlen = sizeof(softlockup_si_mask), + .mode = 0644, + .proc_handler = sysctl_sys_info_handler, + }, #ifdef CONFIG_SMP { .procname = "softlockup_all_cpu_backtrace", @@ -1219,6 +1250,13 @@ static const struct ctl_table watchdog_sysctls[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, + { + .procname = "hardlockup_sys_info", + .data = &hardlockup_si_mask, + .maxlen = sizeof(hardlockup_si_mask), + .mode = 0644, + .proc_handler = sysctl_sys_info_handler, + }, #ifdef CONFIG_SMP { .procname = "hardlockup_all_cpu_backtrace",