From 6fd3ecb724868f826b0b919b70f9037275ad4da4 Mon Sep 17 00:00:00 2001 From: Tzung-Bi Shih Date: Wed, 7 Oct 2026 05:17:26 +0000 Subject: [PATCH] watchdog: force console verbose when reporting lockups When a hard or soft lockup is detected, the watchdog prints a header at KERN_EMERG (<0>), followed by diagnostic details (modules, registers, and backtraces) at KERN_WARNING/KERN_DEFAULT (<4>) and KERN_INFO (<6>). If console_loglevel is quiet (<= 4), the console skips those <4>/<6> diagnostic messages before vpanic() has a chance to call console_verbose(). With the buddy detector, this leaves only the detector CPU's panic stack on the console and nothing about the locked CPU: <0>[ 1535.991833][ C6] watchdog: Watchdog detected hard LOCKUP on cpu 7 <0>[ 1535.995960][ C6] Kernel panic - not syncing: Hard LOCKUP <4>[ 1535.995970][ C6] CPU: 6 UID: 0 PID: 0 Comm: swapper/6 ... <4>[ 1535.995997][ C6] Call trace: ... <4>[ 1535.996063][ C6] watchdog_hardlockup_check+0x1e0/0x288 <4>[ 1535.996075][ C6] watchdog_buddy_check_hardlockup+0xb4/0xc0 Similar to commit 168e06f7937d ("kernel/hung_task.c: force console verbose before panic"), call console_verbose() before printing the lockup report so the diagnostic output is not suppressed. Link: https://lore.kernel.org/20261007051726.4154849-1-tzungbi@kernel.org Signed-off-by: Tzung-Bi Shih Signed-off-by: Andrew Morton Reviewed-by: Sergey Senozhatsky Reviewed-by: Bradley Morgan Tested-by: Bradley Morgan # Power10 / ARM64 Reviewed-by: Douglas Anderson Cc: Petr Mladek Cc: Tomasz Figa --- kernel/watchdog.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index e5134ad7b663..64da2e500144 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -255,6 +255,9 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs) return; } + if (hardlockup_panic) + console_verbose(); + /* * NOTE: we call printk_cpu_sync_get_irqsave() after printing * the lockup message. While it would be nice to serialize @@ -880,6 +883,10 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) /* Start period for the next softlockup warning. */ update_report_ts(); + thresh_count = duration / get_softlockup_thresh(); + if (softlockup_panic && thresh_count >= softlockup_panic) + console_verbose(); + printk_cpu_sync_get_irqsave(flags); pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, @@ -901,7 +908,6 @@ 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); - thresh_count = duration / get_softlockup_thresh(); if (softlockup_panic && thresh_count >= softlockup_panic) panic("softlockup: hung tasks");