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Message-ID: <aUCv1B9Bb5CqkKcz@google.com>
Date: Tue, 16 Dec 2025 01:03:16 +0000
From: Tzung-Bi Shih <tzungbi@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Will Deacon <will@...nel.org>, Boqun Feng <boqun.feng@...il.com>
Cc: Waiman Long <longman@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] lockdep: Add header and footer to surround warning
reports
On Mon, Dec 15, 2025 at 07:26:40AM +0000, Tzung-Bi Shih wrote:
> Add header and footer to improve log parsing and automated analysis.
> This makes lockdep output easier to interpret.
>
> Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>
Oops, for some reason, I failed to cc lkml. Cc lkml.
> ---
> v2:
> - asm/bugs.h -> linux/bug.h.
>
> v1: https://lore.kernel.org/all/20251114062730.1828416-1-tzungbi@kernel.org/
>
> kernel/locking/lockdep.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 2d4c5bab5af8..adbc44c3808d 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -58,6 +58,7 @@
> #include <linux/context_tracking.h>
> #include <linux/console.h>
> #include <linux/kasan.h>
> +#include <linux/bug.h>
>
> #include <asm/sections.h>
>
> @@ -110,6 +111,11 @@ static __init int kernel_lockdep_sysctls_init(void)
> late_initcall(kernel_lockdep_sysctls_init);
> #endif /* CONFIG_SYSCTL */
>
> +static void print_footer(void)
> +{
> + pr_warn("---[ end trace %016llx ]---\n", 0ULL);
> +}
> +
> DEFINE_PER_CPU(unsigned int, lockdep_recursion);
> EXPORT_PER_CPU_SYMBOL_GPL(lockdep_recursion);
>
> @@ -1958,6 +1964,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
> return;
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("======================================================\n");
> pr_warn("WARNING: possible circular locking dependency detected\n");
> print_kernel_ident();
> @@ -2041,6 +2048,7 @@ static noinline void print_circular_bug(struct lock_list *this,
>
> printk("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -2561,6 +2569,7 @@ print_bad_irq_dependency(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=====================================================\n");
> pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
> irqclass, irqclass);
> @@ -2614,6 +2623,7 @@ print_bad_irq_dependency(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
> out:
> nbcon_cpu_emergency_exit();
> }
> @@ -3018,6 +3028,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("============================================\n");
> pr_warn("WARNING: possible recursive locking detected\n");
> print_kernel_ident();
> @@ -3039,6 +3050,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -3641,6 +3653,7 @@ static void print_collision(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("============================\n");
> pr_warn("WARNING: chain_key collision\n");
> print_kernel_ident();
> @@ -3656,6 +3669,7 @@ static void print_collision(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -4013,6 +4027,7 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("================================\n");
> pr_warn("WARNING: inconsistent lock state\n");
> print_kernel_ident();
> @@ -4040,6 +4055,7 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -4079,6 +4095,7 @@ print_irq_inversion_bug(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("========================================================\n");
> pr_warn("WARNING: possible irq lock inversion dependency detected\n");
> print_kernel_ident();
> @@ -4123,6 +4140,7 @@ print_irq_inversion_bug(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
> out:
> nbcon_cpu_emergency_exit();
> }
> @@ -4811,6 +4829,7 @@ print_lock_invalid_wait_context(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=============================\n");
> pr_warn("[ BUG: Invalid wait context ]\n");
> print_kernel_ident();
> @@ -4828,6 +4847,7 @@ print_lock_invalid_wait_context(struct task_struct *curr,
>
> pr_warn("stack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
>
> @@ -5041,6 +5061,7 @@ print_lock_nested_lock_not_held(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("==================================\n");
> pr_warn("WARNING: Nested lock was not taken\n");
> print_kernel_ident();
> @@ -5060,6 +5081,7 @@ print_lock_nested_lock_not_held(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -5281,6 +5303,7 @@ static void print_unlock_imbalance_bug(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=====================================\n");
> pr_warn("WARNING: bad unlock balance detected!\n");
> print_kernel_ident();
> @@ -5296,6 +5319,7 @@ static void print_unlock_imbalance_bug(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -6013,6 +6037,7 @@ static void print_lock_contention_bug(struct task_struct *curr,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=================================\n");
> pr_warn("WARNING: bad contention detected!\n");
> print_kernel_ident();
> @@ -6028,6 +6053,7 @@ static void print_lock_contention_bug(struct task_struct *curr,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -6680,6 +6706,7 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=========================\n");
> pr_warn("WARNING: held lock freed!\n");
> print_kernel_ident();
> @@ -6691,6 +6718,7 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
>
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -6742,6 +6770,7 @@ static void print_held_locks_bug(void)
> nbcon_cpu_emergency_enter();
>
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("====================================\n");
> pr_warn("WARNING: %s/%d still has locks held!\n",
> current->comm, task_pid_nr(current));
> @@ -6750,6 +6779,7 @@ static void print_held_locks_bug(void)
> lockdep_print_held_locks(current);
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
>
> nbcon_cpu_emergency_exit();
> }
> @@ -6811,6 +6841,7 @@ asmlinkage __visible void lockdep_sys_exit(void)
> return;
> nbcon_cpu_emergency_enter();
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("================================================\n");
> pr_warn("WARNING: lock held when returning to user space!\n");
> print_kernel_ident();
> @@ -6818,6 +6849,7 @@ asmlinkage __visible void lockdep_sys_exit(void)
> pr_warn("%s/%d is leaving the kernel with locks still held!\n",
> curr->comm, curr->pid);
> lockdep_print_held_locks(curr);
> + print_footer();
> nbcon_cpu_emergency_exit();
> }
>
> @@ -6837,6 +6869,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
> /* Note: the following can be executed concurrently, so be careful. */
> nbcon_cpu_emergency_enter();
> pr_warn("\n");
> + pr_warn(CUT_HERE);
> pr_warn("=============================\n");
> pr_warn("WARNING: suspicious RCU usage\n");
> print_kernel_ident();
> @@ -6874,6 +6907,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
> lockdep_print_held_locks(curr);
> pr_warn("\nstack backtrace:\n");
> dump_stack();
> + print_footer();
> nbcon_cpu_emergency_exit();
> warn_rcu_exit(rcu);
> }
> --
> 2.52.0.305.g3fc767764a-goog
>
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