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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-11f2e2b51b2sm58816171c88.8.2025.12.17.07.45.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 17 Dec 2025 07:45:13 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <3c727711-ab2c-45f5-86f6-64eed6715ce9@redhat.com> Date: Wed, 17 Dec 2025 10:45:08 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] lockdep: Add header and footer to surround warning reports To: Tzung-Bi Shih , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng Cc: linux-kernel@vger.kernel.org References: <20251217052353.1489154-1-tzungbi@kernel.org> Content-Language: en-US In-Reply-To: <20251217052353.1489154-1-tzungbi@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/17/25 12:23 AM, 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 > --- > v3: > - Drop meaningless 16 '0's in the footer. > > v2: https://lore.kernel.org/all/aUCv1B9Bb5CqkKcz@google.com/T/#u > - 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..8f5d0166118a 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -58,6 +58,7 @@ > #include > #include > #include > +#include > > #include > > @@ -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 ]---\n"); > +} > + Given that the footer here mark the end of the lockdep splat starting from the "CUT_HERE" line, I think we should match the length the two markers to make them easier to spot visually even though this is not needed for automatic script parsing. Cheers, Longman > 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); > }