Messages in this thread Patch in this message | | | Date | Fri, 6 Dec 2019 13:32:01 +0100 | From | Peter Zijlstra <> | Subject | Re: Problem with WARN_ON in mutex_trylock() and rxrpc |
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On Thu, Dec 05, 2019 at 02:22:12PM +0100, Peter Zijlstra wrote:
> At the very least I'm going to do a lockdep patch that verifies the lock > stack is 'empty' for the current irq_context when it changes.
Something like the below..
diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 21619c92c377..c0a314dc9969 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -21,11 +21,13 @@ extern void trace_softirqs_off(unsigned long ip); extern void lockdep_hardirqs_on(unsigned long ip); extern void lockdep_hardirqs_off(unsigned long ip); + extern void lockdep_leave_irq_context(void); #else static inline void trace_softirqs_on(unsigned long ip) { } static inline void trace_softirqs_off(unsigned long ip) { } static inline void lockdep_hardirqs_on(unsigned long ip) { } static inline void lockdep_hardirqs_off(unsigned long ip) { } + static inline void lockdep_leave_irq_context(void) { } #endif #ifdef CONFIG_TRACE_IRQFLAGS @@ -41,6 +43,8 @@ do { \ } while (0) # define trace_hardirq_exit() \ do { \ + if (current->hardirq_context == 1) \ + lockdep_leave_irq_context(); \ current->hardirq_context--; \ } while (0) # define lockdep_softirq_enter() \ @@ -49,6 +53,8 @@ do { \ } while (0) # define lockdep_softirq_exit() \ do { \ + if (current->softirq_context == 1) \ + lockdep_leave_irq_context(); \ current->softirq_context--; \ } while (0) #else diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 32282e7112d3..5c1102967927 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3600,6 +3600,43 @@ static inline unsigned int task_irq_context(struct task_struct *task) return 2 * !!task->hardirq_context + !!task->softirq_context; } +/* + * Validate the current irqcontext holds no locks. + */ +void lockdep_leave_irq_context(void) +{ + struct task_struct *curr = current; + unsigned int irq_context = task_irq_context(curr); + int depth = curr->lockdep_depth; + struct held_lock *hlock; + + if (unlikely(!debug_locks || curr->lockdep_recursion)) + return; + + if (!depth) + return; + + if (curr->held_locks[depth-1].irq_context != irq_context) + return; + + pr_warn("\n"); + pr_warn("========================================================\n"); + pr_warn("WARNING: Leaving (soft/hard) IRQ context with locks held\n"); + print_kernel_ident(); + pr_warn("--------------------------------------------------------\n"); + + for (; depth; depth--) { + hlock = curr->held_locks + depth - 1; + if (hlock->irq_context != irq_context) + break; + print_lock(hlock); + } + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} +NOKPROBE_SYMBOL(lockdep_leave_irq_context); + static int separate_irq_context(struct task_struct *curr, struct held_lock *hlock) {
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