From: Thomas Gleixner might sleep can tell us where interrupts have been disabled, but we have no idea what disabled preemption. Add some debug infrastructure. Cc: stable-rt@vger.kernel.org Signed-off-by: Thomas Gleixner Signed-off-by: Steven Rostedt --- include/linux/sched.h | 4 ++++ kernel/sched.c | 23 +++++++++++++++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 03498cc..12317b6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1612,6 +1612,10 @@ struct task_struct { int kmap_idx; pte_t kmap_pte[KM_TYPE_NR]; #endif + +#ifdef CONFIG_DEBUG_PREEMPT + unsigned long preempt_disable_ip; +#endif }; #ifdef CONFIG_PREEMPT_RT_FULL diff --git a/kernel/sched.c b/kernel/sched.c index 87654e6..cdf9484 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4487,8 +4487,13 @@ void __kprobes add_preempt_count(int val) DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK - 10); #endif - if (preempt_count() == val) - trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); + if (preempt_count() == val) { + unsigned long ip = get_parent_ip(CALLER_ADDR1); +#ifdef CONFIG_DEBUG_PREEMPT + current->preempt_disable_ip = ip; +#endif + trace_preempt_off(CALLER_ADDR0, ip); + } } EXPORT_SYMBOL(add_preempt_count); @@ -4530,6 +4535,13 @@ static noinline void __schedule_bug(struct task_struct *prev) print_modules(); if (irqs_disabled()) print_irqtrace_events(prev); +#ifdef DEBUG_PREEMPT + if (in_atomic_preempt_off()) { + pr_err("Preemption disabled at:"); + print_ip_sym(current->preempt_disable_ip); + pr_cont("\n"); + } +#endif if (regs) show_regs(regs); @@ -8912,6 +8924,13 @@ void __might_sleep(const char *file, int line, int preempt_offset) debug_show_held_locks(current); if (irqs_disabled()) print_irqtrace_events(current); +#ifdef DEBUG_PREEMPT + if (!preempt_count_equals(preempt_offset)) { + pr_err("Preemption disabled at:"); + print_ip_sym(current->preempt_disable_ip); + pr_cont("\n"); + } +#endif dump_stack(); } EXPORT_SYMBOL(__might_sleep); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/