[PATCH RT 1/5] kernel/irq_work: fix no_hz deadlock
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2015-05-14 14:02:43
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), nohz, dynticks support, sparc + ultrasparc (sparc/sparc64), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Anna-Maria Behnsen, Frederic Weisbecker, Ingo Molnar, Thomas Gleixner, "David S. Miller", Andreas Larsson, Linus Torvalds, Borislav Petkov, Dave Hansen
3.12.40-rt56-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Invoking NO_HZ's irq_work callback from timer irq is not working very well if the callback decides to invoke hrtimer_cancel(): |hrtimer_try_to_cancel+0x55/0x5f |hrtimer_cancel+0x16/0x28 |tick_nohz_restart+0x17/0x72 |__tick_nohz_full_check+0x8e/0x93 |nohz_full_kick_work_func+0xe/0x10 |irq_work_run_list+0x39/0x57 |irq_work_tick+0x60/0x67 |update_process_times+0x57/0x67 |tick_sched_handle+0x4a/0x59 |tick_sched_timer+0x3b/0x64 |__run_hrtimer+0x7a/0x149 |hrtimer_interrupt+0x1cc/0x2c5 and here we deadlock while waiting for the lock which we are holding. To fix this I'm doing the same thing that upstream is doing: is the irq_work dedicated IRQ and use it only for what is marked as "hirq" which should only be the FULL_NO_HZ related work. Cc: stable-rt@vger.kernel.org Reported-by: Carsten Emde <redacted> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> [ Added check for in_irq() before calling irq_work_run() ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- arch/powerpc/kernel/time.c | 2 +- arch/sparc/kernel/pcr.c | 2 -- arch/x86/kernel/irq_work.c | 2 -- kernel/irq_work.c | 5 +---- kernel/time/tick-sched.c | 5 +++++ kernel/timer.c | 2 +- 6 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 03cbe6f231dc..945505e6ae9e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c@@ -423,7 +423,7 @@ unsigned long profile_pc(struct pt_regs *regs) EXPORT_SYMBOL(profile_pc); #endif -#if defined(CONFIG_IRQ_WORK) && !defined(CONFIG_PREEMPT_RT_FULL) +#if defined(CONFIG_IRQ_WORK) /* * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
diff --git a/arch/sparc/kernel/pcr.c b/arch/sparc/kernel/pcr.c
index 927d9c5e50f5..7e967c8018c8 100644
--- a/arch/sparc/kernel/pcr.c
+++ b/arch/sparc/kernel/pcr.c@@ -43,12 +43,10 @@ void __irq_entry deferred_pcr_work_irq(int irq, struct pt_regs *regs) set_irq_regs(old_regs); } -#ifndef CONFIG_PREEMPT_RT_FULL void arch_irq_work_raise(void) { set_softint(1 << PIL_DEFERRED_PCR_WORK); } -#endif const struct pcr_ops *pcr_ops; EXPORT_SYMBOL_GPL(pcr_ops);
diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c
index 3d21f7bd7b42..1de84e3ab4e0 100644
--- a/arch/x86/kernel/irq_work.c
+++ b/arch/x86/kernel/irq_work.c@@ -38,7 +38,6 @@ __visible void smp_trace_irq_work_interrupt(struct pt_regs *regs) exiting_irq(); } -#ifndef CONFIG_PREEMPT_RT_FULL void arch_irq_work_raise(void) { #ifdef CONFIG_X86_LOCAL_APIC
@@ -49,4 +48,3 @@ void arch_irq_work_raise(void) apic_wait_icr_idle(); #endif } -#endif
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 35d21f93bbe8..5f7d93d89c7f 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c@@ -16,6 +16,7 @@ #include <linux/tick.h> #include <linux/cpu.h> #include <linux/notifier.h> +#include <linux/interrupt.h> #include <asm/processor.h>
@@ -51,11 +52,7 @@ static bool irq_work_claim(struct irq_work *work) return true; } -#ifdef CONFIG_PREEMPT_RT_FULL -void arch_irq_work_raise(void) -#else void __weak arch_irq_work_raise(void) -#endif { /* * Lame architectures will get the timer tick callback
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 7e5c94b245e8..2cfd4c740042 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c@@ -175,6 +175,11 @@ static bool can_stop_full_tick(void) return false; } + if (!arch_irq_work_has_interrupt()) { + trace_tick_stop(0, "missing irq work interrupt\n"); + return false; + } + /* sched_clock_tick() needs us? */ #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK /*
diff --git a/kernel/timer.c b/kernel/timer.c
index 2d9ba1b9f698..286ca044f767 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c@@ -1450,7 +1450,7 @@ void update_process_times(int user_tick) scheduler_tick(); run_local_timers(); rcu_check_callbacks(cpu, user_tick); -#if defined(CONFIG_IRQ_WORK) +#if defined(CONFIG_IRQ_WORK) && !defined(CONFIG_PREEMPT_RT_FULL) if (in_irq()) irq_work_run(); #endif
--
2.1.4