Re: [debug PATCHes] Re: smp_call_function_single lockups

[Chris J Arges]

On Wed, Apr 01, 2015 at 02:39:13PM +0200, Ingo Molnar wrote:
> 
> * Chris J Arges <chris.j.arges@xxxxxxxxxxxxx> wrote:
> 
> > This was only tested only on the L1, so I can put this on the L0 host and run
> > this as well. The results:
> > 
> > [  124.897002] apic: vector c1, new-domain move in progress                    
> > [  124.954827] apic: vector d1, sent cleanup vector, move completed            
> > [  163.477270] apic: vector d1, new-domain move in progress                    
> > [  164.041938] apic: vector e1, sent cleanup vector, move completed            
> > [  213.466971] apic: vector e1, new-domain move in progress                    
> > [  213.775639] apic: vector 22, sent cleanup vector, move completed            
> > [  365.996747] apic: vector 22, new-domain move in progress                    
> > [  366.011136] apic: vector 42, sent cleanup vector, move completed            
> > [  393.836032] apic: vector 42, new-domain move in progress                    
> > [  393.837727] apic: vector 52, sent cleanup vector, move completed            
> > [  454.977514] apic: vector 52, new-domain move in progress                    
> > [  454.978880] apic: vector 62, sent cleanup vector, move completed            
> > [  467.055730] apic: vector 62, new-domain move in progress                    
> > [  467.058129] apic: vector 72, sent cleanup vector, move completed            
> > [  545.280125] apic: vector 72, new-domain move in progress                    
> > [  545.282801] apic: vector 82, sent cleanup vector, move completed            
> > [  567.631652] apic: vector 82, new-domain move in progress                    
> > [  567.632207] apic: vector 92, sent cleanup vector, move completed            
> > [  628.940638] apic: vector 92, new-domain move in progress                    
> > [  628.965274] apic: vector a2, sent cleanup vector, move completed            
> > [  635.187433] apic: vector a2, new-domain move in progress                    
> > [  635.191643] apic: vector b2, sent cleanup vector, move completed            
> > [  673.548020] apic: vector b2, new-domain move in progress                    
> > [  673.553843] apic: vector c2, sent cleanup vector, move completed            
> > [  688.221906] apic: vector c2, new-domain move in progress                    
> > [  688.229487] apic: vector d2, sent cleanup vector, move completed            
> > [  723.818916] apic: vector d2, new-domain move in progress                    
> > [  723.828970] apic: vector e2, sent cleanup vector, move completed            
> > [  733.485435] apic: vector e2, new-domain move in progress                    
> > [  733.615007] apic: vector 23, sent cleanup vector, move completed            
> > [  824.092036] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [ksmd:26] 
> 
> Are these all the messages? Looks like Linus's warnings went away, or 
> did you filter them out?
>
Ingo,

The patch I ran with included both patches, but I had to modify your patch
to accomodate Linus' vector tracking, I've inlined the complete patch below.

The above kernel log was all kernel messages (no grepping) leading up to the
soft lockup on L1.
 
> But ... the affinity setting message does not appear to trigger, and 
> that's the only real race I can see in the code. Also, the frequency 
> of these messages appears to be low, while the race window is narrow. 
> So I'm not sure the problem is related to the irq-move mechanism.
> 
> One thing that appears to be weird: why is there irq-movement activity 
> to begin with? Is something changing irq-affinities?
>

irqbalance is running on all VMs/Systems (L0,L1,L2) by default. I'll disable
this and re-test.
 
> Could you put a dump_stack() into the call? Something like the patch 
> below, in addition to all patches so far. (if it conflicts with the 
> previous debugging patches then just add the code manually to after 
> the debug printout.)
> 
> Thanks,
> 
> 	Ingo
> 
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index 6cedd7914581..79d6de6fdf0a 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -144,6 +144,8 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
>  			cfg->move_in_progress =
>  			   cpumask_intersects(cfg->old_domain, cpu_online_mask);
>  			cpumask_and(cfg->domain, cfg->domain, tmp_mask);
> +			if (cfg->move_in_progress)
> +				dump_stack();
>  			break;
>  		}
>  
> 

Should I add the dump_stack() to the 'new-domain move' area line ~184 since
that's the path I seem to be triggering?

Thanks,
--chris

--

For completeness, here is the patch that I ran with previously:

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index efc3b22..88b3933 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -395,7 +395,7 @@ static inline void apic_write(u32 reg, u32 val)
	apic->write(reg, val);
 }
 
-static inline void apic_eoi(void)
+static inline void apic_eoi(int vector)
 {
	apic->eoi_write(APIC_EOI, APIC_EOI_ACK);
 }
@@ -426,7 +426,7 @@ extern void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v));
 
 static inline u32 apic_read(u32 reg) { return 0; }
 static inline void apic_write(u32 reg, u32 val) { }
-static inline void apic_eoi(void) { }
+static inline void apic_eoi(int vector) { }
 static inline u64 apic_icr_read(void) { return 0; }
 static inline void apic_icr_write(u32 low, u32 high) { }
 static inline void apic_wait_icr_idle(void) { }
@@ -435,13 +435,26 @@ static inline void apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) {}
 
 #endif /* CONFIG_X86_LOCAL_APIC */
 
-static inline void ack_APIC_irq(void)
+#include <asm/irq_vectors.h>
+typedef int vector_irq_t[NR_VECTORS];
+DECLARE_PER_CPU(vector_irq_t, vector_irq);
+
+static inline void ack_APIC_irq(int vector)
 {
+	/* Is the ISR bit actually set for this vector? */
+	if (vector >= 0) {
+		unsigned v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1));
+		int irq;
+		v >>= vector & 0x1f;
+		irq = __this_cpu_read(vector_irq[vector]);
+
+		WARN(!(v & 1), "ack_APIC_irq: vector = %0x, irq = %0x\n", vector, irq);
+	}
	/*
	 * ack_APIC_irq() actually gets compiled as a single instruction
	 * ... yummie.
	 */
-	apic_eoi();
+	apic_eoi(vector);
 }
 
 static inline unsigned default_get_apic_id(unsigned long x)
@@ -639,9 +652,9 @@ static inline void entering_irq(void)
	exit_idle();
 }
 
-static inline void entering_ack_irq(void)
+static inline void entering_ack_irq(int vector)
 {
-	ack_APIC_irq();
+	ack_APIC_irq(vector);
	entering_irq();
 }
 
@@ -650,11 +663,11 @@ static inline void exiting_irq(void)
	irq_exit();
 }
 
-static inline void exiting_ack_irq(void)
+static inline void exiting_ack_irq(int vector)
 {
	irq_exit();
	/* Ack only at the end to avoid potential reentry */
-	ack_APIC_irq();
+	ack_APIC_irq(vector);
 }
 
 extern void ioapic_zap_locks(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ad3639a..20ef123 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -910,7 +910,7 @@ __visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
	 * Besides, if we don't timer interrupts ignore the global
	 * interrupt lock, which is the WrongThing (tm) to do.
	 */
-	entering_ack_irq();
+	entering_ack_irq(LOCAL_TIMER_VECTOR);
	local_apic_timer_interrupt();
	exiting_irq();
 
@@ -929,7 +929,7 @@ __visible void __irq_entry smp_trace_apic_timer_interrupt(struct pt_regs *regs)
	 * Besides, if we don't timer interrupts ignore the global
	 * interrupt lock, which is the WrongThing (tm) to do.
	 */
-	entering_ack_irq();
+	entering_ack_irq(LOCAL_TIMER_VECTOR);
	trace_local_timer_entry(LOCAL_TIMER_VECTOR);
	local_apic_timer_interrupt();
	trace_local_timer_exit(LOCAL_TIMER_VECTOR);
@@ -1342,7 +1342,7 @@ void setup_local_APIC(void)
			value = apic_read(APIC_ISR + i*0x10);
			for (j = 31; j >= 0; j--) {
				if (value & (1<<j)) {
-					ack_APIC_irq();
+					ack_APIC_irq(-1);
					acked++;
				}
			}
@@ -1868,7 +1868,7 @@ static inline void __smp_spurious_interrupt(u8 vector)
	 */
	v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1));
	if (v & (1 << (vector & 0x1f)))
-		ack_APIC_irq();
+		ack_APIC_irq(vector);
 
	inc_irq_stat(irq_spurious_count);
 
@@ -1917,7 +1917,7 @@ static inline void __smp_error_interrupt(struct pt_regs *regs)
	if (lapic_get_maxlvt() > 3)	/* Due to the Pentium erratum 3AP. */
		apic_write(APIC_ESR, 0);
	v = apic_read(APIC_ESR);
-	ack_APIC_irq();
+	ack_APIC_irq(ERROR_APIC_VECTOR);
	atomic_inc(&irq_err_count);
 
	apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x",
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index f4dc246..b74db5a 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1993,7 +1993,7 @@ static void ack_ioapic_level(struct irq_data *data)
	 * We must acknowledge the irq before we move it or the acknowledge will
	 * not propagate properly.
	 */
-	ack_APIC_irq();
+	ack_APIC_irq(i);
 
	/*
	 * Tail end of clearing remote IRR bit (either by delivering the EOI
@@ -2067,7 +2067,8 @@ static void unmask_lapic_irq(struct irq_data *data)
 
 static void ack_lapic_irq(struct irq_data *data)
 {
-	ack_APIC_irq();
+	struct irq_cfg *cfg = irqd_cfg(data);
+	ack_APIC_irq(cfg->vector);
 }
 
 static struct irq_chip lapic_chip __read_mostly = {
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 6cedd79..a8efbcb 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -143,6 +143,8 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
			cpumask_andnot(cfg->old_domain, cfg->domain, tmp_mask);
			cfg->move_in_progress =
			   cpumask_intersects(cfg->old_domain, cpu_online_mask);
+			if (cfg->move_in_progress)
+				pr_info("apic: vector %02x, same-domain move in progress\n", cfg->vector);
			cpumask_and(cfg->domain, cfg->domain, tmp_mask);
			break;
		}
@@ -178,6 +180,8 @@ next:
			cpumask_copy(cfg->old_domain, cfg->domain);
			cfg->move_in_progress =
			   cpumask_intersects(cfg->old_domain, cpu_online_mask);
+			if (cfg->move_in_progress)
+				pr_info("apic: vector %02x, new-domain move in progress\n", cfg->vector);
		}
		for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
			per_cpu(vector_irq, new_cpu)[vector] = irq;
@@ -232,6 +236,7 @@ void clear_irq_vector(int irq, struct irq_cfg *cfg)
		}
	}
	cfg->move_in_progress = 0;
+	pr_info("apic: vector %02x, vector cleared, move completed\n", cfg->vector);
	raw_spin_unlock_irqrestore(&vector_lock, flags);
 }
 
@@ -335,9 +340,11 @@ int apic_retrigger_irq(struct irq_data *data)
 
 void apic_ack_edge(struct irq_data *data)
 {
-	irq_complete_move(irqd_cfg(data));
+	struct irq_cfg *cfg = irqd_cfg(data);
+	ack_APIC_irq(cfg->vector);
+
+	irq_complete_move(cfg);
	irq_move_irq(data);
-	ack_APIC_irq();
 }
 
 /*
@@ -391,13 +398,14 @@ void send_cleanup_vector(struct irq_cfg *cfg)
		free_cpumask_var(cleanup_mask);
	}
	cfg->move_in_progress = 0;
+	pr_info("apic: vector %02x, sent cleanup vector, move completed\n", cfg->vector);
 }
 
 asmlinkage __visible void smp_irq_move_cleanup_interrupt(void)
 {
	unsigned vector, me;
 
-	ack_APIC_irq();
+	ack_APIC_irq(IRQ_MOVE_CLEANUP_VECTOR);
	irq_enter();
	exit_idle();
 
diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index 1af51b1..89bac1f 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -433,7 +433,7 @@ asmlinkage __visible void smp_thermal_interrupt(struct pt_regs *regs)
 {
	entering_irq();
	__smp_thermal_interrupt();
-	exiting_ack_irq();
+	exiting_ack_irq(THERMAL_APIC_VECTOR);
 }
 
 asmlinkage __visible void smp_trace_thermal_interrupt(struct pt_regs *regs)
@@ -442,7 +442,7 @@ asmlinkage __visible void smp_trace_thermal_interrupt(struct pt_regs *regs)
	trace_thermal_apic_entry(THERMAL_APIC_VECTOR);
	__smp_thermal_interrupt();
	trace_thermal_apic_exit(THERMAL_APIC_VECTOR);
-	exiting_ack_irq();
+	exiting_ack_irq(THERMAL_APIC_VECTOR);
 }
 
 /* Thermal monitoring depends on APIC, ACPI and clock modulation */
diff --git a/arch/x86/kernel/cpu/mcheck/threshold.c b/arch/x86/kernel/cpu/mcheck/threshold.c
index 7245980..03068d1 100644
--- a/arch/x86/kernel/cpu/mcheck/threshold.c
+++ b/arch/x86/kernel/cpu/mcheck/threshold.c
@@ -28,7 +28,7 @@ asmlinkage __visible void smp_threshold_interrupt(void)
 {
	entering_irq();
	__smp_threshold_interrupt();
-	exiting_ack_irq();
+	exiting_ack_irq(THRESHOLD_APIC_VECTOR);
 }
 
 asmlinkage __visible void smp_trace_threshold_interrupt(void)
@@ -37,5 +37,5 @@ asmlinkage __visible void smp_trace_threshold_interrupt(void)
	trace_threshold_apic_entry(THRESHOLD_APIC_VECTOR);
	__smp_threshold_interrupt();
	trace_threshold_apic_exit(THRESHOLD_APIC_VECTOR);
-	exiting_ack_irq();
+	exiting_ack_irq(THRESHOLD_APIC_VECTOR);
 }
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 67b1cbe..fc2b9a0 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -45,7 +45,8 @@ void ack_bad_irq(unsigned int irq)
	 * completely.
	 * But only ack when the APIC is enabled -AK
	 */
-	ack_APIC_irq();
+	/* This doesn't know the vector. It needs the irq descriptor */
+	ack_APIC_irq(-1);
 }
 
 #define irq_stats(x)		(&per_cpu(irq_stat, x))
@@ -198,7 +199,7 @@ __visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
	irq = __this_cpu_read(vector_irq[vector]);
 
	if (!handle_irq(irq, regs)) {
-		ack_APIC_irq();
+		ack_APIC_irq(vector);
 
		if (irq != VECTOR_RETRIGGERED) {
			pr_emerg_ratelimited("%s: %d.%d No irq handler for vector (irq %d)\n",
@@ -230,7 +231,7 @@ __visible void smp_x86_platform_ipi(struct pt_regs *regs)
 {
	struct pt_regs *old_regs = set_irq_regs(regs);
 
-	entering_ack_irq();
+	entering_ack_irq(X86_PLATFORM_IPI_VECTOR);
	__smp_x86_platform_ipi();
	exiting_irq();
	set_irq_regs(old_regs);
@@ -244,7 +245,7 @@ __visible void smp_kvm_posted_intr_ipi(struct pt_regs *regs)
 {
	struct pt_regs *old_regs = set_irq_regs(regs);
 
-	ack_APIC_irq();
+	ack_APIC_irq(POSTED_INTR_VECTOR);
 
	irq_enter();
 
@@ -262,7 +263,7 @@ __visible void smp_trace_x86_platform_ipi(struct pt_regs *regs)
 {
	struct pt_regs *old_regs = set_irq_regs(regs);
 
-	entering_ack_irq();
+	entering_ack_irq(X86_PLATFORM_IPI_VECTOR);
	trace_x86_platform_ipi_entry(X86_PLATFORM_IPI_VECTOR);
	__smp_x86_platform_ipi();
	trace_x86_platform_ipi_exit(X86_PLATFORM_IPI_VECTOR);
diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c
index 15d741d..dfe9263 100644
--- a/arch/x86/kernel/irq_work.c
+++ b/arch/x86/kernel/irq_work.c
@@ -10,10 +10,10 @@
 #include <asm/apic.h>
 #include <asm/trace/irq_vectors.h>
 
-static inline void irq_work_entering_irq(void)
+static inline void irq_work_entering_irq(int vector)
 {
	irq_enter();
-	ack_APIC_irq();
+	ack_APIC_irq(vector);
 }
 
 static inline void __smp_irq_work_interrupt(void)
@@ -24,14 +24,14 @@ static inline void __smp_irq_work_interrupt(void)
 
 __visible void smp_irq_work_interrupt(struct pt_regs *regs)
 {
-	irq_work_entering_irq();
+	irq_work_entering_irq(IRQ_WORK_VECTOR);
	__smp_irq_work_interrupt();
	exiting_irq();
 }
 
 __visible void smp_trace_irq_work_interrupt(struct pt_regs *regs)
 {
-	irq_work_entering_irq();
+	irq_work_entering_irq(IRQ_WORK_VECTOR);
	trace_irq_work_entry(IRQ_WORK_VECTOR);
	__smp_irq_work_interrupt();
	trace_irq_work_exit(IRQ_WORK_VECTOR);
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index be8e1bd..44b74b2 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -170,7 +170,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
 
 asmlinkage __visible void smp_reboot_interrupt(void)
 {
-	ack_APIC_irq();
+	ack_APIC_irq(REBOOT_VECTOR);
	irq_enter();
	stop_this_cpu(NULL);
	irq_exit();
@@ -258,16 +258,16 @@ static inline void __smp_reschedule_interrupt(void)
 
 __visible void smp_reschedule_interrupt(struct pt_regs *regs)
 {
-	ack_APIC_irq();
+	ack_APIC_irq(RESCHEDULE_VECTOR);
	__smp_reschedule_interrupt();
	/*
	 * KVM uses this interrupt to force a cpu out of guest mode
	 */
 }
 
-static inline void smp_entering_irq(void)
+static inline void smp_entering_irq(int vector)
 {
-	ack_APIC_irq();
+	ack_APIC_irq(vector);
	irq_enter();
 }
 
@@ -279,7 +279,7 @@ __visible void smp_trace_reschedule_interrupt(struct pt_regs *regs)
	 * scheduler_ipi(). This is OK, since those functions are allowed
	 * to nest.
	 */
-	smp_entering_irq();
+	smp_entering_irq(RESCHEDULE_VECTOR);
	trace_reschedule_entry(RESCHEDULE_VECTOR);
	__smp_reschedule_interrupt();
	trace_reschedule_exit(RESCHEDULE_VECTOR);
@@ -297,14 +297,14 @@ static inline void __smp_call_function_interrupt(void)
 
 __visible void smp_call_function_interrupt(struct pt_regs *regs)
 {
-	smp_entering_irq();
+	smp_entering_irq(CALL_FUNCTION_VECTOR);
	__smp_call_function_interrupt();
	exiting_irq();
 }
 
 __visible void smp_trace_call_function_interrupt(struct pt_regs *regs)
 {
-	smp_entering_irq();
+	smp_entering_irq(CALL_FUNCTION_VECTOR);
	trace_call_function_entry(CALL_FUNCTION_VECTOR);
	__smp_call_function_interrupt();
	trace_call_function_exit(CALL_FUNCTION_VECTOR);
@@ -319,14 +319,14 @@ static inline void __smp_call_function_single_interrupt(void)
 
 __visible void smp_call_function_single_interrupt(struct pt_regs *regs)
 {
-	smp_entering_irq();
+	smp_entering_irq(CALL_FUNCTION_SINGLE_VECTOR);
	__smp_call_function_single_interrupt();
	exiting_irq();
 }
 
 __visible void smp_trace_call_function_single_interrupt(struct pt_regs *regs)
 {
-	smp_entering_irq();
+	smp_entering_irq(CALL_FUNCTION_SINGLE_VECTOR);
	trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR);
	__smp_call_function_single_interrupt();
	trace_call_function_single_exit(CALL_FUNCTION_SINGLE_VECTOR);
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 390079e..896c4b3 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -334,12 +334,14 @@ void panic_if_irq_remap(const char *msg)
 
 static void ir_ack_apic_edge(struct irq_data *data)
 {
-	ack_APIC_irq();
+	struct irq_cfg *cfg = irqd_cfg(data);
+	ack_APIC_irq(cfg->vector);
 }
 
 static void ir_ack_apic_level(struct irq_data *data)
 {
-	ack_APIC_irq();
+	struct irq_cfg *cfg = irqd_cfg(data);
+	ack_APIC_irq(cfg->vector);
	eoi_ioapic_irq(data->irq, irqd_cfg(data));
 }
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 886d09e..fbdb5bd 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -244,8 +244,10 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
	desc->affinity_hint = m;
	irq_put_desc_unlock(desc, flags);
	/* set the initial affinity to prevent every interrupt being on CPU0 */
-	if (m)
+	if (m) {
+		pr_info("irq/core: Called irq_set_affinity_hint(%d)\n", irq);
		__irq_set_affinity(irq, m, false);
+	}
	return 0;
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);


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