[ANNOUNCE] 3.12.61-rt82

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2016-07-14 14:58:52
Also in: lkml
Subsystem: arm port, function hooks (ftrace), kvm paravirt (kvm/paravirt), memory management, memory management - mglru (multi-gen lru), memory management - swap, networking [general], printk, the rest, tracing, x86 architecture (32-bit and 64-bit) · Maintainers: Russell King, Steven Rostedt, Masami Hiramatsu, Paolo Bonzini, Andrew Morton, Chris Li, Kairui Song, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Petr Mladek, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

Dear RT Folks,

I'm pleased to announce the 3.12.61-rt82 stable release.


You can get this release via the git tree at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

  branch: v3.12-rt
  Head SHA1: 275c808f91fc8e1873873718290a7f242fe127cd


Or to build 3.12.61-rt82 directly, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.12.tar.xz

  http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.12.61.xz

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.12/patch-3.12.61-rt82.patch.xz



You can also build from 3.12.61-rt81 by applying the incremental patch:

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.12/incr/patch-3.12.61-rt81-rt82.patch.xz



Enjoy,

-- Steve


Changes from v3.12.61-rt81:

---

Corey Minyard (1):
      x86: Fix an RT MCE crash

Josh Cartwright (1):
      list_bl: fixup bogus lockdep warning

Luiz Capitulino (1):
      mm: perform lru_add_drain_all() remotely

Rik van Riel (1):
      kvm, rt: change async pagefault code locking for PREEMPT_RT

Sebastian Andrzej Siewior (5):
      net: dev: always take qdisc's busylock in __dev_xmit_skb()
      kernel/printk: Don't try to print from IRQ/NMI region
      arm: lazy preempt: correct resched condition
      locallock: add local_lock_on()
      trace: correct off by one while recording the trace-event

Steven Rostedt (Red Hat) (1):
      Linux 3.12.61-rt82

----
 arch/arm/kernel/entry-armv.S     |  6 +++++-
 arch/x86/kernel/cpu/mcheck/mce.c |  3 ++-
 arch/x86/kernel/kvm.c            | 37 +++++++++++++++++++------------------
 include/linux/list_bl.h          | 12 +++++++-----
 include/linux/locallock.h        |  6 ++++++
 include/trace/ftrace.h           |  3 +++
 kernel/printk/printk.c           | 10 ++++++++++
 localversion-rt                  |  2 +-
 mm/swap.c                        | 37 ++++++++++++++++++++++++++++++-------
 net/core/dev.c                   |  4 ++++
 10 files changed, 87 insertions(+), 33 deletions(-)
---------------------------
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 8c5e809c1f07..96eb4d26a5c1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -234,7 +234,11 @@ svc_preempt:
 	bne	1b
 	tst	r0, #_TIF_NEED_RESCHED_LAZY
 	moveq	pc, r8				@ go again
-	b	1b
+	ldr	r0, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
+	teq	r0, #0				@ if preempt lazy count != 0
+	beq	1b
+	mov	pc, r8				@ go again
+
 #endif
 
 __und_fault:
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 3a7ab0b08cdf..9901b77ed819 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1403,7 +1403,8 @@ static int mce_notify_work_init(void)
 
 static void mce_notify_work(void)
 {
-	wake_up_process(mce_notify_helper);
+	if (mce_notify_helper)
+		wake_up_process(mce_notify_helper);
 }
 #else
 static void mce_notify_work(void)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index e72593338df6..7e640682699d 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 #include <linux/kprobes.h>
 #include <linux/debugfs.h>
+#include <linux/wait-simple.h>
 #include <asm/timer.h>
 #include <asm/cpu.h>
 #include <asm/traps.h>
@@ -90,14 +91,14 @@ static void kvm_io_delay(void)
 
 struct kvm_task_sleep_node {
 	struct hlist_node link;
-	wait_queue_head_t wq;
+	struct swait_head wq;
 	u32 token;
 	int cpu;
 	bool halted;
 };
 
 static struct kvm_task_sleep_head {
-	spinlock_t lock;
+	raw_spinlock_t lock;
 	struct hlist_head list;
 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
 
@@ -121,17 +122,17 @@ void kvm_async_pf_task_wait(u32 token)
 	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 	struct kvm_task_sleep_node n, *e;
-	DEFINE_WAIT(wait);
+	DEFINE_SWAITER(wait);
 
 	rcu_irq_enter();
 
-	spin_lock(&b->lock);
+	raw_spin_lock(&b->lock);
 	e = _find_apf_task(b, token);
 	if (e) {
 		/* dummy entry exist -> wake up was delivered ahead of PF */
 		hlist_del(&e->link);
 		kfree(e);
-		spin_unlock(&b->lock);
+		raw_spin_unlock(&b->lock);
 
 		rcu_irq_exit();
 		return;
@@ -140,13 +141,13 @@ void kvm_async_pf_task_wait(u32 token)
 	n.token = token;
 	n.cpu = smp_processor_id();
 	n.halted = is_idle_task(current) || preempt_count() > 1;
-	init_waitqueue_head(&n.wq);
+	init_swait_head(&n.wq);
 	hlist_add_head(&n.link, &b->list);
-	spin_unlock(&b->lock);
+	raw_spin_unlock(&b->lock);
 
 	for (;;) {
 		if (!n.halted)
-			prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
+			swait_prepare(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 		if (hlist_unhashed(&n.link))
 			break;
 
@@ -165,7 +166,7 @@ void kvm_async_pf_task_wait(u32 token)
 		}
 	}
 	if (!n.halted)
-		finish_wait(&n.wq, &wait);
+		swait_finish(&n.wq, &wait);
 
 	rcu_irq_exit();
 	return;
@@ -177,8 +178,8 @@ static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 	hlist_del_init(&n->link);
 	if (n->halted)
 		smp_send_reschedule(n->cpu);
-	else if (waitqueue_active(&n->wq))
-		wake_up(&n->wq);
+	else if (swaitqueue_active(&n->wq))
+		swait_wake(&n->wq);
 }
 
 static void apf_task_wake_all(void)
@@ -188,14 +189,14 @@ static void apf_task_wake_all(void)
 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 		struct hlist_node *p, *next;
 		struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
-		spin_lock(&b->lock);
+		raw_spin_lock(&b->lock);
 		hlist_for_each_safe(p, next, &b->list) {
 			struct kvm_task_sleep_node *n =
 				hlist_entry(p, typeof(*n), link);
 			if (n->cpu == smp_processor_id())
 				apf_task_wake_one(n);
 		}
-		spin_unlock(&b->lock);
+		raw_spin_unlock(&b->lock);
 	}
 }
 
@@ -211,7 +212,7 @@ void kvm_async_pf_task_wake(u32 token)
 	}
 
 again:
-	spin_lock(&b->lock);
+	raw_spin_lock(&b->lock);
 	n = _find_apf_task(b, token);
 	if (!n) {
 		/*
@@ -224,17 +225,17 @@ again:
 			 * Allocation failed! Busy wait while other cpu
 			 * handles async PF.
 			 */
-			spin_unlock(&b->lock);
+			raw_spin_unlock(&b->lock);
 			cpu_relax();
 			goto again;
 		}
 		n->token = token;
 		n->cpu = smp_processor_id();
-		init_waitqueue_head(&n->wq);
+		init_swait_head(&n->wq);
 		hlist_add_head(&n->link, &b->list);
 	} else
 		apf_task_wake_one(n);
-	spin_unlock(&b->lock);
+	raw_spin_unlock(&b->lock);
 	return;
 }
 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
@@ -484,7 +485,7 @@ void __init kvm_guest_init(void)
 	paravirt_ops_setup();
 	register_reboot_notifier(&kvm_pv_reboot_nb);
 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
-		spin_lock_init(&async_pf_sleepers[i].lock);
+		raw_spin_lock_init(&async_pf_sleepers[i].lock);
 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
 		x86_init.irqs.trap_init = kvm_apf_trap_init;
 
diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
index d8876a0cf036..017d0f1c1eb4 100644
--- a/include/linux/list_bl.h
+++ b/include/linux/list_bl.h
@@ -42,13 +42,15 @@ struct hlist_bl_node {
 	struct hlist_bl_node *next, **pprev;
 };
 
-static inline void INIT_HLIST_BL_HEAD(struct hlist_bl_head *h)
-{
-	h->first = NULL;
 #ifdef CONFIG_PREEMPT_RT_BASE
-	raw_spin_lock_init(&h->lock);
+#define INIT_HLIST_BL_HEAD(h)		\
+do {					\
+	(h)->first = NULL;		\
+	raw_spin_lock_init(&(h)->lock);	\
+} while (0)
+#else
+#define INIT_HLIST_BL_HEAD(h) (h)->first = NULL
 #endif
-}
 
 static inline void INIT_HLIST_BL_NODE(struct hlist_bl_node *h)
 {
diff --git a/include/linux/locallock.h b/include/linux/locallock.h
index 21653e9bfa20..015271ff8ec8 100644
--- a/include/linux/locallock.h
+++ b/include/linux/locallock.h
@@ -66,6 +66,9 @@ static inline void __local_lock(struct local_irq_lock *lv)
 #define local_lock(lvar)					\
 	do { __local_lock(&get_local_var(lvar)); } while (0)
 
+#define local_lock_on(lvar, cpu)				\
+	do { __local_lock(&per_cpu(lvar, cpu)); } while (0)
+
 static inline int __local_trylock(struct local_irq_lock *lv)
 {
 	if (lv->owner != current && spin_trylock_local(&lv->lock)) {
@@ -104,6 +107,9 @@ static inline void __local_unlock(struct local_irq_lock *lv)
 		put_local_var(lvar);				\
 	} while (0)
 
+#define local_unlock_on(lvar, cpu)                       \
+	do { __local_unlock(&per_cpu(lvar, cpu)); } while (0)
+
 static inline void __local_lock_irq(struct local_irq_lock *lv)
 {
 	spin_lock_irqsave(&lv->lock, lv->flags);
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 645d749d3c9c..1c74dcd4c76e 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -536,6 +536,9 @@ ftrace_raw_event_##call(void *__data, proto)				\
 									\
 	local_save_flags(irq_flags);					\
 	pc = preempt_count();						\
+	/* Account for tracepoint preempt disable */			\
+	if (IS_ENABLED(CONFIG_PREEMPT))					\
+		pc--;							\
 									\
 	__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
 									\
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9a751f6c471e..7283909a9943 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1293,6 +1293,11 @@ static void call_console_drivers(int level, const char *text, size_t len)
 	if (!console_drivers)
 		return;
 
+	if (IS_ENABLED(CONFIG_PREEMPT_RT_BASE)) {
+		if (in_irq() || in_nmi())
+			return;
+	}
+
 	migrate_disable();
 	for_each_console(con) {
 		if (exclusive_console && con != exclusive_console)
@@ -2215,6 +2220,11 @@ void console_unblank(void)
 {
 	struct console *c;
 
+	if (IS_ENABLED(CONFIG_PREEMPT_RT_BASE)) {
+		if (in_irq() || in_nmi())
+			return;
+	}
+
 	/*
 	 * console_unblank can no longer be called in interrupt context unless
 	 * oops_in_progress is set to 1..
diff --git a/localversion-rt b/localversion-rt
index 8269ec129c0c..56556986917c 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt81
+-rt82
diff --git a/mm/swap.c b/mm/swap.c
index 8ab73ba62a68..05e75d61c707 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -718,9 +718,15 @@ void lru_add_drain_cpu(int cpu)
 		unsigned long flags;
 
 		/* No harm done if a racing interrupt already did this */
+#ifdef CONFIG_PREEMPT_RT_BASE
+		local_lock_irqsave_on(rotate_lock, flags, cpu);
+		pagevec_move_tail(pvec);
+		local_unlock_irqrestore_on(rotate_lock, flags, cpu);
+#else
 		local_lock_irqsave(rotate_lock, flags);
 		pagevec_move_tail(pvec);
 		local_unlock_irqrestore(rotate_lock, flags);
+#endif
 	}
 
 	pvec = &per_cpu(lru_deactivate_pvecs, cpu);
@@ -763,12 +769,32 @@ void lru_add_drain(void)
 	local_unlock_cpu(swapvec_lock);
 }
 
+
+#ifdef CONFIG_PREEMPT_RT_BASE
+static inline void remote_lru_add_drain(int cpu, struct cpumask *has_work)
+{
+	local_lock_on(swapvec_lock, cpu);
+	lru_add_drain_cpu(cpu);
+	local_unlock_on(swapvec_lock, cpu);
+}
+
+#else
+
 static void lru_add_drain_per_cpu(struct work_struct *dummy)
 {
 	lru_add_drain();
 }
 
 static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
+static inline void remote_lru_add_drain(int cpu, struct cpumask *has_work)
+{
+	struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
+
+	INIT_WORK(work, lru_add_drain_per_cpu);
+	schedule_work_on(cpu, work);
+	cpumask_set_cpu(cpu, has_work);
+}
+#endif
 
 void lru_add_drain_all(void)
 {
@@ -781,20 +807,17 @@ void lru_add_drain_all(void)
 	cpumask_clear(&has_work);
 
 	for_each_online_cpu(cpu) {
-		struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
-
 		if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
 		    pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
 		    pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
-		    need_activate_page_drain(cpu)) {
-			INIT_WORK(work, lru_add_drain_per_cpu);
-			schedule_work_on(cpu, work);
-			cpumask_set_cpu(cpu, &has_work);
-		}
+		    need_activate_page_drain(cpu))
+			remote_lru_add_drain(cpu, &has_work);
 	}
 
+#ifndef CONFIG_PREEMPT_RT_BASE
 	for_each_cpu(cpu, &has_work)
 		flush_work(&per_cpu(lru_add_drain_work, cpu));
+#endif
 
 	put_online_cpus();
 	mutex_unlock(&lock);
diff --git a/net/core/dev.c b/net/core/dev.c
index ee08da0fe0d7..c34af0bf3c0e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2713,7 +2713,11 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
 	 * This permits __QDISC_STATE_RUNNING owner to get the lock more often
 	 * and dequeue packets faster.
 	 */
+#ifdef CONFIG_PREEMPT_RT_FULL
+	contended = true;
+#else
 	contended = qdisc_is_running(q);
+#endif
 	if (unlikely(contended))
 		spin_lock(&q->busylock);
 
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