Merge tag 'v3.5-rc6' into irqdomain/next

Linux 3.5-rc6

14 files changed, 617 insertions, 223 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 72fcd3069a90..2097684cf194 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -255,12 +255,17 @@ int cgroup_lock_is_held(void)
 
 EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
 
+static int css_unbias_refcnt(int refcnt)
+{
+	return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS;
+}
+
 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
 static int css_refcnt(struct cgroup_subsys_state *css)
 {
 	int v = atomic_read(&css->refcnt);
 
-	return v >= 0 ? v : v - CSS_DEACT_BIAS;
+	return css_unbias_refcnt(v);
 }
 
 /* convenient tests for these bits */
@@ -4982,10 +4987,12 @@ EXPORT_SYMBOL_GPL(__css_tryget);
 void __css_put(struct cgroup_subsys_state *css)
 {
 	struct cgroup *cgrp = css->cgroup;
+	int v;
 
 	rcu_read_lock();
-	atomic_dec(&css->refcnt);
-	switch (css_refcnt(css)) {
+	v = css_unbias_refcnt(atomic_dec_return(&css->refcnt));
+
+	switch (v) {
 	case 1:
 		if (notify_on_release(cgrp)) {
 			set_bit(CGRP_RELEASABLE, &cgrp->flags);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f85c0154b333..d7d71d6ec972 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -253,9 +253,9 @@ perf_cgroup_match(struct perf_event *event)
 	return !event->cgrp || event->cgrp == cpuctx->cgrp;
 }
 
-static inline void perf_get_cgroup(struct perf_event *event)
+static inline bool perf_tryget_cgroup(struct perf_event *event)
 {
-	css_get(&event->cgrp->css);
+	return css_tryget(&event->cgrp->css);
 }
 
 static inline void perf_put_cgroup(struct perf_event *event)
@@ -484,7 +484,11 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event,
 	event->cgrp = cgrp;
 
 	/* must be done before we fput() the file */
-	perf_get_cgroup(event);
+	if (!perf_tryget_cgroup(event)) {
+		event->cgrp = NULL;
+		ret = -ENOENT;
+		goto out;
+	}
 
 	/*
 	 * all events in a group must monitor
diff --git a/kernel/exit.c b/kernel/exit.c
index 34867cc5b42a..2f59cc334516 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -72,6 +72,18 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
 		list_del_rcu(&p->tasks);
 		list_del_init(&p->sibling);
 		__this_cpu_dec(process_counts);
+		/*
+		 * If we are the last child process in a pid namespace to be
+		 * reaped, notify the reaper sleeping zap_pid_ns_processes().
+		 */
+		if (IS_ENABLED(CONFIG_PID_NS)) {
+			struct task_struct *parent = p->real_parent;
+
+			if ((task_active_pid_ns(parent)->child_reaper == parent) &&
+			    list_empty(&parent->children) &&
+			    (parent->flags & PF_EXITING))
+				wake_up_process(parent);
+		}
 	}
 	list_del_rcu(&p->thread_group);
 }
@@ -643,6 +655,7 @@ static void exit_mm(struct task_struct * tsk)
 	mm_release(tsk, mm);
 	if (!mm)
 		return;
+	sync_mm_rss(mm);
 	/*
 	 * Serialize with any possible pending coredump.
 	 * We must hold mmap_sem around checking core_state
@@ -719,12 +732,6 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
 
 		zap_pid_ns_processes(pid_ns);
 		write_lock_irq(&tasklist_lock);
-		/*
-		 * We can not clear ->child_reaper or leave it alone.
-		 * There may by stealth EXIT_DEAD tasks on ->children,
-		 * forget_original_parent() must move them somewhere.
-		 */
-		pid_ns->child_reaper = init_pid_ns.child_reaper;
 	} else if (father->signal->has_child_subreaper) {
 		struct task_struct *reaper;
 
diff --git a/kernel/panic.c b/kernel/panic.c
index 8ed89a175d79..d2a5f4ecc6dd 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -27,7 +27,7 @@
 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18
 
-int panic_on_oops;
+int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
 static unsigned long tainted_mask;
 static int pause_on_oops;
 static int pause_on_oops_flag;
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
 	 */
 	crash_kexec(NULL);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic
@@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
 	 */
 	smp_send_stop();
 
+	kmsg_dump(KMSG_DUMP_PANIC);
+
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
 	bust_spinlocks(0);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 16b20e38c4a1..b3c7fd554250 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -184,11 +184,31 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 	}
 	read_unlock(&tasklist_lock);
 
+	/* Firstly reap the EXIT_ZOMBIE children we may have. */
 	do {
 		clear_thread_flag(TIF_SIGPENDING);
 		rc = sys_wait4(-1, NULL, __WALL, NULL);
 	} while (rc != -ECHILD);
 
+	/*
+	 * sys_wait4() above can't reap the TASK_DEAD children.
+	 * Make sure they all go away, see __unhash_process().
+	 */
+	for (;;) {
+		bool need_wait = false;
+
+		read_lock(&tasklist_lock);
+		if (!list_empty(&current->children)) {
+			__set_current_state(TASK_UNINTERRUPTIBLE);
+			need_wait = true;
+		}
+		read_unlock(&tasklist_lock);
+
+		if (!need_wait)
+			break;
+		schedule();
+	}
+
 	if (pid_ns->reboot)
 		current->signal->group_exit_code = pid_ns->reboot;
 
diff --git a/kernel/printk.c b/kernel/printk.c
index 32462d2b364a..dba18211685e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -193,12 +193,19 @@ static int console_may_schedule;
  * separated by ',', and find the message after the ';' character.
  */
 
+enum log_flags {
+	LOG_DEFAULT = 0,
+	LOG_NOCONS = 1,		/* already flushed, do not print to console */
+};
+
 struct log {
 	u64 ts_nsec;		/* timestamp in nanoseconds */
 	u16 len;		/* length of entire record */
 	u16 text_len;		/* length of text buffer */
 	u16 dict_len;		/* length of dictionary buffer */
-	u16 level;		/* syslog level + facility */
+	u8 facility;		/* syslog facility */
+	u8 flags:5;		/* internal record flags */
+	u8 level:3;		/* syslog level */
 };
 
 /*
@@ -227,10 +234,10 @@ static u32 clear_idx;
 #define LOG_LINE_MAX 1024
 
 /* record buffer */
-#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 #define LOG_ALIGN 4
 #else
-#define LOG_ALIGN 8
+#define LOG_ALIGN __alignof__(struct log)
 #endif
 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
@@ -286,6 +293,7 @@ static u32 log_next(u32 idx)
 
 /* insert record into the buffer, discard old ones, update heads */
 static void log_store(int facility, int level,
+		      enum log_flags flags, u64 ts_nsec,
 		      const char *dict, u16 dict_len,
 		      const char *text, u16 text_len)
 {
@@ -329,8 +337,13 @@ static void log_store(int facility, int level,
 	msg->text_len = text_len;
 	memcpy(log_dict(msg), dict, dict_len);
 	msg->dict_len = dict_len;
-	msg->level = (facility << 3) | (level & 7);
-	msg->ts_nsec = local_clock();
+	msg->facility = facility;
+	msg->level = level & 7;
+	msg->flags = flags & 0x1f;
+	if (ts_nsec > 0)
+		msg->ts_nsec = ts_nsec;
+	else
+		msg->ts_nsec = local_clock();
 	memset(log_dict(msg) + dict_len, 0, pad_len);
 	msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
 
@@ -414,7 +427,9 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
 	if (!user)
 		return -EBADF;
 
-	mutex_lock(&user->lock);
+	ret = mutex_lock_interruptible(&user->lock);
+	if (ret)
+		return ret;
 	raw_spin_lock(&logbuf_lock);
 	while (user->seq == log_next_seq) {
 		if (file->f_flags & O_NONBLOCK) {
@@ -444,7 +459,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
 	ts_usec = msg->ts_nsec;
 	do_div(ts_usec, 1000);
 	len = sprintf(user->buf, "%u,%llu,%llu;",
-		      msg->level, user->seq, ts_usec);
+		      (msg->facility << 3) | msg->level, user->seq, ts_usec);
 
 	/* escape non-printable characters */
 	for (i = 0; i < msg->text_len; i++) {
@@ -785,6 +800,21 @@ static bool printk_time;
 #endif
 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
 
+static size_t print_time(u64 ts, char *buf)
+{
+	unsigned long rem_nsec;
+
+	if (!printk_time)
+		return 0;
+
+	if (!buf)
+		return 15;
+
+	rem_nsec = do_div(ts, 1000000000);
+	return sprintf(buf, "[%5lu.%06lu] ",
+		       (unsigned long)ts, rem_nsec / 1000);
+}
+
 static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
 {
 	size_t len = 0;
@@ -801,18 +831,7 @@ static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
 		}
 	}
 
-	if (printk_time) {
-		if (buf) {
-			unsigned long long ts = msg->ts_nsec;
-			unsigned long rem_nsec = do_div(ts, 1000000000);
-
-			len += sprintf(buf + len, "[%5lu.%06lu] ",
-					 (unsigned long) ts, rem_nsec / 1000);
-		} else {
-			len += 15;
-		}
-	}
-
+	len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
 	return len;
 }
 
@@ -860,26 +879,49 @@ static int syslog_print(char __user *buf, int size)
 {
 	char *text;
 	struct log *msg;
-	int len;
+	int len = 0;
 
 	text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
 	if (!text)
 		return -ENOMEM;
 
-	raw_spin_lock_irq(&logbuf_lock);
-	if (syslog_seq < log_first_seq) {
-		/* messages are gone, move to first one */
-		syslog_seq = log_first_seq;
-		syslog_idx = log_first_idx;
-	}
-	msg = log_from_idx(syslog_idx);
-	len = msg_print_text(msg, true, text, LOG_LINE_MAX);
-	syslog_idx = log_next(syslog_idx);
-	syslog_seq++;
-	raw_spin_unlock_irq(&logbuf_lock);
+	while (size > 0) {
+		size_t n;
+
+		raw_spin_lock_irq(&logbuf_lock);
+		if (syslog_seq < log_first_seq) {
+			/* messages are gone, move to first one */
+			syslog_seq = log_first_seq;
+			syslog_idx = log_first_idx;
+		}
+		if (syslog_seq == log_next_seq) {
+			raw_spin_unlock_irq(&logbuf_lock);
+			break;
+		}
+		msg = log_from_idx(syslog_idx);
+		n = msg_print_text(msg, true, text, LOG_LINE_MAX);
+		if (n <= size) {
+			syslog_idx = log_next(syslog_idx);
+			syslog_seq++;
+		} else
+			n = 0;
+		raw_spin_unlock_irq(&logbuf_lock);
+
+		if (!n)
+			break;
+
+		len += n;
+		size -= n;
+		buf += n;
+		n = copy_to_user(buf - n, text, n);
 
-	if (len > 0 && copy_to_user(buf, text, len))
-		len = -EFAULT;
+		if (n) {
+			len -= n;
+			if (!len)
+				len = -EFAULT;
+			break;
+		}
+	}
 
 	kfree(text);
 	return len;
@@ -909,7 +951,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 		/*
 		 * Find first record that fits, including all following records,
 		 * into the user-provided buffer for this dump.
-		*/
+		 */
 		seq = clear_seq;
 		idx = clear_idx;
 		while (seq < log_next_seq) {
@@ -919,6 +961,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 			idx = log_next(idx);
 			seq++;
 		}
+
+		/* move first record forward until length fits into the buffer */
 		seq = clear_seq;
 		idx = clear_idx;
 		while (len > size && seq < log_next_seq) {
@@ -929,7 +973,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 			seq++;
 		}
 
-		/* last message in this dump */
+		/* last message fitting into this dump */
 		next_seq = log_next_seq;
 
 		len = 0;
@@ -974,6 +1018,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 {
 	bool clear = false;
 	static int saved_console_loglevel = -1;
+	static DEFINE_MUTEX(syslog_mutex);
 	int error;
 
 	error = check_syslog_permissions(type, from_file);
@@ -1000,11 +1045,17 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 			error = -EFAULT;
 			goto out;
 		}
+		error = mutex_lock_interruptible(&syslog_mutex);
+		if (error)
+			goto out;
 		error = wait_event_interruptible(log_wait,
 						 syslog_seq != log_next_seq);
-		if (error)
+		if (error) {
+			mutex_unlock(&syslog_mutex);
 			goto out;
+		}
 		error = syslog_print(buf, len);
+		mutex_unlock(&syslog_mutex);
 		break;
 	/* Read/clear last kernel messages */
 	case SYSLOG_ACTION_READ_CLEAR:
@@ -1027,6 +1078,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 	/* Clear ring buffer */
 	case SYSLOG_ACTION_CLEAR:
 		syslog_print_all(NULL, 0, true);
+		break;
 	/* Disable logging to console */
 	case SYSLOG_ACTION_CONSOLE_OFF:
 		if (saved_console_loglevel == -1)
@@ -1259,15 +1311,92 @@ static inline void printk_delay(void)
 	}
 }
 
+/*
+ * Continuation lines are buffered, and not committed to the record buffer
+ * until the line is complete, or a race forces it. The line fragments
+ * though, are printed immediately to the consoles to ensure everything has
+ * reached the console in case of a kernel crash.
+ */
+static struct cont {
+	char buf[LOG_LINE_MAX];
+	size_t len;			/* length == 0 means unused buffer */
+	size_t cons;			/* bytes written to console */
+	struct task_struct *owner;	/* task of first print*/
+	u64 ts_nsec;			/* time of first print */
+	u8 level;			/* log level of first message */
+	u8 facility;			/* log level of first message */
+	bool flushed:1;			/* buffer sealed and committed */
+} cont;
+
+static void cont_flush(void)
+{
+	if (cont.flushed)
+		return;
+	if (cont.len == 0)
+		return;
+
+	log_store(cont.facility, cont.level, LOG_NOCONS, cont.ts_nsec,
+		  NULL, 0, cont.buf, cont.len);
+
+	cont.flushed = true;
+}
+
+static bool cont_add(int facility, int level, const char *text, size_t len)
+{
+	if (cont.len && cont.flushed)
+		return false;
+
+	if (cont.len + len > sizeof(cont.buf)) {
+		cont_flush();
+		return false;
+	}
+
+	if (!cont.len) {
+		cont.facility = facility;
+		cont.level = level;
+		cont.owner = current;
+		cont.ts_nsec = local_clock();
+		cont.cons = 0;
+		cont.flushed = false;
+	}
+
+	memcpy(cont.buf + cont.len, text, len);
+	cont.len += len;
+	return true;
+}
+
+static size_t cont_print_text(char *text, size_t size)
+{
+	size_t textlen = 0;
+	size_t len;
+
+	if (cont.cons == 0) {
+		textlen += print_time(cont.ts_nsec, text);
+		size -= textlen;
+	}
+
+	len = cont.len - cont.cons;
+	if (len > 0) {
+		if (len+1 > size)
+			len = size-1;
+		memcpy(text + textlen, cont.buf + cont.cons, len);
+		textlen += len;
+		cont.cons = cont.len;
+	}
+
+	if (cont.flushed) {
+		text[textlen++] = '\n';
+		/* got everything, release buffer */
+		cont.len = 0;
+	}
+	return textlen;
+}
+
 asmlinkage int vprintk_emit(int facility, int level,
 			    const char *dict, size_t dictlen,
 			    const char *fmt, va_list args)
 {
 	static int recursion_bug;
-	static char cont_buf[LOG_LINE_MAX];
-	static size_t cont_len;
-	static int cont_level;
-	static struct task_struct *cont_task;
 	static char textbuf[LOG_LINE_MAX];
 	char *text = textbuf;
 	size_t text_len;
@@ -1313,7 +1442,8 @@ asmlinkage int vprintk_emit(int facility, int level,
 		recursion_bug = 0;
 		printed_len += strlen(recursion_msg);
 		/* emit KERN_CRIT message */
-		log_store(0, 2, NULL, 0, recursion_msg, printed_len);
+		log_store(0, 2, LOG_DEFAULT, 0,
+			  NULL, 0, recursion_msg, printed_len);
 	}
 
 	/*
@@ -1351,55 +1481,37 @@ asmlinkage int vprintk_emit(int facility, int level,
 	}
 
 	if (!newline) {
-		if (cont_len && (prefix || cont_task != current)) {
-			/*
-			 * Flush earlier buffer, which is either from a
-			 * different thread, or when we got a new prefix.
-			 */
-			log_store(facility, cont_level, NULL, 0, cont_buf, cont_len);
-			cont_len = 0;
-		}
-
-		if (!cont_len) {
-			cont_level = level;
-			cont_task = current;
-		}
+		/*
+		 * Flush the conflicting buffer. An earlier newline was missing,
+		 * or another task also prints continuation lines.
+		 */
+		if (cont.len && (prefix || cont.owner != current))
+			cont_flush();
 
-		/* buffer or append to earlier buffer from the same thread */
-		if (cont_len + text_len > sizeof(cont_buf))
-			text_len = sizeof(cont_buf) - cont_len;
-		memcpy(cont_buf + cont_len, text, text_len);
-		cont_len += text_len;
+		/* buffer line if possible, otherwise store it right away */
+		if (!cont_add(facility, level, text, text_len))
+			log_store(facility, level, LOG_DEFAULT, 0,
+				  dict, dictlen, text, text_len);
 	} else {
-		if (cont_len && cont_task == current) {
-			if (prefix) {
-				/*
-				 * New prefix from the same thread; flush. We
-				 * either got no earlier newline, or we race
-				 * with an interrupt.
-				 */
-				log_store(facility, cont_level,
-					  NULL, 0, cont_buf, cont_len);
-				cont_len = 0;
-			}
+		bool stored = false;
 
-			/* append to the earlier buffer and flush */
-			if (cont_len + text_len > sizeof(cont_buf))
-				text_len = sizeof(cont_buf) - cont_len;
-			memcpy(cont_buf + cont_len, text, text_len);
-			cont_len += text_len;
-			log_store(facility, cont_level,
-				  NULL, 0, cont_buf, cont_len);
-			cont_len = 0;
-			cont_task = NULL;
-			printed_len = cont_len;
-		} else {
-			/* ordinary single and terminated line */
-			log_store(facility, level,
-				  dict, dictlen, text, text_len);
-			printed_len = text_len;
+		/*
+		 * If an earlier newline was missing and it was the same task,
+		 * either merge it with the current buffer and flush, or if
+		 * there was a race with interrupts (prefix == true) then just
+		 * flush it out and store this line separately.
+		 */
+		if (cont.len && cont.owner == current) {
+			if (!prefix)
+				stored = cont_add(facility, level, text, text_len);
+			cont_flush();
 		}
+
+		if (!stored)
+			log_store(facility, level, LOG_DEFAULT, 0,
+				  dict, dictlen, text, text_len);
 	}
+	printed_len += text_len;
 
 	/*
 	 * Try to acquire and then immediately release the console semaphore.
@@ -1486,11 +1598,18 @@ EXPORT_SYMBOL(printk);
 #else
 
 #define LOG_LINE_MAX 0
+static struct cont {
+	size_t len;
+	size_t cons;
+	u8 level;
+	bool flushed:1;
+} cont;
 static struct log *log_from_idx(u32 idx) { return NULL; }
 static u32 log_next(u32 idx) { return 0; }
 static void call_console_drivers(int level, const char *text, size_t len) {}
 static size_t msg_print_text(const struct log *msg, bool syslog,
 			     char *buf, size_t size) { return 0; }
+static size_t cont_print_text(char *text, size_t size) { return 0; }
 
 #endif /* CONFIG_PRINTK */
 
@@ -1782,6 +1901,7 @@ static u32 console_idx;
  */
 void console_unlock(void)
 {
+	static char text[LOG_LINE_MAX];
 	static u64 seen_seq;
 	unsigned long flags;
 	bool wake_klogd = false;
@@ -1794,10 +1914,23 @@ void console_unlock(void)
 
 	console_may_schedule = 0;
 
+	/* flush buffered message fragment immediately to console */
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	if (cont.len && (cont.cons < cont.len || cont.flushed)) {
+		size_t len;
+
+		len = cont_print_text(text, sizeof(text));
+		raw_spin_unlock(&logbuf_lock);
+		stop_critical_timings();
+		call_console_drivers(cont.level, text, len);
+		start_critical_timings();
+		local_irq_restore(flags);
+	} else
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
 again:
 	for (;;) {
 		struct log *msg;
-		static char text[LOG_LINE_MAX];
 		size_t len;
 		int level;
 
@@ -1812,13 +1945,22 @@ again:
 			console_seq = log_first_seq;
 			console_idx = log_first_idx;
 		}
-
+skip:
 		if (console_seq == log_next_seq)
 			break;
 
 		msg = log_from_idx(console_idx);
-		level = msg->level & 7;
+		if (msg->flags & LOG_NOCONS) {
+			/*
+			 * Skip record we have buffered and already printed
+			 * directly to the console when we received it.
+			 */
+			console_idx = log_next(console_idx);
+			console_seq++;
+			goto skip;
+		}
 
+		level = msg->level;
 		len = msg_print_text(msg, false, text, sizeof(text));
 
 		console_idx = log_next(console_idx);
@@ -2300,48 +2442,210 @@ module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
  * kmsg_dump - dump kernel log to kernel message dumpers.
  * @reason: the reason (oops, panic etc) for dumping
  *
- * Iterate through each of the dump devices and call the oops/panic
- * callbacks with the log buffer.
+ * Call each of the registered dumper's dump() callback, which can
+ * retrieve the kmsg records with kmsg_dump_get_line() or
+ * kmsg_dump_get_buffer().
  */
 void kmsg_dump(enum kmsg_dump_reason reason)
 {
-	u64 idx;
 	struct kmsg_dumper *dumper;
-	const char *s1, *s2;
-	unsigned long l1, l2;
 	unsigned long flags;
 
 	if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
 		return;
 
-	/* Theoretically, the log could move on after we do this, but
-	   there's not a lot we can do about that. The new messages
-	   will overwrite the start of what we dump. */
+	rcu_read_lock();
+	list_for_each_entry_rcu(dumper, &dump_list, list) {
+		if (dumper->max_reason && reason > dumper->max_reason)
+			continue;
+
+		/* initialize iterator with data about the stored records */
+		dumper->active = true;
+
+		raw_spin_lock_irqsave(&logbuf_lock, flags);
+		dumper->cur_seq = clear_seq;
+		dumper->cur_idx = clear_idx;
+		dumper->next_seq = log_next_seq;
+		dumper->next_idx = log_next_idx;
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+		/* invoke dumper which will iterate over records */
+		dumper->dump(dumper, reason);
+
+		/* reset iterator */
+		dumper->active = false;
+	}
+	rcu_read_unlock();
+}
+
+/**
+ * kmsg_dump_get_line - retrieve one kmsg log line
+ * @dumper: registered kmsg dumper
+ * @syslog: include the "<4>" prefixes
+ * @line: buffer to copy the line to
+ * @size: maximum size of the buffer
+ * @len: length of line placed into buffer
+ *
+ * Start at the beginning of the kmsg buffer, with the oldest kmsg
+ * record, and copy one record into the provided buffer.
+ *
+ * Consecutive calls will return the next available record moving
+ * towards the end of the buffer with the youngest messages.
+ *
+ * A return value of FALSE indicates that there are no more records to
+ * read.
+ */
+bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+			char *line, size_t size, size_t *len)
+{
+	unsigned long flags;
+	struct log *msg;
+	size_t l = 0;
+	bool ret = false;
+
+	if (!dumper->active)
+		goto out;
 
 	raw_spin_lock_irqsave(&logbuf_lock, flags);
-	if (syslog_seq < log_first_seq)
-		idx = syslog_idx;
-	else
-		idx = log_first_idx;
+	if (dumper->cur_seq < log_first_seq) {
+		/* messages are gone, move to first available one */
+		dumper->cur_seq = log_first_seq;
+		dumper->cur_idx = log_first_idx;
+	}
 
-	if (idx > log_next_idx) {
-		s1 = log_buf;
-		l1 = log_next_idx;
+	/* last entry */
+	if (dumper->cur_seq >= log_next_seq) {
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+		goto out;
+	}
 
-		s2 = log_buf + idx;
-		l2 = log_buf_len - idx;
-	} else {
-		s1 = "";
-		l1 = 0;
+	msg = log_from_idx(dumper->cur_idx);
+	l = msg_print_text(msg, syslog,
+			      line, size);
 
-		s2 = log_buf + idx;
-		l2 = log_next_idx - idx;
+	dumper->cur_idx = log_next(dumper->cur_idx);
+	dumper->cur_seq++;
+	ret = true;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+out:
+	if (len)
+		*len = l;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
+
+/**
+ * kmsg_dump_get_buffer - copy kmsg log lines
+ * @dumper: registered kmsg dumper
+ * @syslog: include the "<4>" prefixes
+ * @buf: buffer to copy the line to
+ * @size: maximum size of the buffer
+ * @len: length of line placed into buffer
+ *
+ * Start at the end of the kmsg buffer and fill the provided buffer
+ * with as many of the the *youngest* kmsg records that fit into it.
+ * If the buffer is large enough, all available kmsg records will be
+ * copied with a single call.
+ *
+ * Consecutive calls will fill the buffer with the next block of
+ * available older records, not including the earlier retrieved ones.
+ *
+ * A return value of FALSE indicates that there are no more records to
+ * read.
+ */
+bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+			  char *buf, size_t size, size_t *len)
+{
+	unsigned long flags;
+	u64 seq;
+	u32 idx;
+	u64 next_seq;
+	u32 next_idx;
+	size_t l = 0;
+	bool ret = false;
+
+	if (!dumper->active)
+		goto out;
+
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	if (dumper->cur_seq < log_first_seq) {
+		/* messages are gone, move to first available one */
+		dumper->cur_seq = log_first_seq;
+		dumper->cur_idx = log_first_idx;
 	}
+
+	/* last entry */
+	if (dumper->cur_seq >= dumper->next_seq) {
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+		goto out;
+	}
+
+	/* calculate length of entire buffer */
+	seq = dumper->cur_seq;
+	idx = dumper->cur_idx;
+	while (seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l += msg_print_text(msg, true, NULL, 0);
+		idx = log_next(idx);
+		seq++;
+	}
+
+	/* move first record forward until length fits into the buffer */
+	seq = dumper->cur_seq;
+	idx = dumper->cur_idx;
+	while (l > size && seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l -= msg_print_text(msg, true, NULL, 0);
+		idx = log_next(idx);
+		seq++;
+	}
+
+	/* last message in next interation */
+	next_seq = seq;
+	next_idx = idx;
+
+	l = 0;
+	while (seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l += msg_print_text(msg, syslog,
+				    buf + l, size - l);
+
+		idx = log_next(idx);
+		seq++;
+	}
+
+	dumper->next_seq = next_seq;
+	dumper->next_idx = next_idx;
+	ret = true;
 	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+out:
+	if (len)
+		*len = l;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(dumper, &dump_list, list)
-		dumper->dump(dumper, reason, s1, l1, s2, l2);
-	rcu_read_unlock();
+/**
+ * kmsg_dump_rewind - reset the interator
+ * @dumper: registered kmsg dumper
+ *
+ * Reset the dumper's iterator so that kmsg_dump_get_line() and
+ * kmsg_dump_get_buffer() can be called again and used multiple
+ * times within the same dumper.dump() callback.
+ */
+void kmsg_dump_rewind(struct kmsg_dumper *dumper)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	dumper->cur_seq = clear_seq;
+	dumper->cur_idx = clear_idx;
+	dumper->next_seq = log_next_seq;
+	dumper->next_idx = log_next_idx;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
 }
+EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
 #endif
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 0da7b88d92d0..38ecdda3f55f 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1397,6 +1397,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
 	rdp->qlen_lazy += rsp->qlen_lazy;
 	rdp->qlen += rsp->qlen;
 	rdp->n_cbs_adopted += rsp->qlen;
+	if (rsp->qlen_lazy != rsp->qlen)
+		rcu_idle_count_callbacks_posted();
 	rsp->qlen_lazy = 0;
 	rsp->qlen = 0;
 
@@ -1528,7 +1530,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 {
 	unsigned long flags;
 	struct rcu_head *next, *list, **tail;
-	int bl, count, count_lazy;
+	int bl, count, count_lazy, i;
 
 	/* If no callbacks are ready, just return.*/
 	if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
@@ -1551,9 +1553,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 	rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL];
 	*rdp->nxttail[RCU_DONE_TAIL] = NULL;
 	tail = rdp->nxttail[RCU_DONE_TAIL];
-	for (count = RCU_NEXT_SIZE - 1; count >= 0; count--)
-		if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL])
-			rdp->nxttail[count] = &rdp->nxtlist;
+	for (i = RCU_NEXT_SIZE - 1; i >= 0; i--)
+		if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL])
+			rdp->nxttail[i] = &rdp->nxtlist;
 	local_irq_restore(flags);
 
 	/* Invoke callbacks. */
@@ -1581,9 +1583,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 	if (list != NULL) {
 		*tail = rdp->nxtlist;
 		rdp->nxtlist = list;
-		for (count = 0; count < RCU_NEXT_SIZE; count++)
-			if (&rdp->nxtlist == rdp->nxttail[count])
-				rdp->nxttail[count] = tail;
+		for (i = 0; i < RCU_NEXT_SIZE; i++)
+			if (&rdp->nxtlist == rdp->nxttail[i])
+				rdp->nxttail[i] = tail;
 			else
 				break;
 	}
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7f5d138dedf5..ea056495783e 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -84,6 +84,20 @@ struct rcu_dynticks {
 				    /* Process level is worth LLONG_MAX/2. */
 	int dynticks_nmi_nesting;   /* Track NMI nesting level. */
 	atomic_t dynticks;	    /* Even value for idle, else odd. */
+#ifdef CONFIG_RCU_FAST_NO_HZ
+	int dyntick_drain;	    /* Prepare-for-idle state variable. */
+	unsigned long dyntick_holdoff;
+				    /* No retries for the jiffy of failure. */
+	struct timer_list idle_gp_timer;
+				    /* Wake up CPU sleeping with callbacks. */
+	unsigned long idle_gp_timer_expires;
+				    /* When to wake up CPU (for repost). */
+	bool idle_first_pass;	    /* First pass of attempt to go idle? */
+	unsigned long nonlazy_posted;
+				    /* # times non-lazy CBs posted to CPU. */
+	unsigned long nonlazy_posted_snap;
+				    /* idle-period nonlazy_posted snapshot. */
+#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
 };
 
 /* RCU's kthread states for tracing. */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 2411000d9869..5271a020887e 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1886,8 +1886,9 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
  * Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs
  * any flavor of RCU.
  */
-int rcu_needs_cpu(int cpu)
+int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+	*delta_jiffies = ULONG_MAX;
 	return rcu_cpu_has_callbacks(cpu);
 }
 
@@ -1962,41 +1963,6 @@ static void rcu_idle_count_callbacks_posted(void)
 #define RCU_IDLE_GP_DELAY 6		/* Roughly one grace period. */
 #define RCU_IDLE_LAZY_GP_DELAY (6 * HZ)	/* Roughly six seconds. */
 
-/* Loop counter for rcu_prepare_for_idle(). */
-static DEFINE_PER_CPU(int, rcu_dyntick_drain);
-/* If rcu_dyntick_holdoff==jiffies, don't try to enter dyntick-idle mode. */
-static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
-/* Timer to awaken the CPU if it enters dyntick-idle mode with callbacks. */
-static DEFINE_PER_CPU(struct timer_list, rcu_idle_gp_timer);
-/* Scheduled expiry time for rcu_idle_gp_timer to allow reposting. */
-static DEFINE_PER_CPU(unsigned long, rcu_idle_gp_timer_expires);
-/* Enable special processing on first attempt to enter dyntick-idle mode. */
-static DEFINE_PER_CPU(bool, rcu_idle_first_pass);
-/* Running count of non-lazy callbacks posted, never decremented. */
-static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted);
-/* Snapshot of rcu_nonlazy_posted to detect meaningful exits from idle. */
-static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted_snap);
-
-/*
- * Allow the CPU to enter dyntick-idle mode if either: (1) There are no
- * callbacks on this CPU, (2) this CPU has not yet attempted to enter
- * dyntick-idle mode, or (3) this CPU is in the process of attempting to
- * enter dyntick-idle mode.  Otherwise, if we have recently tried and failed
- * to enter dyntick-idle mode, we refuse to try to enter it.  After all,
- * it is better to incur scheduling-clock interrupts than to spin
- * continuously for the same time duration!
- */
-int rcu_needs_cpu(int cpu)
-{
-	/* Flag a new idle sojourn to the idle-entry state machine. */
-	per_cpu(rcu_idle_first_pass, cpu) = 1;
-	/* If no callbacks, RCU doesn't need the CPU. */
-	if (!rcu_cpu_has_callbacks(cpu))
-		return 0;
-	/* Otherwise, RCU needs the CPU only if it recently tried and failed. */
-	return per_cpu(rcu_dyntick_holdoff, cpu) == jiffies;
-}
-
 /*
  * Does the specified flavor of RCU have non-lazy callbacks pending on
  * the specified CPU?  Both RCU flavor and CPU are specified by the
@@ -2040,6 +2006,47 @@ static bool rcu_cpu_has_nonlazy_callbacks(int cpu)
 }
 
 /*
+ * Allow the CPU to enter dyntick-idle mode if either: (1) There are no
+ * callbacks on this CPU, (2) this CPU has not yet attempted to enter
+ * dyntick-idle mode, or (3) this CPU is in the process of attempting to
+ * enter dyntick-idle mode.  Otherwise, if we have recently tried and failed
+ * to enter dyntick-idle mode, we refuse to try to enter it.  After all,
+ * it is better to incur scheduling-clock interrupts than to spin
+ * continuously for the same time duration!
+ *
+ * The delta_jiffies argument is used to store the time when RCU is
+ * going to need the CPU again if it still has callbacks.  The reason
+ * for this is that rcu_prepare_for_idle() might need to post a timer,
+ * but if so, it will do so after tick_nohz_stop_sched_tick() has set
+ * the wakeup time for this CPU.  This means that RCU's timer can be
+ * delayed until the wakeup time, which defeats the purpose of posting
+ * a timer.
+ */
+int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
+{
+	struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+
+	/* Flag a new idle sojourn to the idle-entry state machine. */
+	rdtp->idle_first_pass = 1;
+	/* If no callbacks, RCU doesn't need the CPU. */
+	if (!rcu_cpu_has_callbacks(cpu)) {
+		*delta_jiffies = ULONG_MAX;
+		return 0;
+	}
+	if (rdtp->dyntick_holdoff == jiffies) {
+		/* RCU recently tried and failed, so don't try again. */
+		*delta_jiffies = 1;
+		return 1;
+	}
+	/* Set up for the possibility that RCU will post a timer. */
+	if (rcu_cpu_has_nonlazy_callbacks(cpu))
+		*delta_jiffies = RCU_IDLE_GP_DELAY;
+	else
+		*delta_jiffies = RCU_IDLE_LAZY_GP_DELAY;
+	return 0;
+}
+
+/*
  * Handler for smp_call_function_single().  The only point of this
  * handler is to wake the CPU up, so the handler does only tracing.
  */
@@ -2075,21 +2082,24 @@ static void rcu_idle_gp_timer_func(unsigned long cpu_in)
  */
 static void rcu_prepare_for_idle_init(int cpu)
 {
-	per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
-	setup_timer(&per_cpu(rcu_idle_gp_timer, cpu),
-		    rcu_idle_gp_timer_func, cpu);
-	per_cpu(rcu_idle_gp_timer_expires, cpu) = jiffies - 1;
-	per_cpu(rcu_idle_first_pass, cpu) = 1;
+	struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+
+	rdtp->dyntick_holdoff = jiffies - 1;
+	setup_timer(&rdtp->idle_gp_timer, rcu_idle_gp_timer_func, cpu);
+	rdtp->idle_gp_timer_expires = jiffies - 1;
+	rdtp->idle_first_pass = 1;
 }
 
 /*
  * Clean up for exit from idle.  Because we are exiting from idle, there
- * is no longer any point to rcu_idle_gp_timer, so cancel it.  This will
+ * is no longer any point to ->idle_gp_timer, so cancel it.  This will
  * do nothing if this timer is not active, so just cancel it unconditionally.
  */
 static void rcu_cleanup_after_idle(int cpu)
 {
-	del_timer(&per_cpu(rcu_idle_gp_timer, cpu));
+	struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+
+	del_timer(&rdtp->idle_gp_timer);
 	trace_rcu_prep_idle("Cleanup after idle");
 }
 
@@ -2108,42 +2118,41 @@ static void rcu_cleanup_after_idle(int cpu)
  * Because it is not legal to invoke rcu_process_callbacks() with irqs
  * disabled, we do one pass of force_quiescent_state(), then do a
  * invoke_rcu_core() to cause rcu_process_callbacks() to be invoked
- * later.  The per-cpu rcu_dyntick_drain variable controls the sequencing.
+ * later.  The ->dyntick_drain field controls the sequencing.
  *
  * The caller must have disabled interrupts.
  */
 static void rcu_prepare_for_idle(int cpu)
 {
 	struct timer_list *tp;
+	struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
 
 	/*
 	 * If this is an idle re-entry, for example, due to use of
 	 * RCU_NONIDLE() or the new idle-loop tracing API within the idle
 	 * loop, then don't take any state-machine actions, unless the
 	 * momentary exit from idle queued additional non-lazy callbacks.
-	 * Instead, repost the rcu_idle_gp_timer if this CPU has callbacks
+	 * Instead, repost the ->idle_gp_timer if this CPU has callbacks
 	 * pending.
 	 */
-	if (!per_cpu(rcu_idle_first_pass, cpu) &&
-	    (per_cpu(rcu_nonlazy_posted, cpu) ==
-	     per_cpu(rcu_nonlazy_posted_snap, cpu))) {
+	if (!rdtp->idle_first_pass &&
+	    (rdtp->nonlazy_posted == rdtp->nonlazy_posted_snap)) {
 		if (rcu_cpu_has_callbacks(cpu)) {
-			tp = &per_cpu(rcu_idle_gp_timer, cpu);
-			mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
+			tp = &rdtp->idle_gp_timer;
+			mod_timer_pinned(tp, rdtp->idle_gp_timer_expires);
 		}
 		return;
 	}
-	per_cpu(rcu_idle_first_pass, cpu) = 0;
-	per_cpu(rcu_nonlazy_posted_snap, cpu) =
-		per_cpu(rcu_nonlazy_posted, cpu) - 1;
+	rdtp->idle_first_pass = 0;
+	rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted - 1;
 
 	/*
 	 * If there are no callbacks on this CPU, enter dyntick-idle mode.
 	 * Also reset state to avoid prejudicing later attempts.
 	 */
 	if (!rcu_cpu_has_callbacks(cpu)) {
-		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
-		per_cpu(rcu_dyntick_drain, cpu) = 0;
+		rdtp->dyntick_holdoff = jiffies - 1;
+		rdtp->dyntick_drain = 0;
 		trace_rcu_prep_idle("No callbacks");
 		return;
 	}
@@ -2152,36 +2161,37 @@ static void rcu_prepare_for_idle(int cpu)
 	 * If in holdoff mode, just return.  We will presumably have
 	 * refrained from disabling the scheduling-clock tick.
 	 */
-	if (per_cpu(rcu_dyntick_holdoff, cpu) == jiffies) {
+	if (rdtp->dyntick_holdoff == jiffies) {
 		trace_rcu_prep_idle("In holdoff");
 		return;
 	}
 
-	/* Check and update the rcu_dyntick_drain sequencing. */
-	if (per_cpu(rcu_dyntick_drain, cpu) <= 0) {
+	/* Check and update the ->dyntick_drain sequencing. */
+	if (rdtp->dyntick_drain <= 0) {
 		/* First time through, initialize the counter. */
-		per_cpu(rcu_dyntick_drain, cpu) = RCU_IDLE_FLUSHES;
-	} else if (per_cpu(rcu_dyntick_drain, cpu) <= RCU_IDLE_OPT_FLUSHES &&
+		rdtp->dyntick_drain = RCU_IDLE_FLUSHES;
+	} else if (rdtp->dyntick_drain <= RCU_IDLE_OPT_FLUSHES &&
 		   !rcu_pending(cpu) &&
 		   !local_softirq_pending()) {
 		/* Can we go dyntick-idle despite still having callbacks? */
-		trace_rcu_prep_idle("Dyntick with callbacks");
-		per_cpu(rcu_dyntick_drain, cpu) = 0;
-		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
-		if (rcu_cpu_has_nonlazy_callbacks(cpu))
-			per_cpu(rcu_idle_gp_timer_expires, cpu) =
+		rdtp->dyntick_drain = 0;
+		rdtp->dyntick_holdoff = jiffies;
+		if (rcu_cpu_has_nonlazy_callbacks(cpu)) {
+			trace_rcu_prep_idle("Dyntick with callbacks");
+			rdtp->idle_gp_timer_expires =
 					   jiffies + RCU_IDLE_GP_DELAY;
-		else
-			per_cpu(rcu_idle_gp_timer_expires, cpu) =
+		} else {
+			rdtp->idle_gp_timer_expires =
 					   jiffies + RCU_IDLE_LAZY_GP_DELAY;
-		tp = &per_cpu(rcu_idle_gp_timer, cpu);
-		mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
-		per_cpu(rcu_nonlazy_posted_snap, cpu) =
-			per_cpu(rcu_nonlazy_posted, cpu);
+			trace_rcu_prep_idle("Dyntick with lazy callbacks");
+		}
+		tp = &rdtp->idle_gp_timer;
+		mod_timer_pinned(tp, rdtp->idle_gp_timer_expires);
+		rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
 		return; /* Nothing more to do immediately. */
-	} else if (--per_cpu(rcu_dyntick_drain, cpu) <= 0) {
+	} else if (--(rdtp->dyntick_drain) <= 0) {
 		/* We have hit the limit, so time to give up. */
-		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
+		rdtp->dyntick_holdoff = jiffies;
 		trace_rcu_prep_idle("Begin holdoff");
 		invoke_rcu_core();  /* Force the CPU out of dyntick-idle. */
 		return;
@@ -2227,7 +2237,7 @@ static void rcu_prepare_for_idle(int cpu)
  */
 static void rcu_idle_count_callbacks_posted(void)
 {
-	__this_cpu_add(rcu_nonlazy_posted, 1);
+	__this_cpu_add(rcu_dynticks.nonlazy_posted, 1);
 }
 
 #endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
@@ -2238,11 +2248,12 @@ static void rcu_idle_count_callbacks_posted(void)
 
 static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
 {
-	struct timer_list *tltp = &per_cpu(rcu_idle_gp_timer, cpu);
+	struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+	struct timer_list *tltp = &rdtp->idle_gp_timer;
 
 	sprintf(cp, "drain=%d %c timer=%lu",
-		per_cpu(rcu_dyntick_drain, cpu),
-		per_cpu(rcu_dyntick_holdoff, cpu) == jiffies ? 'H' : '.',
+		rdtp->dyntick_drain,
+		rdtp->dyntick_holdoff == jiffies ? 'H' : '.',
 		timer_pending(tltp) ? tltp->expires - jiffies : -1);
 }
 
diff --git a/kernel/relay.c b/kernel/relay.c
index ab56a1764d4d..e8cd2027abbd 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1235,6 +1235,7 @@ static ssize_t subbuf_splice_actor(struct file *in,
 	struct splice_pipe_desc spd = {
 		.pages = pages,
 		.nr_pages = 0,
+		.nr_pages_max = PIPE_DEF_BUFFERS,
 		.partial = partial,
 		.flags = flags,
 		.ops = &relay_pipe_buf_ops,
@@ -1302,8 +1303,8 @@ static ssize_t subbuf_splice_actor(struct file *in,
                 ret += padding;
 
 out:
-	splice_shrink_spd(pipe, &spd);
-        return ret;
+	splice_shrink_spd(&spd);
+	return ret;
 }
 
 static ssize_t relay_file_splice_read(struct file *in,
diff --git a/kernel/sys.c b/kernel/sys.c
index f0ec44dcd415..e0c8ffc50d7f 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2127,9 +2127,6 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 				else
 					return -EINVAL;
 				break;
-		case PR_GET_TID_ADDRESS:
-			error = prctl_get_tid_address(me, (int __user **)arg2);
-			break;
 			default:
 				return -EINVAL;
 			}
@@ -2147,6 +2144,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 		case PR_SET_MM:
 			error = prctl_set_mm(arg2, arg3, arg4, arg5);
 			break;
+		case PR_GET_TID_ADDRESS:
+			error = prctl_get_tid_address(me, (int __user **)arg2);
+			break;
 		case PR_SET_CHILD_SUBREAPER:
 			me->signal->is_child_subreaper = !!arg2;
 			error = 0;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index da70c6db496c..869997833928 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -274,6 +274,7 @@ EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
 static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
 {
 	unsigned long seq, last_jiffies, next_jiffies, delta_jiffies;
+	unsigned long rcu_delta_jiffies;
 	ktime_t last_update, expires, now;
 	struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
 	u64 time_delta;
@@ -322,7 +323,7 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
 		time_delta = timekeeping_max_deferment();
 	} while (read_seqretry(&xtime_lock, seq));
 
-	if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
+	if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
 	    arch_needs_cpu(cpu)) {
 		next_jiffies = last_jiffies + 1;
 		delta_jiffies = 1;
@@ -330,6 +331,10 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
 		/* Get the next timer wheel timer */
 		next_jiffies = get_next_timer_interrupt(last_jiffies);
 		delta_jiffies = next_jiffies - last_jiffies;
+		if (rcu_delta_jiffies < delta_jiffies) {
+			next_jiffies = last_jiffies + rcu_delta_jiffies;
+			delta_jiffies = rcu_delta_jiffies;
+		}
 	}
 	/*
 	 * Do not stop the tick, if we are only one off
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 68032c6177db..a7fa0702be1c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -371,7 +371,7 @@ EXPORT_SYMBOL_GPL(tracing_on);
 void tracing_off(void)
 {
 	if (global_trace.buffer)
-		ring_buffer_record_on(global_trace.buffer);
+		ring_buffer_record_off(global_trace.buffer);
 	/*
 	 * This flag is only looked at when buffers haven't been
 	 * allocated yet. We don't really care about the race
@@ -3609,6 +3609,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		.pages		= pages_def,
 		.partial	= partial_def,
 		.nr_pages	= 0, /* This gets updated below. */
+		.nr_pages_max	= PIPE_DEF_BUFFERS,
 		.flags		= flags,
 		.ops		= &tracing_pipe_buf_ops,
 		.spd_release	= tracing_spd_release_pipe,
@@ -3680,7 +3681,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 
 	ret = splice_to_pipe(pipe, &spd);
 out:
-	splice_shrink_spd(pipe, &spd);
+	splice_shrink_spd(&spd);
 	return ret;
 
 out_err:
@@ -4231,6 +4232,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 	struct splice_pipe_desc spd = {
 		.pages		= pages_def,
 		.partial	= partial_def,
+		.nr_pages_max	= PIPE_DEF_BUFFERS,
 		.flags		= flags,
 		.ops		= &buffer_pipe_buf_ops,
 		.spd_release	= buffer_spd_release,
@@ -4318,7 +4320,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 	}
 
 	ret = splice_to_pipe(pipe, &spd);
-	splice_shrink_spd(pipe, &spd);
+	splice_shrink_spd(&spd);
 out:
 	return ret;
 }
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index e5e1d85b8c7c..4b1dfba70f7c 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -372,6 +372,13 @@ static int watchdog(void *unused)
 
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
+/*
+ * People like the simple clean cpu node info on boot.
+ * Reduce the watchdog noise by only printing messages
+ * that are different from what cpu0 displayed.
+ */
+static unsigned long cpu0_err;
+
 static int watchdog_nmi_enable(int cpu)
 {
 	struct perf_event_attr *wd_attr;
@@ -390,11 +397,21 @@ static int watchdog_nmi_enable(int cpu)
 
 	/* Try to register using hardware perf events */
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
+
+	/* save cpu0 error for future comparision */
+	if (cpu == 0 && IS_ERR(event))
+		cpu0_err = PTR_ERR(event);
+
 	if (!IS_ERR(event)) {
-		pr_info("enabled, takes one hw-pmu counter.\n");
+		/* only print for cpu0 or different than cpu0 */
+		if (cpu == 0 || cpu0_err)
+			pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
 		goto out_save;
 	}
 
+	/* skip displaying the same error again */
+	if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
+		return PTR_ERR(event);
 
 	/* vary the KERN level based on the returned errno */
 	if (PTR_ERR(event) == -EOPNOTSUPP)