Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...

1 files changed, 225 insertions, 119 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 7228258b85ec..ea2d5f6962ed 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -54,20 +54,16 @@
 #include "console_cmdline.h"
 #include "braille.h"
 
-/* printk's without a loglevel use this.. */
-#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
-
-/* We show everything that is MORE important than this.. */
-#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
-#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
-
 int console_printk[4] = {
-	DEFAULT_CONSOLE_LOGLEVEL,	/* console_loglevel */
+	CONSOLE_LOGLEVEL_DEFAULT,	/* console_loglevel */
 	DEFAULT_MESSAGE_LOGLEVEL,	/* default_message_loglevel */
-	MINIMUM_CONSOLE_LOGLEVEL,	/* minimum_console_loglevel */
-	DEFAULT_CONSOLE_LOGLEVEL,	/* default_console_loglevel */
+	CONSOLE_LOGLEVEL_MIN,		/* minimum_console_loglevel */
+	CONSOLE_LOGLEVEL_DEFAULT,	/* default_console_loglevel */
 };
 
+/* Deferred messaged from sched code are marked by this special level */
+#define SCHED_MESSAGE_LOGLEVEL -2
+
 /*
  * Low level drivers may need that to know if they can schedule in
  * their unblank() callback or not. So let's export it.
@@ -91,6 +87,29 @@ static struct lockdep_map console_lock_dep_map = {
 #endif
 
 /*
+ * Helper macros to handle lockdep when locking/unlocking console_sem. We use
+ * macros instead of functions so that _RET_IP_ contains useful information.
+ */
+#define down_console_sem() do { \
+	down(&console_sem);\
+	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
+} while (0)
+
+static int __down_trylock_console_sem(unsigned long ip)
+{
+	if (down_trylock(&console_sem))
+		return 1;
+	mutex_acquire(&console_lock_dep_map, 0, 1, ip);
+	return 0;
+}
+#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
+
+#define up_console_sem() do { \
+	mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
+	up(&console_sem);\
+} while (0)
+
+/*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
  * definitely not the perfect debug tool (we don't know if _WE_
@@ -206,8 +225,9 @@ struct printk_log {
 };
 
 /*
- * The logbuf_lock protects kmsg buffer, indices, counters. It is also
- * used in interesting ways to provide interlocking in console_unlock();
+ * The logbuf_lock protects kmsg buffer, indices, counters.  This can be taken
+ * within the scheduler's rq lock. It must be released before calling
+ * console_unlock() or anything else that might wake up a process.
  */
 static DEFINE_RAW_SPINLOCK(logbuf_lock);
 
@@ -250,9 +270,6 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
 static char *log_buf = __log_buf;
 static u32 log_buf_len = __LOG_BUF_LEN;
 
-/* cpu currently holding logbuf_lock */
-static volatile unsigned int logbuf_cpu = UINT_MAX;
-
 /* human readable text of the record */
 static char *log_text(const struct printk_log *msg)
 {
@@ -297,34 +314,106 @@ static u32 log_next(u32 idx)
 	return idx + msg->len;
 }
 
-/* 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)
+/*
+ * Check whether there is enough free space for the given message.
+ *
+ * The same values of first_idx and next_idx mean that the buffer
+ * is either empty or full.
+ *
+ * If the buffer is empty, we must respect the position of the indexes.
+ * They cannot be reset to the beginning of the buffer.
+ */
+static int logbuf_has_space(u32 msg_size, bool empty)
 {
-	struct printk_log *msg;
-	u32 size, pad_len;
+	u32 free;
 
-	/* number of '\0' padding bytes to next message */
-	size = sizeof(struct printk_log) + text_len + dict_len;
-	pad_len = (-size) & (LOG_ALIGN - 1);
-	size += pad_len;
+	if (log_next_idx > log_first_idx || empty)
+		free = max(log_buf_len - log_next_idx, log_first_idx);
+	else
+		free = log_first_idx - log_next_idx;
+
+	/*
+	 * We need space also for an empty header that signalizes wrapping
+	 * of the buffer.
+	 */
+	return free >= msg_size + sizeof(struct printk_log);
+}
 
+static int log_make_free_space(u32 msg_size)
+{
 	while (log_first_seq < log_next_seq) {
-		u32 free;
+		if (logbuf_has_space(msg_size, false))
+			return 0;
+		/* drop old messages until we have enough continuous space */
+		log_first_idx = log_next(log_first_idx);
+		log_first_seq++;
+	}
 
-		if (log_next_idx > log_first_idx)
-			free = max(log_buf_len - log_next_idx, log_first_idx);
-		else
-			free = log_first_idx - log_next_idx;
+	/* sequence numbers are equal, so the log buffer is empty */
+	if (logbuf_has_space(msg_size, true))
+		return 0;
 
-		if (free >= size + sizeof(struct printk_log))
-			break;
+	return -ENOMEM;
+}
 
-		/* drop old messages until we have enough contiuous space */
-		log_first_idx = log_next(log_first_idx);
-		log_first_seq++;
+/* compute the message size including the padding bytes */
+static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
+{
+	u32 size;
+
+	size = sizeof(struct printk_log) + text_len + dict_len;
+	*pad_len = (-size) & (LOG_ALIGN - 1);
+	size += *pad_len;
+
+	return size;
+}
+
+/*
+ * Define how much of the log buffer we could take at maximum. The value
+ * must be greater than two. Note that only half of the buffer is available
+ * when the index points to the middle.
+ */
+#define MAX_LOG_TAKE_PART 4
+static const char trunc_msg[] = "<truncated>";
+
+static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
+			u16 *dict_len, u32 *pad_len)
+{
+	/*
+	 * The message should not take the whole buffer. Otherwise, it might
+	 * get removed too soon.
+	 */
+	u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
+	if (*text_len > max_text_len)
+		*text_len = max_text_len;
+	/* enable the warning message */
+	*trunc_msg_len = strlen(trunc_msg);
+	/* disable the "dict" completely */
+	*dict_len = 0;
+	/* compute the size again, count also the warning message */
+	return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
+}
+
+/* insert record into the buffer, discard old ones, update heads */
+static int 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)
+{
+	struct printk_log *msg;
+	u32 size, pad_len;
+	u16 trunc_msg_len = 0;
+
+	/* number of '\0' padding bytes to next message */
+	size = msg_used_size(text_len, dict_len, &pad_len);
+
+	if (log_make_free_space(size)) {
+		/* truncate the message if it is too long for empty buffer */
+		size = truncate_msg(&text_len, &trunc_msg_len,
+				    &dict_len, &pad_len);
+		/* survive when the log buffer is too small for trunc_msg */
+		if (log_make_free_space(size))
+			return 0;
 	}
 
 	if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
@@ -341,6 +430,10 @@ static void log_store(int facility, int level,
 	msg = (struct printk_log *)(log_buf + log_next_idx);
 	memcpy(log_text(msg), text, text_len);
 	msg->text_len = text_len;
+	if (trunc_msg_len) {
+		memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
+		msg->text_len += trunc_msg_len;
+	}
 	memcpy(log_dict(msg), dict, dict_len);
 	msg->dict_len = dict_len;
 	msg->facility = facility;
@@ -356,6 +449,8 @@ static void log_store(int facility, int level,
 	/* insert message */
 	log_next_idx += msg->len;
 	log_next_seq++;
+
+	return msg->text_len;
 }
 
 #ifdef CONFIG_SECURITY_DMESG_RESTRICT
@@ -1303,7 +1398,10 @@ static void zap_locks(void)
 	sema_init(&console_sem, 1);
 }
 
-/* Check if we have any console registered that can be called early in boot. */
+/*
+ * Check if we have any console that is capable of printing while cpu is
+ * booting or shutting down. Requires console_sem.
+ */
 static int have_callable_console(void)
 {
 	struct console *con;
@@ -1318,10 +1416,9 @@ static int have_callable_console(void)
 /*
  * Can we actually use the console at this time on this cpu?
  *
- * Console drivers may assume that per-cpu resources have
- * been allocated. So unless they're explicitly marked as
- * being able to cope (CON_ANYTIME) don't call them until
- * this CPU is officially up.
+ * Console drivers may assume that per-cpu resources have been allocated. So
+ * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
+ * call them until this CPU is officially up.
  */
 static inline int can_use_console(unsigned int cpu)
 {
@@ -1333,36 +1430,24 @@ static inline int can_use_console(unsigned int cpu)
  * messages from a 'printk'. Return true (and with the
  * console_lock held, and 'console_locked' set) if it
  * is successful, false otherwise.
- *
- * This gets called with the 'logbuf_lock' spinlock held and
- * interrupts disabled. It should return with 'lockbuf_lock'
- * released but interrupts still disabled.
  */
-static int console_trylock_for_printk(unsigned int cpu)
-	__releases(&logbuf_lock)
+static int console_trylock_for_printk(void)
 {
-	int retval = 0, wake = 0;
+	unsigned int cpu = smp_processor_id();
 
-	if (console_trylock()) {
-		retval = 1;
-
-		/*
-		 * If we can't use the console, we need to release
-		 * the console semaphore by hand to avoid flushing
-		 * the buffer. We need to hold the console semaphore
-		 * in order to do this test safely.
-		 */
-		if (!can_use_console(cpu)) {
-			console_locked = 0;
-			wake = 1;
-			retval = 0;
-		}
+	if (!console_trylock())
+		return 0;
+	/*
+	 * If we can't use the console, we need to release the console
+	 * semaphore by hand to avoid flushing the buffer. We need to hold the
+	 * console semaphore in order to do this test safely.
+	 */
+	if (!can_use_console(cpu)) {
+		console_locked = 0;
+		up_console_sem();
+		return 0;
 	}
-	logbuf_cpu = UINT_MAX;
-	raw_spin_unlock(&logbuf_lock);
-	if (wake)
-		up(&console_sem);
-	return retval;
+	return 1;
 }
 
 int printk_delay_msec __read_mostly;
@@ -1490,11 +1575,19 @@ asmlinkage int vprintk_emit(int facility, int level,
 	static int recursion_bug;
 	static char textbuf[LOG_LINE_MAX];
 	char *text = textbuf;
-	size_t text_len;
+	size_t text_len = 0;
 	enum log_flags lflags = 0;
 	unsigned long flags;
 	int this_cpu;
 	int printed_len = 0;
+	bool in_sched = false;
+	/* cpu currently holding logbuf_lock in this function */
+	static volatile unsigned int logbuf_cpu = UINT_MAX;
+
+	if (level == SCHED_MESSAGE_LOGLEVEL) {
+		level = -1;
+		in_sched = true;
+	}
 
 	boot_delay_msec(level);
 	printk_delay();
@@ -1516,7 +1609,8 @@ asmlinkage int vprintk_emit(int facility, int level,
 		 */
 		if (!oops_in_progress && !lockdep_recursing(current)) {
 			recursion_bug = 1;
-			goto out_restore_irqs;
+			local_irq_restore(flags);
+			return 0;
 		}
 		zap_locks();
 	}
@@ -1530,17 +1624,22 @@ asmlinkage int vprintk_emit(int facility, int level,
 			"BUG: recent printk recursion!";
 
 		recursion_bug = 0;
-		printed_len += strlen(recursion_msg);
+		text_len = strlen(recursion_msg);
 		/* emit KERN_CRIT message */
-		log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
-			  NULL, 0, recursion_msg, printed_len);
+		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+					 NULL, 0, recursion_msg, text_len);
 	}
 
 	/*
 	 * The printf needs to come first; we need the syslog
 	 * prefix which might be passed-in as a parameter.
 	 */
-	text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+	if (in_sched)
+		text_len = scnprintf(text, sizeof(textbuf),
+				     KERN_WARNING "[sched_delayed] ");
+
+	text_len += vscnprintf(text + text_len,
+			       sizeof(textbuf) - text_len, fmt, args);
 
 	/* mark and strip a trailing newline */
 	if (text_len && text[text_len-1] == '\n') {
@@ -1586,9 +1685,12 @@ asmlinkage int vprintk_emit(int facility, int level,
 			cont_flush(LOG_NEWLINE);
 
 		/* buffer line if possible, otherwise store it right away */
-		if (!cont_add(facility, level, text, text_len))
-			log_store(facility, level, lflags | LOG_CONT, 0,
-				  dict, dictlen, text, text_len);
+		if (cont_add(facility, level, text, text_len))
+			printed_len += text_len;
+		else
+			printed_len += log_store(facility, level,
+						 lflags | LOG_CONT, 0,
+						 dict, dictlen, text, text_len);
 	} else {
 		bool stored = false;
 
@@ -1607,26 +1709,35 @@ asmlinkage int vprintk_emit(int facility, int level,
 			cont_flush(LOG_NEWLINE);
 		}
 
-		if (!stored)
-			log_store(facility, level, lflags, 0,
-				  dict, dictlen, text, text_len);
+		if (stored)
+			printed_len += text_len;
+		else
+			printed_len += log_store(facility, level, lflags, 0,
+						 dict, dictlen, text, text_len);
 	}
-	printed_len += text_len;
+
+	logbuf_cpu = UINT_MAX;
+	raw_spin_unlock(&logbuf_lock);
+	lockdep_on();
+	local_irq_restore(flags);
+
+	/* If called from the scheduler, we can not call up(). */
+	if (in_sched)
+		return printed_len;
 
 	/*
+	 * Disable preemption to avoid being preempted while holding
+	 * console_sem which would prevent anyone from printing to console
+	 */
+	preempt_disable();
+	/*
 	 * Try to acquire and then immediately release the console semaphore.
 	 * The release will print out buffers and wake up /dev/kmsg and syslog()
 	 * users.
-	 *
-	 * The console_trylock_for_printk() function will release 'logbuf_lock'
-	 * regardless of whether it actually gets the console semaphore or not.
 	 */
-	if (console_trylock_for_printk(this_cpu))
+	if (console_trylock_for_printk())
 		console_unlock();
-
-	lockdep_on();
-out_restore_irqs:
-	local_irq_restore(flags);
+	preempt_enable();
 
 	return printed_len;
 }
@@ -1882,16 +1993,14 @@ void suspend_console(void)
 	printk("Suspending console(s) (use no_console_suspend to debug)\n");
 	console_lock();
 	console_suspended = 1;
-	up(&console_sem);
-	mutex_release(&console_lock_dep_map, 1, _RET_IP_);
+	up_console_sem();
 }
 
 void resume_console(void)
 {
 	if (!console_suspend_enabled)
 		return;
-	down(&console_sem);
-	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
+	down_console_sem();
 	console_suspended = 0;
 	console_unlock();
 }
@@ -1933,12 +2042,11 @@ void console_lock(void)
 {
 	might_sleep();
 
-	down(&console_sem);
+	down_console_sem();
 	if (console_suspended)
 		return;
 	console_locked = 1;
 	console_may_schedule = 1;
-	mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(console_lock);
 
@@ -1952,15 +2060,14 @@ EXPORT_SYMBOL(console_lock);
  */
 int console_trylock(void)
 {
-	if (down_trylock(&console_sem))
+	if (down_trylock_console_sem())
 		return 0;
 	if (console_suspended) {
-		up(&console_sem);
+		up_console_sem();
 		return 0;
 	}
 	console_locked = 1;
 	console_may_schedule = 0;
-	mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
 	return 1;
 }
 EXPORT_SYMBOL(console_trylock);
@@ -2022,7 +2129,7 @@ void console_unlock(void)
 	bool retry;
 
 	if (console_suspended) {
-		up(&console_sem);
+		up_console_sem();
 		return;
 	}
 
@@ -2043,10 +2150,15 @@ again:
 		}
 
 		if (console_seq < log_first_seq) {
+			len = sprintf(text, "** %u printk messages dropped ** ",
+				      (unsigned)(log_first_seq - console_seq));
+
 			/* messages are gone, move to first one */
 			console_seq = log_first_seq;
 			console_idx = log_first_idx;
 			console_prev = 0;
+		} else {
+			len = 0;
 		}
 skip:
 		if (console_seq == log_next_seq)
@@ -2071,8 +2183,8 @@ skip:
 		}
 
 		level = msg->level;
-		len = msg_print_text(msg, console_prev, false,
-				     text, sizeof(text));
+		len += msg_print_text(msg, console_prev, false,
+				      text + len, sizeof(text) - len);
 		console_idx = log_next(console_idx);
 		console_seq++;
 		console_prev = msg->flags;
@@ -2084,7 +2196,6 @@ skip:
 		local_irq_restore(flags);
 	}
 	console_locked = 0;
-	mutex_release(&console_lock_dep_map, 1, _RET_IP_);
 
 	/* Release the exclusive_console once it is used */
 	if (unlikely(exclusive_console))
@@ -2092,7 +2203,7 @@ skip:
 
 	raw_spin_unlock(&logbuf_lock);
 
-	up(&console_sem);
+	up_console_sem();
 
 	/*
 	 * Someone could have filled up the buffer again, so re-check if there's
@@ -2137,7 +2248,7 @@ void console_unblank(void)
 	 * oops_in_progress is set to 1..
 	 */
 	if (oops_in_progress) {
-		if (down_trylock(&console_sem) != 0)
+		if (down_trylock_console_sem() != 0)
 			return;
 	} else
 		console_lock();
@@ -2413,6 +2524,7 @@ int unregister_console(struct console *console)
 	if (console_drivers != NULL && console->flags & CON_CONSDEV)
 		console_drivers->flags |= CON_CONSDEV;
 
+	console->flags &= ~CON_ENABLED;
 	console_unlock();
 	console_sysfs_notify();
 	return res;
@@ -2437,21 +2549,19 @@ late_initcall(printk_late_init);
 /*
  * Delayed printk version, for scheduler-internal messages:
  */
-#define PRINTK_BUF_SIZE		512
-
 #define PRINTK_PENDING_WAKEUP	0x01
-#define PRINTK_PENDING_SCHED	0x02
+#define PRINTK_PENDING_OUTPUT	0x02
 
 static DEFINE_PER_CPU(int, printk_pending);
-static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
 
 static void wake_up_klogd_work_func(struct irq_work *irq_work)
 {
 	int pending = __this_cpu_xchg(printk_pending, 0);
 
-	if (pending & PRINTK_PENDING_SCHED) {
-		char *buf = __get_cpu_var(printk_sched_buf);
-		pr_warn("[sched_delayed] %s", buf);
+	if (pending & PRINTK_PENDING_OUTPUT) {
+		/* If trylock fails, someone else is doing the printing */
+		if (console_trylock())
+			console_unlock();
 	}
 
 	if (pending & PRINTK_PENDING_WAKEUP)
@@ -2473,23 +2583,19 @@ void wake_up_klogd(void)
 	preempt_enable();
 }
 
-int printk_sched(const char *fmt, ...)
+int printk_deferred(const char *fmt, ...)
 {
-	unsigned long flags;
 	va_list args;
-	char *buf;
 	int r;
 
-	local_irq_save(flags);
-	buf = __get_cpu_var(printk_sched_buf);
-
+	preempt_disable();
 	va_start(args, fmt);
-	r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+	r = vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL, NULL, 0, fmt, args);
 	va_end(args);
 
-	__this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+	__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
 	irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
-	local_irq_restore(flags);
+	preempt_enable();
 
 	return r;
 }