Merge branches 'core/debug', 'core/futexes', 'core/locking', 'core/rcu', 'core/signal', 'core/urgent' and 'core/xen' into core/core

Documentation/lockstat.txt

@@ -71,35 +71,50 @@ Look at the current lock statistics:
 
 # less /proc/lock_stat
 
-01 lock_stat version 0.2
+01 lock_stat version 0.3
 02 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 03                               class name    con-bounces    contentions   waittime-min   waittime-max waittime-total    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total
 04 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 05
-06               &inode->i_data.tree_lock-W:            15          21657           0.18     1093295.30 11547131054.85             58          10415           0.16          87.51        6387.60
+06                          &mm->mmap_sem-W:           233            538 18446744073708       22924.27      607243.51           1342          45806           1.71        8595.89     1180582.34
-07               &inode->i_data.tree_lock-R:             0              0           0.00           0.00           0.00          23302         231198           0.25           8.45       98023.38
+07                          &mm->mmap_sem-R:           205            587 18446744073708       28403.36      731975.00           1940         412426           0.58      187825.45     6307502.88
-08               --------------------------
+08                          ---------------
-09                 &inode->i_data.tree_lock              0          [<ffffffff8027c08f>] add_to_page_cache+0x5f/0x190
+09                            &mm->mmap_sem            487          [<ffffffff8053491f>] do_page_fault+0x466/0x928
-10
+10                            &mm->mmap_sem            179          [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d
-11 ...............................................................................................................................................................................................
+11                            &mm->mmap_sem            279          [<ffffffff80210a57>] sys_mmap+0x75/0xce
-12
+12                            &mm->mmap_sem             76          [<ffffffff802a490b>] sys_munmap+0x32/0x59
-13                              dcache_lock:          1037           1161           0.38          45.32         774.51           6611         243371           0.15         306.48       77387.24
+13                          ---------------
-14                              -----------
+14                            &mm->mmap_sem            270          [<ffffffff80210a57>] sys_mmap+0x75/0xce
-15                              dcache_lock            180          [<ffffffff802c0d7e>] sys_getcwd+0x11e/0x230
+15                            &mm->mmap_sem            431          [<ffffffff8053491f>] do_page_fault+0x466/0x928
-16                              dcache_lock            165          [<ffffffff802c002a>] d_alloc+0x15a/0x210
+16                            &mm->mmap_sem            138          [<ffffffff802a490b>] sys_munmap+0x32/0x59
-17                              dcache_lock             33          [<ffffffff8035818d>] _atomic_dec_and_lock+0x4d/0x70
+17                            &mm->mmap_sem            145          [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d
-18                              dcache_lock              1          [<ffffffff802beef8>] shrink_dcache_parent+0x18/0x130
+18
+19 ...............................................................................................................................................................................................
+20
+21                              dcache_lock:           621            623           0.52         118.26        1053.02           6745          91930           0.29         316.29      118423.41
+22                              -----------
+23                              dcache_lock            179          [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54
+24                              dcache_lock            113          [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb
+25                              dcache_lock             99          [<ffffffff802ca0dc>] d_rehash+0x1b/0x44
+26                              dcache_lock            104          [<ffffffff802cbca0>] d_instantiate+0x36/0x8a
+27                              -----------
+28                              dcache_lock            192          [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54
+29                              dcache_lock             98          [<ffffffff802ca0dc>] d_rehash+0x1b/0x44
+30                              dcache_lock             72          [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb
+31                              dcache_lock            112          [<ffffffff802cbca0>] d_instantiate+0x36/0x8a
 
 This excerpt shows the first two lock class statistics. Line 01 shows the
 output version - each time the format changes this will be updated. Line 02-04
-show the header with column descriptions. Lines 05-10 and 13-18 show the actual
+show the header with column descriptions. Lines 05-18 and 20-31 show the actual
 statistics. These statistics come in two parts; the actual stats separated by a
-short separator (line 08, 14) from the contention points.
+short separator (line 08, 13) from the contention points.
 
-The first lock (05-10) is a read/write lock, and shows two lines above the
+The first lock (05-18) is a read/write lock, and shows two lines above the
 short separator. The contention points don't match the column descriptors,
-they have two: contentions and [<IP>] symbol.
+they have two: contentions and [<IP>] symbol. The second set of contention
+points are the points we're contending with.
 
+The integer part of the time values is in us.
 
 View the top contending locks:
 

arch/um/include/asm/system.h

@@ -11,21 +11,21 @@ extern int get_signals(void);
 extern void block_signals(void);
 extern void unblock_signals(void);
 
-#define local_save_flags(flags) do { typecheck(unsigned long, flags); \
+#define raw_local_save_flags(flags) do { typecheck(unsigned long, flags); \
 				     (flags) = get_signals(); } while(0)
-#define local_irq_restore(flags) do { typecheck(unsigned long, flags); \
+#define raw_local_irq_restore(flags) do { typecheck(unsigned long, flags); \
 				      set_signals(flags); } while(0)
 
-#define local_irq_save(flags) do { local_save_flags(flags); \
+#define raw_local_irq_save(flags) do { raw_local_save_flags(flags); \
-                                   local_irq_disable(); } while(0)
+                                   raw_local_irq_disable(); } while(0)
 
-#define local_irq_enable() unblock_signals()
+#define raw_local_irq_enable() unblock_signals()
-#define local_irq_disable() block_signals()
+#define raw_local_irq_disable() block_signals()
 
 #define irqs_disabled()                 \
 ({                                      \
         unsigned long flags;            \
-        local_save_flags(flags);        \
+        raw_local_save_flags(flags);        \
         (flags == 0);                   \
 })
 

arch/x86/include/asm/uaccess.h

@@ -157,6 +157,7 @@ extern int __get_user_bad(void);
 	int __ret_gu;							\
 	unsigned long __val_gu;						\
 	__chk_user_ptr(ptr);						\
+	might_fault();							\
 	switch (sizeof(*(ptr))) {					\
 	case 1:								\
 		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
@@ -241,6 +242,7 @@ extern void __put_user_8(void);
 	int __ret_pu;						\
 	__typeof__(*(ptr)) __pu_val;				\
 	__chk_user_ptr(ptr);					\
+	might_fault();						\
 	__pu_val = x;						\
 	switch (sizeof(*(ptr))) {				\
 	case 1:							\

arch/x86/include/asm/uaccess_32.h

@@ -82,8 +82,8 @@ __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 static __always_inline unsigned long __must_check
 __copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-       might_sleep();
+	might_fault();
-       return __copy_to_user_inatomic(to, from, n);
+	return __copy_to_user_inatomic(to, from, n);
 }
 
 static __always_inline unsigned long
@@ -137,7 +137,7 @@ __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 static __always_inline unsigned long
 __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	might_sleep();
+	might_fault();
 	if (__builtin_constant_p(n)) {
 		unsigned long ret;
 
@@ -159,7 +159,7 @@ __copy_from_user(void *to, const void __user *from, unsigned long n)
 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 				const void __user *from, unsigned long n)
 {
-	might_sleep();
+	might_fault();
 	if (__builtin_constant_p(n)) {
 		unsigned long ret;
 

arch/x86/include/asm/uaccess_64.h

@@ -29,6 +29,8 @@ static __always_inline __must_check
 int __copy_from_user(void *dst, const void __user *src, unsigned size)
 {
 	int ret = 0;
+
+	might_fault();
 	if (!__builtin_constant_p(size))
 		return copy_user_generic(dst, (__force void *)src, size);
 	switch (size) {
@@ -71,6 +73,8 @@ static __always_inline __must_check
 int __copy_to_user(void __user *dst, const void *src, unsigned size)
 {
 	int ret = 0;
+
+	might_fault();
 	if (!__builtin_constant_p(size))
 		return copy_user_generic((__force void *)dst, src, size);
 	switch (size) {
@@ -113,6 +117,8 @@ static __always_inline __must_check
 int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 {
 	int ret = 0;
+
+	might_fault();
 	if (!__builtin_constant_p(size))
 		return copy_user_generic((__force void *)dst,
 					 (__force void *)src, size);

arch/x86/lib/usercopy_32.c

@@ -39,7 +39,7 @@ static inline int __movsl_is_ok(unsigned long a1, unsigned long a2, unsigned lon
 #define __do_strncpy_from_user(dst, src, count, res)			   \
 do {									   \
 	int __d0, __d1, __d2;						   \
-	might_sleep();							   \
+	might_fault();							   \
 	__asm__ __volatile__(						   \
 		"	testl %1,%1\n"					   \
 		"	jz 2f\n"					   \
@@ -126,7 +126,7 @@ EXPORT_SYMBOL(strncpy_from_user);
 #define __do_clear_user(addr,size)					\
 do {									\
 	int __d0;							\
-	might_sleep();							\
+	might_fault();							\
 	__asm__ __volatile__(						\
 		"0:	rep; stosl\n"					\
 		"	movl %2,%0\n"					\
@@ -155,7 +155,7 @@ do {									\
 unsigned long
 clear_user(void __user *to, unsigned long n)
 {
-	might_sleep();
+	might_fault();
 	if (access_ok(VERIFY_WRITE, to, n))
 		__do_clear_user(to, n);
 	return n;
@@ -197,7 +197,7 @@ long strnlen_user(const char __user *s, long n)
 	unsigned long mask = -__addr_ok(s);
 	unsigned long res, tmp;
 
-	might_sleep();
+	might_fault();
 
 	__asm__ __volatile__(
 		"	testl %0, %0\n"

arch/x86/lib/usercopy_64.c

@@ -15,7 +15,7 @@
 #define __do_strncpy_from_user(dst,src,count,res)			   \
 do {									   \
 	long __d0, __d1, __d2;						   \
-	might_sleep();							   \
+	might_fault();							   \
 	__asm__ __volatile__(						   \
 		"	testq %1,%1\n"					   \
 		"	jz 2f\n"					   \
@@ -64,7 +64,7 @@ EXPORT_SYMBOL(strncpy_from_user);
 unsigned long __clear_user(void __user *addr, unsigned long size)
 {
 	long __d0;
-	might_sleep();
+	might_fault();
 	/* no memory constraint because it doesn't change any memory gcc knows
 	   about */
 	asm volatile(

include/linux/debug_locks.h

@@ -17,7 +17,7 @@ extern int debug_locks_off(void);
 ({									\
 	int __ret = 0;							\
 									\
-	if (unlikely(c)) {						\
+	if (!oops_in_progress && unlikely(c)) {				\
 		if (debug_locks_off() && !debug_locks_silent)		\
 			WARN_ON(1);					\
 		__ret = 1;						\

include/linux/futex.h

@@ -164,6 +164,8 @@ union futex_key {
 	} both;
 };
 
+#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
+
 #ifdef CONFIG_FUTEX
 extern void exit_robust_list(struct task_struct *curr);
 extern void exit_pi_state_list(struct task_struct *curr);

include/linux/kernel.h

@@ -141,6 +141,15 @@ extern int _cond_resched(void);
 		(__x < 0) ? -__x : __x;		\
 	})
 
+#ifdef CONFIG_PROVE_LOCKING
+void might_fault(void);
+#else
+static inline void might_fault(void)
+{
+	might_sleep();
+}
+#endif
+
 extern struct atomic_notifier_head panic_notifier_list;
 extern long (*panic_blink)(long time);
 NORET_TYPE void panic(const char * fmt, ...)
@@ -188,6 +197,8 @@ extern unsigned long long memparse(const char *ptr, char **retptr);
 extern int core_kernel_text(unsigned long addr);
 extern int __kernel_text_address(unsigned long addr);
 extern int kernel_text_address(unsigned long addr);
+extern int func_ptr_is_kernel_text(void *ptr);
+
 struct pid;
 extern struct pid *session_of_pgrp(struct pid *pgrp);
 

include/linux/lockdep.h

@@ -73,6 +73,8 @@ struct lock_class_key {
 	struct lockdep_subclass_key	subkeys[MAX_LOCKDEP_SUBCLASSES];
 };
 
+#define LOCKSTAT_POINTS		4
+
 /*
  * The lock-class itself:
  */
@@ -119,7 +121,8 @@ struct lock_class {
 	int				name_version;
 
 #ifdef CONFIG_LOCK_STAT
-	unsigned long			contention_point[4];
+	unsigned long			contention_point[LOCKSTAT_POINTS];
+	unsigned long			contending_point[LOCKSTAT_POINTS];
 #endif
 };
 
@@ -144,6 +147,7 @@ enum bounce_type {
 
 struct lock_class_stats {
 	unsigned long			contention_point[4];
+	unsigned long			contending_point[4];
 	struct lock_time		read_waittime;
 	struct lock_time		write_waittime;
 	struct lock_time		read_holdtime;
@@ -165,6 +169,7 @@ struct lockdep_map {
 	const char			*name;
 #ifdef CONFIG_LOCK_STAT
 	int				cpu;
+	unsigned long			ip;
 #endif
 };
 
@@ -356,7 +361,7 @@ struct lock_class_key { };
 #ifdef CONFIG_LOCK_STAT
 
 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
-extern void lock_acquired(struct lockdep_map *lock);
+extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 
 #define LOCK_CONTENDED(_lock, try, lock)			\
 do {								\
@@ -364,13 +369,13 @@ do {								\
 		lock_contended(&(_lock)->dep_map, _RET_IP_);	\
 		lock(_lock);					\
 	}							\
-	lock_acquired(&(_lock)->dep_map);			\
+	lock_acquired(&(_lock)->dep_map, _RET_IP_);			\
 } while (0)
 
 #else /* CONFIG_LOCK_STAT */
 
 #define lock_contended(lockdep_map, ip) do {} while (0)
-#define lock_acquired(lockdep_map) do {} while (0)
+#define lock_acquired(lockdep_map, ip) do {} while (0)
 
 #define LOCK_CONTENDED(_lock, try, lock) \
 	lock(_lock)
@@ -481,4 +486,22 @@ static inline void print_irqtrace_events(struct task_struct *curr)
 # define lock_map_release(l)			do { } while (0)
 #endif
 
+#ifdef CONFIG_PROVE_LOCKING
+# define might_lock(lock) 						\
+do {									\
+	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
+	lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);	\
+	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
+} while (0)
+# define might_lock_read(lock) 						\
+do {									\
+	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
+	lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);	\
+	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
+} while (0)
+#else
+# define might_lock(lock) do { } while (0)
+# define might_lock_read(lock) do { } while (0)
+#endif
+
 #endif /* __LINUX_LOCKDEP_H */

include/linux/mutex.h

@@ -144,6 +144,8 @@ extern int __must_check mutex_lock_killable(struct mutex *lock);
 /*
  * NOTE: mutex_trylock() follows the spin_trylock() convention,
  *       not the down_trylock() convention!
+ *
+ * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
  */
 extern int mutex_trylock(struct mutex *lock);
 extern void mutex_unlock(struct mutex *lock);

include/linux/rcuclassic.h

@@ -41,7 +41,7 @@
 #include <linux/seqlock.h>
 
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-#define RCU_SECONDS_TILL_STALL_CHECK	( 3 * HZ) /* for rcp->jiffies_stall */
+#define RCU_SECONDS_TILL_STALL_CHECK	(10 * HZ) /* for rcp->jiffies_stall */
 #define RCU_SECONDS_TILL_STALL_RECHECK	(30 * HZ) /* for rcp->jiffies_stall */
 #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 

include/linux/uaccess.h

@@ -78,7 +78,7 @@ static inline unsigned long __copy_from_user_nocache(void *to,
 							\
 		set_fs(KERNEL_DS);			\
 		pagefault_disable();			\
-		ret = __get_user(retval, (__force typeof(retval) __user *)(addr));		\
+		ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval));		\
 		pagefault_enable();			\
 		set_fs(old_fs);				\
 		ret;					\

kernel/exit.c

@@ -1321,10 +1321,10 @@ static int wait_task_zombie(struct task_struct *p, int options,
 		 * group, which consolidates times for all threads in the
 		 * group including the group leader.
 		 */
+		thread_group_cputime(p, &cputime);
 		spin_lock_irq(&p->parent->sighand->siglock);
 		psig = p->parent->signal;
 		sig = p->signal;
-		thread_group_cputime(p, &cputime);
 		psig->cutime =
 			cputime_add(psig->cutime,
 			cputime_add(cputime.utime,

kernel/extable.c

@@ -66,3 +66,19 @@ int kernel_text_address(unsigned long addr)
 		return 1;
 	return module_text_address(addr) != NULL;
 }
+
+/*
+ * On some architectures (PPC64, IA64) function pointers
+ * are actually only tokens to some data that then holds the
+ * real function address. As a result, to find if a function
+ * pointer is part of the kernel text, we need to do some
+ * special dereferencing first.
+ */
+int func_ptr_is_kernel_text(void *ptr)
+{
+	unsigned long addr;
+	addr = (unsigned long) dereference_function_descriptor(ptr);
+	if (core_kernel_text(addr))
+		return 1;
+	return module_text_address(addr) != NULL;
+}

kernel/futex.c

@@ -122,24 +122,6 @@ struct futex_hash_bucket {
 
 static struct futex_hash_bucket futex_queues[1<<FUTEX_HASHBITS];
 
-/*
- * Take mm->mmap_sem, when futex is shared
- */
-static inline void futex_lock_mm(struct rw_semaphore *fshared)
-{
-	if (fshared)
-		down_read(fshared);
-}
-
-/*
- * Release mm->mmap_sem, when the futex is shared
- */
-static inline void futex_unlock_mm(struct rw_semaphore *fshared)
-{
-	if (fshared)
-		up_read(fshared);
-}
-
 /*
  * We hash on the keys returned from get_futex_key (see below).
  */
@@ -161,6 +143,45 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2)
 		&& key1->both.offset == key2->both.offset);
 }
 
+/*
+ * Take a reference to the resource addressed by a key.
+ * Can be called while holding spinlocks.
+ *
+ */
+static void get_futex_key_refs(union futex_key *key)
+{
+	if (!key->both.ptr)
+		return;
+
+	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
+	case FUT_OFF_INODE:
+		atomic_inc(&key->shared.inode->i_count);
+		break;
+	case FUT_OFF_MMSHARED:
+		atomic_inc(&key->private.mm->mm_count);
+		break;
+	}
+}
+
+/*
+ * Drop a reference to the resource addressed by a key.
+ * The hash bucket spinlock must not be held.
+ */
+static void drop_futex_key_refs(union futex_key *key)
+{
+	if (!key->both.ptr)
+		return;
+
+	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
+	case FUT_OFF_INODE:
+		iput(key->shared.inode);
+		break;
+	case FUT_OFF_MMSHARED:
+		mmdrop(key->private.mm);
+		break;
+	}
+}
+
 /**
  * get_futex_key - Get parameters which are the keys for a futex.
  * @uaddr: virtual address of the futex
@@ -179,12 +200,10 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2)
  * For other futexes, it points to &current->mm->mmap_sem and
  * caller must have taken the reader lock. but NOT any spinlocks.
  */
-static int get_futex_key(u32 __user *uaddr, struct rw_semaphore *fshared,
+static int get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
-			 union futex_key *key)
 {
 	unsigned long address = (unsigned long)uaddr;
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
 	struct page *page;
 	int err;
 
@@ -208,100 +227,50 @@ static int get_futex_key(u32 __user *uaddr, struct rw_semaphore *fshared,
 			return -EFAULT;
 		key->private.mm = mm;
 		key->private.address = address;
+		get_futex_key_refs(key);
 		return 0;
 	}
-	/*
-	 * The futex is hashed differently depending on whether
-	 * it's in a shared or private mapping.  So check vma first.
-	 */
-	vma = find_extend_vma(mm, address);
-	if (unlikely(!vma))
-		return -EFAULT;
 
-	/*
+again:
-	 * Permissions.
+	err = get_user_pages_fast(address, 1, 0, &page);
-	 */
+	if (err < 0)
-	if (unlikely((vma->vm_flags & (VM_IO|VM_READ)) != VM_READ))
+		return err;
-		return (vma->vm_flags & VM_IO) ? -EPERM : -EACCES;
+
+	lock_page(page);
+	if (!page->mapping) {
+		unlock_page(page);
+		put_page(page);
+		goto again;
+	}
 
 	/*
 	 * Private mappings are handled in a simple way.
 	 *
 	 * NOTE: When userspace waits on a MAP_SHARED mapping, even if
 	 * it's a read-only handle, it's expected that futexes attach to
-	 * the object not the particular process.  Therefore we use
+	 * the object not the particular process.
-	 * VM_MAYSHARE here, not VM_SHARED which is restricted to shared
-	 * mappings of _writable_ handles.
 	 */
-	if (likely(!(vma->vm_flags & VM_MAYSHARE))) {
+	if (PageAnon(page)) {
-		key->both.offset |= FUT_OFF_MMSHARED; /* reference taken on mm */
+		key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */
 		key->private.mm = mm;
 		key->private.address = address;
-		return 0;
+	} else {
+		key->both.offset |= FUT_OFF_INODE; /* inode-based key */
+		key->shared.inode = page->mapping->host;
+		key->shared.pgoff = page->index;
 	}
 
-	/*
+	get_futex_key_refs(key);
-	 * Linear file mappings are also simple.
-	 */
-	key->shared.inode = vma->vm_file->f_path.dentry->d_inode;
-	key->both.offset |= FUT_OFF_INODE; /* inode-based key. */
-	if (likely(!(vma->vm_flags & VM_NONLINEAR))) {
-		key->shared.pgoff = (((address - vma->vm_start) >> PAGE_SHIFT)
-				     + vma->vm_pgoff);
-		return 0;
-	}
 
-	/*
+	unlock_page(page);
-	 * We could walk the page table to read the non-linear
+	put_page(page);
-	 * pte, and get the page index without fetching the page
+	return 0;
-	 * from swap.  But that's a lot of code to duplicate here
-	 * for a rare case, so we simply fetch the page.
-	 */
-	err = get_user_pages(current, mm, address, 1, 0, 0, &page, NULL);
-	if (err >= 0) {
-		key->shared.pgoff =
-			page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
-		put_page(page);
-		return 0;
-	}
-	return err;
 }
 
-/*
+static inline
- * Take a reference to the resource addressed by a key.
+void put_futex_key(int fshared, union futex_key *key)
- * Can be called while holding spinlocks.
- *
- */
-static void get_futex_key_refs(union futex_key *key)
 {
-	if (key->both.ptr == NULL)
+	drop_futex_key_refs(key);
-		return;
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-		case FUT_OFF_INODE:
-			atomic_inc(&key->shared.inode->i_count);
-			break;
-		case FUT_OFF_MMSHARED:
-			atomic_inc(&key->private.mm->mm_count);
-			break;
-	}
-}
-
-/*
- * Drop a reference to the resource addressed by a key.
- * The hash bucket spinlock must not be held.
- */
-static void drop_futex_key_refs(union futex_key *key)
-{
-	if (!key->both.ptr)
-		return;
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-		case FUT_OFF_INODE:
-			iput(key->shared.inode);
-			break;
-		case FUT_OFF_MMSHARED:
-			mmdrop(key->private.mm);
-			break;
-	}
 }
 
 static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval)
@@ -328,10 +297,8 @@ static int get_futex_value_locked(u32 *dest, u32 __user *from)
 
 /*
  * Fault handling.
- * if fshared is non NULL, current->mm->mmap_sem is already held
  */
-static int futex_handle_fault(unsigned long address,
+static int futex_handle_fault(unsigned long address, int attempt)
-			      struct rw_semaphore *fshared, int attempt)
 {
 	struct vm_area_struct * vma;
 	struct mm_struct *mm = current->mm;
@@ -340,8 +307,7 @@ static int futex_handle_fault(unsigned long address,
 	if (attempt > 2)
 		return ret;
 
-	if (!fshared)
+	down_read(&mm->mmap_sem);
-		down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
 	if (vma && address >= vma->vm_start &&
 	    (vma->vm_flags & VM_WRITE)) {
@@ -361,8 +327,7 @@ static int futex_handle_fault(unsigned long address,
 				current->min_flt++;
 		}
 	}
-	if (!fshared)
+	up_read(&mm->mmap_sem);
-		up_read(&mm->mmap_sem);
 	return ret;
 }
 
@@ -385,6 +350,7 @@ static int refill_pi_state_cache(void)
 	/* pi_mutex gets initialized later */
 	pi_state->owner = NULL;
 	atomic_set(&pi_state->refcount, 1);
+	pi_state->key = FUTEX_KEY_INIT;
 
 	current->pi_state_cache = pi_state;
 
@@ -462,7 +428,7 @@ void exit_pi_state_list(struct task_struct *curr)
 	struct list_head *next, *head = &curr->pi_state_list;
 	struct futex_pi_state *pi_state;
 	struct futex_hash_bucket *hb;
-	union futex_key key;
+	union futex_key key = FUTEX_KEY_INIT;
 
 	if (!futex_cmpxchg_enabled)
 		return;
@@ -719,20 +685,17 @@ double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
  * Wake up all waiters hashed on the physical page that is mapped
  * to this virtual address:
  */
-static int futex_wake(u32 __user *uaddr, struct rw_semaphore *fshared,
+static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
-		      int nr_wake, u32 bitset)
 {
 	struct futex_hash_bucket *hb;
 	struct futex_q *this, *next;
 	struct plist_head *head;
-	union futex_key key;
+	union futex_key key = FUTEX_KEY_INIT;
 	int ret;
 
 	if (!bitset)
 		return -EINVAL;
 
-	futex_lock_mm(fshared);
-
 	ret = get_futex_key(uaddr, fshared, &key);
 	if (unlikely(ret != 0))
 		goto out;
@@ -760,7 +723,7 @@ static int futex_wake(u32 __user *uaddr, struct rw_semaphore *fshared,
 
 	spin_unlock(&hb->lock);
 out:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &key);
 	return ret;
 }
 
@@ -769,19 +732,16 @@ out:
  * to this virtual address:
  */
 static int
-futex_wake_op(u32 __user *uaddr1, struct rw_semaphore *fshared,
+futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
-	      u32 __user *uaddr2,
 	      int nr_wake, int nr_wake2, int op)
 {
-	union futex_key key1, key2;
+	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
 	struct futex_hash_bucket *hb1, *hb2;
 	struct plist_head *head;
 	struct futex_q *this, *next;
 	int ret, op_ret, attempt = 0;
 
 retryfull:
-	futex_lock_mm(fshared);
-
 	ret = get_futex_key(uaddr1, fshared, &key1);
 	if (unlikely(ret != 0))
 		goto out;
@@ -826,18 +786,12 @@ retry:
 		 */
 		if (attempt++) {
 			ret = futex_handle_fault((unsigned long)uaddr2,
-						 fshared, attempt);
+						 attempt);
 			if (ret)
 				goto out;
 			goto retry;
 		}
 
-		/*
-		 * If we would have faulted, release mmap_sem,
-		 * fault it in and start all over again.
-		 */
-		futex_unlock_mm(fshared);
-
 		ret = get_user(dummy, uaddr2);
 		if (ret)
 			return ret;
@@ -873,7 +827,8 @@ retry:
 	if (hb1 != hb2)
 		spin_unlock(&hb2->lock);
 out:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &key2);
+	put_futex_key(fshared, &key1);
 
 	return ret;
 }
@@ -882,19 +837,16 @@ out:
  * Requeue all waiters hashed on one physical page to another
  * physical page.
  */
-static int futex_requeue(u32 __user *uaddr1, struct rw_semaphore *fshared,
+static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
-			 u32 __user *uaddr2,
 			 int nr_wake, int nr_requeue, u32 *cmpval)
 {
-	union futex_key key1, key2;
+	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
 	struct futex_hash_bucket *hb1, *hb2;
 	struct plist_head *head1;
 	struct futex_q *this, *next;
 	int ret, drop_count = 0;
 
  retry:
-	futex_lock_mm(fshared);
-
 	ret = get_futex_key(uaddr1, fshared, &key1);
 	if (unlikely(ret != 0))
 		goto out;
@@ -917,12 +869,6 @@ static int futex_requeue(u32 __user *uaddr1, struct rw_semaphore *fshared,
 			if (hb1 != hb2)
 				spin_unlock(&hb2->lock);
 
-			/*
-			 * If we would have faulted, release mmap_sem, fault
-			 * it in and start all over again.
-			 */
-			futex_unlock_mm(fshared);
-
 			ret = get_user(curval, uaddr1);
 
 			if (!ret)
@@ -974,7 +920,8 @@ out_unlock:
 		drop_futex_key_refs(&key1);
 
 out:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &key2);
+	put_futex_key(fshared, &key1);
 	return ret;
 }
 
@@ -1096,8 +1043,7 @@ static void unqueue_me_pi(struct futex_q *q)
  * private futexes.
  */
 static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
-				struct task_struct *newowner,
+				struct task_struct *newowner, int fshared)
-				struct rw_semaphore *fshared)
 {
 	u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
 	struct futex_pi_state *pi_state = q->pi_state;
@@ -1176,7 +1122,7 @@ retry:
 handle_fault:
 	spin_unlock(q->lock_ptr);
 
-	ret = futex_handle_fault((unsigned long)uaddr, fshared, attempt++);
+	ret = futex_handle_fault((unsigned long)uaddr, attempt++);
 
 	spin_lock(q->lock_ptr);
 
@@ -1200,7 +1146,7 @@ handle_fault:
 
 static long futex_wait_restart(struct restart_block *restart);
 
-static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
+static int futex_wait(u32 __user *uaddr, int fshared,
 		      u32 val, ktime_t *abs_time, u32 bitset)
 {
 	struct task_struct *curr = current;
@@ -1218,8 +1164,7 @@ static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
 	q.pi_state = NULL;
 	q.bitset = bitset;
  retry:
-	futex_lock_mm(fshared);
+	q.key = FUTEX_KEY_INIT;
-
 	ret = get_futex_key(uaddr, fshared, &q.key);
 	if (unlikely(ret != 0))
 		goto out_release_sem;
@@ -1251,12 +1196,6 @@ static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
 	if (unlikely(ret)) {
 		queue_unlock(&q, hb);
 
-		/*
-		 * If we would have faulted, release mmap_sem, fault it in and
-		 * start all over again.
-		 */
-		futex_unlock_mm(fshared);
-
 		ret = get_user(uval, uaddr);
 
 		if (!ret)
@@ -1270,12 +1209,6 @@ static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
 	/* Only actually queue if *uaddr contained val.  */
 	queue_me(&q, hb);
 
-	/*
-	 * Now the futex is queued and we have checked the data, we
-	 * don't want to hold mmap_sem while we sleep.
-	 */
-	futex_unlock_mm(fshared);
-
 	/*
 	 * There might have been scheduling since the queue_me(), as we
 	 * cannot hold a spinlock across the get_user() in case it
@@ -1363,7 +1296,7 @@ static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
 	queue_unlock(&q, hb);
 
  out_release_sem:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &q.key);
 	return ret;
 }
 
@@ -1371,13 +1304,13 @@ static int futex_wait(u32 __user *uaddr, struct rw_semaphore *fshared,
 static long futex_wait_restart(struct restart_block *restart)
 {
 	u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
-	struct rw_semaphore *fshared = NULL;
+	int fshared = 0;
 	ktime_t t;
 
 	t.tv64 = restart->futex.time;
 	restart->fn = do_no_restart_syscall;
 	if (restart->futex.flags & FLAGS_SHARED)
-		fshared = &current->mm->mmap_sem;
+		fshared = 1;
 	return (long)futex_wait(uaddr, fshared, restart->futex.val, &t,
 				restart->futex.bitset);
 }
@@ -1389,7 +1322,7 @@ static long futex_wait_restart(struct restart_block *restart)
  * if there are waiters then it will block, it does PI, etc. (Due to
  * races the kernel might see a 0 value of the futex too.)
  */
-static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
+static int futex_lock_pi(u32 __user *uaddr, int fshared,
 			 int detect, ktime_t *time, int trylock)
 {
 	struct hrtimer_sleeper timeout, *to = NULL;
@@ -1412,8 +1345,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 
 	q.pi_state = NULL;
  retry:
-	futex_lock_mm(fshared);
+	q.key = FUTEX_KEY_INIT;
-
 	ret = get_futex_key(uaddr, fshared, &q.key);
 	if (unlikely(ret != 0))
 		goto out_release_sem;
@@ -1502,7 +1434,6 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 			 * exit to complete.
 			 */
 			queue_unlock(&q, hb);
-			futex_unlock_mm(fshared);
 			cond_resched();
 			goto retry;
 
@@ -1534,12 +1465,6 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 	 */
 	queue_me(&q, hb);
 
-	/*
-	 * Now the futex is queued and we have checked the data, we
-	 * don't want to hold mmap_sem while we sleep.
-	 */
-	futex_unlock_mm(fshared);
-
 	WARN_ON(!q.pi_state);
 	/*
 	 * Block on the PI mutex:
@@ -1552,7 +1477,6 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 		ret = ret ? 0 : -EWOULDBLOCK;
 	}
 
-	futex_lock_mm(fshared);
 	spin_lock(q.lock_ptr);
 
 	if (!ret) {
@@ -1618,7 +1542,6 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 
 	/* Unqueue and drop the lock */
 	unqueue_me_pi(&q);
-	futex_unlock_mm(fshared);
 
 	if (to)
 		destroy_hrtimer_on_stack(&to->timer);
@@ -1628,7 +1551,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 	queue_unlock(&q, hb);
 
  out_release_sem:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &q.key);
 	if (to)
 		destroy_hrtimer_on_stack(&to->timer);
 	return ret;
@@ -1645,15 +1568,12 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
 	queue_unlock(&q, hb);
 
 	if (attempt++) {
-		ret = futex_handle_fault((unsigned long)uaddr, fshared,
+		ret = futex_handle_fault((unsigned long)uaddr, attempt);
-					 attempt);
 		if (ret)
 			goto out_release_sem;
 		goto retry_unlocked;
 	}
 
-	futex_unlock_mm(fshared);
-
 	ret = get_user(uval, uaddr);
 	if (!ret && (uval != -EFAULT))
 		goto retry;
@@ -1668,13 +1588,13 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
  * This is the in-kernel slowpath: we look up the PI state (if any),
  * and do the rt-mutex unlock.
  */
-static int futex_unlock_pi(u32 __user *uaddr, struct rw_semaphore *fshared)
+static int futex_unlock_pi(u32 __user *uaddr, int fshared)
 {
 	struct futex_hash_bucket *hb;
 	struct futex_q *this, *next;
 	u32 uval;
 	struct plist_head *head;
-	union futex_key key;
+	union futex_key key = FUTEX_KEY_INIT;
 	int ret, attempt = 0;
 
 retry:
@@ -1685,10 +1605,6 @@ retry:
 	 */
 	if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
 		return -EPERM;
-	/*
-	 * First take all the futex related locks:
-	 */
-	futex_lock_mm(fshared);
 
 	ret = get_futex_key(uaddr, fshared, &key);
 	if (unlikely(ret != 0))
@@ -1747,7 +1663,7 @@ retry_unlocked:
 out_unlock:
 	spin_unlock(&hb->lock);
 out:
-	futex_unlock_mm(fshared);
+	put_futex_key(fshared, &key);
 
 	return ret;
 
@@ -1763,16 +1679,13 @@ pi_faulted:
 	spin_unlock(&hb->lock);
 
 	if (attempt++) {
-		ret = futex_handle_fault((unsigned long)uaddr, fshared,
+		ret = futex_handle_fault((unsigned long)uaddr, attempt);
-					 attempt);
 		if (ret)
 			goto out;
 		uval = 0;
 		goto retry_unlocked;
 	}
 
-	futex_unlock_mm(fshared);
-
 	ret = get_user(uval, uaddr);
 	if (!ret && (uval != -EFAULT))
 		goto retry;
@@ -1898,8 +1811,7 @@ retry:
 		 * PI futexes happens in exit_pi_state():
 		 */
 		if (!pi && (uval & FUTEX_WAITERS))
-			futex_wake(uaddr, &curr->mm->mmap_sem, 1,
+			futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY);
-				   FUTEX_BITSET_MATCH_ANY);
 	}
 	return 0;
 }
@@ -1995,10 +1907,10 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 {
 	int ret = -ENOSYS;
 	int cmd = op & FUTEX_CMD_MASK;
-	struct rw_semaphore *fshared = NULL;
+	int fshared = 0;
 
 	if (!(op & FUTEX_PRIVATE_FLAG))
-		fshared = &current->mm->mmap_sem;
+		fshared = 1;
 
 	switch (cmd) {
 	case FUTEX_WAIT:

kernel/lockdep.c

@@ -136,16 +136,16 @@ static inline struct lock_class *hlock_class(struct held_lock *hlock)
 #ifdef CONFIG_LOCK_STAT
 static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);
 
-static int lock_contention_point(struct lock_class *class, unsigned long ip)
+static int lock_point(unsigned long points[], unsigned long ip)
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
-		if (class->contention_point[i] == 0) {
+		if (points[i] == 0) {
-			class->contention_point[i] = ip;
+			points[i] = ip;
 			break;
 		}
-		if (class->contention_point[i] == ip)
+		if (points[i] == ip)
 			break;
 	}
 
@@ -185,6 +185,9 @@ struct lock_class_stats lock_stats(struct lock_class *class)
 		for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
 			stats.contention_point[i] += pcs->contention_point[i];
 
+		for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
+			stats.contending_point[i] += pcs->contending_point[i];
+
 		lock_time_add(&pcs->read_waittime, &stats.read_waittime);
 		lock_time_add(&pcs->write_waittime, &stats.write_waittime);
 
@@ -209,6 +212,7 @@ void clear_lock_stats(struct lock_class *class)
 		memset(cpu_stats, 0, sizeof(struct lock_class_stats));
 	}
 	memset(class->contention_point, 0, sizeof(class->contention_point));
+	memset(class->contending_point, 0, sizeof(class->contending_point));
 }
 
 static struct lock_class_stats *get_lock_stats(struct lock_class *class)
@@ -2999,7 +3003,7 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
 	struct held_lock *hlock, *prev_hlock;
 	struct lock_class_stats *stats;
 	unsigned int depth;
-	int i, point;
+	int i, contention_point, contending_point;
 
 	depth = curr->lockdep_depth;
 	if (DEBUG_LOCKS_WARN_ON(!depth))
@@ -3023,18 +3027,22 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
 found_it:
 	hlock->waittime_stamp = sched_clock();
 
-	point = lock_contention_point(hlock_class(hlock), ip);
+	contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
+	contending_point = lock_point(hlock_class(hlock)->contending_point,
+				      lock->ip);
 
 	stats = get_lock_stats(hlock_class(hlock));
-	if (point < ARRAY_SIZE(stats->contention_point))
+	if (contention_point < LOCKSTAT_POINTS)
-		stats->contention_point[point]++;
+		stats->contention_point[contention_point]++;
+	if (contending_point < LOCKSTAT_POINTS)
+		stats->contending_point[contending_point]++;
 	if (lock->cpu != smp_processor_id())
 		stats->bounces[bounce_contended + !!hlock->read]++;
 	put_lock_stats(stats);
 }
 
 static void
-__lock_acquired(struct lockdep_map *lock)
+__lock_acquired(struct lockdep_map *lock, unsigned long ip)
 {
 	struct task_struct *curr = current;
 	struct held_lock *hlock, *prev_hlock;
@@ -3083,6 +3091,7 @@ found_it:
 	put_lock_stats(stats);
 
 	lock->cpu = cpu;
+	lock->ip = ip;
 }
 
 void lock_contended(struct lockdep_map *lock, unsigned long ip)
@@ -3104,7 +3113,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip)
 }
 EXPORT_SYMBOL_GPL(lock_contended);
 
-void lock_acquired(struct lockdep_map *lock)
+void lock_acquired(struct lockdep_map *lock, unsigned long ip)
 {
 	unsigned long flags;
 
@@ -3117,7 +3126,7 @@ void lock_acquired(struct lockdep_map *lock)
 	raw_local_irq_save(flags);
 	check_flags(flags);
 	current->lockdep_recursion = 1;
-	__lock_acquired(lock);
+	__lock_acquired(lock, ip);
 	current->lockdep_recursion = 0;
 	raw_local_irq_restore(flags);
 }
@@ -3276,10 +3285,10 @@ void __init lockdep_info(void)
 {
 	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
 
-	printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);
+	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
 	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
 	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
-	printk("... CLASSHASH_SIZE:           %lu\n", CLASSHASH_SIZE);
+	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
 	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
 	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
 	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);

kernel/lockdep_proc.c

@@ -470,11 +470,12 @@ static void seq_line(struct seq_file *m, char c, int offset, int length)
 
 static void snprint_time(char *buf, size_t bufsiz, s64 nr)
 {
-	unsigned long rem;
+	s64 div;
+	s32 rem;
 
 	nr += 5; /* for display rounding */
-	rem = do_div(nr, 1000); /* XXX: do_div_signed */
+	div = div_s64_rem(nr, 1000, &rem);
-	snprintf(buf, bufsiz, "%lld.%02d", (long long)nr, (int)rem/10);
+	snprintf(buf, bufsiz, "%lld.%02d", (long long)div, (int)rem/10);
 }
 
 static void seq_time(struct seq_file *m, s64 time)
@@ -556,7 +557,7 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 	if (stats->read_holdtime.nr)
 		namelen += 2;
 
-	for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
 		char sym[KSYM_SYMBOL_LEN];
 		char ip[32];
 
@@ -573,6 +574,23 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 				stats->contention_point[i],
 				ip, sym);
 	}
+	for (i = 0; i < LOCKSTAT_POINTS; i++) {
+		char sym[KSYM_SYMBOL_LEN];
+		char ip[32];
+
+		if (class->contending_point[i] == 0)
+			break;
+
+		if (!i)
+			seq_line(m, '-', 40-namelen, namelen);
+
+		sprint_symbol(sym, class->contending_point[i]);
+		snprintf(ip, sizeof(ip), "[<%p>]",
+				(void *)class->contending_point[i]);
+		seq_printf(m, "%40s %14lu %29s %s\n", name,
+				stats->contending_point[i],
+				ip, sym);
+	}
 	if (i) {
 		seq_puts(m, "\n");
 		seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
@@ -582,7 +600,7 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
 
 static void seq_header(struct seq_file *m)
 {
-	seq_printf(m, "lock_stat version 0.2\n");
+	seq_printf(m, "lock_stat version 0.3\n");
 	seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
 	seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
 			"%14s %14s\n",

kernel/mutex.c

@@ -59,7 +59,7 @@ EXPORT_SYMBOL(__mutex_init);
  * We also put the fastpath first in the kernel image, to make sure the
  * branch is predicted by the CPU as default-untaken.
  */
-static void noinline __sched
+static __used noinline void __sched
 __mutex_lock_slowpath(atomic_t *lock_count);
 
 /***
@@ -96,7 +96,7 @@ void inline __sched mutex_lock(struct mutex *lock)
 EXPORT_SYMBOL(mutex_lock);
 #endif
 
-static noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
+static __used noinline void __sched __mutex_unlock_slowpath(atomic_t *lock_count);
 
 /***
  * mutex_unlock - release the mutex
@@ -184,7 +184,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 	}
 
 done:
-	lock_acquired(&lock->dep_map);
+	lock_acquired(&lock->dep_map, ip);
 	/* got the lock - rejoice! */
 	mutex_remove_waiter(lock, &waiter, task_thread_info(task));
 	debug_mutex_set_owner(lock, task_thread_info(task));
@@ -268,7 +268,7 @@ __mutex_unlock_common_slowpath(atomic_t *lock_count, int nested)
 /*
  * Release the lock, slowpath:
  */
-static noinline void
+static __used noinline void
 __mutex_unlock_slowpath(atomic_t *lock_count)
 {
 	__mutex_unlock_common_slowpath(lock_count, 1);
@@ -313,7 +313,7 @@ int __sched mutex_lock_killable(struct mutex *lock)
 }
 EXPORT_SYMBOL(mutex_lock_killable);
 
-static noinline void __sched
+static __used noinline void __sched
 __mutex_lock_slowpath(atomic_t *lock_count)
 {
 	struct mutex *lock = container_of(lock_count, struct mutex, count);

kernel/notifier.c

@@ -82,6 +82,14 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
 
 	while (nb && nr_to_call) {
 		next_nb = rcu_dereference(nb->next);
+
+#ifdef CONFIG_DEBUG_NOTIFIERS
+		if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
+			WARN(1, "Invalid notifier called!");
+			nb = next_nb;
+			continue;
+		}
+#endif
 		ret = nb->notifier_call(nb, val, v);
 
 		if (nr_calls)

kernel/posix-cpu-timers.c

@@ -58,21 +58,21 @@ void thread_group_cputime(
 	struct task_struct *tsk,
 	struct task_cputime *times)
 {
-	struct signal_struct *sig;
+	struct task_cputime *totals, *tot;
 	int i;
-	struct task_cputime *tot;
 
-	sig = tsk->signal;
+	totals = tsk->signal->cputime.totals;
-	if (unlikely(!sig) || !sig->cputime.totals) {
+	if (!totals) {
 		times->utime = tsk->utime;
 		times->stime = tsk->stime;
 		times->sum_exec_runtime = tsk->se.sum_exec_runtime;
 		return;
 	}
+
 	times->stime = times->utime = cputime_zero;
 	times->sum_exec_runtime = 0;
 	for_each_possible_cpu(i) {
-		tot = per_cpu_ptr(tsk->signal->cputime.totals, i);
+		tot = per_cpu_ptr(totals, i);
 		times->utime = cputime_add(times->utime, tot->utime);
 		times->stime = cputime_add(times->stime, tot->stime);
 		times->sum_exec_runtime += tot->sum_exec_runtime;

kernel/rcuclassic.c

@@ -191,7 +191,7 @@ static void print_other_cpu_stall(struct rcu_ctrlblk *rcp)
 
 	/* OK, time to rat on our buddy... */
 
-	printk(KERN_ERR "RCU detected CPU stalls:");
+	printk(KERN_ERR "INFO: RCU detected CPU stalls:");
 	for_each_possible_cpu(cpu) {
 		if (cpu_isset(cpu, rcp->cpumask))
 			printk(" %d", cpu);
@@ -204,7 +204,7 @@ static void print_cpu_stall(struct rcu_ctrlblk *rcp)
 {
 	unsigned long flags;
 
-	printk(KERN_ERR "RCU detected CPU %d stall (t=%lu/%lu jiffies)\n",
+	printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu/%lu jiffies)\n",
 			smp_processor_id(), jiffies,
 			jiffies - rcp->gp_start);
 	dump_stack();

kernel/sched.c

@@ -4202,7 +4202,6 @@ void account_steal_time(struct task_struct *p, cputime_t steal)
 
 	if (p == rq->idle) {
 		p->stime = cputime_add(p->stime, steal);
-		account_group_system_time(p, steal);
 		if (atomic_read(&rq->nr_iowait) > 0)
 			cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
 		else
@@ -4338,7 +4337,7 @@ void __kprobes sub_preempt_count(int val)
 	/*
 	 * Underflow?
 	 */
-	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
+       if (DEBUG_LOCKS_WARN_ON(val > preempt_count() - (!!kernel_locked())))
 		return;
 	/*
 	 * Is the spinlock portion underflowing?

kernel/softlockup.c

@@ -164,7 +164,7 @@ unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
 /*
  * Zero means infinite timeout - no checking done:
  */
-unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
+unsigned long __read_mostly sysctl_hung_task_timeout_secs = 480;
 
 unsigned long __read_mostly sysctl_hung_task_warnings = 10;
 

kernel/sys.c

@@ -858,8 +858,8 @@ void do_sys_times(struct tms *tms)
 	struct task_cputime cputime;
 	cputime_t cutime, cstime;
 
-	spin_lock_irq(&current->sighand->siglock);
 	thread_group_cputime(current, &cputime);
+	spin_lock_irq(&current->sighand->siglock);
 	cutime = current->signal->cutime;
 	cstime = current->signal->cstime;
 	spin_unlock_irq(&current->sighand->siglock);

lib/Kconfig.debug

@@ -545,6 +545,16 @@ config DEBUG_SG
 
 	  If unsure, say N.
 
+config DEBUG_NOTIFIERS
+	bool "Debug notifier call chains"
+	depends on DEBUG_KERNEL
+	help
+	  Enable this to turn on sanity checking for notifier call chains.
+	  This is most useful for kernel developers to make sure that
+	  modules properly unregister themselves from notifier chains.
+	  This is a relatively cheap check but if you care about maximum
+	  performance, say N.
+
 config FRAME_POINTER
 	bool "Compile the kernel with frame pointers"
 	depends on DEBUG_KERNEL && \

mm/memory.c

@@ -3049,3 +3049,18 @@ void print_vma_addr(char *prefix, unsigned long ip)
 	}
 	up_read(&current->mm->mmap_sem);
 }
+
+#ifdef CONFIG_PROVE_LOCKING
+void might_fault(void)
+{
+	might_sleep();
+	/*
+	 * it would be nicer only to annotate paths which are not under
+	 * pagefault_disable, however that requires a larger audit and
+	 * providing helpers like get_user_atomic.
+	 */
+	if (!in_atomic() && current->mm)
+		might_lock_read(&current->mm->mmap_sem);
+}
+EXPORT_SYMBOL(might_fault);
+#endif