Merge branch 'akpm' (Andrew's patch-bomb)

Merge patches through Andrew Morton:
 "180 patches - err 181 - listed below:

   - most of MM.  I held back the (large) "memcg: add hugetlb extension"
     series because a bunfight has recently broken out.

   - leds.  After this, Bryan Wu will be handling drivers/leds/

   - backlight

   - lib/

   - rtc"

* emailed from Andrew Morton <akpm@linux-foundation.org>: (181 patches)
  drivers/rtc/rtc-s3c.c: fix compiler warning
  drivers/rtc/rtc-tegra.c: clean up probe/remove routines
  drivers/rtc/rtc-pl031.c: remove RTC timer interrupt handling
  drivers/rtc/rtc-lpc32xx.c: add device tree support
  drivers/rtc/rtc-m41t93.c: don't let get_time() reset M41T93_FLAG_OF
  rtc: ds1307: add trickle charger support
  rtc: ds1307: remove superfluous initialization
  rtc: rename CONFIG_RTC_MXC to CONFIG_RTC_DRV_MXC
  drivers/rtc/Kconfig: place RTC_DRV_IMXDI and RTC_MXC under "on-CPU RTC drivers"
  drivers/rtc/rtc-pcf8563.c: add RTC_VL_READ/RTC_VL_CLR ioctl feature
  rtc: add ioctl to get/clear battery low voltage status
  drivers/rtc/rtc-ep93xx.c: convert to use module_platform_driver()
  rtc/spear: add Device Tree probing capability
  lib/vsprintf.c: "%#o",0 becomes '0' instead of '00'
  radix-tree: fix preload vector size
  spinlock_debug: print kallsyms name for lock
  vsprintf: fix %ps on non symbols when using kallsyms
  lib/bitmap.c: fix documentation for scnprintf() functions
  lib/string_helpers.c: make arrays static
  lib/test-kstrtox.c: mark const init data with __initconst instead of __initdata
  ...

11 files changed, 393 insertions, 28 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-backlight-driver-lm3533 b/Documentation/ABI/testing/sysfs-class-backlight-driver-lm3533
new file mode 100644
index 000000000000..77cf7ac949af
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-backlight-driver-lm3533
@@ -0,0 +1,48 @@
+What:		/sys/class/backlight/<backlight>/als_channel
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the ALS output channel used as input in
+		ALS-current-control mode (0, 1), where
+
+		0 - out_current0 (backlight 0)
+		1 - out_current1 (backlight 1)
+
+What:		/sys/class/backlight/<backlight>/als_en
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Enable ALS-current-control mode (0, 1).
+
+What:		/sys/class/backlight/<backlight>/id
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the id of this backlight (0, 1).
+
+What:		/sys/class/backlight/<backlight>/linear
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the brightness-mapping mode (0, 1), where
+
+		0 - exponential mode
+		1 - linear mode
+
+What:		/sys/class/backlight/<backlight>/pwm
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the PWM-input control mask (5 bits), where
+
+		bit 5 - PWM-input enabled in Zone 4
+		bit 4 - PWM-input enabled in Zone 3
+		bit 3 - PWM-input enabled in Zone 2
+		bit 2 - PWM-input enabled in Zone 1
+		bit 1 - PWM-input enabled in Zone 0
+		bit 0 - PWM-input enabled
diff --git a/Documentation/ABI/testing/sysfs-class-led-driver-lm3533 b/Documentation/ABI/testing/sysfs-class-led-driver-lm3533
new file mode 100644
index 000000000000..620ebb3b9baa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-driver-lm3533
@@ -0,0 +1,65 @@
+What:		/sys/class/leds/<led>/als_channel
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the ALS output channel to use as input in
+		ALS-current-control mode (1, 2), where
+
+		1 - out_current1
+		2 - out_current2
+
+What:		/sys/class/leds/<led>/als_en
+Date:		May 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Enable ALS-current-control mode (0, 1).
+
+What:		/sys/class/leds/<led>/falltime
+What:		/sys/class/leds/<led>/risetime
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the pattern generator fall and rise times (0..7), where
+
+		0 - 2048 us
+		1 - 262 ms
+		2 - 524 ms
+		3 - 1.049 s
+		4 - 2.097 s
+		5 - 4.194 s
+		6 - 8.389 s
+		7 - 16.78 s
+
+What:		/sys/class/leds/<led>/id
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Get the id of this led (0..3).
+
+What:		/sys/class/leds/<led>/linear
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the brightness-mapping mode (0, 1), where
+
+		0 - exponential mode
+		1 - linear mode
+
+What:		/sys/class/leds/<led>/pwm
+Date:		April 2012
+KernelVersion:	3.5
+Contact:	Johan Hovold <jhovold@gmail.com>
+Description:
+		Set the PWM-input control mask (5 bits), where
+
+		bit 5 - PWM-input enabled in Zone 4
+		bit 4 - PWM-input enabled in Zone 3
+		bit 3 - PWM-input enabled in Zone 2
+		bit 2 - PWM-input enabled in Zone 1
+		bit 1 - PWM-input enabled in Zone 0
+		bit 0 - PWM-input enabled
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 9b1067afb224..dd88540bb995 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -184,12 +184,14 @@ behind this approach is that a cgroup that aggressively uses a shared
 page will eventually get charged for it (once it is uncharged from
 the cgroup that brought it in -- this will happen on memory pressure).
 
+But see section 8.2: when moving a task to another cgroup, its pages may
+be recharged to the new cgroup, if move_charge_at_immigrate has been chosen.
+
 Exception: If CONFIG_CGROUP_CGROUP_MEM_RES_CTLR_SWAP is not used.
 When you do swapoff and make swapped-out pages of shmem(tmpfs) to
 be backed into memory in force, charges for pages are accounted against the
 caller of swapoff rather than the users of shmem.
 
-
 2.4 Swap Extension (CONFIG_CGROUP_MEM_RES_CTLR_SWAP)
 
 Swap Extension allows you to record charge for swap. A swapped-in page is
@@ -374,14 +376,15 @@ cgroup might have some charge associated with it, even though all
 tasks have migrated away from it. (because we charge against pages, not
 against tasks.)
 
-Such charges are freed or moved to their parent. At moving, both of RSS
-and CACHES are moved to parent.
-rmdir() may return -EBUSY if freeing/moving fails. See 5.1 also.
+We move the stats to root (if use_hierarchy==0) or parent (if
+use_hierarchy==1), and no change on the charge except uncharging
+from the child.
 
 Charges recorded in swap information is not updated at removal of cgroup.
 Recorded information is discarded and a cgroup which uses swap (swapcache)
 will be charged as a new owner of it.
 
+About use_hierarchy, see Section 6.
 
 5. Misc. interfaces.
 
@@ -394,13 +397,15 @@ will be charged as a new owner of it.
 
   Almost all pages tracked by this memory cgroup will be unmapped and freed.
   Some pages cannot be freed because they are locked or in-use. Such pages are
-  moved to parent and this cgroup will be empty. This may return -EBUSY if
-  VM is too busy to free/move all pages immediately.
+  moved to parent(if use_hierarchy==1) or root (if use_hierarchy==0) and this
+  cgroup will be empty.
 
   Typical use case of this interface is that calling this before rmdir().
   Because rmdir() moves all pages to parent, some out-of-use page caches can be
   moved to the parent. If you want to avoid that, force_empty will be useful.
 
+  About use_hierarchy, see Section 6.
+
 5.2 stat file
 
 memory.stat file includes following statistics
@@ -430,17 +435,10 @@ hierarchical_memory_limit - # of bytes of memory limit with regard to hierarchy
 hierarchical_memsw_limit - # of bytes of memory+swap limit with regard to
 			hierarchy under which memory cgroup is.
 
-total_cache		- sum of all children's "cache"
-total_rss		- sum of all children's "rss"
-total_mapped_file	- sum of all children's "cache"
-total_pgpgin		- sum of all children's "pgpgin"
-total_pgpgout		- sum of all children's "pgpgout"
-total_swap		- sum of all children's "swap"
-total_inactive_anon	- sum of all children's "inactive_anon"
-total_active_anon	- sum of all children's "active_anon"
-total_inactive_file	- sum of all children's "inactive_file"
-total_active_file	- sum of all children's "active_file"
-total_unevictable	- sum of all children's "unevictable"
+total_<counter>		- # hierarchical version of <counter>, which in
+			addition to the cgroup's own value includes the
+			sum of all hierarchical children's values of
+			<counter>, i.e. total_cache
 
 # The following additional stats are dependent on CONFIG_DEBUG_VM.
 
@@ -622,8 +620,7 @@ memory cgroup.
   bit | what type of charges would be moved ?
  -----+------------------------------------------------------------------------
    0  | A charge of an anonymous page(or swap of it) used by the target task.
-      | Those pages and swaps must be used only by the target task. You must
-      | enable Swap Extension(see 2.4) to enable move of swap charges.
+      | You must enable Swap Extension(see 2.4) to enable move of swap charges.
  -----+------------------------------------------------------------------------
    1  | A charge of file pages(normal file, tmpfs file(e.g. ipc shared memory)
       | and swaps of tmpfs file) mmapped by the target task. Unlike the case of
@@ -636,8 +633,6 @@ memory cgroup.
 
 8.3 TODO
 
-- Implement madvise(2) to let users decide the vma to be moved or not to be
-  moved.
 - All of moving charge operations are done under cgroup_mutex. It's not good
   behavior to hold the mutex too long, so we may need some trick.
 
diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index f3c4ec3626a2..0c4a344e78fa 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt
@@ -92,6 +92,14 @@ to work with it.
 
 	The _locked routines imply that the res_counter->lock is taken.
 
+ f. void res_counter_uncharge_until
+		(struct res_counter *rc, struct res_counter *top,
+		 unsinged long val)
+
+	Almost same as res_cunter_uncharge() but propagation of uncharge
+	stops when rc == top. This is useful when kill a res_coutner in
+	child cgroup.
+
  2.1 Other accounting routines
 
     There are more routines that may help you with common needs, like
diff --git a/Documentation/devicetree/bindings/rtc/lpc32xx-rtc.txt b/Documentation/devicetree/bindings/rtc/lpc32xx-rtc.txt
new file mode 100644
index 000000000000..a87a1e9bc060
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/lpc32xx-rtc.txt
@@ -0,0 +1,15 @@
+* NXP LPC32xx SoC Real Time Clock controller
+
+Required properties:
+- compatible: must be "nxp,lpc3220-rtc"
+- reg: physical base address of the controller and length of memory mapped
+  region.
+- interrupts: The RTC interrupt
+
+Example:
+
+	rtc@40024000 {
+		compatible = "nxp,lpc3220-rtc";
+		reg = <0x40024000 0x1000>;
+		interrupts = <52 0>;
+	};
diff --git a/Documentation/devicetree/bindings/rtc/spear-rtc.txt b/Documentation/devicetree/bindings/rtc/spear-rtc.txt
new file mode 100644
index 000000000000..ca67ac62108e
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/spear-rtc.txt
@@ -0,0 +1,17 @@
+* SPEAr RTC
+
+Required properties:
+- compatible : "st,spear600-rtc"
+- reg : Address range of the rtc registers
+- interrupt-parent: Should be the phandle for the interrupt controller
+  that services interrupts for this device
+- interrupt: Should contain the rtc interrupt number
+
+Example:
+
+	rtc@fc000000 {
+		compatible = "st,spear600-rtc";
+		reg = <0xfc000000 0x1000>;
+		interrupt-parent = <&vic1>;
+		interrupts = <12>;
+	};
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 4fca82e5276e..d449e632e6a0 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -60,7 +60,6 @@ ata *);
 	ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
 	int (*removexattr) (struct dentry *, const char *);
-	void (*truncate_range)(struct inode *, loff_t, loff_t);
 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len);
 
 locking rules:
@@ -87,7 +86,6 @@ setxattr:	yes
 getxattr:	no
 listxattr:	no
 removexattr:	yes
-truncate_range:	yes
 fiemap:		no
 	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
 victim.
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index ef088e55ab2e..912af6ce5626 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -743,6 +743,7 @@ Committed_AS:   100056 kB
 VmallocTotal:   112216 kB
 VmallocUsed:       428 kB
 VmallocChunk:   111088 kB
+AnonHugePages:   49152 kB
 
     MemTotal: Total usable ram (i.e. physical ram minus a few reserved
               bits and the kernel binary code)
@@ -776,6 +777,7 @@ VmallocChunk:   111088 kB
        Dirty: Memory which is waiting to get written back to the disk
    Writeback: Memory which is actively being written back to the disk
    AnonPages: Non-file backed pages mapped into userspace page tables
+AnonHugePages: Non-file backed huge pages mapped into userspace page tables
       Mapped: files which have been mmaped, such as libraries
         Slab: in-kernel data structures cache
 SReclaimable: Part of Slab, that might be reclaimed, such as caches
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 0d0492028082..ef19f91a0f12 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -363,7 +363,6 @@ struct inode_operations {
 	ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
 	int (*removexattr) (struct dentry *, const char *);
-	void (*truncate_range)(struct inode *, loff_t, loff_t);
 };
 
 Again, all methods are called without any locks being held, unless
@@ -472,9 +471,6 @@ otherwise noted.
   removexattr: called by the VFS to remove an extended attribute from
   	a file. This method is called by removexattr(2) system call.
 
-  truncate_range: a method provided by the underlying filesystem to truncate a
-  	range of blocks , i.e. punch a hole somewhere in a file.
-
 
 The Address Space Object
 ========================
@@ -760,7 +756,7 @@ struct file_operations
 ----------------------
 
 This describes how the VFS can manipulate an open file. As of kernel
-2.6.22, the following members are defined:
+3.5, the following members are defined:
 
 struct file_operations {
 	struct module *owner;
@@ -790,6 +786,8 @@ struct file_operations {
 	int (*flock) (struct file *, int, struct file_lock *);
 	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int);
 	ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int);
+	int (*setlease)(struct file *, long arg, struct file_lock **);
+	long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len);
 };
 
 Again, all methods are called without any locks being held, unless
@@ -858,6 +856,11 @@ otherwise noted.
   splice_read: called by the VFS to splice data from file to a pipe. This
 	       method is used by the splice(2) system call
 
+  setlease: called by the VFS to set or release a file lock lease.
+	    setlease has the file_lock_lock held and must not sleep.
+
+  fallocate: called by the VFS to preallocate blocks or punch a hole.
+
 Note that the file operations are implemented by the specific
 filesystem in which the inode resides. When opening a device node
 (character or block special) most filesystems will call special
diff --git a/Documentation/leds/ledtrig-transient.txt b/Documentation/leds/ledtrig-transient.txt
new file mode 100644
index 000000000000..3bd38b487df1
--- /dev/null
+++ b/Documentation/leds/ledtrig-transient.txt
@@ -0,0 +1,152 @@
+LED Transient Trigger
+=====================
+
+The leds timer trigger does not currently have an interface to activate
+a one shot timer. The current support allows for setting two timers, one for
+specifying how long a state to be on, and the second for how long the state
+to be off. The delay_on value specifies the time period an LED should stay
+in on state, followed by a delay_off value that specifies how long the LED
+should stay in off state. The on and off cycle repeats until the trigger
+gets deactivated. There is no provision for one time activation to implement
+features that require an on or off state to be held just once and then stay in
+the original state forever.
+
+Without one shot timer interface, user space can still use timer trigger to
+set a timer to hold a state, however when user space application crashes or
+goes away without deactivating the timer, the hardware will be left in that
+state permanently.
+
+As a specific example of this use-case, let's look at vibrate feature on
+phones. Vibrate function on phones is implemented using PWM pins on SoC or
+PMIC. There is a need to activate one shot timer to control the vibrate
+feature, to prevent user space crashes leaving the phone in vibrate mode
+permanently causing the battery to drain.
+
+Transient trigger addresses the need for one shot timer activation. The
+transient trigger can be enabled and disabled just like the other leds
+triggers.
+
+When an led class device driver registers itself, it can specify all leds
+triggers it supports and a default trigger. During registration, activation
+routine for the default trigger gets called. During registration of an led
+class device, the LED state does not change.
+
+When the driver unregisters, deactivation routine for the currently active
+trigger will be called, and LED state is changed to LED_OFF.
+
+Driver suspend changes the LED state to LED_OFF and resume doesn't change
+the state. Please note that there is no explicit interaction between the
+suspend and resume actions and the currently enabled trigger. LED state
+changes are suspended while the driver is in suspend state. Any timers
+that are active at the time driver gets suspended, continue to run, without
+being able to actually change the LED state. Once driver is resumed, triggers
+start functioning again.
+
+LED state changes are controlled using brightness which is a common led
+class device property. When brightness is set to 0 from user space via
+echo 0 > brightness, it will result in deactivating the current trigger.
+
+Transient trigger uses standard register and unregister interfaces. During
+trigger registration, for each led class device that specifies this trigger
+as its default trigger, trigger activation routine will get called. During
+registration, the LED state does not change, unless there is another trigger
+active, in which case LED state changes to LED_OFF.
+
+During trigger unregistration, LED state gets changed to LED_OFF.
+
+Transient trigger activation routine doesn't change the LED state. It
+creates its properties and does its initialization. Transient trigger
+deactivation routine, will cancel any timer that is active before it cleans
+up and removes the properties it created. It will restore the LED state to
+non-transient state. When driver gets suspended, irrespective of the transient
+state, the LED state changes to LED_OFF.
+
+Transient trigger can be enabled and disabled from user space on led class
+devices, that support this trigger as shown below:
+
+echo transient > trigger
+echo none > trigger
+
+NOTE: Add a new property trigger state to control the state.
+
+This trigger exports three properties, activate, state, and duration. When
+transient trigger is activated these properties are set to default values.
+
+- duration allows setting timer value in msecs. The initial value is 0.
+- activate allows activating and deactivating the timer specified by
+  duration as needed. The initial and default value is 0.  This will allow
+  duration to be set after trigger activation.
+- state allows user to specify a transient state to be held for the specified
+  duration.
+
+	activate - one shot timer activate mechanism.
+		1 when activated, 0 when deactivated.
+		default value is zero when transient trigger is enabled,
+		to allow duration to be set.
+
+		activate state indicates a timer with a value of specified
+		duration running.
+		deactivated state indicates that there is no active timer
+		running.
+
+	duration - one shot timer value. When activate is set, duration value
+		is used to start a timer that runs once. This value doesn't
+		get changed by the trigger unless user does a set via
+		echo new_value > duration
+
+	state - transient state to be held. It has two values 0 or 1. 0 maps
+		to LED_OFF and 1 maps to LED_FULL. The specified state is
+		held for the duration of the one shot timer and then the
+		state gets changed to the non-transient state which is the
+		inverse of transient state.
+		If state = LED_FULL, when the timer runs out the state will
+		go back to LED_OFF.
+		If state = LED_OFF, when the timer runs out the state will
+		go back to LED_FULL.
+		Please note that current LED state is not checked prior to
+		changing the state to the specified state.
+		Driver could map these values to inverted depending on the
+		default states it defines for the LED in its brightness_set()
+		interface which is called from the led brightness_set()
+		interfaces to control the LED state.
+
+When timer expires activate goes back to deactivated state, duration is left
+at the set value to be used when activate is set at a future time. This will
+allow user app to set the time once and activate it to run it once for the
+specified value as needed. When timer expires, state is restored to the
+non-transient state which is the inverse of the transient state.
+
+	echo 1 > activate - starts timer = duration when duration is not 0.
+	echo 0 > activate - cancels currently running timer.
+	echo n > duration - stores timer value to be used upon next
+                            activate. Currently active timer if
+                            any, continues to run for the specified time.
+	echo 0 > duration - stores timer value to be used upon next
+                            activate. Currently active timer if any,
+                            continues to run for the specified time.
+	echo 1 > state    - stores desired transient state LED_FULL to be
+			    held for the specified duration.
+	echo 0 > state    - stores desired transient state LED_OFF to be
+			    held for the specified duration.
+
+What is not supported:
+======================
+- Timer activation is one shot and extending and/or shortening the timer
+  is not supported.
+
+Example use-case 1:
+	echo transient > trigger
+	echo n > duration
+	echo 1 > state
+repeat the following step as needed:
+	echo 1 > activate - start timer = duration to run once
+	echo 1 > activate - start timer = duration to run once
+	echo none > trigger
+
+This trigger is intended to be used for for the following example use cases:
+ - Control of vibrate (phones, tablets etc.) hardware by user space app.
+ - Use of LED by user space app as activity indicator.
+ - Use of LED by user space app as a kind of watchdog indicator -- as
+       long as the app is alive, it can keep the LED illuminated, if it dies
+       the LED will be extinguished automatically.
+ - Use by any user space app that needs a transient GPIO output.
diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt
index 29bdf62aac09..f734bb2a78dc 100644
--- a/Documentation/vm/transhuge.txt
+++ b/Documentation/vm/transhuge.txt
@@ -166,6 +166,68 @@ behavior. So to make them effective you need to restart any
 application that could have been using hugepages. This also applies to
 the regions registered in khugepaged.
 
+== Monitoring usage ==
+
+The number of transparent huge pages currently used by the system is
+available by reading the AnonHugePages field in /proc/meminfo. To
+identify what applications are using transparent huge pages, it is
+necessary to read /proc/PID/smaps and count the AnonHugePages fields
+for each mapping. Note that reading the smaps file is expensive and
+reading it frequently will incur overhead.
+
+There are a number of counters in /proc/vmstat that may be used to
+monitor how successfully the system is providing huge pages for use.
+
+thp_fault_alloc is incremented every time a huge page is successfully
+	allocated to handle a page fault. This applies to both the
+	first time a page is faulted and for COW faults.
+
+thp_collapse_alloc is incremented by khugepaged when it has found
+	a range of pages to collapse into one huge page and has
+	successfully allocated a new huge page to store the data.
+
+thp_fault_fallback is incremented if a page fault fails to allocate
+	a huge page and instead falls back to using small pages.
+
+thp_collapse_alloc_failed is incremented if khugepaged found a range
+	of pages that should be collapsed into one huge page but failed
+	the allocation.
+
+thp_split is incremented every time a huge page is split into base
+	pages. This can happen for a variety of reasons but a common
+	reason is that a huge page is old and is being reclaimed.
+
+As the system ages, allocating huge pages may be expensive as the
+system uses memory compaction to copy data around memory to free a
+huge page for use. There are some counters in /proc/vmstat to help
+monitor this overhead.
+
+compact_stall is incremented every time a process stalls to run
+	memory compaction so that a huge page is free for use.
+
+compact_success is incremented if the system compacted memory and
+	freed a huge page for use.
+
+compact_fail is incremented if the system tries to compact memory
+	but failed.
+
+compact_pages_moved is incremented each time a page is moved. If
+	this value is increasing rapidly, it implies that the system
+	is copying a lot of data to satisfy the huge page allocation.
+	It is possible that the cost of copying exceeds any savings
+	from reduced TLB misses.
+
+compact_pagemigrate_failed is incremented when the underlying mechanism
+	for moving a page failed.
+
+compact_blocks_moved is incremented each time memory compaction examines
+	a huge page aligned range of pages.
+
+It is possible to establish how long the stalls were using the function
+tracer to record how long was spent in __alloc_pages_nodemask and
+using the mm_page_alloc tracepoint to identify which allocations were
+for huge pages.
+
 == get_user_pages and follow_page ==
 
 get_user_pages and follow_page if run on a hugepage, will return the