Merge branch 'akpm' (incoming from Andrew)

Merge second patch-bomb from Andrew Morton:
 - the rest of MM
 - zram updates
 - zswap updates
 - exit
 - procfs
 - exec
 - wait
 - crash dump
 - lib/idr
 - rapidio
 - adfs, affs, bfs, ufs
 - cris
 - Kconfig things
 - initramfs
 - small amount of IPC material
 - percpu enhancements
 - early ioremap support
 - various other misc things

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (156 commits)
  MAINTAINERS: update Intel C600 SAS driver maintainers
  fs/ufs: remove unused ufs_super_block_third pointer
  fs/ufs: remove unused ufs_super_block_second pointer
  fs/ufs: remove unused ufs_super_block_first pointer
  fs/ufs/super.c: add __init to init_inodecache()
  doc/kernel-parameters.txt: add early_ioremap_debug
  arm64: add early_ioremap support
  arm64: initialize pgprot info earlier in boot
  x86: use generic early_ioremap
  mm: create generic early_ioremap() support
  x86/mm: sparse warning fix for early_memremap
  lglock: map to spinlock when !CONFIG_SMP
  percpu: add preemption checks to __this_cpu ops
  vmstat: use raw_cpu_ops to avoid false positives on preemption checks
  slub: use raw_cpu_inc for incrementing statistics
  net: replace __this_cpu_inc in route.c with raw_cpu_inc
  modules: use raw_cpu_write for initialization of per cpu refcount.
  mm: use raw_cpu ops for determining current NUMA node
  percpu: add raw_cpu_ops
  slub: fix leak of 'name' in sysfs_slab_add
  ...

15 files changed, 182 insertions, 54 deletions

diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index 3f0b9ae61d8c..70ec992514d0 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -43,6 +43,36 @@ Description:
 		The invalid_io file is read-only and specifies the number of
 		non-page-size-aligned I/O requests issued to this device.
 
+What:		/sys/block/zram<id>/failed_reads
+Date:		February 2014
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		The failed_reads file is read-only and specifies the number of
+		failed reads happened on this device.
+
+What:		/sys/block/zram<id>/failed_writes
+Date:		February 2014
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		The failed_writes file is read-only and specifies the number of
+		failed writes happened on this device.
+
+What:		/sys/block/zram<id>/max_comp_streams
+Date:		February 2014
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		The max_comp_streams file is read-write and specifies the
+		number of backend's zcomp_strm compression streams (number of
+		concurrent compress operations).
+
+What:		/sys/block/zram<id>/comp_algorithm
+Date:		February 2014
+Contact:	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+		The comp_algorithm file is read-write and lets to show
+		available and selected compression algorithms, change
+		compression algorithm selection.
+
 What:		/sys/block/zram<id>/notify_free
 Date:		August 2010
 Contact:	Nitin Gupta <ngupta@vflare.org>
@@ -53,15 +83,6 @@ Description:
 		is freed. This statistic is applicable only when this disk is
 		being used as a swap disk.
 
-What:		/sys/block/zram<id>/discard
-Date:		August 2010
-Contact:	Nitin Gupta <ngupta@vflare.org>
-Description:
-		The discard file is read-only and specifies the number of
-		discard requests received by this device. These requests
-		provide information to block device regarding blocks which are
-		no longer used by filesystem.
-
 What:		/sys/block/zram<id>/zero_pages
 Date:		August 2010
 Contact:	Nitin Gupta <ngupta@vflare.org>
diff --git a/Documentation/DocBook/kernel-hacking.tmpl b/Documentation/DocBook/kernel-hacking.tmpl
index bd9015d10cff..e84f09467cd7 100644
--- a/Documentation/DocBook/kernel-hacking.tmpl
+++ b/Documentation/DocBook/kernel-hacking.tmpl
@@ -671,7 +671,7 @@ printk(KERN_INFO "my ip: %pI4\n", &amp;ipaddress);
 
   <sect1 id="routines-local-irqs">
    <title><function>local_irq_save()</function>/<function>local_irq_restore()</function>
-    <filename class="headerfile">include/asm/system.h</filename>
+    <filename class="headerfile">include/linux/irqflags.h</filename>
    </title>
 
    <para>
diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index 85e24c4f215c..d50fa618371b 100644
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -39,7 +39,7 @@ ffffffbffa000000	ffffffbffaffffff	  16MB		PCI I/O space
 
 ffffffbffb000000	ffffffbffbbfffff	  12MB		[guard]
 
-ffffffbffbc00000	ffffffbffbdfffff	   2MB		earlyprintk device
+ffffffbffbc00000	ffffffbffbdfffff	   2MB		fixed mappings
 
 ffffffbffbe00000	ffffffbffbffffff	   2MB		[guard]
 
@@ -66,7 +66,7 @@ fffffdfffa000000	fffffdfffaffffff	  16MB		PCI I/O space
 
 fffffdfffb000000	fffffdfffbbfffff	  12MB		[guard]
 
-fffffdfffbc00000	fffffdfffbdfffff	   2MB		earlyprintk device
+fffffdfffbc00000	fffffdfffbdfffff	   2MB		fixed mappings
 
 fffffdfffbe00000	fffffdfffbffffff	   2MB		[guard]
 
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 2eccddffa6c8..0595c3f56ccf 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -21,7 +21,43 @@ Following shows a typical sequence of steps for using zram.
 	This creates 4 devices: /dev/zram{0,1,2,3}
 	(num_devices parameter is optional. Default: 1)
 
-2) Set Disksize
+2) Set max number of compression streams
+	Compression backend may use up to max_comp_streams compression streams,
+	thus allowing up to max_comp_streams concurrent compression operations.
+	By default, compression backend uses single compression stream.
+
+	Examples:
+	#show max compression streams number
+	cat /sys/block/zram0/max_comp_streams
+
+	#set max compression streams number to 3
+	echo 3 > /sys/block/zram0/max_comp_streams
+
+Note:
+In order to enable compression backend's multi stream support max_comp_streams
+must be initially set to desired concurrency level before ZRAM device
+initialisation. Once the device initialised as a single stream compression
+backend (max_comp_streams equals to 1), you will see error if you try to change
+the value of max_comp_streams because single stream compression backend
+implemented as a special case by lock overhead issue and does not support
+dynamic max_comp_streams. Only multi stream backend supports dynamic
+max_comp_streams adjustment.
+
+3) Select compression algorithm
+	Using comp_algorithm device attribute one can see available and
+	currently selected (shown in square brackets) compression algortithms,
+	change selected compression algorithm (once the device is initialised
+	there is no way to change compression algorithm).
+
+	Examples:
+	#show supported compression algorithms
+	cat /sys/block/zram0/comp_algorithm
+	lzo [lz4]
+
+	#select lzo compression algorithm
+	echo lzo > /sys/block/zram0/comp_algorithm
+
+4) Set Disksize
         Set disk size by writing the value to sysfs node 'disksize'.
         The value can be either in bytes or you can use mem suffixes.
         Examples:
@@ -33,32 +69,38 @@ Following shows a typical sequence of steps for using zram.
             echo 512M > /sys/block/zram0/disksize
             echo 1G > /sys/block/zram0/disksize
 
-3) Activate:
+Note:
+There is little point creating a zram of greater than twice the size of memory
+since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
+size of the disk when not in use so a huge zram is wasteful.
+
+5) Activate:
 	mkswap /dev/zram0
 	swapon /dev/zram0
 
 	mkfs.ext4 /dev/zram1
 	mount /dev/zram1 /tmp
 
-4) Stats:
+6) Stats:
 	Per-device statistics are exported as various nodes under
 	/sys/block/zram<id>/
 		disksize
 		num_reads
 		num_writes
+		failed_reads
+		failed_writes
 		invalid_io
 		notify_free
-		discard
 		zero_pages
 		orig_data_size
 		compr_data_size
 		mem_used_total
 
-5) Deactivate:
+7) Deactivate:
 	swapoff /dev/zram0
 	umount /dev/zram1
 
-6) Reset:
+8) Reset:
 	Write any positive value to 'reset' sysfs node
 	echo 1 > /sys/block/zram0/reset
 	echo 1 > /sys/block/zram1/reset
diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index ce94a83a7d9a..80ac454704b8 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/Documentation/cgroups/memcg_test.txt
@@ -24,7 +24,7 @@ Please note that implementation details can be changed.
 
    a page/swp_entry may be charged (usage += PAGE_SIZE) at
 
-	mem_cgroup_newpage_charge()
+	mem_cgroup_charge_anon()
 	  Called at new page fault and Copy-On-Write.
 
 	mem_cgroup_try_charge_swapin()
@@ -32,7 +32,7 @@ Please note that implementation details can be changed.
 	  Followed by charge-commit-cancel protocol. (With swap accounting)
 	  At commit, a charge recorded in swap_cgroup is removed.
 
-	mem_cgroup_cache_charge()
+	mem_cgroup_charge_file()
 	  Called at add_to_page_cache()
 
 	mem_cgroup_cache_charge_swapin()
diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index 5108afb3645c..762ca54eb929 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt
@@ -76,15 +76,7 @@ to work with it.
 	limit_fail_at parameter is set to the particular res_counter element
 	where the charging failed.
 
- d. int res_counter_charge_locked
-			(struct res_counter *rc, unsigned long val, bool force)
-
-	The same as res_counter_charge(), but it must not acquire/release the
-	res_counter->lock internally (it must be called with res_counter->lock
-	held). The force parameter indicates whether we can bypass the limit.
-
- e. u64 res_counter_uncharge[_locked]
-			(struct res_counter *rc, unsigned long val)
+ d. u64 res_counter_uncharge(struct res_counter *rc, unsigned long val)
 
 	When a resource is released (freed) it should be de-accounted
 	from the resource counter it was accounted to.  This is called
@@ -93,7 +85,7 @@ to work with it.
 
 	The _locked routines imply that the res_counter->lock is taken.
 
- f. u64 res_counter_uncharge_until
+ e. u64 res_counter_uncharge_until
 		(struct res_counter *rc, struct res_counter *top,
 		 unsigned long val)
 
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f424e0e5b46b..efca5c1bbb10 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -529,6 +529,7 @@ locking rules:
 open:		yes
 close:		yes
 fault:		yes		can return with page locked
+map_pages:	yes
 page_mkwrite:	yes		can return with page locked
 access:		yes
 
@@ -540,6 +541,15 @@ the page, then ensure it is not already truncated (the page lock will block
 subsequent truncate), and then return with VM_FAULT_LOCKED, and the page
 locked. The VM will unlock the page.
 
+	->map_pages() is called when VM asks to map easy accessible pages.
+Filesystem should find and map pages associated with offsets from "pgoff"
+till "max_pgoff". ->map_pages() is called with page table locked and must
+not block.  If it's not possible to reach a page without blocking,
+filesystem should skip it. Filesystem should use do_set_pte() to setup
+page table entry. Pointer to entry associated with offset "pgoff" is
+passed in "pte" field in vm_fault structure. Pointers to entries for other
+offsets should be calculated relative to "pte".
+
 	->page_mkwrite() is called when a previously read-only pte is
 about to become writeable. The filesystem again must ensure that there are
 no truncate/invalidate races, and then return with the page locked. If
diff --git a/Documentation/filesystems/affs.txt b/Documentation/filesystems/affs.txt
index 81ac488e3758..71b63c2b9841 100644
--- a/Documentation/filesystems/affs.txt
+++ b/Documentation/filesystems/affs.txt
@@ -49,6 +49,10 @@ mode=mode	Sets the mode flags to the given (octal) value, regardless
 		This is useful since most of the plain AmigaOS files
 		will map to 600.
 
+nofilenametruncate
+		The file system will return an error when filename exceeds
+		standard maximum filename length (30 characters).
+
 reserved=num	Sets the number of reserved blocks at the start of the
 		partition to num. You should never need this option.
 		Default is 2.
@@ -181,9 +185,8 @@ tested, though several hundred MB have been read and written using
 this fs. For a most up-to-date list of bugs please consult
 fs/affs/Changes.
 
-Filenames are truncated to 30 characters without warning (this
-can be changed by setting the compile-time option AFFS_NO_TRUNCATE
-in include/linux/amigaffs.h).
+By default, filenames are truncated to 30 characters without warning.
+'nofilenametruncate' mount option can change that behavior.
 
 Case is ignored by the affs in filename matching, but Linux shells
 do care about the case. Example (with /wb being an affs mounted fs):
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index f00bee144add..8b9cd8eb3f91 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1648,18 +1648,21 @@ pids, so one need to either stop or freeze processes being inspected
 if precise results are needed.
 
 
-3.7	/proc/<pid>/fdinfo/<fd> - Information about opened file
+3.8	/proc/<pid>/fdinfo/<fd> - Information about opened file
 ---------------------------------------------------------------
 This file provides information associated with an opened file. The regular
-files have at least two fields -- 'pos' and 'flags'. The 'pos' represents
-the current offset of the opened file in decimal form [see lseek(2) for
-details] and 'flags' denotes the octal O_xxx mask the file has been
-created with [see open(2) for details].
+files have at least three fields -- 'pos', 'flags' and mnt_id. The 'pos'
+represents the current offset of the opened file in decimal form [see lseek(2)
+for details], 'flags' denotes the octal O_xxx mask the file has been
+created with [see open(2) for details] and 'mnt_id' represents mount ID of
+the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo
+for details].
 
 A typical output is
 
 	pos:	0
 	flags:	0100002
+	mnt_id:	19
 
 The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
 pair provide additional information particular to the objects they represent.
@@ -1668,6 +1671,7 @@ pair provide additional information particular to the objects they represent.
 	~~~~~~~~~~~~~
 	pos:	0
 	flags:	04002
+	mnt_id:	9
 	eventfd-count:	5a
 
 	where 'eventfd-count' is hex value of a counter.
@@ -1676,6 +1680,7 @@ pair provide additional information particular to the objects they represent.
 	~~~~~~~~~~~~~~
 	pos:	0
 	flags:	04002
+	mnt_id:	9
 	sigmask:	0000000000000200
 
 	where 'sigmask' is hex value of the signal mask associated
@@ -1685,6 +1690,7 @@ pair provide additional information particular to the objects they represent.
 	~~~~~~~~~~~
 	pos:	0
 	flags:	02
+	mnt_id:	9
 	tfd:        5 events:       1d data: ffffffffffffffff
 
 	where 'tfd' is a target file descriptor number in decimal form,
@@ -1718,6 +1724,7 @@ pair provide additional information particular to the objects they represent.
 
 	pos:	0
 	flags:	02
+	mnt_id:	9
 	fanotify flags:10 event-flags:0
 	fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
 	fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
diff --git a/Documentation/irqflags-tracing.txt b/Documentation/irqflags-tracing.txt
index 67aa71e73035..f6da05670e16 100644
--- a/Documentation/irqflags-tracing.txt
+++ b/Documentation/irqflags-tracing.txt
@@ -22,13 +22,6 @@ rather straightforward and risk-free manner.
 Architectures that want to support this need to do a couple of
 code-organizational changes first:
 
-- move their irq-flags manipulation code from their asm/system.h header
-  to asm/irqflags.h
-
-- rename local_irq_disable()/etc to raw_local_irq_disable()/etc. so that
-  the linux/irqflags.h code can inject callbacks and can construct the
-  real local_irq_disable()/etc APIs.
-
 - add and enable TRACE_IRQFLAGS_SUPPORT in their arch level Kconfig file
 
 and then a couple of functional changes are needed as well to implement
diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index c420676c6fe3..350f733bf2c7 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -157,6 +157,10 @@ applicable everywhere (see syntax).
     to the build environment (if this is desired, it can be done via
     another symbol).
 
+  - "allnoconfig_y"
+    This declares the symbol as one that should have the value y when
+    using "allnoconfig". Used for symbols that hide other symbols.
+
 Menu dependencies
 -----------------
 
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bc3478581f67..b6c67d592be5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -884,6 +884,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Enable debug messages at boot time.  See
 			Documentation/dynamic-debug-howto.txt for details.
 
+	early_ioremap_debug [KNL]
+			Enable debug messages in early_ioremap support. This
+			is useful for tracking down temporary early mappings
+			which are not unmapped.
+
 	earlycon=	[KNL] Output early console device and options.
 		uart[8250],io,<addr>[,options]
 		uart[8250],mmio,<addr>[,options]
diff --git a/Documentation/rapidio/sysfs.txt b/Documentation/rapidio/sysfs.txt
index 271438c0617f..47ce9a5336e1 100644
--- a/Documentation/rapidio/sysfs.txt
+++ b/Documentation/rapidio/sysfs.txt
@@ -2,8 +2,8 @@
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-1. Device Subdirectories
-------------------------
+1. RapidIO Device Subdirectories
+--------------------------------
 
 For each RapidIO device, the RapidIO subsystem creates files in an individual
 subdirectory with the following name, /sys/bus/rapidio/devices/<device_name>.
@@ -25,8 +25,8 @@ seen by the enumerating host (destID = 1):
 NOTE: An enumerating or discovering endpoint does not create a sysfs entry for
 itself, this is why an endpoint with destID=1 is not shown in the list.
 
-2. Attributes Common for All Devices
-------------------------------------
+2. Attributes Common for All RapidIO Devices
+--------------------------------------------
 
 Each device subdirectory contains the following informational read-only files:
 
@@ -52,16 +52,16 @@ This attribute is similar in behavior to the "config" attribute of PCI devices
 and provides an access to the RapidIO device registers using standard file read
 and write operations.
 
-3. Endpoint Device Attributes
------------------------------
+3. RapidIO Endpoint Device Attributes
+-------------------------------------
 
 Currently Linux RapidIO subsystem does not create any endpoint specific sysfs
 attributes. It is possible that RapidIO master port drivers and endpoint device
 drivers will add their device-specific sysfs attributes but such attributes are
 outside the scope of this document.
 
-4. Switch Device Attributes
----------------------------
+4. RapidIO Switch Device Attributes
+-----------------------------------
 
 RapidIO switches have additional attributes in sysfs. RapidIO subsystem supports
 common and device-specific sysfs attributes for switches. Because switches are
@@ -106,3 +106,53 @@ attribute:
 	 for that controller always will be 0.
 	 To initiate RapidIO enumeration/discovery on all available mports
 	 a user must write '-1' (or RIO_MPORT_ANY) into this attribute file.
+
+
+6. RapidIO Bus Controllers/Ports
+--------------------------------
+
+On-chip RapidIO controllers and PCIe-to-RapidIO bridges (referenced as
+"Master Port" or "mport") are presented in sysfs as the special class of
+devices: "rapidio_port".
+
+The /sys/class/rapidio_port subdirectory contains individual subdirectories
+named as "rapidioN" where N = mport ID registered with RapidIO subsystem.
+
+NOTE: An mport ID is not a RapidIO destination ID assigned to a given local
+mport device.
+
+Each mport device subdirectory in addition to standard entries contains the
+following device-specific attributes:
+
+   port_destid - reports RapidIO destination ID assigned to the given RapidIO
+                 mport device. If value 0xFFFFFFFF is returned this means that
+                 no valid destination ID have been assigned to the mport (yet).
+                 Normally, before enumeration/discovery have been executed only
+                 fabric enumerating mports have a valid destination ID assigned
+                 to them using "hdid=..." rapidio module parameter.
+      sys_size - reports RapidIO common transport system size:
+                   0 = small (8-bit destination ID, max. 256 devices),
+                   1 = large (16-bit destination ID, max. 65536 devices).
+
+After enumeration or discovery was performed for a given mport device,
+the corresponding subdirectory will also contain subdirectories for each
+child RapidIO device connected to the mport. Naming conventions for RapidIO
+devices are described in Section 1 above.
+
+The example below shows mport device subdirectory with several child RapidIO
+devices attached to it.
+
+[rio@rapidio ~]$ ls /sys/class/rapidio_port/rapidio0/ -l
+total 0
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0001
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0004
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:e:0007
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0002
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0003
+drwxr-xr-x 3 root root    0 Feb 11 15:10 00:s:0005
+lrwxrwxrwx 1 root root    0 Feb 11 15:11 device -> ../../../0000:01:00.0
+-r--r--r-- 1 root root 4096 Feb 11 15:11 port_destid
+drwxr-xr-x 2 root root    0 Feb 11 15:11 power
+lrwxrwxrwx 1 root root    0 Feb 11 15:04 subsystem -> ../../../../../../class/rapidio_port
+-r--r--r-- 1 root root 4096 Feb 11 15:11 sys_size
+-rw-r--r-- 1 root root 4096 Feb 11 15:04 uevent
diff --git a/Documentation/scheduler/sched-arch.txt b/Documentation/scheduler/sched-arch.txt
index 9290de703450..a2f27bbf2cba 100644
--- a/Documentation/scheduler/sched-arch.txt
+++ b/Documentation/scheduler/sched-arch.txt
@@ -8,7 +8,7 @@ Context switch
 By default, the switch_to arch function is called with the runqueue
 locked. This is usually not a problem unless switch_to may need to
 take the runqueue lock. This is usually due to a wake up operation in
-the context switch. See arch/ia64/include/asm/system.h for an example.
+the context switch. See arch/ia64/include/asm/switch_to.h for an example.
 
 To request the scheduler call switch_to with the runqueue unlocked,
 you must `#define __ARCH_WANT_UNLOCKED_CTXSW` in a header file
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 271a09db6629..9886c3d57fc2 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -317,6 +317,7 @@ for more than this value report a warning.
 This file shows up if CONFIG_DETECT_HUNG_TASK is enabled.
 
 0: means infinite timeout - no checking done.
+Possible values to set are in range {0..LONG_MAX/HZ}.
 
 ==============================================================