Adding declaration of printk_ratelimit_state in ratelimit.h removes
potential build breakage and following sparse warning:

 kernel/printk.c:1426:1: warning: symbol 'printk_ratelimit_state' was not declared. Should it be static?

[akpm@linux-foundation.org: remove unneeded ifdef]
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Robin Holt tried to boot a 16TB system and found af_unix was overflowing
a 32bit value :

<quote>

We were seeing a failure which prevented boot.  The kernel was incapable
of creating either a named pipe or unix domain socket.  This comes down
to a common kernel function called unix_create1() which does:

        atomic_inc(&unix_nr_socks);
        if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
                goto out;

The function get_max_files() is a simple return of files_stat.max_files.
files_stat.max_files is a signed integer and is computed in
fs/file_table.c's files_init().

        n = (mempages * (PAGE_SIZE / 1024)) / 10;
        files_stat.max_files = n;

In our case, mempages (total_ram_pages) is approx 3,758,096,384
(0xe0000000).  That leaves max_files at approximately 1,503,238,553.
This causes 2 * get_max_files() to integer overflow.

</quote>

Fix is to let /proc/sys/fs/file-nr & /proc/sys/fs/file-max use long
integers, and change af_unix to use an atomic_long_t instead of atomic_t.

get_max_files() is changed to return an unsigned long.  get_nr_files() is
changed to return a long.

unix_nr_socks is changed from atomic_t to atomic_long_t, while not
strictly needed to address Robin problem.

Before patch (on a 64bit kernel) :
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
-18446744071562067968

After patch:
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
2147483648
# cat /proc/sys/fs/file-nr
704     0       2147483648
Reported-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid Miller <davem@davemloft.net>
Reviewed-by: NRobin Holt <holt@sgi.com>
Tested-by: NRobin Holt <holt@sgi.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The nr_dentry stat is a globally touched cacheline and atomic operation
twice over the lifetime of a dentry. It is used for the benfit of userspace
only. Turn it into a per-cpu counter and always decrement it in d_free instead
of doing various batching operations to reduce lock hold times in the callers.

Based on an earlier patch from Nick Piggin <npiggin@suse.de>.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The number of inodes allocated does not need to be tied to the
addition or removal of an inode to/from a list. If we are not tied
to a list lock, we could update the counters when inodes are
initialised or destroyed, but to do that we need to convert the
counters to be per-cpu (i.e. independent of a lock). This means that
we have the freedom to change the list/locking implementation
without needing to care about the counters.

Based on a patch originally from Eric Dumazet.

[AV: cleaned up a bit, fixed build breakage on weird configs
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Andrew,

Could you please review this patch, you probably are the right guy to
take it, because it crosses fs and net trees.

Note : /proc/sys/fs/file-nr is a read-only file, so this patch doesnt
depend on previous patch (sysctl: fix min/max handling in
__do_proc_doulongvec_minmax())

Thanks !

[PATCH V4] fs: allow for more than 2^31 files

Robin Holt tried to boot a 16TB system and found af_unix was overflowing
a 32bit value :

<quote>

We were seeing a failure which prevented boot.  The kernel was incapable
of creating either a named pipe or unix domain socket.  This comes down
to a common kernel function called unix_create1() which does:

        atomic_inc(&unix_nr_socks);
        if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
                goto out;

The function get_max_files() is a simple return of files_stat.max_files.
files_stat.max_files is a signed integer and is computed in
fs/file_table.c's files_init().

        n = (mempages * (PAGE_SIZE / 1024)) / 10;
        files_stat.max_files = n;

In our case, mempages (total_ram_pages) is approx 3,758,096,384
(0xe0000000).  That leaves max_files at approximately 1,503,238,553.
This causes 2 * get_max_files() to integer overflow.

</quote>

Fix is to let /proc/sys/fs/file-nr & /proc/sys/fs/file-max use long
integers, and change af_unix to use an atomic_long_t instead of
atomic_t.

get_max_files() is changed to return an unsigned long.
get_nr_files() is changed to return a long.

unix_nr_socks is changed from atomic_t to atomic_long_t, while not
strictly needed to address Robin problem.

Before patch (on a 64bit kernel) :
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
-18446744071562067968

After patch:
# echo 2147483648 >/proc/sys/fs/file-max
# cat /proc/sys/fs/file-max
2147483648
# cat /proc/sys/fs/file-nr
704     0       2147483648
Reported-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid Miller <davem@davemloft.net>
Reviewed-by: NRobin Holt <holt@sgi.com>
Tested-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

When proc_doulongvec_minmax() is used with an array of longs, and no
min/max check requested (.extra1 or .extra2 being NULL), we dereference a
NULL pointer for the second element of the array.

Noticed while doing some changes in network stack for the "16TB problem"

Fix is to not change min & max pointers in __do_proc_doulongvec_minmax(),
so that all elements of the vector share an unique min/max limit, like
proc_dointvec_minmax().

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No real bugs I believe, just some dead code.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: andi@firstfloor.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The three oom killer sysctl variables (sysctl_oom_dump_tasks,
sysctl_oom_kill_allocating_task, and sysctl_panic_on_oom) are better
declared in include/linux/oom.h rather than kernel/sysctl.c.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The kernel/hotplug sysctl variable (/proc/sys/kernel/hotplug file) was
made conditional on CONFIG_NET by commit
f743ca5e (applied in 2.6.18) to fix
problems with undefined references in 2.6.16 when CONFIG_HOTPLUG=y &&
!CONFIG_NET, but this restriction is no longer needed.

This patch makes the kernel/hotplug sysctl variable depend only on
CONFIG_HOTPLUG.
Signed-off-by: NIan Abbott <abbotti@mev.co.uk>
Acked-by: NRandy Dunlap <randy.dunlap@oracle.COM>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Extern declarations in sysctl.c should be move to their own head file, and
then include them in relavant .c files.

Move inotify_table extern declaration to linux/inotify.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NEric Paris <eparis@redhat.com>

Move dir_notify_enable declaration to where it belongs -- dnotify.h .
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NEric Paris <eparis@redhat.com>

slow-work doesn't have any user left.  Kill it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NDavid Howells <dhowells@redhat.com>

This changes the interface to be based on bytes instead. The API
matches that of F_SETPIPE_SZ in that it rounds up the passed in
size so that the resulting page array is a power-of-2 in size.

The proc file is renamed to /proc/sys/fs/pipe-max-size to
reflect this change.
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

The commit 00b7c339
"sysctl: refactor integer handling proc code"
modified the behaviour of writing to /proc.
Before the commit, write("1\n") to /proc/sys/kernel/printk succeeded. But
now it returns EINVAL.

This commit supports writing a single value to a multi-valued entry.
Signed-off-by: NJ. R. Okajima <hooanon05@yahoo.co.jp>
Reviewed-and-tested-by: NWANG Cong <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

mm: compaction: add a tunable that decides when memory should be compacted and when it should be reclaimed

The kernel applies some heuristics when deciding if memory should be
compacted or reclaimed to satisfy a high-order allocation.  One of these
is based on the fragmentation.  If the index is below 500, memory will not
be compacted.  This choice is arbitrary and not based on data.  To help
optimise the system and set a sensible default for this value, this patch
adds a sysctl extfrag_threshold.  The kernel will only compact memory if
the fragmentation index is above the extfrag_threshold.

[randy.dunlap@oracle.com: Fix build errors when proc fs is not configured]
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a proc file /proc/sys/vm/compact_memory.  When an arbitrary value is
written to the file, all zones are compacted.  The expected user of such a
trigger is a job scheduler that prepares the system before the target
application runs.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix kernel-doc warnings, kernel-doc special characters, and
typos in recent kernel/sysctl.c additions.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Amerigo Wang <amwang@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We need at least two to guarantee proper POSIX behaviour, so
never allow a smaller limit than that.

Also expose a /proc/sys/fs/pipe-max-pages sysctl file that allows
root to define a sane upper limit. Make it default to 16 times the
default size, which is 16 pages.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The exception-trace facility on x86 and other architectures prints
traces to dmesg whenever a user space application crashes.
s390 has such a feature since ages however it is called
userprocess_debug and is enabled differently.
This patch makes sure that whenever one of the two procfs files

/proc/sys/kernel/userprocess_debug
/proc/sys/debug/exception-trace

is modified the contents of the second one changes as well.
That way we keep backwards compatibilty but also support the same
interface like other architectures do.
Besides that the output of the traces is improved since it will now
also contain the corresponding filename of the vma (when available)
where the process caused a fault or trap.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The new function can be used to read/write large bitmaps via /proc. A
comma separated range format is used for compact output and input
(e.g. 1,3-4,10-10).

Writing into the file will first reset the bitmap then update it
based on the given input.
Signed-off-by: NOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: NWANG Cong <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

(Based on Octavian's work, and I modified a lot.)

As we are about to add another integer handling proc function a little
bit of cleanup is in order: add a few helper functions to improve code
readability and decrease code duplication.

In the process a bug is also fixed: if the user specifies a number
with more then 20 digits it will be interpreted as two integers
(e.g. 10000...13 will be interpreted as 100.... and 13).

Behavior for EFAULT handling was changed as well. Previous to this
patch, when an EFAULT error occurred in the middle of a write
operation, although some of the elements were set, that was not
acknowledged to the user (by shorting the write and returning the
number of bytes accepted). EFAULT is now treated just like any other
errors by acknowledging the amount of bytes accepted.
Signed-off-by: NOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: NWANG Cong <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that is no longer compiled or used, just remove it.

Also move some of the code wrapped with DETECT_SOFTLOCKUP to the
LOCKUP_DETECTOR wrappers because that is the code that uses it now.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-4-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Just some code cleanup to make touch_softlockup clearer and remove the
softlockup_tick function as it is no longer needed.

Also remove the /proc softlockup_thres call as it has been changed to
watchdog_thres.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-3-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

The new nmi_watchdog (which uses the perf event subsystem) is very
similar in structure to the softlockup detector.  Using Ingo's
suggestion, I combined the two functionalities into one file:
kernel/watchdog.c.

Now both the nmi_watchdog (or hardlockup detector) and softlockup
detector sit on top of the perf event subsystem, which is run every
60 seconds or so to see if there are any lockups.

To detect hardlockups, cpus not responding to interrupts, I
implemented an hrtimer that runs 5 times for every perf event
overflow event.  If that stops counting on a cpu, then the cpu is
most likely in trouble.

To detect softlockups, tasks not yielding to the scheduler, I used the
previous kthread idea that now gets kicked every time the hrtimer fires.
If the kthread isn't being scheduled neither is anyone else and the
warning is printed to the console.

I tested this on x86_64 and both the softlockup and hardlockup paths
work.

V2:
- cleaned up the Kconfig and softlockup combination
- surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI
- seperated out the softlockup case from perf event subsystem
- re-arranged the enabling/disabling nmi watchdog from proc space
- added cpumasks for hardlockup failure cases
- removed fallback to soft events if no PMU exists for hard events

V3:
- comment cleanups
- drop support for older softlockup code
- per_cpu cleanups
- completely remove software clock base hardlockup detector
- use per_cpu masking on hard/soft lockup detection
- #ifdef cleanups
- rename config option NMI_WATCHDOG to LOCKUP_DETECTOR
- documentation additions

V4:
- documentation fixes
- convert per_cpu to __get_cpu_var
- powerpc compile fixes

V5:
- split apart warn flags for hard and soft lockups

TODO:
- figure out how to make an arch-agnostic clock2cycles call
  (if possible) to feed into perf events as a sample period

[fweisbec: merged conflict patch]
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

Instead of keeping SysRq support inside of legacy keyboard driver split
it out into a separate input handler (filter). This stops most SysRq input
events from leaking into evdev clients (some events, such as first SysRq
scancode - not keycode - event, are still leaked into both legacy keyboard
and evdev).

[martinez.javier@gmail.com: fix compile error when CONFIG_MAGIC_SYSRQ is
 not defined]
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move lockdep extern declarations to linux/lockdep.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move max_lock_depth extern declaration to linux/rtmutex.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move acct_parm extern declaration to linux/acct.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move sg_big_buff extern declaration to scsi/sg.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Acked-by: NDoug Gilbert <dgilbert@interlog.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move modprobe_path extern declaration to linux/kmod.h
Move modules_disabled extern declaration to linux/module.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move rcutorture_runnable extern declaration to linux/rcupdate.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Acked-by: NJosh Triplett <josh@joshtriplett.org>
Reviewed-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move print_fatal_signals extern declaration to linux/signal.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extern declarations in sysctl.c should be moved to their own header file,
and then include them in relavant .c files.

Move C_A_D extern variable declaration to linux/reboot.h
Signed-off-by: NDave Young <hidave.darkstar@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just faults right now, will add other traps later.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add /proc/sys/debug/kprobes-optimization sysctl which enables
and disables kprobes jump optimization on the fly for debugging.

Changes in v7:
 - Remove ctl_name = CTL_UNNUMBERED for upstream compatibility.

Changes in v6:
- Update comments and coding style.
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133415.6725.8274.stgit@localhost6.localdomain6>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The original patch was x86_64 centric.  Changed the code to make
it less so.

ested by building and running on a powerpc.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: peterz@infradead.org
Cc: gorcunov@gmail.com
Cc: aris@redhat.com
LKML-Reference: <1266013161-31197-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

It is a mistake that we used 'proc_dointvec', it should be
'proc_dointvec_minmax', as in the original patch.
Signed-off-by: NWANG Cong <amwang@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In NOMMU mode clamp dac_mmap_min_addr to zero to cause the tests on it to be
skipped by the compiler.  We do this as the minimum mmap address doesn't make
any sense in NOMMU mode.

mmap_min_addr and round_hint_to_min() can be discarded entirely in NOMMU mode.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

Jan Engelhardt reported we have this problem:

setting max_map_count to a value large enough results in programs dying at
first try.  This is on 2.6.31.6:

15:59 borg:/proc/sys/vm # echo $[1<<31-1] >max_map_count
15:59 borg:/proc/sys/vm # cat max_map_count
1073741824
15:59 borg:/proc/sys/vm # echo $[1<<31] >max_map_count
15:59 borg:/proc/sys/vm # cat max_map_count
Killed

This is because we have a chance to make 'max_map_count' negative.  but
it's meaningless.  Make it only accept non-negative values.
Reported-by: NJan Engelhardt <jengelh@medozas.de>
Signed-off-by: NWANG Cong <amwang@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: James Morris <jmorris@namei.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch derives a "nodes_allowed" node mask from the numa mempolicy of
the task modifying the number of persistent huge pages to control the
allocation, freeing and adjusting of surplus huge pages when the pool page
count is modified via the new sysctl or sysfs attribute
"nr_hugepages_mempolicy".  The nodes_allowed mask is derived as follows:

* For "default" [NULL] task mempolicy, a NULL nodemask_t pointer
  is produced.  This will cause the hugetlb subsystem to use
  node_online_map as the "nodes_allowed".  This preserves the
  behavior before this patch.
* For "preferred" mempolicy, including explicit local allocation,
  a nodemask with the single preferred node will be produced.
  "local" policy will NOT track any internode migrations of the
  task adjusting nr_hugepages.
* For "bind" and "interleave" policy, the mempolicy's nodemask
  will be used.
* Other than to inform the construction of the nodes_allowed node
  mask, the actual mempolicy mode is ignored.  That is, all modes
  behave like interleave over the resulting nodes_allowed mask
  with no "fallback".

See the updated documentation [next patch] for more information
about the implications of this patch.

Examples:

Starting with:

	Node 0 HugePages_Total:     0
	Node 1 HugePages_Total:     0
	Node 2 HugePages_Total:     0
	Node 3 HugePages_Total:     0

Default behavior [with or without this patch] balances persistent
hugepage allocation across nodes [with sufficient contiguous memory]:

	sysctl vm.nr_hugepages[_mempolicy]=32

yields:

	Node 0 HugePages_Total:     8
	Node 1 HugePages_Total:     8
	Node 2 HugePages_Total:     8
	Node 3 HugePages_Total:     8

Of course, we only have nr_hugepages_mempolicy with the patch,
but with default mempolicy, nr_hugepages_mempolicy behaves the
same as nr_hugepages.

Applying mempolicy--e.g., with numactl [using '-m' a.k.a.
'--membind' because it allows multiple nodes to be specified
and it's easy to type]--we can allocate huge pages on
individual nodes or sets of nodes.  So, starting from the
condition above, with 8 huge pages per node, add 8 more to
node 2 using:

	numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40

This yields:

	Node 0 HugePages_Total:     8
	Node 1 HugePages_Total:     8
	Node 2 HugePages_Total:    16
	Node 3 HugePages_Total:     8

The incremental 8 huge pages were restricted to node 2 by the
specified mempolicy.

Similarly, we can use mempolicy to free persistent huge pages
from specified nodes:

	numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32

yields:

	Node 0 HugePages_Total:     4
	Node 1 HugePages_Total:     4
	Node 2 HugePages_Total:    16
	Node 3 HugePages_Total:     8

The 8 huge pages freed were balanced over nodes 0 and 1.

[rientjes@google.com: accomodate reworked NODEMASK_ALLOC]
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>