In function find_busiest_group(), the sched-domain avg_load isn't
calculated at all if there is a group imbalance within the domain. This
will cause erroneous imbalance calculation.

The reason is that calculate_imbalance() sees sds->avg_load = 0 and it
will dump entire sds->max_load into imbalance variable, which is used
later on to migrate entire load from busiest CPU to the puller CPU.

This has two really bad effect:

1. stampede of task migration, and they won't be able to break out
   of the bad state because of positive feedback loop: large load
   delta -> heavier load migration -> larger imbalance and the cycle
   goes on.

2. severe imbalance in CPU queue depth.  This causes really long
   scheduling latency blip which affects badly on application that
   has tight latency requirement.

The fix is to have kernel calculate domain avg_load in both cases. This
will ensure that imbalance calculation is always sensible and the target
is usually half way between busiest and puller CPU.
Signed-off-by: NKen Chen <kenchen@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20110408002322.3A0D812217F@elm.corp.google.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Fix erroneous syscall kernel-doc comments in kernel/signal.c.
Reported-by: NMatt Fleming <matt@console-pimps.org>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of the possible multiple-evaluation of num_online_cpus()
in rebalance_domains() that Linus reported, avoid it altogether
in the normal case since it's implemented with a Hamming weight
function over a cpu bitmask which can be darn expensive for those
with big iron.

This also makes it cleaner, smaller and documents the code.
Reported-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1301991265.2225.12.camel@twins>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add kernel-doc to syscalls in signal.c.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

General coding style and comment fixes; no code changes:

 - Use multi-line-comment coding style.
 - Put some function signatures completely on one line.
 - Hyphenate some words.
 - Spell Posix as POSIX.
 - Correct typos & spellos in some comments.
 - Drop trailing whitespace.
 - End sentences with periods.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The ADJ_SETOFFSET bit added in commit 094aa188 ("ntp: Add ADJ_SETOFFSET
mode bit") also introduced a way for any user to change the system time.
Sneaky or buggy calls to adjtimex() could set

    ADJ_OFFSET_SS_READ | ADJ_SETOFFSET

which would result in a successful call to timekeeping_inject_offset().
This patch fixes the issue by adding the capability check.
Signed-off-by: NRichard Cochran <richard.cochran@omicron.at>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The allocated cpumask should be freed in __setup_irq().
Signed-off-by: NXiaotian Feng <dfeng@redhat.com>
LKML-Reference: <1301744375-6812-1-git-send-email-dfeng@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

On ppc64 the crashkernel region almost always overlaps an area of firmware.
This works fine except when using the sysfs interface to reduce the kdump
region. If we free the firmware area we are guaranteed to crash.

Rename free_reserved_phys_range to crash_free_reserved_phys_range and make
it a weak function so we can override it.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

sys_perf_event_open() had an imbalance in the number of task refs it
took causing memory leakage

Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: stable@kernel.org # .37+
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Ensure we allow 512 kiB + 1 page for user control without
assuming a 4096 bytes page size.
Reported-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: <stable@kernel.org>
LKML-Reference: <1301535209-9679-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The interval for checking scheduling domains if they are due to be
balanced currently depends on boot state NR_CPUS, which may not
accurately reflect the number of online CPUs at the time of check.

Thus replace NR_CPUS with num_online_cpus().

 (ed: Should only affect those who set NR_CPUS really high, such as 4096
      or so :-)
Signed-off-by: NSisir Koppaka <sisir.koppaka@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <AANLkTikqHWid2Q93F5U5Qw5snJH8C5PXoa7J6=6hYO94@mail.gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

sched_setscheduler() (in sched.c) is called in order of changing the
scheduling policy and/or the real-time priority of a task. Thus,
if we find out that neither of those are actually being modified, it
is possible to return earlier and save the overhead of a full
deactivate+activate cycle of the task in question.

Beside that, if we have more than one SCHED_FIFO task with the same
priority on the same rq (which means they share the same priority queue)
having one of them changing its position in the priority queue because of
a sched_setscheduler (as it happens by means of the deactivate+activate)
that does not actually change the priority violates POSIX which states,
for SCHED_FIFO:

  "If a thread whose policy or priority has been modified by
   pthread_setschedprio() is a running thread or is runnable, the effect on
   its position in the thread list depends on the direction of the
   modification, as follows: a. <...> b. If the priority is unchanged, the
   thread does not change position in the thread list. c. <...>"

     http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_08.html

 (ed: And the POSIX specification here does, briefly and somewhat unexpectedly,
      match what common sense tells us as well. )
Signed-off-by: NDario Faggioli <raistlin@linux.it>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1300971618.3960.82.camel@Palantir>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Fixes these errors:

  kernel/irq/chip.c: In function 'handle_edge_eoi_irq':
  kernel/irq/chip.c:517: warning: label 'out_unlock' defined but not used
  kernel/irq/chip.c:503: error: label 'out_eoi' used but not defined
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reported-by: michael@ellerman.id.au
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org

All users converted to new interface.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The only subtle difference is that alpha uses ACTUAL_NR_IRQS and
prints the IRQF_DISABLED flag.

Change the generic implementation to deal with ACTUAL_NR_IRQS if
defined.

The IRQF_DISABLED printing is pointless, as we nowadays run all
interrupts with irqs disabled.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The late night fixup missed to convert the data type from irq_desc to
irq_data, which results in a harmless but annoying warning.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

I missed the CONFIG_GENERIC_PENDING_IRQ dependency in the affinity
related functions and the IRQ_LEVEL propagation into irq_data
state. Did not pop up on my main test platforms. :(
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NDavid Daney <ddaney@caviumnetworks.com>

Commit da48524e ("Prevent rt_sigqueueinfo and rt_tgsigqueueinfo
from spoofing the signal code") made the check on si_code too strict.
There are several legitimate places where glibc wants to queue a
negative si_code different from SI_QUEUE:

 - This was first noticed with glibc's aio implementation, which wants
   to queue a signal with si_code SI_ASYNCIO; the current kernel
   causes glibc's tst-aio4 test to fail because rt_sigqueueinfo()
   fails with EPERM.

 - Further examination of the glibc source shows that getaddrinfo_a()
   wants to use SI_ASYNCNL (which the kernel does not even define).
   The timer_create() fallback code wants to queue signals with SI_TIMER.

As suggested by Oleg Nesterov <oleg@redhat.com>, loosen the check to
forbid only the problematic SI_TKILL case.
Reported-by: NKlaus Dittrich <kladit@arcor.de>
Acked-by: NJulien Tinnes <jln@google.com>
Cc: <stable@kernel.org>
Signed-off-by: NRoland Dreier <roland@purestorage.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sigh, I'm overworked.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Fix new irq-related kernel-doc warnings in 2.6.38:

Warning(kernel/irq/manage.c:149): No description found for parameter 'mask'
Warning(kernel/irq/manage.c:149): Excess function parameter 'cpumask' description in 'irq_set_affinity'
Warning(include/linux/irq.h:161): No description found for parameter 'state_use_accessors'
Warning(include/linux/irq.h:161): Excess struct/union/enum/typedef member 'state_use_accessor' description in 'irq_data'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <20110318093356.b939558d.randy.dunlap@oracle.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Last user gone.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This is a replacment for the cell flow handler which is in the way of
cleanups. Must be selected to avoid general bloat.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

We really need these flags for some of the interrupt chips. Move it
from internal state to irq_data and provide proper accessors.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: David Daney <ddaney@caviumnetworks.com>

The .irq_cpu_online() and .irq_cpu_offline() functions may need to
adjust affinity, but they are called with the descriptor lock held.
Create __irq_set_affinity_locked() which is called with the lock held.
Make irq_set_affinity() just a wrapper that acquires the lock.

[ tglx: Changed the argument to irq_data, added a !desc check and
        moved the !irq_set_affinity check where it belongs ]
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
LKML-Reference: <1301081931-11240-4-git-send-email-ddaney@caviumnetworks.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Add a flag which indicates that the on/offline callback should only be
called on enabled interrupts.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

[ tglx: Removed the enabled argument as this is now available in
irq_data ]
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
LKML-Reference: <1301081931-11240-3-git-send-email-ddaney@caviumnetworks.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Some irq_chip implementation require to know the disabled state of the
interrupt in certain callbacks. Add a state flag and accessor to
irq_data.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The helper macros and functions like for_each_active_irq() don't work
unless the irq is in the allocated_irqs set.

In the case of !CONFIG_SPARSE_IRQ, instead of forcing all users of the
irq infrastructure to explicitly call irq_reserve_irq(), do it for
them.
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
LKML-Reference: <1301081931-11240-2-git-send-email-ddaney@caviumnetworks.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

It's better to use macro KDB_BASE_CMD_MAX instead of 50
Signed-off-by: NJovi Zhang <bookjovi@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Some archs want to print extra information for certain irq_chips which
is per irq and not per chip. Allow them to provide a chip callback to
print the chip name and the extra information.

PowerPC wants to print the LEVEL/EDGE type information. Make it configurable.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

An update of the futex code had a

	WARN_ON(!spin_is_locked(q->lock_ptr))

But on UP, spin_is_locked() is always false, and will
trigger this warning, and even worse, it will exit the function
without doing the necessary work.

Converting this to a WARN_ON_SMP() fixes the problem.
Reported-by: NRichard Weinberger <richard@nod.at>
Tested-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NDarren Hart <dvhart@linux.intel.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <20110317192208.682654502@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The %pB format specifier is for stack backtrace. Its handler
sprint_backtrace() does symbol lookup using (address-1) to
ensure the address will not point outside of the function.

If there is a tail-call to the function marked "noreturn",
gcc optimized out the code after the call then causes saved
return address points outside of the function (i.e. the start
of the next function), so pollutes call trace somewhat.

This patch adds the %pB printk mechanism that allows architecture
call-trace printout functions to improve backtrace printouts.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
LKML-Reference: <1300934550-21394-1-git-send-email-namhyung@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn

The Xen PV drivers in a crashed HVM guest can not connect to the dom0
backend drivers because both frontend and backend drivers are still in
connected state.  To run the connection reset function only in case of a
crashdump, the is_kdump_kernel() function needs to be available for the PV
driver modules.

Consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn into
kernel/crash_dump.c Also export elfcorehdr_addr to make is_kdump_kernel()
usable for modules.

Leave 'elfcorehdr' as early_param().  This changes powerpc from __setup()
to early_param().  It adds an address range check from x86 also on ia64
and powerpc.

[akpm@linux-foundation.org: additional #includes]
[akpm@linux-foundation.org: remove elfcorehdr_addr export]
[akpm@linux-foundation.org: fix for Tejun's mm/nobootmem.c changes]
Signed-off-by: NOlaf Hering <olaf@aepfle.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

printk()s without a priority level default to KERN_WARNING.  To reduce
noise at KERN_WARNING, this patch set the priority level appriopriately
for unleveled printks()s.  This should be useful to folks that look at
dmesg warnings closely.
Signed-off-by: NMandeep Singh Baines <msb@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

CAP_IPC_OWNER and CAP_IPC_LOCK can be checked against current_user_ns(),
because the resource comes from current's own ipc namespace.

setuid/setgid are to uids in own namespace, so again checks can be against
current_user_ns().

Changelog:
	Jan 11: Use task_ns_capable() in place of sched_capable().
	Jan 11: Use nsown_capable() as suggested by Bastian Blank.
	Jan 11: Clarify (hopefully) some logic in futex and sched.c
	Feb 15: use ns_capable for ipc, not nsown_capable
	Feb 23: let copy_ipcs handle setting ipc_ns->user_ns
	Feb 23: pass ns down rather than taking it from current

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NSerge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: NDaniel Lezcano <daniel.lezcano@free.fr>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>