To help migrate archtectures over to the new update_vsyscall method,
redfine CONFIG_GENERIC_TIME_VSYSCALL as CONFIG_GENERIC_TIME_VSYSCALL_OLD

Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Since users will need to include timekeeper_internal.h, move
update_vsyscall definitions to timekeeper_internal.h.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

We're going to need to access the timekeeper in update_vsyscall,
so make the structure available for those who need it.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

CLOCK_TICK_RATE is used to accurately caclulate exactly how
a tick will be at a given HZ.

This is useful, because while we'd expect NSEC_PER_SEC/HZ,
the underlying hardware will have some granularity limit,
so we won't be able to have exactly HZ ticks per second.

This slight error can cause timekeeping quality problems
when using the jiffies or other jiffies driven clocksources.
Thus we currently use compile time CLOCK_TICK_RATE value to
generate SHIFTED_HZ and NSEC_PER_JIFFIES, which we then use
to adjust the jiffies clocksource to correct this error.

Unfortunately though, since CLOCK_TICK_RATE is a compile
time value, and the jiffies clocksource is registered very
early during boot, there are a number of cases where there
are different possible hardware timers that have different
tick rates. This causes problems in cases like ARM where
there are numerous different types of hardware, each having
their own compile-time CLOCK_TICK_RATE, making it hard to
accurately support different hardware with a single kernel.

For the most part, this doesn't matter all that much, as not
too many systems actually utilize the jiffies or jiffies driven
clocksource. Usually there are other highres clocksources
who's granularity error is negligable.

Even so, we have some complicated calcualtions that we do
everywhere to handle these edge cases.

This patch removes the compile time SHIFTED_HZ value, and
introduces a register_refined_jiffies() function. This results
in the default jiffies clock as being assumed a perfect HZ
freq, and allows archtectures that care about jiffies accuracy
to call register_refined_jiffies() with the tick rate, specified
dynamically at boot.

This allows us, where necessary, to not have a compile time
CLOCK_TICK_RATE constant, simplifies the jiffies code, and
still provides a way to have an accurate jiffies clock.

NOTE: Since this patch does not add register_refinied_jiffies()
calls for every arch, it may cause time quality regressions
in some cases. Its likely these will not be noticable, but
if they are an issue, adding the following to the end of
setup_arch() should resolve the regression:
	register_refinied_jiffies(CLOCK_TICK_RATE)

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Now that alarmtimer_remove has been simplified, change
its name to _dequeue to better match its paired _enqueue
function.

Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Arve Hjønnevåg reported numerous crashes from the
"BUG_ON(timer->state != HRTIMER_STATE_CALLBACK)" check
in __run_hrtimer after it called alarmtimer_fired.

It ends up the alarmtimer code was not properly handling
possible failures of hrtimer_try_to_cancel, and because
these faulres occur when the underlying base hrtimer is
being run, this limits the ability to properly handle
modifications to any alarmtimers on that base.

Because much of the logic duplicates the hrtimer logic,
it seems that we might as well have a per-alarmtimer
hrtimer, and avoid the extra complextity of trying to
multiplex many alarmtimers off of one hrtimer.

Thus this patch moves the hrtimer to the alarm structure
and simplifies the management logic.

Changelog:
v2:
* Includes a fix for double alarm_start calls found by
  Arve

Cc: Arve Hjønnevåg <arve@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: NArve Hjønnevåg <arve@android.com>
Tested-by: NArve Hjønnevåg <arve@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

alarmtimer suspend return -EBUSY if the next alarm will fire in less
than 2 seconds.  This allows one RTC seconds tick to occur subsequent
to this check before the alarm wakeup time is set, ensuring the wakeup
time is still in the future (assuming the RTC does not tick one more
second prior to setting the alarm).

If suspend is rejected due to an imminent alarm, hold a wakeup source
for 2 seconds to process the alarm prior to reattempting suspend.

If setting the alarm incurs an -ETIME for an alarm set in the past,
or any other problem setting the alarm, abort suspend and hold a
wakelock for 1 second while the alarm is allowed to be serviced or
other hopefully transient conditions preventing the alarm clear up.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Daniel Lezcano reported seeing multi-second stalls from
keyboard input on his T61 laptop when NOHZ and CPU_IDLE
were enabled on a 32bit kernel.

He bisected the problem down to commit
1e75fa8b ("time: Condense timekeeper.xtime into xtime_sec").

After reproducing this issue, I narrowed the problem down
to the fact that timekeeping_get_ns() returns a 64bit
nsec value that hasn't been accumulated. In some cases
this value was being then stored in timespec.tv_nsec
(which is a long).

On 32bit systems, with idle times larger then 4 seconds
(or less, depending on the value of xtime_nsec), the
returned nsec value would overflow 32bits. This limited
kept time from increasing, causing timers to not expire.

The fix is to make sure we don't directly store the
result of timekeeping_get_ns() into a tv_nsec field,
instead using a 64bit nsec value which can then be
added into the timespec via timespec_add_ns().
Reported-and-bisected-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NPrarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1347405963-35715-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

To simplify both normal and CPU hotplug paths, worker management is
prevented while CPU hoplug is in progress.  This is achieved by CPU
hotplug holding the same exclusion mechanism used by workers to ensure
there's only one manager per pool.

If someone else seems to be performing the manager role, workers
proceed to execute work items.  CPU hotplug using the same mechanism
can lead to idle worker depletion because all workers could proceed to
execute work items while CPU hotplug is in progress and CPU hotplug
itself wouldn't actually perform the worker management duty - it
doesn't guarantee that there's an idle worker left when it releases
management.

This idle worker depletion, under extreme circumstances, can break
forward-progress guarantee and thus lead to deadlock.

This patch fixes the bug by using separate mechanisms for manager
exclusion among workers and hotplug exclusion.  For manager exclusion,
POOL_MANAGING_WORKERS which was restored by the previous patch is
used.  pool->manager_mutex is now only used for exclusion between the
elected manager and CPU hotplug.  The elected manager won't proceed
without holding pool->manager_mutex.

This ensures that the worker which won the manager position can't skip
managing while CPU hotplug is in progress.  It will block on
manager_mutex and perform management after CPU hotplug is complete.

Note that hotplug may happen while waiting for manager_mutex.  A
manager isn't either on idle or busy list and thus the hoplug code
can't unbind/rebind it.  Make the manager handle its own un/rebinding.

tj: Updated comment and description.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

This patch restores POOL_MANAGING_WORKERS which was replaced by
pool->manager_mutex by 60373152 "workqueue: use mutex for global_cwq
manager exclusion".

There's a subtle idle worker depletion bug across CPU hotplug events
and we need to distinguish an actual manager and CPU hotplug
preventing management.  POOL_MANAGING_WORKERS will be used for the
former and manager_mutex the later.

This patch just lays POOL_MANAGING_WORKERS on top of the existing
manager_mutex and doesn't introduce any synchronization changes.  The
next patch will update it.

Note that this patch fixes a non-critical anomaly where
too_many_workers() may return %true spuriously while CPU hotplug is in
progress.  While the issue could schedule idle timer spuriously, it
didn't trigger any actual misbehavior.

tj: Rewrote patch description.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

Currently, rebind_workers() and idle_worker_rebind() are two-way
interlocked.  rebind_workers() waits for idle workers to finish
rebinding and rebound idle workers wait for rebind_workers() to finish
rebinding busy workers before proceeding.

Unfortunately, this isn't enough.  The second wait from idle workers
is implemented as follows.

	wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));

rebind_workers() clears WORKER_REBIND, wakes up the idle workers and
then returns.  If CPU hotplug cycle happens again before one of the
idle workers finishes the above wait_event(), rebind_workers() will
repeat the first part of the handshake - set WORKER_REBIND again and
wait for the idle worker to finish rebinding - and this leads to
deadlock because the idle worker would be waiting for WORKER_REBIND to
clear.

This is fixed by adding another interlocking step at the end -
rebind_workers() now waits for all the idle workers to finish the
above WORKER_REBIND wait before returning.  This ensures that all
rebinding steps are complete on all idle workers before the next
hotplug cycle can happen.

This problem was diagnosed by Lai Jiangshan who also posted a patch to
fix the issue, upon which this patch is based.

This is the minimal fix and further patches are scheduled for the next
merge window to simplify the CPU hotplug path.
Signed-off-by: NTejun Heo <tj@kernel.org>
Original-patch-by: NLai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1346516916-1991-3-git-send-email-laijs@cn.fujitsu.com>

This doesn't make any functional difference and is purely to help the
next patch to be simpler.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>

The compiler may compile the following code into TWO write/modify
instructions.

	worker->flags &= ~WORKER_UNBOUND;
	worker->flags |= WORKER_REBIND;

so the other CPU may temporarily see worker->flags which doesn't have
either WORKER_UNBOUND or WORKER_REBIND set and perform local wakeup
prematurely.

Fix it by using single explicit assignment via ACCESS_ONCE().

Because idle workers have another WORKER_NOT_RUNNING flag, this bug
doesn't exist for them; however, update it to use the same pattern for
consistency.

tj: Applied the change to idle workers too and updated comments and
    patch description a bit.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

Andreas Bombe reported that the added ktime_t overflow checking added to
timespec_valid in commit 4e8b1452 ("time: Improve sanity checking of
timekeeping inputs") was causing problems with X.org because it caused
timeouts larger then KTIME_T to be invalid.

Previously, these large timeouts would be clamped to KTIME_MAX and would
never expire, which is valid.

This patch splits the ktime_t overflow checking into a new
timespec_valid_strict function, and converts the timekeeping codes
internal checking to use this more strict function.
Reported-and-tested-by: NAndreas Bombe <aeb@debian.org>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It seems commit 4a9d4b02 (switch fput to task_work_add) reintroduced
the problem addressed in commit 944be0b2 (close_files(): add scheduling
point)

If a server process with a lot of files (say 2 million tcp sockets)
is killed, we can spend a lot of time in task_work_run() and trigger
a soft lockup.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

If update_wall_time() is called and the current offset isn't large
enough to accumulate, avoid re-calling timekeeping_adjust which may
change the clock freq and can cause 1ns inconsistencies with
CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Andreas Schwab noticed that the 1 << tk->shift could overflow if the
shift value was greater than 30, since 1 would be a 32bit long on
32bit architectures. This issue was introduced by 1e75fa8b (time:
Condense timekeeper.xtime into xtime_sec)

Use 1ULL instead to ensure we don't overflow on the shift.
Reported-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-4-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

arch_gettimeoffset returns a u32 value which when shifted by tk->shift
can overflow. This issue was introduced with 1e75fa8b (time: Condense
timekeeper.xtime into xtime_sec)

Cast it to u64 first.
Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-3-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Andreas noticed problems with resume on specific hardware after commit
1e75fa8b (time: Condense timekeeper.xtime into xtime_sec) combined
with commit b44d50dc (time: Fix casting issue in tk_set_xtime and
tk_xtime_add)

After some digging I realized we aren't normalizing the timekeeper
after the add. Add the missing normalize call.
Reported-by: NAndreas Schwab <schwab@linux-m68k.org>
Tested-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1345595449-34965-2-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

It seems commit 4a9d4b02 ("switch fput to task_work_add") re-
introduced the problem addressed in 944be0b2 ("close_files(): add
scheduling point")

If a server process with a lot of files (say 2 million tcp sockets) is
killed, we can spend a lot of time in task_work_run() and trigger a soft
lockup.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch fixes:

  https://bugzilla.redhat.com/show_bug.cgi?id=843640

If mmap_region()->uprobe_mmap() fails, unmap_and_free_vma path
does unmap_region() but does not remove the soon-to-be-freed vma
from rb tree. Actually there are more problems but this is how
William noticed this bug.

Perhaps we could do do_munmap() + return in this case, but in
fact it is simply wrong to abort if uprobe_mmap() fails. Until
at least we move the !UPROBE_COPY_INSN code from
install_breakpoint() to uprobe_register().

For example, uprobe_mmap()->install_breakpoint() can fail if the
probed insn is not supported (remember, uprobe_register()
succeeds if nobody mmaps inode/offset), mmap() should not fail
in this case.

dup_mmap()->uprobe_mmap() is wrong too by the same reason,
fork() can race with uprobe_register() and fail for no reason if
it wins the race and does install_breakpoint() first.

And, if nothing else, both mmap_region() and dup_mmap() return
success if uprobe_mmap() fails. Change them to ignore the error
code from uprobe_mmap().
Reported-and-tested-by: NWilliam Cohen <wcohen@redhat.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # v3.5
Cc: Anton Arapov <anton@redhat.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120819171042.GB26957@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

New helper: current_thread_info().  Allows to do a bunch of odd syscalls
in C. While we are at it, there had never been a reason to do
osf_getpriority() in assembler.  We also get "namespace"-aware (read:
consistent with getuid(2), etc.) behaviour from getx?id() syscalls now.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NMichael Cree <mcree@orcon.net.nz>
Acked-by: NMatt Turner <mattst88@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

syscall_get_nr can return -1 in the case that the task is not executing
a system call.

This patch fixes perf_syscall_{enter,exit} to check that the syscall
number is valid before using it as an index into a bitmap.

Link: http://lkml.kernel.org/r/1345137254-7377-1-git-send-email-will.deacon@arm.com

Cc: Jason Baron <jbaron@redhat.com>
Cc: Wade Farnsworth <wade_farnsworth@mentor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Unexpected behavior could occur if the time is set to a value large
enough to overflow a 64bit ktime_t (which is something larger then the
year 2262).

Also unexpected behavior could occur if large negative offsets are
injected via adjtimex.

So this patch improves the sanity check timekeeping inputs by
improving the timespec_valid() check, and then makes better use of
timespec_valid() to make sure we don't set the time to an invalid
negative value or one that overflows ktime_t.

Note: This does not protect from setting the time close to overflowing
ktime_t and then letting natural accumulation cause the overflow.
Reported-by: NCAI Qian <caiqian@redhat.com>
Reported-by: NSasha Levin <levinsasha928@gmail.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Drop the initial reference by fsnotify_init_mark early instead of
audit_tree_freeing_mark() at destroy time.

In the cases we destroy the mark before we drop the initial reference we need to
get rid of the get_mark that balances the put_mark in audit_tree_freeing_mark().
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Refcounting of fsnotify_mark in audit tree is broken.  E.g:

                              refcount
create_chunk
  alloc_chunk                 1
  fsnotify_add_mark           2

untag_chunk
  fsnotify_get_mark           3
  fsnotify_destroy_mark
    audit_tree_freeing_mark   2
  fsnotify_put_mark           1
  fsnotify_put_mark           0
  via destroy_list
    fsnotify_mark_destroy    -1

This was reported by various people as triggering Oops when stopping auditd.

We could just remove the put_mark from audit_tree_freeing_mark() but that would
break freeing via inode destruction.  So this patch simply omits a put_mark
after calling destroy_mark or adds a get_mark before.

The additional get_mark is necessary where there's no other put_mark after
fsnotify_destroy_mark() since it assumes that the caller is holding a reference
(or the inode is keeping the mark pinned, not the case here AFAICS).
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Reported-by: NValentin Avram <aval13@gmail.com>
Reported-by: NPeter Moody <pmoody@google.com>
Acked-by: NEric Paris <eparis@redhat.com>
CC: stable@vger.kernel.org

Don't do free_chunk() after fsnotify_add_mark().  That one does a delayed unref
via the destroy list and this results in use-after-free.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Acked-by: NEric Paris <eparis@redhat.com>
CC: stable@vger.kernel.org

Make stop scheduler class do the same accounting as other classes,

Migration threads can be caught in the act while doing exec balancing,
leading to the below due to use of unmaintained ->se.exec_start.  The
load that triggered this particular instance was an apparently out of
control heavily threaded application that does system monitoring in
what equated to an exec bomb, with one of the VERY frequently migrated
tasks being ps.

%CPU   PID USER     CMD
99.3    45 root     [migration/10]
97.7    53 root     [migration/12]
97.0    57 root     [migration/13]
90.1    49 root     [migration/11]
89.6    65 root     [migration/15]
88.7    17 root     [migration/3]
80.4    37 root     [migration/8]
78.1    41 root     [migration/9]
44.2    13 root     [migration/2]
Signed-off-by: NMike Galbraith <mgalbraith@suse.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Root task group bandwidth replenishment must service all CPUs, regardless of
where the timer was last started, and regardless of the isolation mechanism,
lest 'Quoth the Raven, "Nevermore"' become rt scheduling policy.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344326558.6968.25.camel@marge.simpson.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

With multiple instances of task_groups, for_each_rt_rq() is a noop,
no task groups having been added to the rt.c list instance.  This
renders __enable/disable_runtime() and print_rt_stats() noop, the
user (non) visible effect being that rt task groups are missing in
/proc/sched_debug.
Signed-off-by: NMike Galbraith <efault@gmx.de>
Cc: stable@kernel.org # v3.3+
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344308413.6846.7.camel@marge.simpson.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

On architectures where cputime_t is 64 bit type, is possible to trigger
divide by zero on do_div(temp, (__force u32) total) line, if total is a
non zero number but has lower 32 bit's zeroed. Removing casting is not
a good solution since some do_div() implementations do cast to u32
internally.

This problem can be triggered in practice on very long lived processes:

  PID: 2331   TASK: ffff880472814b00  CPU: 2   COMMAND: "oraagent.bin"
   #0 [ffff880472a51b70] machine_kexec at ffffffff8103214b
   #1 [ffff880472a51bd0] crash_kexec at ffffffff810b91c2
   #2 [ffff880472a51ca0] oops_end at ffffffff814f0b00
   #3 [ffff880472a51cd0] die at ffffffff8100f26b
   #4 [ffff880472a51d00] do_trap at ffffffff814f03f4
   #5 [ffff880472a51d60] do_divide_error at ffffffff8100cfff
   #6 [ffff880472a51e00] divide_error at ffffffff8100be7b
      [exception RIP: thread_group_times+0x56]
      RIP: ffffffff81056a16  RSP: ffff880472a51eb8  RFLAGS: 00010046
      RAX: bc3572c9fe12d194  RBX: ffff880874150800  RCX: 0000000110266fad
      RDX: 0000000000000000  RSI: ffff880472a51eb8  RDI: 001038ae7d9633dc
      RBP: ffff880472a51ef8   R8: 00000000b10a3a64   R9: ffff880874150800
      R10: 00007fcba27ab680  R11: 0000000000000202  R12: ffff880472a51f08
      R13: ffff880472a51f10  R14: 0000000000000000  R15: 0000000000000007
      ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
   #7 [ffff880472a51f00] do_sys_times at ffffffff8108845d
   #8 [ffff880472a51f40] sys_times at ffffffff81088524
   #9 [ffff880472a51f80] system_call_fastpath at ffffffff8100b0f2
      RIP: 0000003808caac3a  RSP: 00007fcba27ab6d8  RFLAGS: 00000202
      RAX: 0000000000000064  RBX: ffffffff8100b0f2  RCX: 0000000000000000
      RDX: 00007fcba27ab6e0  RSI: 000000000076d58e  RDI: 00007fcba27ab6e0
      RBP: 00007fcba27ab700   R8: 0000000000000020   R9: 000000000000091b
      R10: 00007fcba27ab680  R11: 0000000000000202  R12: 00007fff9ca41940
      R13: 0000000000000000  R14: 00007fcba27ac9c0  R15: 00007fff9ca41940
      ORIG_RAX: 0000000000000064  CS: 0033  SS: 002b

Cc: stable@vger.kernel.org
Signed-off-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120808092714.GA3580@redhat.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Peter Portante reported that for large cgroup hierarchies (and or on
large CPU counts) we get immense lock contention on rq->lock and stuff
stops working properly.

His workload was a ton of processes, each in their own cgroup,
everybody idling except for a sporadic wakeup once every so often.

It was found that:

  schedule()
    idle_balance()
      load_balance()
        local_irq_save()
        double_rq_lock()
        update_h_load()
          walk_tg_tree(tg_load_down)
            tg_load_down()

Results in an entire cgroup hierarchy walk under rq->lock for every
new-idle balance and since new-idle balance isn't throttled this
results in a lot of work while holding the rq->lock.

This patch does two things, it removes the work from under rq->lock
based on the good principle of race and pray which is widely employed
in the load-balancer as a whole. And secondly it throttles the
update_h_load() calculation to max once per jiffy.

I considered excluding update_h_load() for new-idle balance
all-together, but purely relying on regular balance passes to update
this data might not work out under some rare circumstances where the
new-idle busiest isn't the regular busiest for a while (unlikely, but
a nightmare to debug if someone hits it and suffers).

Cc: pjt@google.com
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Reported-by: NPeter Portante <pportant@redhat.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-aaarrzfpnaam7pqrekofu8a6@git.kernel.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

While tracking down a weird buffer overflow issue in a program that
looked to be sane, I started double checking the length returned by
syslog(SYSLOG_ACTION_READ_ALL, ...) to make sure it wasn't overflowing
the buffer.

Sure enough, it was.  I saw this in strace:

  11339 syslog(SYSLOG_ACTION_READ_ALL, "<5>[244017.708129] REISERFS (dev"..., 8192) = 8279

It turns out that the loops that calculate how much space the entries
will take when they're copied don't include the newlines and prefixes
that will be included in the final output since prev flags is passed as
zero.

This patch properly accounts for it and fixes the overflow.

CC: stable@kernel.org
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Revert commit 45226e94 (NMI watchdog: fix for lockup detector breakage
on resume) which breaks resume from system suspend on my SH7372
Mackerel board (by causing a NULL pointer dereference to happen) and
is generally wrong, because it abuses the CPU hotplug functionality
in a shamelessly blatant way.

The original issue should be addressed through appropriate syscore
resume callback instead.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Tetsuo Handa reported that sporadically the system clock starts
counting up too quickly which is enough to confuse the hangcheck
timer to print a bogus stall warning.

Commit 2a8c0883 "time: Move xtime_nsec adjustment underflow handling
timekeeping_adjust" overlooked this exit path:

        } else
                return;

which should really be a proper exit sequence, fixing the bug as a
side effect.

Also make the flow more readable by properly balancing curly
braces.

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Cc: john.stultz@linaro.org
Cc: a.p.zijlstra@chello.nl
Cc: richardcochran@gmail.com
Cc: prarit@redhat.com
Link: http://lkml.kernel.org/r/20120804192114.GA28347@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This is needed to allow network softirq packet processing to make use of
PF_MEMALLOC.

Currently softirq context cannot use PF_MEMALLOC due to it not being
associated with a task, and therefore not having task flags to fiddle with
- thus the gfp to alloc flag mapping ignores the task flags when in
interrupts (hard or soft) context.

Allowing softirqs to make use of PF_MEMALLOC therefore requires some
trickery.  This patch borrows the task flags from whatever process happens
to be preempted by the softirq.  It then modifies the gfp to alloc flags
mapping to not exclude task flags in softirq context, and modify the
softirq code to save, clear and restore the PF_MEMALLOC flag.

The save and clear, ensures the preempted task's PF_MEMALLOC flag doesn't
leak into the softirq.  The restore ensures a softirq's PF_MEMALLOC flag
cannot leak back into the preempted process.  This should be safe due to
the following reasons

Softirqs can run on multiple CPUs sure but the same task should not be
	executing the same softirq code. Neither should the softirq
	handler be preempted by any other softirq handler so the flags
	should not leak to an unrelated softirq.

Softirqs re-enable hardware interrupts in __do_softirq() so can be
	preempted by hardware interrupts so PF_MEMALLOC is inherited
	by the hard IRQ. However, this is similar to a process in
	reclaim being preempted by a hardirq. While PF_MEMALLOC is
	set, gfp_to_alloc_flags() distinguishes between hard and
	soft irqs and avoids giving a hardirq the ALLOC_NO_WATERMARKS
	flag.

If the softirq is deferred to ksoftirq then its flags may be used
        instead of a normal tasks but as the softirq cannot be preempted,
        the PF_MEMALLOC flag does not leak to other code by accident.

[davem@davemloft.net: Document why PF_MEMALLOC is safe]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NMel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When hotadd_new_pgdat() is called to create new pgdat for a new node, a
fallback zonelist should be created for the new node.  There's code to try
to achieve that in hotadd_new_pgdat() as below:

	/*
	 * The node we allocated has no zone fallback lists. For avoiding
	 * to access not-initialized zonelist, build here.
	 */
	mutex_lock(&zonelists_mutex);
	build_all_zonelists(pgdat, NULL);
	mutex_unlock(&zonelists_mutex);

But it doesn't work as expected.  When hotadd_new_pgdat() is called, the
new node is still in offline state because node_set_online(nid) hasn't
been called yet.  And build_all_zonelists() only builds zonelists for
online nodes as:

        for_each_online_node(nid) {
                pg_data_t *pgdat = NODE_DATA(nid);

                build_zonelists(pgdat);
                build_zonelist_cache(pgdat);
        }

Though we hope to create zonelist for the new pgdat, but it doesn't.  So
add a new parameter "pgdat" the build_all_zonelists() to build pgdat for
the new pgdat too.
Signed-off-by: NJiang Liu <liuj97@gmail.com>
Signed-off-by: NXishi Qiu <qiuxishi@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sanity:

CONFIG_CGROUP_MEM_RES_CTLR -> CONFIG_MEMCG
CONFIG_CGROUP_MEM_RES_CTLR_SWAP -> CONFIG_MEMCG_SWAP
CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED -> CONFIG_MEMCG_SWAP_ENABLED
CONFIG_CGROUP_MEM_RES_CTLR_KMEM -> CONFIG_MEMCG_KMEM

[mhocko@suse.cz: fix missed bits]
Cc: Glauber Costa <glommer@parallels.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since per-BDI flusher threads were introduced in 2.6, the pdflush
mechanism is not used any more.  But the old interface exported through
/proc/sys/vm/nr_pdflush_threads still exists and is obviously useless.

For back-compatibility, printk warning information and return 2 to notify
the users that the interface is removed.
Signed-off-by: NWanpeng Li <liwp@linux.vnet.ibm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

vm_stat_account() accounts the shared_vm, stack_vm and reserved_vm now.
But we can also account for total_vm in the vm_stat_account() which makes
the code tidy.

Even for mprotect_fixup(), we can get the right result in the end.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>