We call hrtimer_enqueue_reprogram() only when we are in high resolution
mode now so we don't need to check that again in hrtimer_enqueue_reprogram().
Once the check is removed, hrtimer_enqueue_reprogram() turns to be an
useless wrapper over hrtimer_reprogram() and can be dropped.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In lowres mode, hrtimers are serviced by the tick instead of a clock
event. It works well as long as the tick stays periodic but we must also
make sure that the hrtimers are serviced in dynticks mode targets,
pretty much like timer list timers do.
Note that all dynticks modes are concerned: get_nohz_timer_target()
tries not to return remote idle CPUs but there is nothing to prevent
the elected target from entering dynticks idle mode until we lock its
base. It's also prefectly legal to enqueue hrtimers on full dynticks CPU.
So there are two requirements to correctly handle dynticks:
1) On target's tick stop time, we must not delay the next tick further
the next hrtimer.
2) On hrtimer queue time. If the tick of the target is stopped, we must
wake up that CPU such that it sees the new hrtimer and recalculate
the next tick accordingly.
The point 1 is well handled currently through get_nohz_timer_interrupt() and
cmp_next_hrtimer_event().
But the point 2 isn't handled at all.
Fixing this is easy though as we have the necessary API ready for that.
All we need is to call wake_up_nohz_cpu() on a target when a newly
enqueued hrtimer requires tick rescheduling, like timer list timer do.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/3d7ea08ce008698e26bd39fe10f55949391073ab.1403507178.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In lowres mode, hrtimers are serviced by the tick instead of a clock
event. Now it works well as long as the tick stays periodic but we
must also make sure that the hrtimers are serviced in dynticks mode.
Part of that job consist in kicking a dynticks hrtimer target in order
to make it reconsider the next tick to schedule to correctly handle the
hrtimer's expiring time. And that part isn't handled by the hrtimers
subsystem.
To prepare for fixing this, we need __hrtimer_start_range_ns() to be
able to resolve the CPU target associated to a hrtimer's object
'cpu_base' so that the kick can be centralized there.
So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU
without overhead. It is set once at CPU's online notification.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When a timer is enqueued or modified on a dynticks target, that CPU
must re-evaluate the next tick to service that timer.
The tick re-evaluation is performed by an IPI kick on the target.
Now while we correctly call wake_up_nohz_cpu() from add_timer_on(), the
mod_timer*() API family doesn't support so well dynticks targets.
The reason for this is likely that __mod_timer() isn't supposed to
select an idle target for a timer, unless that target is the current
CPU, in which case a dynticks idle kick isn't actually needed.
But there is a small race window lurking behind that assumption: the
elected target has all the time to turn dynticks idle between the call
to get_nohz_timer_target() and the locking of its base. Hence a risk
that we enqueue a timer on a dynticks idle destination without kicking
it. As a result, the timer might be serviced too late in the future.
Also a target elected by __mod_timer() can be in full dynticks mode
and thus require to be kicked as well. And unlike idle dynticks, this
concern both local and remote targets.
To fix this whole issue, lets centralize the dynticks kick to
internal_add_timer() so that it is well handled for all sort of timer
enqueue. Even timer migration is concerned so that a full dynticks target
is correctly kicked as needed when timers are migrating to it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Timers are serviced by the tick. But when a timer is enqueued on a
dynticks target, we need to kick it in order to make it reconsider the
next tick to schedule to correctly handle the timer's expiring time.
Now while this kick is correctly performed for add_timer_on(), the
mod_timer*() family has been a bit neglected.
To prepare for fixing this, we need internal_add_timer() to be able to
resolve the CPU target associated to a timer's object 'base' so that the
kick can be centralized there.
This can't be passed as an argument as not all the callers know the CPU
number of a timer's base. So lets store it in the struct tvec_base to
resolve the CPU without much overhead. It is set once for good at every
CPU's first boot.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Export irq_domain_disassociate() to architecture interrupt drivers,
so it could be used to handle legacy IRQ descriptors on x86.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1402302011-23642-37-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
futex_lock_pi_atomic() is a maze of retry hoops and loops.
Reduce it to simple and understandable states:
First step is to lookup existing waiters (state) in the kernel.
If there is an existing waiter, validate it and attach to it.
If there is no existing waiter, check the user space value
If the TID encoded in the user space value is 0, take over the futex
preserving the owner died bit.
If the TID encoded in the user space value is != 0, lookup the owner
task, validate it and attach to it.
Reduces text size by 128 bytes on x8664.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Cc: Darren Hart <darren@dvhart.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1406131137020.5170@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We want to be a bit more clever in futex_lock_pi_atomic() and separate
the possible states. Split out the code which attaches the first
waiter to the owner into a separate function. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.271300614@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We want to be a bit more clever in futex_lock_pi_atomic() and separate
the possible states. Split out the waiter verification into a separate
function. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.180458410@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
No point in open coding the same function again.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.092947239@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The kernel tries to atomically unlock the futex without checking
whether there is kernel state associated to the futex.
So if user space manipulated the user space value, this will leave
kernel internal state around associated to the owner task.
For robustness sake, lookup first whether there are waiters on the
futex. If there are waiters, wake the top priority waiter with all the
proper sanity checks applied.
If there are no waiters, do the atomic release. We do not have to
preserve the waiters bit in this case, because a potentially incoming
waiter is blocked on the hb->lock and will acquire the futex
atomically. We neither have to preserve the owner died bit. The caller
is the owner and it was supposed to cleanup the mess.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <darren@dvhart.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.016987332@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In case the dead lock detector is enabled we follow the lock chain to
the end in rt_mutex_adjust_prio_chain, even if we could stop earlier
due to the priority/waiter constellation.
But once we are no longer the top priority waiter in a certain step
or the task holding the lock has already the same priority then there
is no point in dequeing and enqueing along the lock chain as there is
no change at all.
So stop the queueing at this point.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/20140522031950.280830190@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The conditions under which deadlock detection is conducted are unclear
and undocumented.
Add constants instead of using 0/1 and provide a selection function
which hides the additional debug dependency from the calling code.
Add comments where needed.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/20140522031949.947264874@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The deadlock logic is only required for futexes.
Remove the extra arguments for the public functions and also for the
futex specific ones which get always called with deadlock detection
enabled.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Exit right away, when the removed waiter was not the top priority
waiter on the lock. Get rid of the extra indent level.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Add commentry to document the chain walk and the protection mechanisms
and their scope.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Add a separate local variable for the boost/deboost logic to make the
code more readable. Add comments where appropriate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
There is no point to keep the task ref across the check for lock
owner. Drop the ref before that, so the protection context is clear.
Found while documenting the chain walk.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
The current implementation of try_to_take_rtmutex() is correct, but
requires more than a single brain twist to understand the clever
encoded conditionals.
Untangle it and document the cases proper.
Looks less efficient at the first glance, but actually reduces the
binary code size on x8664 by 80 bytes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Oleg noticed that rtmutex_slowtrylock() has a pointless check for
rt_mutex_owner(lock) != current.
To avoid calling try_to_take_rtmutex() we really want to check whether
the lock has an owner at all or whether the trylock failed because the
owner is NULL, but the RT_MUTEX_HAS_WAITERS bit is set. This covers
the lock is owned by caller situation as well.
We can actually do this check lockless. trylock is taking a chance
whether we take lock->wait_lock to do the check or not.
Add comments to the function while at it.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Pull perf fixes from Ingo Molnar:
"This is larger than usual: the main reason are the ARM symbol lookup
speedups that came in late and were hard to resist.
There's also a kprobes fix and various tooling fixes, plus the minimal
re-enablement of the mmap2 support interface"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
x86/kprobes: Fix build errors and blacklist context_track_user
perf tests: Add test for closing dso objects on EMFILE error
perf tests: Add test for caching dso file descriptors
perf tests: Allow reuse of test_file function
perf tests: Spawn child for each test
perf tools: Add dso__data_* interface descriptons
perf tools: Allow to close dso fd in case of open failure
perf tools: Add file size check and factor dso__data_read_offset
perf tools: Cache dso data file descriptor
perf tools: Add global count of opened dso objects
perf tools: Add global list of opened dso objects
perf tools: Add data_fd into dso object
perf tools: Separate dso data related variables
perf tools: Cache register accesses for unwind processing
perf record: Fix to honor user freq/interval properly
perf timechart: Reflow documentation
perf probe: Improve error messages in --line option
perf probe: Improve an error message of perf probe --vars mode
perf probe: Show error code and description in verbose mode
perf probe: Improve error message for unknown member of data structure
...
Pull rtmutex fixes from Thomas Gleixner:
"Another three patches to make the rtmutex code more robust. That's
the last urgent fallout from the big futex/rtmutex investigation"
* 'locking-urgent-for-linus.patch' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rtmutex: Plug slow unlock race
rtmutex: Detect changes in the pi lock chain
rtmutex: Handle deadlock detection smarter
syscall_regfunc() ignores the kernel threads because "it has no effect",
see cc3b13c1 "Don't trace kernel thread syscalls" which added this check.
However, this means that a user-space task spawned by call_usermodehelper()
will run without TIF_SYSCALL_TRACEPOINT if sys_tracepoint_refcount != 0.
Remove this check. The unnecessary report from ret_from_fork path mentioned
by cc3b13c1 is no longer possible, see See commit fb45550d76 "make sure
that kernel_thread() callbacks call do_exit() themselves".
A kernel_thread() callback can only return and take the int_ret_from_sys_call
path after do_execve() succeeds, otherwise the kernel will crash. But in this
case it is no longer a kernel thread and thus is needs TIF_SYSCALL_TRACEPOINT.
Link: http://lkml.kernel.org/p/20140413185938.GD20668@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1. Remove _irqsafe from syscall_regfunc/syscall_unregfunc,
read_lock(tasklist) doesn't need to disable irqs.
2. Change this code to avoid the deprecated do_each_thread()
and use for_each_process_thread() (stolen from the patch
from Frederic).
3. Change syscall_regfunc() to check PF_KTHREAD to skip
the kernel threads, ->mm != NULL is the common mistake.
Note: probably this check should be simply removed, needs
another patch.
[fweisbec@gmail.com: s/do_each_thread/for_each_process_thread/]
Link: http://lkml.kernel.org/p/20140413185918.GC20668@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
syscall_regfunc() and syscall_unregfunc() should set/clear
TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race
with copy_process() and miss the new child which was not added to
the process/thread lists yet.
Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT
under tasklist.
Link: http://lkml.kernel.org/p/20140413185854.GB20668@redhat.com
Cc: stable@vger.kernel.org # 2.6.33
Fixes: a871bd33a6 "tracing: Add syscall tracepoints"
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
- Fix for an ia64 regression introduced during the 3.11 cycle by a
commit that modified the hardware initialization ordering and made
device discovery fail on some systems.
- Fix for a build problem on systems where the cpufreq-cpu0 driver
is built-in and the cpu-thermal driver is modular from Arnd Bergmann.
- Fix for a recently introduced computational mistake in the
intel_pstate driver that leads to excessive rounding errors from
Doug Smythies.
- Fix for a failure code path in cpufreq_update_policy() that fails
to unlock the locks acquired previously from Aaron Plattner.
- Fix for the cpuidle mvebu driver to use shorter state names which
will prevent the sysfs interface from returning mangled strings.
From Gregory Clement.
- ACPI LPSS driver fix to make sure that the I2C controllers
included in BayTrail SoCs are not held in the reset state while
they are being probed from Mika Westerberg.
- New kernel command line arguments making it possible to build
kernel images with hibernation and kASLR included at the same
time and to select which of them will be used via the command
line (they are still functionally mutually exclusive, though).
From Kees Cook.
- ACPI battery driver quirk for Acer Aspire V5-573G that fails
to send battery status change notifications timely from
Alexander Mezin.
- Two ACPI core cleanups from Christoph Jaeger and Fabian Frederick.
/
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Merge tag 'pm+acpi-3.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI and power management fixes from Rafael Wysocki:
"These are fixes mostly (ia64 regression related to the ACPI
enumeration of devices, cpufreq regressions, fix for I2C controllers
included in Intel SoCs, mvebu cpuidle driver fix related to sysfs)
plus additional kernel command line arguments from Kees to make it
possible to build kernel images with hibernation and the kernel
address space randomization included simultaneously, a new ACPI
battery driver quirk for a system with a broken BIOS and a couple of
ACPI core cleanups.
Specifics:
- Fix for an ia64 regression introduced during the 3.11 cycle by a
commit that modified the hardware initialization ordering and made
device discovery fail on some systems.
- Fix for a build problem on systems where the cpufreq-cpu0 driver is
built-in and the cpu-thermal driver is modular from Arnd Bergmann.
- Fix for a recently introduced computational mistake in the
intel_pstate driver that leads to excessive rounding errors from
Doug Smythies.
- Fix for a failure code path in cpufreq_update_policy() that fails
to unlock the locks acquired previously from Aaron Plattner.
- Fix for the cpuidle mvebu driver to use shorter state names which
will prevent the sysfs interface from returning mangled strings.
From Gregory Clement.
- ACPI LPSS driver fix to make sure that the I2C controllers included
in BayTrail SoCs are not held in the reset state while they are
being probed from Mika Westerberg.
- New kernel command line arguments making it possible to build
kernel images with hibernation and kASLR included at the same time
and to select which of them will be used via the command line (they
are still functionally mutually exclusive, though). From Kees
Cook.
- ACPI battery driver quirk for Acer Aspire V5-573G that fails to
send battery status change notifications timely from Alexander
Mezin.
- Two ACPI core cleanups from Christoph Jaeger and Fabian Frederick"
* tag 'pm+acpi-3.16-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpuidle: mvebu: Fix the name of the states
cpufreq: unlock when failing cpufreq_update_policy()
intel_pstate: Correct rounding in busy calculation
ACPI: use kstrto*() instead of simple_strto*()
ACPI / processor replace __attribute__((packed)) by __packed
ACPI / battery: add quirk for Acer Aspire V5-573G
ACPI / battery: use callback for setting up quirks
ACPI / LPSS: Take I2C host controllers out of reset
x86, kaslr: boot-time selectable with hibernation
PM / hibernate: introduce "nohibernate" boot parameter
cpufreq: cpufreq-cpu0: fix CPU_THERMAL dependency
ACPI / ia64 / sba_iommu: Restore the working initialization ordering
Export symbol of alarmtimer_get_rtcdev so that it is used by
any driver when built as module like,
drivers/staging/android/alarm-dev.c.
CC: John Stultz <john.stultz@linaro.org>
CC: Marcus Gelderie <redmnic@gmail.com>
Signed-off-by: Pramod Gurav <pramod.gurav.etc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After the recent changes, when POOL_DISASSOCIATED is cleared, the
running worker's local CPU should be the same as pool->cpu without any
exception even during cpu-hotplug. Update the sanity check in
process_one_work() accordingly.
This patch changes "(proposition_A && proposition_B && proposition_C)"
to "(proposition_B && proposition_C)", so if the old compound
proposition is true, the new one must be true too. so this will not
hide any possible bug which can be caught by the old test.
tj: Minor updates to the description.
CC: Jason J. Herne <jjherne@linux.vnet.ibm.com>
CC: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit a9ab775bca ("workqueue: directly restore CPU affinity of
workers from CPU_ONLINE") moved the pool->lock into rebind_workers()
without also moving "pool->flags &= ~POOL_DISASSOCIATED".
There is nothing wrong with "pool->flags &= ~POOL_DISASSOCIATED" not
being moved together, but there isn't any benefit either. We move it
into rebind_workers() and achieve these benefits:
1) Better readability. POOL_DISASSOCIATED is cleared in
rebind_workers() as expected.
2) When POOL_DISASSOCIATED is cleared, we can ensure that all the
running workers of the pool are on the local CPU (pool->cpu).
tj: Cosmetic updates to the code and description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In theory, pool->cpu is equals to @cpu in wq_worker_sleeping() after
worker->flags is checked.
And "pool->cpu != cpu" sanity check will help us if something wrong.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When a worker is detached, the worker->flags may still have WORKER_UNBOUND
or WORKER_REBOUND, it is OK for all cases:
1) if it is a normal worker, the worker will be dead, it is OK.
2) if it is a rescuer, it may re-attach to a pool with this leftover flag[s],
it is still correct except it may cause unneeded wakeup.
It is correct but not good, so we just remove the leftover flags.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The @cpu is fetched via smp_processor_id() in this function,
so the check is useless.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
schedule_timeout_interruptible(CREATE_COOLDOWN) is exactly the same as
the original code.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit ea1abd6197 ("workqueue: reimplement idle worker rebinding")
used a trick which simply removes all to-be-bound idle workers from the
idle list and lets them add themselves back after completing rebinding.
And this trick caused the @worker_pool->nr_idle may deviate than the actual
number of idle workers on @worker_pool->idle_list. More specifically,
nr_idle may be non-zero while ->idle_list is empty. All users of
->nr_idle and ->idle_list are audited. The only affected one is
too_many_workers() which is updated to check %false if ->idle_list is
empty regardless of ->nr_idle.
The commit/trick was complicated due to it just tried to simplify an even
more complicated problem (workers had to rebind itself). But the commit
a9ab775bca ("workqueue: directly restore CPU affinity of workers
from CPU_ONLINE") fixed all these problems and the mentioned trick was
useless and is gone.
So, now the @worker_pool->nr_idle is exactly the actual number of workers
on @worker_pool->idle_list. too_many_workers() should recover as it was
before the trick. So we remove the empty check.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is a piece of sanity checks code in the put_unbound_pool().
The meaning of this code is "if it is not an unbound pool, it will complain
and return" IIUC. But the code uses "pool->flags & POOL_DISASSOCIATED"
imprecisely due to a non-unbound pool may also have this flags.
We should use "pool->cpu < 0" to stand for an unbound pool, so we covert the
code to it.
There is no strictly wrong if we still keep "pool->flags & POOL_DISASSOCIATED"
here, but it is just a noise if we keep it:
1) we focus on "unbound" here, not "[dis]association".
2) "pool->cpu < 0" already implies "pool->flags & POOL_DISASSOCIATED".
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When computing cache hot, we should check if the migration dst cpu is idle,
instead of the current cpu. Though they are same in normal balancing, that
is false nowadays in nohz idle balancing at least.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140607090452.4696E301D2@webmail.sinamail.sina.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is possible that at task_numa_placement() time, the task's
numa_preferred_nid does not change, but the task is not
actually running on the preferred node at the time.
In that case, we still want to attempt migration to the
preferred node.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140604163315.1dbc7b56@cuia.bos.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The first thing task_numa_migrate() does is check to see if there is
CPU capacity available on the preferred node, in order to move the
task there.
However, if the preferred node is all busy, we would skip considering
that node for tasks swaps in the subsequent loop. This prevents NUMA
convergence of tasks on busy systems.
However, swapping locations with a task on our preferred nid, when
the preferred nid is busy, is perfectly fine.
The fix is to also look for a CPU on our preferred nid when it is
totally busy.
This changes "perf bench numa mem -p 4 -t 20 -m -0 -P 1000" from
not converging in 15 minutes on my 4 node system, to converging in
10-20 seconds.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140604160942.6969b101@cuia.bos.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After running:
# mount -t cgroup cpu xxx /cgroup && mkdir /cgroup/sub && \
rmdir /cgroup/sub && umount /cgroup
I found the cgroup root still existed:
# cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 0 1 1
cpu 1 1 1
...
It turned out css_has_online_children() is broken.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Sigend-off-by: Tejun Heo <tj@kernel.org>
Changes kASLR from being compile-time selectable (blocked by
CONFIG_HIBERNATION), to being boot-time selectable (with hibernation
available by default) via the "kaslr" kernel command line.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To support using kernel features that are not compatible with hibernation,
this creates the "nohibernate" kernel boot parameter to disable both
hibernation and resume. This allows hibernation support to be a boot-time
choice instead of only a compile-time choice.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
A full dynticks CPU is allowed to stop its tick when a single task runs.
Meanwhile when a new task gets enqueued, the CPU must be notified so that
it can restart its tick to maintain local fairness and other accounting
details.
This notification is performed by way of an IPI. Then when the target
receives the IPI, we expect it to see the new value of rq->nr_running.
Hence the following ordering scenario:
CPU 0 CPU 1
write rq->running get IPI
smp_wmb() smp_rmb()
send IPI read rq->nr_running
But Paul Mckenney says that nowadays IPIs imply a full barrier on
all architectures. So we can safely remove this pair and rely on the
implicit barriers that come along IPI send/receive. Lets
just comment on this new assumption.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Now that we have a nohz full remote kick based on irq work, lets use
it to notify a CPU that it's exiting single task mode.
This unbloats a bit the scheduler IPI that the nohz code was abusing
for its cool "callable anywhere/anytime" properties.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
When a new timer is enqueued on a full dynticks target, that CPU must
re-evaluate the next tick to handle the timer correctly.
This is currently performed through the scheduler IPI. Meanwhile this
happens at the cost of off-topic workarounds in that fast path to make
it call irq_exit().
As we plan to remove this hack off the scheduler IPI, lets use
the nohz full kick instead. Pretty much any IPI fits for that job
as long at it calls irq_exit(). The nohz full kick just happens to be
handy and readily available here.
If it happens to be too much an overkill in the future, we can still
turn that timer kick into an empty IPI.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Remotely kicking a full nohz CPU in order to make it re-evaluate its
next tick is currently implemented using the scheduler IPI.
However this bloats a scheduler fast path with an off-topic feature.
The scheduler tick was abused here for its cool "callable
anywhere/anytime" properties.
But now that the irq work subsystem can queue remote callbacks, it's
a perfect fit to safely queue IPIs when interrupts are disabled
without worrying about concurrent callers.
So lets implement remote kick on top of irq work. This is going to
be used when a new event requires the next tick to be recalculated:
more than 1 task competing on the CPU, timer armed, ...
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
irq work currently only supports local callbacks. However its code
is mostly ready to run remote callbacks and we have some potential user.
The full nohz subsystem currently open codes its own remote irq work
on top of the scheduler ipi when it wants a CPU to reevaluate its next
tick. However this ad hoc solution bloats the scheduler IPI.
Lets just extend the irq work subsystem to support remote queuing on top
of the generic SMP IPI to handle this kind of user. This shouldn't add
noticeable overhead.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
