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new_cpu is reassigned below, so we do not need this here.
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529276.3569.24.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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schedule()
schedule(), io_schedule() and schedule_timeout() always return
with TASK_RUNNING state set, so one more setting is unnecessary.
(All places in patch are visible good, only exception is
kiblnd_scheduler() from:
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
Its schedule() is one line above standard 3 lines of unified diff)
No places where set_current_state() is used for mb().
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529254.3569.23.camel@tkhai
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Anil Belur <askb23@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: David Airlie <airlied@linux.ie>
Cc: David Howells <dhowells@redhat.com>
Cc: Dmitry Eremin <dmitry.eremin@intel.com>
Cc: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Isaac Huang <he.huang@intel.com>
Cc: James E.J. Bottomley <JBottomley@parallels.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Liang Zhen <liang.zhen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masaru Nomura <massa.nomura@gmail.com>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleg Drokin <green@linuxhacker.ru>
Cc: Peng Tao <bergwolf@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Ursula Braun <ursula.braun@de.ibm.com>
Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: devel@driverdev.osuosl.org
Cc: dm-devel@redhat.com
Cc: dri-devel@lists.freedesktop.org
Cc: fcoe-devel@open-fcoe.org
Cc: jfs-discussion@lists.sourceforge.net
Cc: linux390@de.ibm.com
Cc: linux-afs@lists.infradead.org
Cc: linux-cris-kernel@axis.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-nfs@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: qla2xxx-upstream@qlogic.com
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The sig->stats_lock nests inside the tasklist_lock and the
sighand->siglock in __exit_signal and wait_task_zombie.
However, both of those locks can be taken from irq context,
which means we need to use the interrupt safe variant of
read_seqbegin_or_lock. This blocks interrupts when the "lock"
branch is taken (seq is odd), preventing the lock inversion.
On the first (lockless) pass through the loop, irqs are not
blocked.
Reported-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: prarit@redhat.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1410527535-9814-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Currently kick_all_cpus_sync() can break non-polling idle cpus
thru IPI interrupts.
But sometimes we need to break the polling idle cpus immediately
to reselect the suitable c-state, also for non-idle cpus, we need
to do nothing if we try to wake up them.
Here adding one new function wake_up_all_idle_cpus() to let all cpus
out of idle based on function wake_up_if_idle().
Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: daniel.lezcano@linaro.org
Cc: rjw@rjwysocki.net
Cc: linux-pm@vger.kernel.org
Cc: changcheng.liu@intel.com
Cc: xiaoming.wang@intel.com
Cc: souvik.k.chakravarty@intel.com
Cc: luto@amacapital.net
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1409815075-4180-2-git-send-email-chuansheng.liu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Implementing one new API wake_up_if_idle(), which is used to
wake up the idle CPU.
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: daniel.lezcano@linaro.org
Cc: rjw@rjwysocki.net
Cc: linux-pm@vger.kernel.org
Cc: changcheng.liu@intel.com
Cc: xiaoming.wang@intel.com
Cc: souvik.k.chakravarty@intel.com
Cc: chuansheng.liu@intel.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409815075-4180-1-git-send-email-chuansheng.liu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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task_numa_move()
The code in task_numa_compare() will only examine at most one idle CPU per node,
because they all have the same score. However, some idle CPUs are better
candidates than others, due to busy or idle SMT siblings, etc...
The scheduler has logic to find the best CPU within an LLC to place a
task. The NUMA code should probably use it.
This seems to reduce the standard deviation for single instance SPECjbb2005
with a low warehouse count on my 4 node test system.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140904163530.189d410a@cuia.bos.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Currently, the expedited grace-period primitives do get_online_cpus().
This greatly simplifies their implementation, but means that calls
to them holding locks that are acquired by CPU-hotplug notifiers (to
say nothing of calls to these primitives from CPU-hotplug notifiers)
can deadlock. But this is starting to become inconvenient, as can be
seen here: https://lkml.org/lkml/2014/8/5/754. The problem in this
case is that some developers need to acquire a mutex from a CPU-hotplug
notifier, but also need to hold it across a synchronize_rcu_expedited().
As noted above, this currently results in deadlock.
This commit avoids the deadlock and retains the simplicity by creating
a try_get_online_cpus(), which returns false if the get_online_cpus()
reference count could not immediately be incremented. If a call to
try_get_online_cpus() returns true, the expedited primitives operate as
before. If a call returns false, the expedited primitives fall back to
normal grace-period operations. This falling back of course results in
increased grace-period latency, but only during times when CPU hotplug
operations are actually in flight. The effect should therefore be
negligible during normal operation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Tested-by: Lan Tianyu <tianyu.lan@intel.com>
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Use the ONE macro instead of REG, and we can simplify proc_cpuset_show().
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Use the ONE macro instead of REG, and we can simplify proc_cgroup_show().
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Instead of using a global work to schedule release agent on removable
cgroups, we change to use a per-cgroup work to do this, which makes
the code much simpler.
v2: use a dedicated work instead of reusing css->destroy_work. (Tejun)
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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cgroup_pidlist_start() holds cgrp->pidlist_mutex and then calls
pidlist_array_load(), and cgroup_pidlist_stop() releases the mutex.
It is wrong that we release the mutex in the failure path in
pidlist_array_load(), because cgroup_pidlist_stop() will be called
no matter if cgroup_pidlist_start() returns errno or not.
Fixes: 4bac00d16a8760eae7205e41d2c246477d42a210
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
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We never grab cgroup mutex in fork and exit paths no matter whether
notify_on_release is set or not.
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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We no longer clear kn->priv in cgroup_rmdir(), so we don't need
to get an extra refcnt.
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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ra.kernel.org:/pub/scm/linux/kernel/git/tj/cgroup into for-3.18
Pull to receive a4189487da1b ("cgroup: delay the clearing of
cgrp->kn->priv") for the scheduled clean up patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
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This commit changes rcutorture_runnable to torture_runnable, which is
consistent with the names of the other parameters and is a bit shorter
as well.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The amount of global variables is getting pretty ugly. Group variables
related to the execution (ie: not parameters) in a new context structure.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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We can easily do so with our new reader lock support. Just an arbitrary
design default: readers have higher (5x) critical region latencies than
writers: 50 ms and 10 ms, respectively.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Most of it is based on what we already have for writers. This allows
readers to be very independent (and thus configurable), enabling
future module parameters to control things such as rw distribution.
Furthermore, readers have their own delaying function, allowing us
to test different rw critical region latencies, and stress locking
internals. Similarly, statistics, for now will only serve for the
number of lock acquisitions -- as opposed to writers, readers have
no failure detection.
In addition, introduce a new nreaders_stress module parameter. The
default number of readers will be the same number of writers threads.
Writer threads are interleaved with readers. Documentation is updated,
respectively.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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When performing module cleanups by calling torture_cleanup() the
'torture_type' string in nullified However, callers are not necessarily
done, and might still need to reference the variable. This impacts
both rcutorture and locktorture, causing printing things like:
[ 94.226618] (null)-torture: Stopping lock_torture_writer task
[ 94.226624] (null)-torture: Stopping lock_torture_stats task
Thus delay this operation until the very end of the cleanup process.
The consequence (which shouldn't matter for this kid of program) is,
of course, that we delay the window between rmmod and modprobing,
for instance in module_torture_begin().
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The statistics structure can serve well for both reader and writer
locks, thus simply rename some fields that mention 'write' and leave
the declaration of lwsa.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Regular locks are very different than locks with debugging. For instance
for mutexes, debugging forces to only take the slowpaths. As such, the
locktorture module should take this into account when printing related
information -- specifically when printing user passed parameters, it seems
the right place for such info.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Add a "mutex_lock" torture test. The main difference with the already
existing spinlock tests is that the latency of the critical region
is much larger. We randomly delay for (arbitrarily) either 500 ms or,
otherwise, 25 ms. While this can considerably reduce the amount of
writes compared to non blocking locks, if run long enough it can have
the same torturous effect. Furthermore it is more representative of
mutex hold times and can stress better things like thrashing.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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... to just 'torture_runnable'. It follows other variable naming
and is shorter.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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rcu-tasks.2014.09.10a: Add RCU-tasks flavor of RCU.
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'nocb-nohz.2014.09.16b' and 'torture.2014.09.07a' into HEAD
doc.2014.09.07a: Documentation updates.
fixes.2014.09.10a: Miscellaneous fixes.
nocb-nohz.2014.09.16b: No-CBs CPUs and NO_HZ_FULL updates.
torture.2014.09.07a: Torture-test updates.
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The NOCB follower wakeup ordering depends on the store to the tail
pointer happening before the wakeup. However, because atomic_long_add()
does not return a value, it does not provide ordering guarantees, and
the locking in wake_up() only guarantees that the store will happen
before the unlock, which might be too late. Even though this is only a
theoretical issue, this commit adds a smp_mb__after_atomic() after the
final atomic_long_add() to provide the needed ordering guarantee.
Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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If an RCU callback is queued on a no-CBs CPU from idle code with irqs
disabled, and if that CPU stays idle forever after, the callback will
never be invoked. This commit therefore adds a check for this situation
in ____call_rcu_nocb(), invoking the RCU core solely for the purpose
of the ensuing return-to-idle transition. (If the CPU doesn't return
to idle, the next scheduling-clock interrupt will fix things up.)
Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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The NOCB leader wakeup ordering depends on the store to the header
happening before the check for the leader already being awake. However,
because atomic_long_add() does not return a value, it does not provide
ordering guarantees, the incorrect comment in wake_nocb_leader()
notwithstanding. This commit therefore adds a smp_mb__after_atomic()
after the final atomic_long_add() to provide the needed ordering
guarantee.
Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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If there are no nohz_full= CPUs, then there is currently no reason to
track sysidle state. This commit therefore short-circuits this state
tracking if !tick_nohz_full_enabled().
Note that these checks will need to be revisited if nohz_full= state
can ever be changed at runtime.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Now that we have rcu_state_p, which references rcu_preempt_state for
TREE_PREEMPT_RCU and rcu_sched_state for TREE_RCU, we don't need a
separate rcu_sysidle_state variable. This commit therefore eliminates
rcu_preempt_state in favor of rcu_state_p.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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If we configure a kernel with CONFIG_NOCB_CPU=y, CONFIG_RCU_NOCB_CPU_NONE=y and
CONFIG_CPUMASK_OFFSTACK=n and do not pass in a rcu_nocb= boot parameter, the
cpumask rcu_nocb_mask can be garbage instead of NULL.
Hence this commit replaces checks for rcu_nocb_mask == NULL with a check for
have_rcu_nocb_mask.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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RCU currently uses for_each_possible_cpu() to spawn rcuo kthreads,
which can result in more rcuo kthreads than one would expect, for
example, derRichard reported 64 CPUs worth of rcuo kthreads on an
8-CPU image. This commit therefore creates rcuo kthreads only for
those CPUs that actually come online.
This was reported by derRichard on the OFTC IRC network.
Reported-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Currently, RCU spawns kthreads from several different early_initcall()
functions. Although this has served RCU well for quite some time,
as more kthreads are added a more deterministic approach is required.
This commit therefore causes all of RCU's early-boot kthreads to be
spawned from a single early_initcall() function.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Return false instead of 0 in rcu_nocb_adopt_orphan_cbs() as this has
bool as return type.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Return false instead of 0 in __call_rcu_nocb() as this has bool as
return type.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Return true/false in rcu_nocb_adopt_orphan_cbs() instead of 0/1 as
this function has return type of bool.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Return true/false instead of 0/1 in __call_rcu_nocb() as this returns a
bool type.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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This commit checks the return value of the zalloc_cpumask_var() used for
allocating cpumask for rcu_nocb_mask.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Commit b58cc46c5f6b (rcu: Don't offload callbacks unless specifically
requested) failed to adjust the callback lists of the CPUs that are
known to be no-CBs CPUs only because they are also nohz_full= CPUs.
This failure can result in callbacks that are posted during early boot
getting stranded on nxtlist for CPUs whose no-CBs property becomes
apparent late, and there can also be spurious warnings about offline
CPUs posting callbacks.
This commit fixes these problems by adding an early-boot rcu_init_nohz()
that properly initializes the no-CBs CPUs.
Note that kernels built with CONFIG_RCU_NOCB_CPU_ALL=y or with
CONFIG_RCU_NOCB_CPU=n do not exhibit this bug. Neither do kernels
booted without the nohz_full= boot parameter.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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Revert PERF_EVENT_STATE_EXIT check on read syscall path.
It breaks standard way to read counter, which is to open
the counter, wait for the monitored process to die and
read the counter.
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/20140908143107.GG17728@krava.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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rw-semaphore is the only type of lock doing this ugliness of
exporting at the end of the file.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: dave@stgolabs.net
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1410500066-5909-1-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex and timer fixes from Thomas Gleixner:
"A oneliner bugfix for the jinxed futex code:
- Drop hash bucket lock in the error exit path. I really could slap
myself for intruducing that bug while fixing all the other horror
in that code three month ago ...
and the timer department is not too proud about the following fixes:
- Deal with a long standing rounding bug in the timeval to jiffies
conversion. It's a real issue and this fix fell through the cracks
for quite some time.
- Another round of alarmtimer fixes. Finally this code gets used
more widely and the subtle issues hidden for quite some time are
noticed and fixed. Nothing really exciting, just the itty bitty
details which bite the serious users here and there"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Unlock hb->lock in futex_wait_requeue_pi() error path
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
alarmtimer: Lock k_itimer during timer callback
alarmtimer: Do not signal SIGEV_NONE timers
alarmtimer: Return relative times in timer_gettime
jiffies: Fix timeval conversion to jiffies
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The nohz full functionality depends on IRQ work to trigger its own
interrupts. As it's used to restart the tick, we can't rely on the tick
fallback for irq work callbacks, ie: we can't use the tick to restart
the tick itself.
Lets reject the full dynticks initialization if that arch support isn't
available.
As a side effect, this makes sure that nohz kick is never called from
the tick. That otherwise would result in illegal hrtimer self-cancellation
and lockup.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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The supports for CONFIG_NO_HZ_FULL_ALL=y and the nohz_full= kernel
parameter both have their own way to do the same thing: allocate
full dynticks cpumasks, fill them and initialize some state variables.
Lets consolidate that all in the same place.
While at it, convert some regular printk message to warnings when
fundamental allocations fail.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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The nohz full kick, which restarts the tick when any resource depend
on it, can't be executed anywhere given the operation it does on timers.
If it is called from the scheduler or timers code, chances are that
we run into a deadlock.
This is why we run the nohz full kick from an irq work. That way we make
sure that the kick runs on a virgin context.
However if that's the case when irq work runs in its own dedicated
self-ipi, things are different for the big bunch of archs that don't
support the self triggered way. In order to support them, irq works are
also handled by the timer interrupt as fallback.
Now when irq works run on the timer interrupt, the context isn't blank.
More precisely, they can run in the context of the hrtimer that runs the
tick. But the nohz kick cancels and restarts this hrtimer and cancelling
an hrtimer from itself isn't allowed. This is why we run in an endless
loop:
Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 2
CPU: 2 PID: 7538 Comm: kworker/u8:8 Not tainted 3.16.0+ #34
Workqueue: btrfs-endio-write normal_work_helper [btrfs]
ffff880244c06c88 000000001b486fe1 ffff880244c06bf0 ffffffff8a7f1e37
ffffffff8ac52a18 ffff880244c06c78 ffffffff8a7ef928 0000000000000010
ffff880244c06c88 ffff880244c06c20 000000001b486fe1 0000000000000000
Call Trace:
<NMI[<ffffffff8a7f1e37>] dump_stack+0x4e/0x7a
[<ffffffff8a7ef928>] panic+0xd4/0x207
[<ffffffff8a1450e8>] watchdog_overflow_callback+0x118/0x120
[<ffffffff8a186b0e>] __perf_event_overflow+0xae/0x350
[<ffffffff8a184f80>] ? perf_event_task_disable+0xa0/0xa0
[<ffffffff8a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
[<ffffffff8a187934>] perf_event_overflow+0x14/0x20
[<ffffffff8a020386>] intel_pmu_handle_irq+0x206/0x410
[<ffffffff8a01937b>] perf_event_nmi_handler+0x2b/0x50
[<ffffffff8a007b72>] nmi_handle+0xd2/0x390
[<ffffffff8a007aa5>] ? nmi_handle+0x5/0x390
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a008062>] default_do_nmi+0x72/0x1c0
[<ffffffff8a008268>] do_nmi+0xb8/0x100
[<ffffffff8a7ff66a>] end_repeat_nmi+0x1e/0x2e
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
[<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
<<EOE><IRQ[<ffffffff8a0ccd2f>] lock_acquired+0xaf/0x450
[<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a7fc678>] _raw_spin_lock_irqsave+0x78/0x90
[<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a0f74c5>] lock_hrtimer_base.isra.20+0x25/0x50
[<ffffffff8a0f7723>] hrtimer_try_to_cancel+0x33/0x1e0
[<ffffffff8a0f78ea>] hrtimer_cancel+0x1a/0x30
[<ffffffff8a109237>] tick_nohz_restart+0x17/0x90
[<ffffffff8a10a213>] __tick_nohz_full_check+0xc3/0x100
[<ffffffff8a10a25e>] nohz_full_kick_work_func+0xe/0x10
[<ffffffff8a17c884>] irq_work_run_list+0x44/0x70
[<ffffffff8a17c8da>] irq_work_run+0x2a/0x50
[<ffffffff8a0f700b>] update_process_times+0x5b/0x70
[<ffffffff8a109005>] tick_sched_handle.isra.21+0x25/0x60
[<ffffffff8a109b81>] tick_sched_timer+0x41/0x60
[<ffffffff8a0f7aa2>] __run_hrtimer+0x72/0x470
[<ffffffff8a109b40>] ? tick_sched_do_timer+0xb0/0xb0
[<ffffffff8a0f8707>] hrtimer_interrupt+0x117/0x270
[<ffffffff8a034357>] local_apic_timer_interrupt+0x37/0x60
[<ffffffff8a80010f>] smp_apic_timer_interrupt+0x3f/0x50
[<ffffffff8a7fe52f>] apic_timer_interrupt+0x6f/0x80
To fix this we force non-lazy irq works to run on irq work self-IPIs
when available. That ability of the arch to trigger irq work self IPIs
is available with arch_irq_work_has_interrupt().
Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Reported-by: Dave Jones <davej@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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This way we unbloat a bit main.c and more importantly we initialize
nohz full after init_IRQ(). This dependency will be needed in further
patches because nohz full needs irq work to raise its own IRQ.
Information about the support for this ability on ARM64 is obtained on
init_IRQ() which initialize the pointer to __smp_call_function.
Since tick_init() is called right after init_IRQ(), this is a good place
to call tick_nohz_init() and prepare for that dependency.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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The ftrace_enabled variable is set to zero in the self tests to keep
delayed functions from being traced and messing with the checks. This
only needs to be done when the checks are being performed, otherwise,
if ftrace_enabled is off when calls back to the utility that is being
tested, it can cause errors to happen and the tests can fail with
false positives.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When the last ftrace_ops is unregistered, all the function records should
have a zeroed flags value. Make sure that is the case when the last ftrace_ops
is unregistered.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Locks the k_itimer's it_lock member when handling the alarm timer's
expiry callback.
The regular posix timers defined in posix-timers.c have this lock held
during timout processing because their callbacks are routed through
posix_timer_fn(). The alarm timers follow a different path, so they
ought to grab the lock somewhere else.
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
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