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2014-02-24smp: Teach __smp_call_function_single() to check for offline cpusJan Kara
Align __smp_call_function_single() with smp_call_function_single() so that it also checks whether requested cpu is still online. Signed-off-by: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-02-24smp: Iterate functions through llist_for_each_entry_safe()Jan Kara
The IPI function llist iteration is open coded. Lets simplify this with using an llist iterator. Also we want to keep the iteration safe against possible csd.llist->next value reuse from the IPI handler. At least the block subsystem used to do such things so lets stay careful and use llist_for_each_entry_safe(). Signed-off-by: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-02-24capability: Use current logging stylesJoe Perches
Prefix logging output with "capability: " via pr_fmt. Convert printks to pr_<level>. Use pr_<level>_once instead of guard flags. Coalesce formats. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
2014-02-23Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fix from Thomas Gleixner: "Serialize the registration of a new sched_clock in the currently ARM only generic sched_clock facilty to avoid sched_clock havoc" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched_clock: Prevent callers from seeing half-updated data
2014-02-23rcutorture: Add a lock_busted to test the testPaul E. McKenney
This commit adds a maximally broken locking primitive in which lock acquisition and release are both no-ops. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Gracefully handle NULL cleanup hooksPaul E. McKenney
Although most torture tests will have some cleanup hook, it is possible that one might not. This commit therefore enables graceful handling of a NULL cleanup hook during torture-test shutdown. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Add an rcu_busted to test the testPaul E. McKenney
This commit adds a deliberately buggy RCU implementation into rcutorture to allow easy checking that rcutorture correctly flags buggy RCU implementations. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23locktorture: Add a lock-torture kernel modulePaul E. McKenney
This commit adds the locking counterpart to rcutorture. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Make n_lock_torture_errors and torture_spinlock static as suggested by Fengguang Wu. ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Stop generic kthreads in torture_cleanup()Paul E. McKenney
The specific torture modules (like rcutorture) need to call torture_cleanup() in any case, so this commit makes torture_cleanup() deal with torture_shutdown_cleanup() and torture_stutter_cleanup() so that the specific modules don't have to deal with these details. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_stop_kthread()Paul E. McKenney
Stopping of kthreads is not RCU-specific, so this commit abstracts out torture_stop_kthread(), saving a few lines of code in the process. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_create_kthread()Paul E. McKenney
Creation of kthreads is not RCU-specific, so this commit abstracts out torture_create_kthread(), saving a few tens of lines of code in the process. This change requires modifying VERBOSE_TOROUT_ERRSTRING() to take a non-const string, so that _torture_create_kthread() can avoid an open-coded substitute. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Fix missing-return bug in rcu_torture_barrier_init()Paul E. McKenney
This commit adds a missing error return to the code path that creates the rcu_torture_barrier() kthread. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Fix rcutorture shutdown racesPaul E. McKenney
Not all of the rcutorture kthreads waited for kthread_should_stop() before returning from their top-level functions, and none of them used torture_shutdown_absorb() properly. These problems can result in segfaults and hangs at shutdown time, and some recent changes perturbed timing sufficiently to make them much more probable. This commit therefore creates a torture_kthread_stopping() function that does the proper kthread shutdown dance in one centralized location. Accommodate this grouping by making VERBOSE_TOROUT_STRING() capable of taking a non-const string as its argument, which allows the new torture_kthread_stopping() to pass its "title" argument directly to the updated version of VERBOSE_TOROUT_STRING(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23rcutorture: Announce task creationPaul E. McKenney
A few "stealth-start rcutorture kthreads" have accumulated over the years, so this commit adds console-log announcements (but only if the torture tests are running verbose). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Clean up rcu_torture_init() error checkingPaul E. McKenney
This commit applies some simple cleanups to rcu_torture_init() error checking. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_shutdown()Paul E. McKenney
Because auto-shutdown of torture testing is not specific to RCU, this commit moves the auto-shutdown function to kernel/torture.c. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Apply ACCESS_ONCE() to racy fullstop accessesPaul E. McKenney
Because the fullstop variable can be accessed while it is being updated, this commit avoids any resulting compiler mischief through use of ACCESS_ONCE() for non-initialization accesses to this shared variable. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract stutter_wait()Paul E. McKenney
Because stuttering the test load (stopping and restarting it) is useful for non-RCU testing, this commit moves the load-stuttering functionality to kernel/torture.c. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Add diagnostic for unscheduled system shutdownPaul E. McKenney
Currently, rcutorture can terminate via rmmod, via self-shutdown, via something else shutting the system down, or of course the usual catastrophic termination. The first two get flagged, so this commit adds a message for the third. For the fourth, your warranty is void as always. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Privatize fullstopPaul E. McKenney
This commit introduces the torture_must_stop() function in order to keep use of the fullstop variable local to kernel/torture.c. There is also a torture_must_stop_irq() counterpart for use from RCU callbacks, timeout handlers, and the like. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_shutdown_notify()Paul E. McKenney
Because handling the race between rmmod and system shutdown is not specific to RCU, this commit abstracts torture_shutdown_notify(), placing this code into kernel/torture.c. This change also allows fullstop_mutex to be private to kernel/torture.c. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture-test cleanupPaul E. McKenney
This commit creates a torture_cleanup() that handles the generic cleanup actions local to kernel/torture.c. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture-test initializationPaul E. McKenney
This commit creates torture_init_begin() and torture_init_end() functions to abstract locking and allow the torture_type and verbose variables in kernel/torture.o to become static. With a bit more abstraction, fullstop_mutex will also become static. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_onoff()Paul E. McKenney
Because online/offline torturing is not specific to RCU, this commit abstracts it into the kernel/torture.c module to allow other torture tests to use it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_shuffle()Paul E. McKenney
The torture_shuffle() function forces each CPU in turn to go idle periodically in order to check for problems interacting with per-CPU variables and with dyntick-idle mode. Because this sort of debugging is not specific to RCU, this commit abstracts that functionality. This in turn requires abstracting some additional infrastructure. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_shutdown_absorb()Paul E. McKenney
Because handling races between rmmod and normal shutdown is not specific to rcutorture, this commit renames rcutorture_shutdown_absorb() to torture_shutdown_absorb() and pulls it out into then kernel/torture.c module. This implies pulling the fullstop mechanism into kernel/torture.c as well. The exporting of fullstop and fullstop_mutex is ugly and must die. And it does in fact die in later commits that introduce higher-level APIs that encapsulate both of these variables. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>`
2014-02-23rcutorture: Abstract TOROUT_STRING() and friendsPaul E. McKenney
These diagnostic macros are not confined to torturing RCU, so this commit makes them available to other torture tests. Also removed the do-while from TOROUT_STRING() in response to checkpatch complaints. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23rcutorture: Rename PRINTK to TOROUTPaul E. McKenney
Since it doesn't do printk()s anymore anyway, this commit renames these macros from PRINTK to TOROUT (short for torture output). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-02-23rcutorture: Abstract torture_param()Paul E. McKenney
Create a torture_param() macro and apply it to rcutorture in order to save a few lines of code. This same macro may be applied to other torture frameworks. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23rcutorture: Abstract rcu_torture_random()Paul E. McKenney
Because rcu_torture_random() will be used by the locking equivalent to rcutorture, pull it out into its own module. This new module cannot be separately configured, instead, use the Kconfig "select" statement from the Kconfig options of tests depending on it. Suggested-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-23rcutorture: Fix checkpatch complaintPaul E. McKenney
This commit does a code-style cleanup so that the first curly brace of an initializer does not appear at the beginning of a line. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-02-22sched, nohz: Exclude isolated cores from load balancingMike Galbraith
The user explicitly disabled load balancing, else this core would not be disconnected. Don't add these to nohz.idle_cpus_mask. Signed-off-by: Mike Galbraith <mgalbraith@suse.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Lei Wen <leiwen@marvell.com> Link: http://lkml.kernel.org/n/tip-vmme4f49psirp966pklm5l9j@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Fix select_task_rq_fair() description commentsMorten Rasmussen
Brings select_task_rq_fair() description comments up-to-date. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1392732864-10927-1-git-send-email-morten.rasmussen@arm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22workqueue: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICEDongsheng Yang
Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/6d85138180c00ce86975addab6e34b24b84f00a5.1392103744.git.yangds.fnst@cn.fujitsu.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICEDongsheng Yang
Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Robin Holt <holt@sgi.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Link: http://lkml.kernel.org/r/0261f094b836f1acbcdf52e7166487c0c77323c8.1392103744.git.yangds.fnst@cn.fujitsu.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICEDongsheng Yang
Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/bd80780f19b4f9b4a765acc353c8dbc130274dd6.1392103744.git.yangds.fnst@cn.fujitsu.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22rcu: Use MAX_NICE to replace hardcoding of 19Dongsheng Yang
Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/5b3bf232f41b33ab703a1595e94671b303e2d1fc.1392103744.git.yangds.fnst@cn.fujitsu.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched/rt: Make init_sched_rt_calss() __initLi Zefan
It's a bootstrap function. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/52F5CC09.1080502@huawei.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched/rt: Remove 'leaf_rt_rq_list' from 'struct rq'Li Zefan
This is a leftover from commit e23ee74777f389369431d77390c4b09332ce026a ("sched/rt: Simplify pull_rt_task() logic and remove .leaf_rt_rq_list"). Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/52F5CBF6.4060901@huawei.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Consider pi boosting in setscheduler()Thomas Gleixner
If a PI boosted task policy/priority is modified by a setscheduler() call we unconditionally dequeue and requeue the task if it is on the runqueue even if the new priority is lower than the current effective boosted priority. This can result in undesired reordering of the priority bucket list. If the new priority is less or equal than the current effective we just store the new parameters in the task struct and leave the scheduler class and the runqueue untouched. This is handled when the task deboosts itself. Only if the new priority is higher than the effective boosted priority we apply the change immediately. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Rebase ontop of v3.14-rc1. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Dario Faggioli <raistlin@linux.it> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-7-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Queue RT tasks to head when prio dropsThomas Gleixner
The following scenario does not work correctly: Runqueue of CPUx contains two runnable and pinned tasks: T1: SCHED_FIFO, prio 80 T2: SCHED_FIFO, prio 80 T1 is on the cpu and executes the following syscalls (classic priority ceiling scenario): sys_sched_setscheduler(pid(T1), SCHED_FIFO, .prio = 90); ... sys_sched_setscheduler(pid(T1), SCHED_FIFO, .prio = 80); ... Now T1 gets preempted by T3 (SCHED_FIFO, prio 95). After T3 goes back to sleep the scheduler picks T2. Surprise! The same happens w/o actual preemption when T1 is forced into the scheduler due to a sporadic NEED_RESCHED event. The scheduler invokes pick_next_task() which returns T2. So T1 gets preempted and scheduled out. This happens because sched_setscheduler() dequeues T1 from the prio 90 list and then enqueues it on the tail of the prio 80 list behind T2. This violates the POSIX spec and surprises user space which relies on the guarantee that SCHED_FIFO tasks are not scheduled out unless they give the CPU up voluntarily or are preempted by a higher priority task. In the latter case the preempted task must get back on the CPU after the preempting task schedules out again. We fixed a similar issue already in commit 60db48c (sched: Queue a deboosted task to the head of the RT prio queue). The same treatment is necessary for sched_setscheduler(). So enqueue to head of the prio bucket list if the priority of the task is lowered. It might be possible that existing user space relies on the current behaviour, but it can be considered highly unlikely due to the corner case nature of the application scenario. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-6-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Adjust p->sched_reset_on_fork when nothing else changesThomas Gleixner
If the policy and priority remain unchanged a possible modification of p->sched_reset_on_fork gets lost in the early exit path. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Rebase ontop of v3.14-rc1. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-5-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Add better debug output for might_sleep()Thomas Gleixner
might_sleep() can tell us where interrupts have been disabled, but we have no idea what disabled preemption. Add some debug infrastructure. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-4-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Check for idle task in might_sleep()Thomas Gleixner
Idle is not allowed to call sleeping functions ever! Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-3-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-22sched: Init idle->on_rq in init_idle()Thomas Gleixner
We stumbled in RT over a SMP bringup issue on ARM where the idle->on_rq == 0 was causing try_to_wakeup() on the other cpu to run into nada land. After adding that idle->on_rq = 1; I was able to find the root cause of the lockup: the idle task on the newly woken up cpu was fiddling with a sleeping spinlock, which is a nono. I kept the init of idle->on_rq to keep the state consistent and to avoid another long lasting debug session. As a side note, the whole debug mess could have been avoided if might_sleep() would have yelled when called from the idle task. That's fixed with patch 2/6 - and that one actually has a changelog :) Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1391803122-4425-2-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-02-21perf/x86: Warn to early_printk() in case irq_work is too slowPeter Zijlstra
On Mon, Feb 10, 2014 at 08:45:16AM -0800, Dave Hansen wrote: > The reason I coded this up was that NMIs were firing off so fast that > nothing else was getting a chance to run. With this patch, at least the > printk() would come out and I'd have some idea what was going on. It will start spewing to early_printk() (which is a lot nicer to use from NMI context too) when it fails to queue the IRQ-work because its already enqueued. It does have the false-positive for when two CPUs trigger the warn concurrently, but that should be rare and some extra clutter on the early printk shouldn't be a problem. Cc: hpa@zytor.com Cc: tglx@linutronix.de Cc: dzickus@redhat.com Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: mingo@kernel.org Fixes: 6a02ad66b2c4 ("perf/x86: Push the duration-logging printk() to IRQ context") Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140211150116.GO27965@twins.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21sched: Remove some #ifdefferyPeter Zijlstra
Remove a few gratuitous #ifdefs in pick_next_task*(). Cc: Ingo Molnar <mingo@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-nnzddp5c4fijyzzxxrwlxghf@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21sched: Fix hotplug task migrationPeter Zijlstra
Dan Carpenter reported: > kernel/sched/rt.c:1347 pick_next_task_rt() warn: variable dereferenced before check 'prev' (see line 1338) > kernel/sched/deadline.c:1011 pick_next_task_dl() warn: variable dereferenced before check 'prev' (see line 1005) Kirill also spotted that migrate_tasks() will have an instant NULL deref because pick_next_task() will immediately deref prev. Instead of fixing all the corner cases because migrate_tasks() can pass in a NULL prev task in the unlikely case of hot-un-plug, provide a fake task such that we can remove all the NULL checks from the far more common paths. A further problem; not previously spotted; is that because we pushed pre_schedule() and idle_balance() into pick_next_task() we now need to avoid those getting called and pulling more tasks on our dying CPU. We avoid pull_{dl,rt}_task() by setting fake_task.prio to MAX_PRIO+1. We also note that since we call pick_next_task() exactly the amount of times we have runnable tasks present, we should never land in idle_balance(). Fixes: 38033c37faab ("sched: Push down pre_schedule() and idle_balance()") Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Reported-by: Kirill Tkhai <tkhai@yandex.ru> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140212094930.GB3545@laptop.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21sched/fair: Remove idle_balance() declaration in sched.hPeter Zijlstra
Remove idle_balance() from the public life; also reduce some #ifdef clutter by folding the pick_next_task_fair() idle path into idle_balance(). Cc: mingo@kernel.org Reported-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140211151148.GP27965@twins.programming.kicks-ass.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-21sched/fair: Reset se-depth when task switched to FAIRMichael wang
Sasha reported: [ 522.645288] BUG: unable to handle kernel NULL pointer dereference at ... [ 522.646271] IP: [<ffffffff81186c6f>] check_preempt_wakeup+0x11f/0x210 ... [ 522.650021] Call Trace: [ 522.650021] <IRQ> [ 522.650021] [<ffffffff8117361d>] check_preempt_curr+0x3d/0xb0 [ 522.650021] [<ffffffff81175d88>] ttwu_do_wakeup+0x18/0x130 ... which was caused by the se-depth changed during the time when task is not FAIR, and we will use the wrong depth value after it switched back to FAIR. This patch reset the depth at the time when task switched to FAIR, make sure that we always have the correct value when task is FAIR. Cc: Ingo Molnar <mingo@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/5305732D.70001@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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