- 04 12月, 2015 6 次提交
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由 Peter Zijlstra 提交于
Oleg noticed that its possible to falsely observe p->on_cpu == 0 such that we'll prematurely continue with the wakeup and effectively run p on two CPUs at the same time. Even though the overlap is very limited; the task is in the middle of being scheduled out; it could still result in corruption of the scheduler data structures. CPU0 CPU1 set_current_state(...) <preempt_schedule> context_switch(X, Y) prepare_lock_switch(Y) Y->on_cpu = 1; finish_lock_switch(X) store_release(X->on_cpu, 0); try_to_wake_up(X) LOCK(p->pi_lock); t = X->on_cpu; // 0 context_switch(Y, X) prepare_lock_switch(X) X->on_cpu = 1; finish_lock_switch(Y) store_release(Y->on_cpu, 0); </preempt_schedule> schedule(); deactivate_task(X); X->on_rq = 0; if (X->on_rq) // false if (t) while (X->on_cpu) cpu_relax(); context_switch(X, ..) finish_lock_switch(X) store_release(X->on_cpu, 0); Avoid the load of X->on_cpu being hoisted over the X->on_rq load. Reported-by: NOleg Nesterov <oleg@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Explain how the control dependency and smp_rmb() end up providing ACQUIRE semantics and pair with smp_store_release() in finish_lock_switch(). Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Hiroshi Shimamoto 提交于
/proc/stats shows invalid gtime when the thread is running in guest. When vtime accounting is not enabled, we cannot get a valid delta. The delta is calculated with now - tsk->vtime_snap, but tsk->vtime_snap is only updated when vtime accounting is runtime enabled. This patch makes task_gtime() just return gtime without computing the buggy non-existing tickless delta when vtime accounting is not enabled. Use context_tracking_is_enabled() to check if vtime is accounting on some cpu, in which case only we need to check the tickless delta. This way we fix the gtime value regression on machines not running nohz full. The kernel config contains CONFIG_VIRT_CPU_ACCOUNTING_GEN=y and CONFIG_NO_HZ_FULL_ALL=n and boot without nohz_full. I ran and stop a busy loop in VM and see the gtime in host. Dump the 43rd field which shows the gtime in every second: # while :; do awk '{print $3" "$43}' /proc/3955/task/4014/stat; sleep 1; done S 4348 R 7064566 R 7064766 R 7064967 R 7065168 S 4759 S 4759 During running busy loop, it returns large value. After applying this patch, we can see right gtime. # while :; do awk '{print $3" "$43}' /proc/10913/task/10956/stat; sleep 1; done S 5338 R 5365 R 5465 R 5566 R 5666 S 5726 S 5726 Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-2-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Xunlei Pang 提交于
root_domain::rto_mask allocated through alloc_cpumask_var() contains garbage data, this may cause problems. For instance, When doing pull_rt_task(), it may do useless iterations if rto_mask retains some extra garbage bits. Worse still, this violates the isolated domain rule for clustered scheduling using cpuset, because the tasks(with all the cpus allowed) belongs to one root domain can be pulled away into another root domain. The patch cleans the garbage by using zalloc_cpumask_var() instead of alloc_cpumask_var() for root_domain::rto_mask allocation, thereby addressing the issues. Do the same thing for root_domain's other cpumask memembers: dlo_mask, span, and online. Signed-off-by: NXunlei Pang <xlpang@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1449057179-29321-1-git-send-email-xlpang@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Sasha Levin 提交于
Because wakeups can (fundamentally) be late, a task might not be in the expected state. Therefore testing against a task's state is racy, and can yield false positives. Signed-off-by: NSasha Levin <sasha.levin@oracle.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: oleg@redhat.com Fixes: 9067ac85 ("wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task") Link: http://lkml.kernel.org/r/1448933660-23082-1-git-send-email-sasha.levin@oracle.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Vladimir reported getting RCU stall warnings and bisected it back to commit: 74316201 ("sched: Remove proliferation of wait_on_bit() action functions") That commit inadvertently reversed the calls to schedule() and signal_pending(), thereby not handling the case where the signal receives while we sleep. Reported-by: NVladimir Murzin <vladimir.murzin@arm.com> Tested-by: NVladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mark.rutland@arm.com Cc: neilb@suse.de Cc: oleg@redhat.com Fixes: 74316201 ("sched: Remove proliferation of wait_on_bit() action functions") Fixes: cbbce822 ("SCHED: add some "wait..on_bit...timeout()" interfaces.") Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 23 11月, 2015 9 次提交
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由 Byungchul Park 提交于
The comment describing migrate_task_rq_fair() says that the caller should hold p->pi_lock. But in some cases the caller can hold task_rq(p)->lock instead of p->pi_lock. So the comment is broken and this patch fixes it. Signed-off-by: NByungchul Park <byungchul.park@lge.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447806899-20303-1-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Geliang Tang 提交于
Use list_is_singular() to check if run_list has only one entry. Signed-off-by: NGeliang Tang <geliangtang@163.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a5453fafd735affcf28e53a1d0a3d6965cb5dbb5.1447582547.git.geliangtang@163.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Joonwoo Park 提交于
At present scheduler resets task's wait start timestamp when the task migrates to another rq. This misleads scheduler itself into reporting less wait time than actual by omitting time spent for waiting prior to migration and also more wait count than actual by counting migration as wait end event which can be seen by trace or /proc/<pid>/sched with CONFIG_SCHEDSTATS=y. Carry forward migrating task's wait time prior to migration and don't count migration as a wait end event to fix such statistics error. In order to determine whether task is migrating mark task->on_rq with TASK_ON_RQ_MIGRATING while dequeuing and enqueuing due to migration. Signed-off-by: NJoonwoo Park <joonwoop@codeaurora.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: ohaugan@codeaurora.org Link: http://lkml.kernel.org/r/20151113033854.GA4247@codeaurora.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Rik van Riel 提交于
There is a fundamental mismatch between the runtime based NUMA scanning at the task level, and the wall clock time NUMA scanning at the mm level. On a severely overloaded system, with very large processes, this mismatch can cause the system to spend all of its time in change_prot_numa(). This can happen if the task spends at least two ticks in change_prot_numa(), and only gets two ticks of CPU time in the real time between two scan intervals of the mm. This patch ensures that a task never spends more than 3% of run time scanning PTEs. It does that by ensuring that in-between task_numa_work() runs, the task spends at least 32x as much time on other things than it did on task_numa_work(). This is done stochastically: if a timer tick happens, or the task gets rescheduled during task_numa_work(), we delay a future run of task_numa_work() until the task has spent at least 32x the amount of CPU time doing something else, as it spent inside task_numa_work(). The longer task_numa_work() takes, the more likely it is this happens. If task_numa_work() takes very little time, chances are low that that code will do anything, but we will not care. Reported-and-tested-by: NJan Stancek <jstancek@redhat.com> Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mgorman@suse.de Link: http://lkml.kernel.org/r/1446756983-28173-3-git-send-email-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Byungchul Park 提交于
Usually the tick can be stopped for an idle CPU in NOHZ. However in NOHZ_FULL mode, a non-idle CPU's tick can also be stopped. However, update_cpu_load_nohz() does not consider the case a non-idle CPU's tick has been stopped at all. This patch makes the update_cpu_load_nohz() know if the calling path comes from NOHZ_FULL or idle NOHZ. Signed-off-by: NByungchul Park <byungchul.park@lge.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447115762-19734-3-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Byungchul Park 提交于
There are some cases where distance between ticks is more than one tick while the CPU is not idle, e.g. full NOHZ. However __update_cpu_load() assumes it is the idle tickless case if the distance between ticks is more than 1, even though it can be the active tickless case as well. Thus in the active tickless case, updating the CPU load will not be performed correctly. Where the current code assumes the load for each tick is zero, this is (obviously) not true in non-idle tickless case. We can approximately consider the load ~= this_rq->cpu_load[0] during tickless in non-idle tickless case. Signed-off-by: NByungchul Park <byungchul.park@lge.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1444816056-11886-2-git-send-email-byungchul.park@lge.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Dietmar Eggemann 提交于
Commit cd126afe ("sched/fair: Remove rq's runnable avg") got rid of rq->avg and so there is no need to update it any more when entering or exiting idle. Remove the now empty functions idle_{enter|exit}_fair(). Signed-off-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Link: http://lkml.kernel.org/r/1445342681-17171-1-git-send-email-dietmar.eggemann@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Arnd Bergmann 提交于
The push_irq_work_func() function is conditionally defined only when both CONFIG_SMP and HAVE_RT_PUSH_IPI are defined, but the forward declaration remains visibile without HAVE_RT_PUSH_IPI, causing a gcc warning in ARM64 allnoconfig: kernel/sched/rt.c:68:13: warning: 'push_irq_work_func' declared 'static' but never defined [-Wunused-function] This changes the code to use the same condition for both the declaration and the function definition, which gets rid of the warning. As Peter Zijlstra, we can possibly get rid of the whole HAVE_RT_PUSH_IPI thing after: 8053871d ("smp: Fix smp_call_function_single_async() locking") Until that is done, this patch can be used to avoid the warning. Signed-off-by: NArnd Bergmann <arnd@arndb.de> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: b6366f04 ("sched/rt: Use IPI to trigger RT task push migration instead of pulling") Link: http://lkml.kernel.org/r/3828565.oKfGk7yNIT@wuerfelSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 09 11月, 2015 1 次提交
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由 Rik van Riel 提交于
The NUMA balancing code implements delays in scanning by advancing curr->node_stamp beyond curr->se.sum_exec_runtime. With unsigned math, that creates an underflow, which results in task_numa_work being queued all the time, even when we don't want to. Avoiding the math underflow makes it possible to reduce CPU overhead in the NUMA balancing code. Reported-and-tested-by: NJan Stancek <jstancek@redhat.com> Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: mgorman@suse.de Link: http://lkml.kernel.org/r/1446756983-28173-2-git-send-email-riel@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 23 10月, 2015 1 次提交
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由 Peter Zijlstra 提交于
Luca and Wanpeng reported two missing annotations that led to false lockdep complaints. Add the missing annotations. Reported-by: NLuca Abeni <luca.abeni@unitn.it> Reported-by: NWanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: cbce1a68 ("sched,lockdep: Employ lock pinning") Link: http://lkml.kernel.org/r/20151023095008.GY17308@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 20 10月, 2015 7 次提交
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由 Oleg Nesterov 提交于
If CONFIG_CPUSETS=n then "case cpuset" changes the state and runs the already failed for_each_cpu() loop again for no reason. Signed-off-by: NOleg Nesterov <oleg@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: heiko.carstens@de.ibm.com Link: http://lkml.kernel.org/r/20151010185315.GA24100@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
The cpu_active() tests are not fundamentally part of stop_two_cpus(), move then into the scheduler where they belong. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Ensure the stopper thread is active 'early', because the load balancer pretty much assumes that its available. And when 'online && active' the load-balancer is fully available. Not only the numa balancing stop_two_cpus() caller relies on it, but also the self migration stuff does, and at CPU_ONLINE time the cpu really is 'free' to run anything. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: NOleg Nesterov <oleg@redhat.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: heiko.carstens@de.ibm.com Link: http://lkml.kernel.org/r/20151009160054.GA10176@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Luca Abeni 提交于
Commit: 9d514262 ("sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target") broke select_task_rq_dl() and find_lock_later_rq(), because it introduced a comparison between the local task's deadline and dl.earliest_dl.curr of the remote queue. However, if the remote runqueue does not contain any SCHED_DEADLINE task its earliest_dl.curr is 0 (always smaller than the deadline of the local task) and the remote runqueue is not selected for pushing. As a result, if an application creates multiple SCHED_DEADLINE threads, they will never be pushed to runqueues that do not already contain SCHED_DEADLINE tasks. This patch fixes the issue by checking if dl.dl_nr_running == 0. Signed-off-by: NLuca Abeni <luca.abeni@unitn.it> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@linux.intel.com> Fixes: 9d514262 ("sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target") Link: http://lkml.kernel.org/r/1444982781-15608-1-git-send-email-luca.abeni@unitn.itSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Frederic Weisbecker 提交于
This reverts: 8cb9764f ("nohz: Set isolcpus when nohz_full is set") We assumed that full-nohz users always want scheduler isolation on full dynticks CPUs, therefore we included full-nohz CPUs on cpu_isolated_map. This means that tasks run by default on CPUs outside the nohz_full range unless their affinity is explicity overwritten. This suits pure isolation workloads but when the machine is needed to run common workloads, the available sets of CPUs to run common tasks becomes reduced. We reach an extreme case when CONFIG_NO_HZ_FULL_ALL is enabled as it leaves only CPU 0 for non-isolation tasks, which makes people think that their supercomputer regressed to 90's UP - which is true in a sense. Some full-nohz users appear to be interested in running normal workloads either before or after an isolation workload. Full-nohz isn't optimized toward normal workloads but it's still better than UP performance. We are reaching a limitation in kernel presets here. Lets revert this cpu_isolated_map inclusion and let userspace do its own scheduler isolation using cpusets or explicit affinity settings. Reported-by: NIngo Molnar <mingo@kernel.org> Reported-by: NMike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NThomas Gleixner <tglx@linutronix.de> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dave Jones <davej@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Link: http://lkml.kernel.org/r/1444663283-30068-1-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Yuyang Du 提交于
When cfs_rq has cfs_rq->removed_load_avg set (when a task migrates from this cfs_rq), we need to update its contribution to the group's load_avg. This should not increase tg's update too much, because in most cases, the cfs_rq has already decayed its load_avg. Tested-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: NYuyang Du <yuyang.du@intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1444699103-20272-2-git-send-email-yuyang.du@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Yuyang Du 提交于
Commit: 9d89c257 ("sched/fair: Rewrite runnable load and utilization average tracking") led to an overly small weight for interactive group entities. The bad case can be easily reproduced when a number of CPU hogs compete for the CPUs at the same time (thanks to Mike). This is largly because the task group's load average tracking cross CPUs lags behind the real changes. To fix this we accelerate the group share distribution process by using the load.weight of the cfs_rq. This may increase the entire group's share, but we have to do so to protect the (fragile) interactive tasks, especially from CPU hogs. Reported-by: NMike Galbraith <umgwanakikbuti@gmail.com> Tested-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Tested-by: NMike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: NYuyang Du <yuyang.du@intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Acked-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1444699103-20272-1-git-send-email-yuyang.du@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 16 10月, 2015 1 次提交
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由 Tejun Heo 提交于
cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
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- 12 10月, 2015 1 次提交
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When using idle=poll, the preemptoff tracer is always showing the idle task as the culprit for long latencies. That happens because critical timings are not stopped before idle loop. This patch stops critical timings before entering the idle loop, starting it again after the idle loop. This problem does not affect the irqsoff tracer because interruptions are enabled before entering the idle loop. Signed-off-by: NDaniel Bristot de Oliveira <bristot@redhat.com> Reviewed-by: NLuis Claudio R. Goncalves <lgoncalv@redhat.com> Acked-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/10fc3705874aef11dbe152a068b591a7be1899b4.1444314899.git.bristot@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 07 10月, 2015 1 次提交
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由 Davidlohr Bueso 提交于
The new locktorture rtmutex_lock tests exercise priority boosting, which means that they need to set some tasks to real-time priority. To do this, they use sched_setscheduler_nocheck(). However, this is not exported to modules, which results in the following error when building locktorture as a module: ERROR: "sched_setscheduler_nocheck" [kernel/locking/locktorture.ko] undefined! This commit therefore adds an EXPORT_SYMBOL_GPL() to allow this function to be invoked from locktorture when built as a module. Reported-by: NStephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: NDavidlohr Bueso <dave@stgolabs.net> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: NIngo Molnar <mingo@kernel.org> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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- 06 10月, 2015 13 次提交
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由 xiaofeng.yan 提交于
The parameter "int next_cpu" in the following function is unused: migrate_task_rq(struct task_struct *p, int next_cpu) Remove it. Signed-off-by: Nxiaofeng.yan <yanxiaofeng@inspur.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1442991360-31945-1-git-send-email-yanxiaofeng@inspur.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Geliang Tang 提交于
(1) For !CONFIG_BUG cases, the bug call is a no-op, so we couldn't care less and the change is ok. (2) PPC and MIPS, which HAVE_ARCH_BUG_ON, do not rely on branch predictions as it seems to be pointless [1] and thus callers should not be trying to push an optimization in the first place. (3) For CONFIG_BUG and !HAVE_ARCH_BUG_ON cases, BUG_ON() contains an unlikely compiler flag already. Hence, we can drop unlikely behind BUG_ON(). [1] http://lkml.iu.edu/hypermail/linux/kernel/1101.3/02289.htmlSigned-off-by: NGeliang Tang <geliangtang@163.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/6fa7125979f98bbeac26e268271769b6ca935c8d.1444051018.git.geliangtang@163.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Mike Meyer reported the following bug: > During evaluation of some performance data, it was discovered thread > and run queue run_delay accounting data was inconsistent with the other > accounting data that was collected. Further investigation found under > certain circumstances execution time was leaking into the task and > run queue accounting of run_delay. > > Consider the following sequence: > > a. thread is running. > b. thread moves beween cgroups, changes scheduling class or priority. > c. thread sleeps OR > d. thread involuntarily gives up cpu. > > a. implies: > > thread->sched_info.last_queued = 0 > > a. and b. results in the following: > > 1. dequeue_task(rq, thread) > > sched_info_dequeued(rq, thread) > delta = 0 > > sched_info_reset_dequeued(thread) > thread->sched_info.last_queued = 0 > > thread->sched_info.run_delay += delta > > 2. enqueue_task(rq, thread) > > sched_info_queued(rq, thread) > > /* thread is still on cpu at this point. */ > thread->sched_info.last_queued = task_rq(thread)->clock; > > c. results in: > > dequeue_task(rq, thread) > > sched_info_dequeued(rq, thread) > > /* delta is execution time not run_delay. */ > delta = task_rq(thread)->clock - thread->sched_info.last_queued > > sched_info_reset_dequeued(thread) > thread->sched_info.last_queued = 0 > > thread->sched_info.run_delay += delta > > Since thread was running between enqueue_task(rq, thread) and > dequeue_task(rq, thread), the delta above is really execution > time and not run_delay. > > d. results in: > > __sched_info_switch(thread, next_thread) > > sched_info_depart(rq, thread) > > sched_info_queued(rq, thread) > > /* last_queued not updated due to being non-zero */ > return > > Since thread was running between enqueue_task(rq, thread) and > __sched_info_switch(thread, next_thread), the execution time > between enqueue_task(rq, thread) and > __sched_info_switch(thread, next_thread) now will become > associated with run_delay due to when last_queued was last updated. > This alternative patch solves the problem by not calling sched_info_{de,}queued() in {de,en}queue_task(). Therefore the sched_info state is preserved and things work as expected. By inlining the {de,en}queue_task() functions the new condition becomes (mostly) a compile-time constant and we'll not emit any new branch instructions. It even shrinks the code (due to inlining {en,de}queue_task()): $ size defconfig-build/kernel/sched/core.o defconfig-build/kernel/sched/core.o.orig text data bss dec hex filename 64019 23378 2344 89741 15e8d defconfig-build/kernel/sched/core.o 64149 23378 2344 89871 15f0f defconfig-build/kernel/sched/core.o.orig Reported-by: NMike Meyer <Mike.Meyer@Teradata.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20150930154413.GO3604@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Srikar Dronamraju 提交于
If static branch 'sched_numa_balancing' is enabled, it should kickstart NUMA balancing through task_tick_numa(). However the following commit: 2a595721 ("sched/numa: Convert sched_numa_balancing to a static_branch") erroneously disables this. Fix this anomaly by enabling task_tick_numa() when the static branch 'sched_numa_balancing' is enabled. Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443752305-27413-1-git-send-email-srikar@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Ingo requested I keep my debug check for the preempt_count invariant. Requested-by: NIngo Molnar <mingo@kernel.org> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
preempt_schedule_common() is marked notrace, but it does not use _notrace() preempt_count functions and __schedule() is also not marked notrace, which means that its perfectly possible to end up in the tracer from preempt_schedule_common(). Steve says: | Yep, there's some history to this. This was originally the issue that | caused function tracing to go into infinite recursion. But now we have | preempt_schedule_notrace(), which is used by the function tracer, and | that function must not be traced till preemption is disabled. | | Now if function tracing is running and we take an interrupt when | NEED_RESCHED is set, it calls | | preempt_schedule_common() (not traced) | | But then that calls preempt_disable() (traced) | | function tracer calls preempt_disable_notrace() followed by | preempt_enable_notrace() which will see NEED_RESCHED set, and it will | call preempt_schedule_notrace(), which stops the recursion, but | still calls __schedule() here, and that means when we return, we call | the __schedule() from preempt_schedule_common(). | | That said, I prefer this patch. Preemption is disabled before calling | __schedule(), and we get rid of a one round recursion with the | scheduler. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Since we stopped setting PREEMPT_ACTIVE, there is no need to mask it out of preempt_count() tests. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
When we warn about a preempt_count leak; reset the preempt_count to the known good value such that the problem does not ripple forward. This is most important on x86 which has a per cpu preempt_count that is not saved/restored (after this series). So if you schedule with an invalid (!2*PREEMPT_DISABLE_OFFSET) preempt_count the next task is messed up too. Enforcing this invariant limits the borkage to just the one task. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Now that nothing tests for PREEMPT_ACTIVE anymore, stop setting it. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
__trace_sched_switch_state() is the last remaining PREEMPT_ACTIVE user, move trace_sched_switch() from prepare_task_switch() to __schedule() and propagate the @preempt argument. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
There is only a single PREEMPT_ACTIVE use in the regular __schedule() path and that is to circumvent the task->state check. Since the code setting PREEMPT_ACTIVE is the immediate caller of __schedule() we can replace this with a function argument. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
Assuming units of PREEMPT_DISABLE_OFFSET for preempt_count() numbers. Now that TASK_DEAD no longer results in preempt_count() == 3 during scheduling, we will always call context_switch() with preempt_count() == 2. However, we don't always end up with preempt_count() == 2 in finish_task_switch() because new tasks get created with preempt_count() == 1. Create FORK_PREEMPT_COUNT and set it to 2 and use that in the right places. Note that we cannot use INIT_PREEMPT_COUNT as that serves another purpose (boot). After this, preempt_count() is invariant across the context switch, with exception of PREEMPT_ACTIVE. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
TASK_DEAD is special in that the final schedule call from do_exit() must be done with preemption disabled. This means we end up scheduling with a preempt_count() higher than usual (3 instead of the 'expected' 2). Since future patches will want to rely on an invariant preempt_count() value during schedule, fix this up. Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: NThomas Gleixner <tglx@linutronix.de> Reviewed-by: NFrederic Weisbecker <fweisbec@gmail.com> Reviewed-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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