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Steven Rostedt 6fa46fa526 sched: balance RT task resched only on runqueue 
Sripathi Kodi reported a crash in the -rt kernel:

  https://bugzilla.redhat.com/show_bug.cgi?id=435674

this is due to a place that can reschedule a task without holding
the tasks runqueue lock.  This was caused by the RT balancing code
that pulls RT tasks to the current run queue and will reschedule the
current task.

There's a slight chance that the pulling of the RT tasks will release
the current runqueue's lock and retake it (in the double_lock_balance).
During this time that the runqueue is released, the current task can
migrate to another runqueue.

In the prio_changed_rt code, after the pull, if the current task is of
lesser priority than one of the RT tasks pulled, resched_task is called
on the current task. If the current task had migrated in that small
window, resched_task will be called without holding the runqueue lock
for the runqueue that the task is on.

This race condition also exists in the mainline kernel and this patch
adds a check to make sure the task hasn't migrated before calling
resched_task.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Tested-by: Sripathi Kodi <sripathik@in.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
 		2008-03-07 16:43:00 +01:00
..
irq genirq: do not leave interupts enabled on free_irq 2008-02-19 10:43:58 +01:00
power freezer vs stopped or traced 2008-03-04 07:59:54 -08:00
time rcu: add support for dynamic ticks and preempt rcu 2008-02-29 18:46:50 +01:00
.gitignore Update kernel/.gitignore with new auto-generated files 2008-02-09 23:27:01 -08:00
Kconfig.hz sched: high-res preemption tick 2008-01-25 21:08:29 +01:00
Kconfig.preempt sched: remove the !PREEMPT_BKL code 2008-01-25 21:08:33 +01:00
Makefile avoid overflows in kernel/time.c 2008-02-08 09:22:39 -08:00
acct.c acct: real_parent ppid 2008-01-07 14:55:37 -08:00
audit.c [PATCH] drop EOE records from printk 2008-03-01 07:16:06 -05:00
audit.h [PATCH] audit: watching subtrees 2007-10-21 02:37:45 -04:00
audit_tree.c Introduce path_put() 2008-02-14 21:13:33 -08:00
auditfilter.c Introduce path_put() 2008-02-14 21:13:33 -08:00
auditsc.c [PATCH] Audit: Fix the format type for size_t variables 2008-03-01 07:16:06 -05:00
backtracetest.c x86: add a simple backtrace test module 2008-01-30 13:33:08 +01:00
capability.c Add 64-bit capability support to the kernel 2008-02-05 09:44:20 -08:00
cgroup.c cgroup: fix default notify_on_release setting 2008-03-04 16:35:09 -08:00
cgroup_debug.c Task Control Groups: simple task cgroup debug info subsystem 2007-10-19 11:53:36 -07:00
compat.c hrtimer: don't modify restart_block->fn in restart functions 2008-02-10 10:48:03 +01:00
configs.c use simple_read_from_buffer in kernel/ 2007-05-09 12:30:49 -07:00
cpu.c cpu: fix section mismatch warnings for enable_nonboot_cpus 2008-02-08 09:22:41 -08:00
cpuset.c cpusets: fix obsolete comment 2008-03-05 17:53:33 -08:00
delayacct.c Add scaled time to taskstats based process accounting 2007-10-18 14:37:28 -07:00
dma.c whitespace fixes: DMA channel allocator 2007-10-18 14:37:24 -07:00
exec_domain.c whitespace fixes: execution domains 2007-10-18 14:37:26 -07:00
exit.c exit_notify: fix kill_orphaned_pgrp() usage with mt exit 2008-03-03 14:53:16 -08:00
extable.c module: Don't report discarded init pages as kernel text. 2008-01-29 17:13:18 +11:00
fork.c Use struct path in fs_struct 2008-02-14 21:13:33 -08:00
futex.c futex: runtime enable pi and robust functionality 2008-02-23 17:12:15 -08:00
futex_compat.c futex: runtime enable pi and robust functionality 2008-02-23 17:12:15 -08:00
hrtimer.c hrtimer: catch expired CLOCK_REALTIME timers early 2008-02-14 22:08:30 +01:00
itimer.c ITIMER_REAL: convert to use struct pid 2008-02-08 09:22:29 -08:00
kallsyms.c remove support for un-needed _extratext section 2008-02-06 10:41:01 -08:00
kexec.c vmcoreinfo: add "VMCOREINFO_" to all the call for vmcoreinfo_append_str() 2008-02-07 08:42:25 -08:00
kfifo.c is_power_of_2: kernel/kfifo.c 2007-07-16 09:05:50 -07:00
kmod.c Dont touch fs_struct in usermodehelper 2008-02-14 21:13:32 -08:00
kprobes.c kprobes: fix a null pointer bug in register_kretprobe() 2008-03-04 16:35:19 -08:00
ksysfs.c Kobject: convert remaining kobject_unregister() to kobject_put() 2008-01-24 20:40:40 -08:00
kthread.c sched: fix, always create kernel threads with normal priority 2008-01-25 21:08:33 +01:00
latencytop.c sched: latencytop support 2008-01-25 21:08:34 +01:00
lockdep.c Subject: lockdep: include all lock classes in all_lock_classes 2008-02-25 23:03:02 +01:00
lockdep_internals.h [PATCH] lockdep: more chains 2006-12-07 08:39:43 -08:00
lockdep_proc.c lockdep: Avoid /proc/lockdep & lock_stat infinite output 2007-10-11 22:11:11 +02:00
marker.c markers: don't risk NULL deref in marker 2008-03-04 16:35:14 -08:00
module.c module: allow ndiswrapper to use GPL-only symbols 2008-03-04 20:29:40 -08:00
mutex-debug.c kernel: remove fastcall in kernel/* 2008-02-08 09:22:31 -08:00
mutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
mutex.c kernel: remove fastcall in kernel/* 2008-02-08 09:22:31 -08:00
mutex.h [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
notifier.c kernel/notifier.c should #include <linux/reboot.h> 2008-02-06 10:41:02 -08:00
ns_cgroup.c cgroups: implement namespace tracking subsystem 2007-10-19 11:53:37 -07:00
nsproxy.c namespaces: move the IPC namespace under IPC_NS option 2008-02-08 09:22:23 -08:00
panic.c ACPI: Taint kernel on ACPI table override (format corrected) 2008-02-06 22:07:51 -05:00
params.c Add new string functions strict_strto* and convert kernel params to use them 2008-02-08 09:22:41 -08:00
pid.c kernel: remove fastcall in kernel/* 2008-02-08 09:22:31 -08:00
pid_namespace.c namespaces: cleanup the code managed with PID_NS option 2008-02-08 09:22:23 -08:00
pm_qos_params.c pm qos infrastructure and interface 2008-02-05 09:44:22 -08:00
posix-cpu-timers.c Use find_task_by_vpid in posix timers 2008-02-08 09:22:41 -08:00
posix-timers.c hrtimer: check relative timeouts for overflow 2008-02-14 22:08:30 +01:00
printk.c printk: fix possible printk overrun 2008-02-26 07:42:37 -08:00
profile.c Nuke a duplicate include from profile.c 2008-02-08 09:22:34 -08:00
ptrace.c ptrace_check_attach: remove unneeded ->signal != NULL check 2008-02-08 09:22:26 -08:00
rcuclassic.c Preempt-RCU: implementation 2008-01-25 21:08:24 +01:00
rcupdate.c rcupdate: fix comment 2008-02-13 16:21:18 -08:00
rcupreempt.c rcupreempt: remove never-migrates assumption from rcu_process_callbacks() 2008-02-29 20:21:13 +01:00
rcupreempt_trace.c Preempt-RCU: implementation 2008-01-25 21:08:24 +01:00
rcutorture.c cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus() 2008-01-25 21:08:02 +01:00
relay.c relay: nopage 2008-02-06 10:41:07 -08:00
res_counter.c Memory Resource Controller use strstrip while parsing arguments 2008-03-04 16:35:09 -08:00
resource.c [POWERPC] Add arch-specific walk_memory_remove() for 64-bit powerpc 2008-02-08 19:52:48 +11:00
rtmutex-debug.c Don't operate with pid_t in rtmutex tester 2008-02-08 09:22:41 -08:00
rtmutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex-tester.c Driver core: change sysdev classes to use dynamic kobject names 2008-01-24 20:40:40 -08:00
rtmutex.c hrtimer: more hrtimer_init_sleeper() fallout. 2008-02-13 15:45:36 +01:00
rtmutex.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex_common.h Don't operate with pid_t in rtmutex tester 2008-02-08 09:22:41 -08:00
rwsem.c sched: mark rwsem functions as __sched for wchan/profiling 2007-12-18 15:21:13 +01:00
sched.c sched: retain vruntime 2008-03-07 16:42:59 +01:00
sched_debug.c sched: keep total / count stats in addition to the max for 2008-01-25 21:08:35 +01:00
sched_fair.c sched: retain vruntime 2008-03-07 16:42:59 +01:00
sched_idletask.c sched: high-res preemption tick 2008-01-25 21:08:29 +01:00
sched_rt.c sched: balance RT task resched only on runqueue 2008-03-07 16:43:00 +01:00
sched_stats.h sched: clean up kernel/sched_stat.h 2007-11-28 15:52:56 +01:00
seccomp.c make seccomp zerocost in schedule 2007-07-16 09:05:50 -07:00
signal.c freezer vs stopped or traced 2008-03-04 07:59:54 -08:00
softirq.c rcu: add support for dynamic ticks and preempt rcu 2008-02-29 18:46:50 +01:00
softlockup.c softlockup: fix task state setting 2008-02-29 18:46:53 +01:00
spinlock.c spinlock: lockbreak cleanup 2008-01-30 13:31:20 +01:00
srcu.c make srcu_readers_active() static 2008-02-06 10:41:02 -08:00
stacktrace.c [PATCH] lockdep: stacktrace subsystem, core 2006-07-03 15:27:02 -07:00
stop_machine.c stopmachine: semaphore to mutex 2008-02-06 10:41:08 -08:00
sys.c Pidns: make full use of xxx_vnr() calls 2008-02-08 09:22:29 -08:00
sys_ni.c timerfd: new timerfd API 2008-02-05 09:44:07 -08:00
sysctl.c sched: revert load_balance_monitor() changes 2008-03-04 17:54:06 +01:00
sysctl_check.c constify tables in kernel/sysctl_check.c 2008-02-08 09:22:31 -08:00
taskstats.c kernel/taskstats.c: fix bogus nlmsg_free() 2007-11-14 18:45:44 -08:00
test_kprobes.c kprobes: kretprobe user entry-handler 2008-02-06 10:41:11 -08:00
time.c avoid overflows in kernel/time.c 2008-02-08 09:22:39 -08:00
timeconst.pl timeconst.pl: correct reversal of USEC_TO_HZ and HZ_TO_USEC 2008-02-12 14:29:26 -08:00
timer.c kernel: remove fastcall in kernel/* 2008-02-08 09:22:31 -08:00
tsacct.c Add scaled time to taskstats based process accounting 2007-10-18 14:37:28 -07:00
uid16.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
user.c sched: rt-group: make rt groups scheduling configurable 2008-02-13 15:45:40 +01:00
user_namespace.c namespaces: cleanup the code managed with the USER_NS option 2008-02-08 09:22:23 -08:00
utsname.c Fix UTS corruption during clone(CLONE_NEWUTS) 2007-09-19 11:24:17 -07:00
utsname_sysctl.c Isolate the UTS namespace's domainname and hostname back 2007-11-29 09:24:53 -08:00
wait.c kernel: remove fastcall in kernel/* 2008-02-08 09:22:31 -08:00
workqueue.c workqueue: make delayed_work_timer_fn() static 2008-02-08 09:22:37 -08:00