Michal Hocko 7a05c0f7bb watchdog: make sure the watchdog thread gets CPU on loaded system ... If the system is loaded while hotplugging a CPU we might end up with a bogus hardlockup detection. This has been seen during LTP pounder test executed in parallel with hotplug test. The main problem is that enable_watchdog (called when CPU is brought up) registers perf event which periodically checks per-cpu counter (hrtimer_interrupts), updated from a hrtimer callback, but the hrtimer is fired from the kernel thread. This means that while we already do check for the hard lockup the kernel thread might be sitting on the runqueue with zillions of tasks so there is nobody to update the value we rely on and so we KABOOM. Let's fix this by boosting the watchdog thread priority before we wake it up rather than when it's already running. This still doesn't handle a case where we have the same amount of high prio FIFO tasks but that doesn't seem to be common. The current implementation doesn't handle that case anyway so this is not worse at least. Unfortunately, we cannot start perf counter from the watchdog thread because we could miss a real lock up and also we cannot start the hrtimer watchdog_enable because we there is no way (at least I don't know any) to start a hrtimer from a different CPU. [dzickus@redhat.com: fix compile issue with param] Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Mandeep Singh Baines <msb@chromium.org> Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2012-03-23 16:58:32 -07:00
..
debug	Fixes:	2012-03-23 09:29:44 -07:00
events	Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2012-03-20 18:11:21 -07:00
gcov
irq	Generialize powerpc's irq_host as irq_domain	2012-03-21 10:27:19 -07:00
power	Power management updates for 3.4	2012-03-21 10:15:51 -07:00
sched	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2012-03-21 13:25:04 -07:00
time	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input	2012-03-22 20:20:18 -07:00
trace	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2012-03-21 13:36:41 -07:00
.gitignore
acct.c	Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2012-01-08 12:19:57 -08:00
async.c	kernel/async: remove redundant declaration.	2012-01-13 09:32:18 +10:30
audit.c	constify path argument of audit_log_d_path()	2012-03-20 21:29:40 -04:00
audit.h	audit: remove AUDIT_SETUP_CONTEXT as it isn't used	2012-01-17 16:16:57 -05:00
audit_tree.c
audit_watch.c
auditfilter.c	audit: allow interfield comparison in audit rules	2012-01-17 16:17:01 -05:00
auditsc.c	kernel-doc: fix new warnings in auditsc.c	2012-01-23 08:44:53 -08:00
backtracetest.c
bounds.c
capability.c	Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call"	2012-01-17 10:19:41 -08:00
cgroup.c	Merge branch 'akpm' (Andrew's patch-bomb)	2012-03-22 09:04:48 -07:00
cgroup_freezer.c	cgroup: remove cgroup_subsys argument from callbacks	2012-02-02 09:20:22 -08:00
compat.c
configs.c
cpu.c	Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm	2012-01-08 13:10:57 -08:00
cpu_pm.c
cpuset.c	cpuset: mm: reduce large amounts of memory barrier related damage v3	2012-03-21 17:54:59 -07:00
crash_dump.c
cred.c	security: trim security.h	2012-02-14 10:45:42 +11:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	kernel/exit.c: if init dies, log a signal which killed it, if any	2012-03-23 16:58:32 -07:00
extable.c
fork.c	prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision	2012-03-23 16:58:32 -07:00
freezer.c	PM / Freezer: Remove references to TIF_FREEZE in comments	2012-03-04 23:08:54 +01:00
futex.c	Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-03-19 17:11:15 -07:00
futex_compat.c
groups.c
hrtimer.c
hung_task.c	hung_task: fix the broken rcu_lock_break() logic	2012-03-05 15:49:42 -08:00
irq_work.c
itimer.c
jump_label.c	static keys: Inline the static_key_enabled() function	2012-02-28 20:01:08 +01:00
kallsyms.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c	PM / Sleep: Introduce "late suspend" and "early resume" of devices	2012-01-29 20:38:29 +01:00
kfifo.c
kmod.c
kprobes.c	kprobes: return proper error code from register_kprobe()	2012-03-05 15:49:42 -08:00
ksysfs.c
kthread.c
latencytop.c
lockdep.c	lockdep: Add CPU-idle/offline warning to lockdep-RCU splat	2012-02-21 09:06:06 -08:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
Makefile	PM: Make sysrq-o be available for CONFIG_PM unset	2012-01-14 00:33:03 +01:00
module.c	error: implicit declaration of function 'module_flags_taint'	2012-01-15 16:21:07 -08:00
mutex-debug.c
mutex-debug.h
mutex.c	sched/rt: Use schedule_preempt_disabled()	2012-03-01 10:28:03 +01:00
mutex.h
notifier.c
nsproxy.c
padata.c	padata: Fix race on sequence number wrap	2012-03-14 17:25:56 +08:00
panic.c	panic: don't print redundant backtraces on oops	2012-01-12 20:13:11 -08:00
params.c	module: make module param bint handle nul value	2012-02-14 11:02:15 +10:30
pid.c	vfs: fix panic in __d_lookup() with high dentry hashtable counts	2012-02-13 20:45:38 -05:00
pid_namespace.c	sysctl: add the kernel.ns_last_pid control	2012-01-12 20:13:11 -08:00
posix-cpu-timers.c
posix-timers.c
printk.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-03-20 10:31:44 -07:00
profile.c
ptrace.c	Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-security	2012-01-14 18:36:33 -08:00
range.c
rcu.h	rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit()	2012-02-21 09:06:12 -08:00
rcupdate.c	rcu: Check for illegal use of RCU from offlined CPUs	2012-02-21 09:06:03 -08:00
rcutiny.c	rcu: Add RCU_NONIDLE() for idle-loop RCU read-side critical sections	2012-02-21 09:06:13 -08:00
rcutiny_plugin.h	rcu: Simplify unboosting checks	2012-02-21 09:03:43 -08:00
rcutorture.c	PTR_ERR should be called before its argument is cleared.	2012-02-21 09:06:10 -08:00
rcutree.c	rcu: Stop spurious warnings from synchronize_sched_expedited	2012-02-21 15:33:34 -08:00
rcutree.h	rcu: Rework detection of use of RCU by offline CPUs	2012-02-21 09:06:07 -08:00
rcutree_plugin.h	rcu: Hold off RCU_FAST_NO_HZ after timer posted	2012-02-21 09:42:30 -08:00
rcutree_trace.c	rcu: Rework detection of use of RCU by offline CPUs	2012-02-21 09:06:07 -08:00
relay.c	relay: prevent integer overflow in relay_open()	2012-02-10 09:04:49 +01:00
res_counter.c	net: introduce res_counter_charge_nofail() for socket allocations	2012-01-22 15:08:46 -05:00
resource.c	kernel/resource.c: move EXPORT_SYMBOL right after definition	2012-02-03 23:37:07 +01:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rtmutex_common.h
rwsem.c
seccomp.c	seccomp: audit abnormal end to a process due to seccomp	2012-01-17 16:16:55 -05:00
semaphore.c
signal.c	exit_signal: fix the "parent has changed security domain" logic	2012-03-20 14:16:50 -07:00
smp.c
softirq.c	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-03-20 10:32:09 -07:00
spinlock.c
srcu.c	rcu: Call out dangers of expedited RCU primitives	2012-02-21 09:06:08 -08:00
stacktrace.c
stop_machine.c
sys.c	prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision	2012-03-23 16:58:32 -07:00
sys_ni.c
sysctl.c	security: trim security.h	2012-02-14 10:45:42 +11:00
sysctl_binary.c
sysctl_check.c
taskstats.c
test_kprobes.c
time.c
timeconst.pl
timer.c
tracepoint.c	static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()	2012-02-24 10:05:59 +01:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
wait.c
watchdog.c	watchdog: make sure the watchdog thread gets CPU on loaded system	2012-03-23 16:58:32 -07:00
workqueue.c	Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq	2012-03-20 18:13:22 -07:00
workqueue_sched.h