Paul E. McKenney 237c80c5c8 rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang ... If the following sequence of events occurs, then TREE_PREEMPT_RCU will hang waiting for a grace period to complete, eventually OOMing the system: o A TREE_PREEMPT_RCU build of the kernel is booted on a system with more than 64 physical CPUs present (32 on a 32-bit system). Alternatively, a TREE_PREEMPT_RCU build of the kernel is booted with RCU_FANOUT set to a sufficiently small value that the physical CPUs populate two or more leaf rcu_node structures. o A task is preempted in an RCU read-side critical section while running on a CPU corresponding to a given leaf rcu_node structure. o All CPUs corresponding to this same leaf rcu_node structure record quiescent states for the current grace period. o All of these same CPUs go offline (hence the need for enough physical CPUs to populate more than one leaf rcu_node structure). This causes the preempted task to be moved to the root rcu_node structure. At this point, there is nothing left to cause the quiescent state to be propagated up the rcu_node tree, so the current grace period never completes. The simplest fix, especially after considering the deadlock possibilities, is to detect this situation when the last CPU is offlined, and to set that CPU's ->qsmask bit in its leaf rcu_node structure. This will cause the next invocation of force_quiescent_state() to end the grace period. Without this fix, this hang can be triggered in an hour or so on some machines with rcutorture and random CPU onlining/offlining. With this fix, these same machines pass a full 10 hours of this sort of abuse. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <20091015162614.GA19131@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2009-10-15 20:33:01 +02:00
..
gcov	microblaze: Enable GCOV_PROFILE_ALL	2009-09-21 14:29:21 +02:00
irq	Merge branch 'irq-threaded-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-09-11 13:21:31 -07:00
power	headers: utsname.h redux	2009-09-23 18:13:10 -07:00
time	NOHZ: update idle state also when NOHZ is inactive	2009-10-07 13:05:05 +02:00
trace	Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-10-08 12:06:09 -07:00
.gitignore
acct.c	bsdacct: switch credentials for writing to the accounting file	2009-08-24 11:33:40 +10:00
async.c	async: Fix lack of boot-time console due to insufficient synchronization	2009-06-08 12:31:53 -07:00
audit.c	Audit: send signal info if selinux is disabled	2009-09-24 03:50:26 -04:00
audit.h	Fix rule eviction order for AUDIT_DIR	2009-06-24 00:02:38 -04:00
audit_tree.c	Fix rule eviction order for AUDIT_DIR	2009-06-24 00:02:38 -04:00
audit_watch.c	Audit: reorganize struct audit_watch to save 8 bytes	2009-09-24 03:50:25 -04:00
auditfilter.c	Audit: clean up all op= output to include string quoting	2009-06-24 00:00:52 -04:00
auditsc.c	Audit: rearrange audit_context to save 16 bytes per struct	2009-09-24 03:50:26 -04:00
backtracetest.c
bounds.c
capability.c
cgroup.c	cgroup: catch bad css refcnt at css_put	2009-10-01 16:11:12 -07:00
cgroup_freezer.c	cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time	2009-09-24 07:20:58 -07:00
compat.c
configs.c
cpu.c	Merge branch 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-09-15 09:19:38 -07:00
cpuset.c	cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time	2009-09-24 07:20:58 -07:00
cred-internals.h
cred.c	creds_are_invalid() needs to be exported for use by modules:	2009-09-23 11:02:26 -07:00
delayacct.c	headers: taskstats_kern.h trim	2009-09-18 09:48:52 -07:00
dma.c
exec_domain.c
exit.c	Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-10-08 12:16:35 -07:00
extable.c
fork.c	Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-10-08 12:16:35 -07:00
freezer.c	sched: fix nr_uninterruptible accounting of frozen tasks really	2009-07-18 14:19:53 +02:00
futex.c	futex: Check for NULL keys in match_futex	2009-10-14 22:00:14 +02:00
futex_compat.c	futex: Fix compat_futex to be same as futex for REQUEUE_PI	2009-08-10 15:41:12 +02:00
groups.c	groups: move code to kernel/groups.c	2009-06-16 19:47:48 -07:00
hrtimer.c	Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-10-05 12:04:16 -07:00
hung_task.c	sysctl: remove "struct file *" argument of ->proc_handler	2009-09-24 07:21:04 -07:00
itimer.c	itimers: Add tracepoints for itimer	2009-08-29 14:10:07 +02:00
kallsyms.c	kallsyms: use new arch_is_kernel_text()	2009-09-23 07:39:30 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.preempt
kexec.c	kexec: fix omitting offset in extended crashkernel syntax	2009-07-29 19:10:34 -07:00
kfifo.c	kfifo: Use "const" definitions	2009-09-19 13:13:17 -07:00
kgdb.c	sysrq, intel_fb: fix sysrq g collision	2009-05-15 07:56:24 -05:00
kmod.c	Revert "kmod: fix race in usermodehelper code"	2009-09-23 18:12:10 -07:00
kprobes.c	const: constify remaining file_operations	2009-10-01 16:11:11 -07:00
ksysfs.c
kthread.c	sched: Keep kthreads at default priority	2009-09-09 17:30:06 +02:00
latencytop.c
lockdep.c	lockdep: Use cpu_clock() for lockstat	2009-10-09 15:56:44 +02:00
lockdep_internals.h	lockdep: BFS cleanup	2009-07-24 10:53:29 +02:00
lockdep_proc.c	seq_file: constify seq_operations	2009-09-23 07:39:29 -07:00
lockdep_states.h
Makefile	cgroups: move the cgroup debug subsys into cgroup.c to access internal state	2009-09-24 07:20:57 -07:00
module.c	module: fix up CONFIG_KALLSYMS=n build.	2009-10-01 16:11:11 -07:00
mutex-debug.c
mutex-debug.h
mutex.c	Merge branch 'linus' into perfcounters/core	2009-06-11 17:55:42 +02:00
mutex.h
notifier.c
ns_cgroup.c	cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time	2009-09-24 07:20:58 -07:00
nsproxy.c	nsproxy: extract create_nsproxy()	2009-06-18 13:03:56 -07:00
panic.c	Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-10-08 12:16:35 -07:00
params.c	param: allow whitespace as kernel parameter separator	2009-09-25 00:32:58 +09:30
perf_event.c	perf_event: Provide vmalloc() based mmap() backing	2009-10-06 14:21:50 +02:00
pid.c	mm: also use alloc_large_system_hash() for the PID hash table	2009-09-22 07:17:38 -07:00
pid_namespace.c	pidns: deny CLONE_PARENT|CLONE_NEWPID combination	2009-09-24 07:21:04 -07:00
pm_qos_params.c
posix-cpu-timers.c	itimers: Add tracepoints for itimer	2009-08-29 14:10:07 +02:00
posix-timers.c	time: Introduce CLOCK_REALTIME_COARSE	2009-08-21 21:43:46 +02:00
printk.c	printk: add printk_delay to make messages readable for some scenarios	2009-09-23 07:39:28 -07:00
profile.c	kernel/profile.c: Switch /proc/irq/prof_cpu_mask to seq_file	2009-09-20 20:15:40 +02:00
ptrace.c	ptrace: __ptrace_detach: do __wake_up_parent() if we reap the tracee	2009-09-24 07:20:59 -07:00
rcupdate.c	rcu: Move rcu_barrier() to rcutree	2009-10-07 08:11:20 +02:00
rcutorture.c	rcu: Clean up code to address Ingo's checkpatch feedback	2009-09-23 19:46:30 +02:00
rcutree.c	rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang	2009-10-15 20:33:01 +02:00
rcutree.h	rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang	2009-10-15 20:33:01 +02:00
rcutree_plugin.h	rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang	2009-10-15 20:33:01 +02:00
rcutree_trace.c	rcu: Make hot-unplugged CPU relinquish its own RCU callbacks	2009-10-07 08:11:20 +02:00
relay.c	const: mark struct vm_struct_operations	2009-09-27 11:39:25 -07:00
res_counter.c	memcg: some modification to softlimit under hierarchical memory reclaim.	2009-10-01 16:11:13 -07:00
resource.c	walk system ram range	2009-09-23 07:39:41 -07:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c	rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock()	2009-08-06 05:50:21 +02:00
rtmutex.h
rtmutex_common.h
rwsem.c
sched.c	sched: Set correct normal_prio and prio values in sched_fork()	2009-10-05 13:42:20 +02:00
sched_clock.c	sched_clock: Fix atomicity/continuity bug by using cmpxchg64()	2009-09-30 22:56:10 +02:00
sched_cpupri.c	sched: Add new prio to cpupri before removing old prio	2009-08-02 14:26:09 +02:00
sched_cpupri.h
sched_debug.c	sched: Add new wakeup preemption mode: WAKEUP_RUNNING	2009-09-17 10:17:25 +02:00
sched_fair.c	sysctl: remove "struct file *" argument of ->proc_handler	2009-09-24 07:21:04 -07:00
sched_features.h	sched: Add new wakeup preemption mode: WAKEUP_RUNNING	2009-09-17 10:17:25 +02:00
sched_idletask.c	sched: Simplify sys_sched_rr_get_interval() system call	2009-09-21 09:53:55 +02:00
sched_rt.c	sched: Simplify sys_sched_rr_get_interval() system call	2009-09-21 09:53:55 +02:00
sched_stats.h
seccomp.c
semaphore.c
signal.c	signals: inline __fatal_signal_pending	2009-09-24 07:21:01 -07:00
slow-work.c	sysctl: remove "struct file *" argument of ->proc_handler	2009-09-24 07:21:04 -07:00
smp.c	cpumask: remove arch_send_call_function_ipi	2009-09-24 09:34:47 +09:30
softirq.c	softirq: add BLOCK_IOPOLL to softirq_to_name	2009-09-17 15:53:44 -04:00
softlockup.c	sysctl: remove "struct file *" argument of ->proc_handler	2009-09-24 07:21:04 -07:00
spinlock.c	locking: Allow arch-inlined spinlocks	2009-08-31 18:08:50 +02:00
srcu.c
stacktrace.c
stop_machine.c
sys.c	Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6	2009-09-24 07:53:22 -07:00
sys_ni.c	Merge branch 'master' of /home/davem/src/GIT/linux-2.6/	2009-09-24 15:13:11 -07:00
sysctl.c	Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6	2009-09-24 07:53:22 -07:00
sysctl_check.c
taskstats.c	genetlink: make netns aware	2009-07-12 14:03:27 -07:00
test_kprobes.c
time.c	time: Prevent 32 bit overflow with set_normalized_timespec()	2009-09-15 10:17:30 +02:00
timeconst.pl
timer.c	Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-09-23 09:46:15 -07:00
tracepoint.c	trivial: fix typo "to to" in multiple files	2009-09-21 15:14:55 +02:00
tsacct.c
uid16.c	headers: utsname.h redux	2009-09-23 18:13:10 -07:00
up.c
user.c	sched: delayed cleanup of user_struct	2009-06-15 21:30:23 -07:00
user_namespace.c
utsname.c	utsns: extract creeate_uts_ns()	2009-06-18 13:03:55 -07:00
utsname_sysctl.c	sysctl: remove "struct file *" argument of ->proc_handler	2009-09-24 07:21:04 -07:00
wait.c	locking, sched: Give waitqueue spinlocks their own lockdep classes	2009-08-10 14:43:09 +02:00
workqueue.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-09-11 13:23:18 -07:00