Repository files (latest commit first)

Filename	Latest commit message	Latest commit date
Paul E. McKenney d7c0651390 rcu: fix rcu_try_flip_waitack_needed() to prevent grace-period stall ... The comment was correct -- need to make the code match the comment. Without this patch, if a CPU goes dynticks idle (and stays there forever) in just the right phase of preemptible-RCU grace-period processing, grace periods stall. The offending sequence of events (courtesy of Promela/spin, at least after I got the liveness criterion coded correctly...) is as follows: o CPU 0 is in dynticks-idle mode. Its dynticks_progress_counter is (say) 10. o CPU 0 takes an interrupt, so rcu_irq_enter() increments CPU 0's dynticks_progress_counter to 11. o CPU 1 is doing RCU grace-period processing in rcu_try_flip_idle(), sees rcu_pending(), so invokes dyntick_save_progress_counter(), which in turn takes a snapshot of CPU 0's dynticks_progress_counter into CPU 0's rcu_dyntick_snapshot -- now set to 11. CPU 1 then updates the RCU grace-period state to rcu_try_flip_waitack(). o CPU 0 returns from its interrupt, so rcu_irq_exit() increments CPU 0's dynticks_progress_counter to 12. o CPU 1 later invokes rcu_try_flip_waitack(), which notices that CPU 0 has not yet responded, and hence in turn invokes rcu_try_flip_waitack_needed(). This function examines the state of CPU 0's dynticks_progress_counter and rcu_dyntick_snapshot variables, which it copies to curr (== 12) and snap (== 11), respectively. Because curr!=snap, the first condition fails. Because curr-snap is only 1 and snap is odd, the second condition fails. rcu_try_flip_waitack_needed() therefore incorrectly concludes that it must wait for CPU 0 to explicitly acknowledge the counter flip. o CPU 0 remains forever in dynticks-idle mode, never taking any more hardware interrupts or any NMIs, and never running any more tasks. (Of course, -something- will usually eventually happen, which might be why we haven't seen this one in the wild. Still should be fixed!) Therefore the grace period never ends. Fix is to make the code match the comment, as shown below. With this fix, the above scenario would be satisfied with curr being even, and allow the grace period to proceed. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Josh Triplett <josh@kernel.org> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2008-05-19 10:03:38 +02:00
..
irq	genirq: reenable a nobody cared disabled irq when a new driver arrives	2008-05-02 13:40:34 +02:00
power	Merge branches 'release', 'acpica', 'bugzilla-10224', 'bugzilla-9772', 'bugzilla-9916', 'ec', 'eeepc', 'idle', 'misc', 'pm-legacy', 'sysfs-links-2.6.26', 'thermal', 'thinkpad' and 'video' into release	2008-04-30 13:58:00 -04:00
time	clocksource: allow read access to available/current_clocksource	2008-05-03 18:11:48 +02:00
.gitignore	Update kernel/.gitignore with new auto-generated files	2008-02-09 23:27:01 -08:00
acct.c	bsd_acct: using task_struct->tgid is not right in pid-namespaces	2008-03-24 19:22:20 -07:00
audit.c	[patch 2/2] Use find_task_by_vpid in audit code	2008-04-28 06:28:30 -04:00
audit.h	[PATCH 1/2] audit: move extern declarations to audit.h	2008-04-28 06:28:04 -04:00
audit_tree.c	Introduce path_put()	2008-02-14 21:13:33 -08:00
auditfilter.c	Merge branch 'audit.b50' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current	2008-04-29 11:41:22 -07:00
auditsc.c	[PATCH] new predicate - AUDIT_FILETYPE	2008-04-28 06:28:37 -04:00
backtracetest.c
bounds.c	Add kbuild.h that contains common definitions for kbuild users	2008-04-29 08:06:29 -07:00
capability.c
cgroup.c	mm: bdi: add separate writeback accounting capability	2008-04-30 08:29:50 -07:00
cgroup_debug.c	CGroup API files: move "releasable" to cgroup_debug subsystem	2008-04-29 08:06:09 -07:00
compat.c	ntp: support for TAI	2008-05-01 08:03:59 -07:00
configs.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
cpu.c	kernel: replace remaining __FUNCTION__ occurrences	2008-04-30 08:29:54 -07:00
cpuset.c	Fix cpuset sched_relax_domain_level control file	2008-05-08 10:46:56 -07:00
delayacct.c
dma.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
exec_domain.c
exit.c	[PATCH] split linux/file.h	2008-05-01 13:08:16 -04:00
extable.c
fork.c	[PATCH] split linux/file.h	2008-05-01 13:08:16 -04:00
futex.c	Removal of FUTEX_FD	2008-05-05 08:18:45 -07:00
futex_compat.c	futex_compat __user annotation	2008-03-30 14:18:41 -07:00
hrtimer.c	hrtimer: remove duplicate helper function	2008-05-03 18:11:48 +02:00
itimer.c
kallsyms.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
Kconfig.hz
Kconfig.preempt	rcu: move PREEMPT_RCU config option back under PREEMPT	2008-03-10 18:01:20 -07:00
kexec.c	kexec: make extended crashkernel= syntax less confusing	2008-05-01 08:04:00 -07:00
kfifo.c
kgdb.c	lib: create common ascii hex array	2008-05-14 19:11:14 -07:00
kmod.c	[PATCH] split linux/file.h	2008-05-01 13:08:16 -04:00
kprobes.c	kprobes: add (un)register_jprobes for batch registration	2008-04-28 08:58:32 -07:00
ksysfs.c
kthread.c	Deprecate find_task_by_pid()	2008-04-30 08:29:48 -07:00
latencytop.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
lockdep.c	Subject: lockdep: include all lock classes in all_lock_classes	2008-02-25 23:03:02 +01:00
lockdep_internals.h
lockdep_proc.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
Makefile	sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK	2008-05-05 23:56:18 +02:00
marker.c	make marker_debug static	2008-04-30 08:29:49 -07:00
module.c	module: don't ignore vermagic string if module doesn't have modversions	2008-05-09 07:45:18 -07:00
mutex-debug.c
mutex-debug.h
mutex.c
mutex.h
notifier.c	ipc: re-enable msgmni automatic recomputing msgmni if set to negative	2008-04-29 08:06:13 -07:00
ns_cgroup.c	cgroups: kernel/ns_cgroup.c should #include <linux/nsproxy.h>	2008-04-29 08:06:07 -07:00
nsproxy.c	ipc: sysvsem: refuse clone(CLONE_SYSVSEM|CLONE_NEWIPC)	2008-04-29 08:06:14 -07:00
panic.c	Taint kernel after WARN_ON(condition)	2008-04-29 08:05:59 -07:00
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	rcu: split list.h and move rcu-protected lists into rculist.h	2008-05-19 10:01:37 +02:00
pid_namespace.c	pidns: make pid->level and pid_ns->level unsigned	2008-04-30 08:29:49 -07:00
pm_qos_params.c
posix-cpu-timers.c	remove div_long_long_rem	2008-05-01 08:03:58 -07:00
posix-timers.c	signals: join send_sigqueue() with send_group_sigqueue()	2008-04-30 08:29:36 -07:00
printk.c	printk: don't read beyond string arguments' terminating zero	2008-04-30 08:29:52 -07:00
profile.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
ptrace.c	make generic sys_ptrace unconditional	2008-05-01 10:21:54 -07:00
rcuclassic.c	rcu: add memory barriers and comments to rcu_check_callbacks()	2008-05-19 10:01:36 +02:00
rcupdate.c	rcu: add rcu_barrier_sched() and rcu_barrier_bh()	2008-05-19 10:01:36 +02:00
rcupreempt.c	rcu: fix rcu_try_flip_waitack_needed() to prevent grace-period stall	2008-05-19 10:03:38 +02:00
rcupreempt_trace.c
rcutorture.c	rcu: add call_rcu_sched() and friends to rcutorture	2008-05-19 10:01:37 +02:00
relay.c	Revert "relay: fix splice problem"	2008-05-08 14:06:19 +02:00
res_counter.c	memcgroup: add the max_usage member on the res_counter	2008-04-29 08:06:10 -07:00
resource.c	kernel: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
rtmutex-debug.c	Don't operate with pid_t in rtmutex tester	2008-02-08 09:22:41 -08:00
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c	hrtimer: more hrtimer_init_sleeper() fallout.	2008-02-13 15:45:36 +01:00
rtmutex.h
rtmutex_common.h	Don't operate with pid_t in rtmutex tester	2008-02-08 09:22:41 -08:00
rwsem.c
sched.c	cgroups: fix compile warning	2008-05-14 19:11:14 -07:00
sched_clock.c	sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK	2008-05-05 23:56:18 +02:00
sched_debug.c	sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK	2008-05-05 23:56:18 +02:00
sched_fair.c	sched: fix weight calculations	2008-05-08 17:00:42 +02:00
sched_features.h	sched: /debug/sched_features	2008-04-19 19:45:00 +02:00
sched_idletask.c	sched: make rt_sched_class, idle_sched_class static	2008-05-05 23:56:17 +02:00
sched_rt.c	sched: fix RT task-wakeup logic	2008-05-05 23:56:18 +02:00
sched_stats.h	cpumask: use new cpus_scnprintf function	2008-04-19 19:44:59 +02:00
seccomp.c
semaphore.c	Revert "semaphore: fix"	2008-05-10 20:43:22 -07:00
signal.c	signals: add set_restore_sigmask	2008-04-30 08:29:37 -07:00
softirq.c	Fix cpu hotplug problem in softirq code	2008-05-01 08:03:58 -07:00
softlockup.c	softlockup: fix task state setting	2008-02-29 18:46:53 +01:00
spinlock.c
srcu.c
stacktrace.c
stop_machine.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/juhl/trivial	2008-04-21 16:36:46 -07:00
sys.c	pids: sys_getpgid: fix unsafe *pid usage, s/tasklist/rcu/	2008-04-30 08:29:49 -07:00
sys_ni.c
sysctl.c	sysctl: add the ->permissions callback on the ctl_table_root	2008-04-29 08:06:23 -07:00
sysctl_check.c
taskstats.c	Use find_task_by_vpid in taskstats	2008-04-30 08:29:48 -07:00
test_kprobes.c
time.c	Make constants in kernel/timeconst.h fixed 64 bits	2008-05-02 16:18:42 -07:00
timeconst.pl	Make constants in kernel/timeconst.h fixed 64 bits	2008-05-02 16:18:42 -07:00
timer.c	debugobjects: add timer specific object debugging code	2008-04-30 08:29:53 -07:00
tsacct.c
uid16.c	asmlinkage_protect replaces prevent_tail_call	2008-04-10 17:28:26 -07:00
user.c	alloc_uid: cleanup	2008-04-30 08:29:53 -07:00
user_namespace.c	eCryptfs: make key module subsystem respect namespaces	2008-04-29 08:06:07 -07:00
utsname.c	kernel: explicitly include required header files under kernel/	2008-04-29 08:06:04 -07:00
utsname_sysctl.c
wait.c
workqueue.c	workqueue: remove redundant function invocation	2008-05-01 08:04:02 -07:00