Jason Wessel 9c106c119e softlockup: fix NMI hangs due to lock race - 2.6.26-rc regression ... The touch_nmi_watchdog() routine on x86 ultimately calls touch_softlockup_watchdog(). The problem is that to touch the softlockup watchdog, the cpu_clock code has to be called which could involve multiple cpu locks and can lead to a hard hang if one of the locks is held by a processor that is not going to return anytime soon (such as could be the case with kgdb or perhaps even with some other kind of exception). This patch causes the public version of the touch_softlockup_watchdog() to defer the cpu clock access to a later point. The test case for this problem is to use the following kernel config options: CONFIG_KGDB_TESTS=y CONFIG_KGDB_TESTS_ON_BOOT=y CONFIG_KGDB_TESTS_BOOT_STRING="V1F100I100000" It should be noted that kgdb test suite and these options were not available until 2.6.26-rc2, so it was necessary to patch the kgdb test suite during the bisection. I would consider this patch a regression fix because the problem first appeared in commit 27ec440779 when some logic was added to try to periodically sync the clocks. It was possible to work around this particular problem by simply not performing the sync anytime the system was in a critical context. This was ok until commit 3e51f33fcc, which added config option CONFIG_HAVE_UNSTABLE_SCHED_CLOCK and some multi-cpu locks to sync the clocks. It became clear that accessing this code from an nmi was the source of the lockups. Avoiding the access to the low level clock code from an code inside the NMI processing also fixed the problem with the 27ec44... commit. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2008-06-19 09:45:38 +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
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 1/1] audit_send_reply(): fix error-path memory leak	2008-05-17 03:30:22 -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	[PATCH] list_for_each_rcu must die: audit	2008-05-17 03:30:23 -04:00
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	capabilities: remain source compatible with 32-bit raw legacy capability support.	2008-05-31 16:36:16 -07:00
cgroup.c	cgroups: remove node_ prefix_from ns subsystem	2008-05-24 09:56:14 -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	cpuset: limit the input of cpuset.sched_relax_domain_level	2008-06-19 09:45:36 +02:00
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	signals: fix sigqueue_free() vs __exit_signal() race	2008-05-24 09:56:10 -07:00
extable.c
fork.c	[PATCH] dup_fd() fixes, part 1	2008-05-16 17:22:26 -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	kgdb: use common ascii helpers and put_unaligned_be32 helper	2008-05-28 12:49:56 -05:00
kmod.c	[PATCH] split linux/file.h	2008-05-01 13:08:16 -04:00
kprobes.c	kprobes: fix error checking of batch registration	2008-06-12 18:05:40 -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	modules: proper cleanup of kobject without CONFIG_SYSFS	2008-05-23 13:09:33 +10:00
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
pid.c	pids: introduce change_pid() helper	2008-04-30 08:29:48 -07:00
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
rcupdate.c
rcupreempt.c	rcupreempt: remove export of rcu_batches_completed_bh	2008-06-19 09:45:37 +02:00
rcupreempt_trace.c
rcutorture.c	kernel: explicitly include required header files under kernel/	2008-04-29 08:06:04 -07:00
relay.c	splice: fix sendfile() issue with relay	2008-05-28 14:49:27 +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
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rtmutex_common.h
rwsem.c
sched.c	cpuset: limit the input of cpuset.sched_relax_domain_level	2008-06-19 09:45:36 +02:00
sched_clock.c	sched: fix sched_clock_cpu()	2008-05-29 11:29:19 +02:00
sched_debug.c	revert ("sched: fair-group: SMP-nice for group scheduling")	2008-05-29 11:28:57 +02:00
sched_fair.c	sched: stop wake_affine from causing serious imbalance	2008-05-29 11:29:20 +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	revert ("sched: fair-group: SMP-nice for group scheduling")	2008-05-29 11:28:57 +02:00
sched_stats.h	show_schedstat(): fix memleak	2008-05-29 11:25:15 +02:00
seccomp.c
semaphore.c	Revert "semaphore: fix"	2008-05-10 20:43:22 -07:00
signal.c	posix timers: discard SI_TIMER signals on exec	2008-05-26 10:37:07 -07:00
softirq.c	Fix cpu hotplug problem in softirq code	2008-05-01 08:03:58 -07:00
softlockup.c	softlockup: fix NMI hangs due to lock race - 2.6.26-rc regression	2008-06-19 09:45:38 +02:00
spinlock.c
srcu.c
stacktrace.c
stop_machine.c	stop_machine: make stop_machine_run more virtualization friendly	2008-05-23 13:09:34 +10:00
sys.c	sys_prctl(): fix return of uninitialized value	2008-05-24 09:56:13 -07:00
sys_ni.c
sysctl.c	[PATCH] avoid multiplication overflows and signedness issues for max_fds	2008-05-16 17:22:52 -04:00
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