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4f48f8b7fd
linux/kernel
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Lai Jiangshan 4f48f8b7fd tracing: Fix circular dead lock in stack trace 
When we cat <debugfs>/tracing/stack_trace, we may cause circular lock:
sys_read()
  t_start()
     arch_spin_lock(&max_stack_lock);

  t_show()
     seq_printf(), vsnprintf() .... /* they are all trace-able,
       when they are traced, max_stack_lock may be required again. */

The following script can trigger this circular dead lock very easy:
#!/bin/bash

echo 1 > /proc/sys/kernel/stack_tracer_enabled

mount -t debugfs xxx /mnt > /dev/null 2>&1

(
# make check_stack() zealous to require max_stack_lock
for ((; ;))
{
	echo 1 > /mnt/tracing/stack_max_size
}
) &

for ((; ;))
{
	cat /mnt/tracing/stack_trace > /dev/null
}

To fix this bug, we increase the percpu trace_active before
require the lock.

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4B67D4F9.9080905@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-02-02 10:20:18 -05:00
..
gcov
irq genirq: Convert irq_desc.lock to raw_spinlock 2009-12-14 23:55:33 +01:00
power vt: introduce and use vt_kmsg_redirect() function 2009-12-15 08:53:28 -08:00
time clocksource: Prevent potential kgdb dead lock 2010-01-26 14:53:16 +01:00
trace tracing: Fix circular dead lock in stack trace 2010-02-02 10:20:18 -05:00
.gitignore
acct.c bsdacct: fix uid/gid misreporting 2009-12-15 08:53:10 -08:00
async.c
audit_tree.c fix more leaks in audit_tree.c tag_chunk() 2009-12-19 09:27:43 -08:00
audit_watch.c
audit.c
audit.h
auditfilter.c
auditsc.c Sanitize f_flags helpers 2009-12-22 12:27:34 -05:00
backtracetest.c
bounds.c kbuild: move bounds.h to include/generated 2009-12-12 13:08:14 +01:00
capability.c remove CONFIG_SECURITY_FILE_CAPABILITIES compile option 2009-11-24 15:06:47 +11:00
cgroup_freezer.c
cgroup.c cgroups: fix 2.6.32 regression causing BUG_ON() in cgroup_diput() 2010-01-11 09:34:05 -08:00
compat.c
configs.c
cpu.c sched: Correct printk whitespace in warning from cpu down task check 2010-01-28 06:59:55 +01:00
cpuset.c sched: Fix balance vs hotplug race 2009-12-06 21:10:56 +01:00
cred-internals.h
cred.c
delayacct.c
dma.c
exec_domain.c
exit.c do_wait() optimization: do not place sub-threads on task_struct->children list 2009-12-17 15:45:31 -08:00
extable.c
fork.c sched: Fix fork vs hotplug vs cpuset namespaces 2010-01-21 23:25:31 +01:00
freezer.c
futex_compat.c
futex.c futexes: Remove rw parameter from get_futex_key() 2010-01-13 09:17:36 +01:00
groups.c
hrtimer.c hrtimers: Convert to raw_spinlocks 2009-12-14 23:55:34 +01:00
hung_task.c softlockup: Fix hung_task_check_count sysctl 2009-11-27 06:21:57 +01:00
hw_breakpoint.c perf, hw_breakpoint, kgdb: Do not take mutex for kernel debugger 2010-01-30 08:42:21 +01:00
itimer.c itimers: Fix racy writes to cpu_itimer fields 2009-11-18 16:32:12 +01:00
kallsyms.c hw-breakpoints: Fix broken hw-breakpoint sample module 2009-11-10 11:23:29 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks mutex: Better control mutex adaptive spinning config 2009-12-03 11:50:11 +01:00
Kconfig.preempt
kexec.c Merge git://git.infradead.org/~dwmw2/mtd-2.6.33 2010-01-24 10:31:34 -08:00
kfifo.c kfifo: document everywhere that size has to be power of two 2010-01-16 12:15:38 -08:00
kgdb.c x86, hw_breakpoints, kgdb: Fix kgdb to use hw_breakpoint API 2010-01-30 08:42:20 +01:00
kmod.c kmod: fix resource leak in call_usermodehelper_pipe() 2010-01-11 09:34:04 -08:00
kprobes.c kprobes: Fix distinct type warning 2009-12-28 10:25:31 +01:00
ksysfs.c kexec: premit reduction of the reserved memory size 2009-12-16 07:20:13 -08:00
kthread.c sched: Move kthread_bind() back to kthread.c 2009-12-16 19:01:57 +01:00
latencytop.c
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
lockdep.c lockdep: Fix check_usage_backwards() error message 2010-01-27 08:34:02 +01:00
Makefile Merge branch 'kvm-updates/2.6.33' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2009-12-08 08:02:38 -08:00
module.c modules: Skip empty sections when exporting section notes 2010-01-06 01:11:29 -08:00
mutex-debug.c
mutex-debug.h locking: Implement new raw_spinlock 2009-12-14 23:55:32 +01:00
mutex.c mutex: Better control mutex adaptive spinning config 2009-12-03 11:50:11 +01:00
mutex.h
notifier.c
ns_cgroup.c
nsproxy.c
panic.c kmsg_dump: Dump on crash_kexec as well 2009-12-31 19:45:04 +00:00
params.c tree-wide: convert open calls to remove spaces to skip_spaces() lib function 2009-12-15 08:53:32 -08:00
perf_event.c perf: Honour event state for aux stream data 2010-01-21 13:40:40 +01:00
pid_namespace.c
pid.c pid: reduce code size by using a pointer to iterate over array 2009-12-16 07:20:12 -08:00
pm_qos_params.c pm_qos: clean up racy global "name" variable 2009-10-14 15:31:10 +02:00
posix-cpu-timers.c posix-cpu-timers: optimize and document timer_create callback 2009-11-18 12:36:05 +01:00
posix-timers.c
printk.c Merge git://git.infradead.org/~dwmw2/mtd-2.6.33 2010-01-24 10:31:34 -08:00
profile.c
ptrace.c
rcupdate.c rcu: Re-arrange code to reduce #ifdef pain 2009-11-22 18:58:16 +01:00
rcutiny.c rcu: Eliminate unneeded function wrapping 2009-11-22 18:58:16 +01:00
rcutorture.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2009-12-14 09:58:24 -08:00
rcutree_plugin.h rcu: Add expedited grace-period support for preemptible RCU 2009-12-03 11:35:25 +01:00
rcutree_trace.c rcu: Add expedited grace-period support for preemptible RCU 2009-12-03 11:35:25 +01:00
rcutree.c rcu: Add expedited grace-period support for preemptible RCU 2009-12-03 11:35:25 +01:00
rcutree.h rcu: Add expedited grace-period support for preemptible RCU 2009-12-03 11:35:25 +01:00
relay.c const: constify remaining pipe_buf_operations 2009-12-16 07:20:05 -08:00
res_counter.c
resource.c resources: fix call to alignf() in allocate_resource() 2009-12-21 10:42:29 -08:00
rtmutex_common.h
rtmutex-debug.c sched: Convert pi_lock to raw_spinlock 2009-12-14 23:55:33 +01:00
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c rtmutes: Convert rtmutex.lock to raw_spinlock 2009-12-14 23:55:33 +01:00
rtmutex.h
rwsem.c
sched_clock.c sched: Fix cpu_clock() in NMIs, on !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK 2009-12-15 09:04:36 +01:00
sched_cpupri.c sched: Convert cpupri lock to raw_spinlock 2009-12-14 23:55:33 +01:00
sched_cpupri.h sched: Convert cpupri lock to raw_spinlock 2009-12-14 23:55:33 +01:00
sched_debug.c sched: Convert rq->lock to raw_spinlock 2009-12-14 23:55:33 +01:00
sched_fair.c sched: Fix vmark regression on big machines 2010-01-21 13:39:03 +01:00
sched_features.h sched: Discard some old bits 2009-12-09 10:03:07 +01:00
sched_idletask.c sched: Restore printk sanity 2009-12-20 19:05:02 +01:00
sched_rt.c sched: Add pre and post wakeup hooks 2009-12-16 19:01:58 +01:00
sched_stats.h
sched.c sched: Fix fork vs hotplug vs cpuset namespaces 2010-01-21 23:25:31 +01:00
seccomp.c
semaphore.c
signal.c kernel/signal.c: fix kernel information leak with print-fatal-signals=1 2010-01-11 09:34:05 -08:00
slow-work-debugfs.c SLOW_WORK: Move slow_work's proc file to debugfs 2009-12-01 08:20:31 -08:00
slow-work.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6 2009-12-08 07:38:50 -08:00
slow-work.h SLOW_WORK: Move slow_work's proc file to debugfs 2009-12-01 08:20:31 -08:00
smp.c smp_call_function_any(): pass the node value to cpumask_of_node() 2010-01-16 12:15:39 -08:00
softirq.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2009-12-14 09:58:24 -08:00
softlockup.c percpu: make percpu symbols under kernel/ and mm/ unique 2009-10-29 22:34:13 +09:00
spinlock.c locking: Cleanup the name space completely 2009-12-14 23:55:33 +01:00
srcu.c rcu: Add synchronize_srcu_expedited() 2009-10-26 09:40:30 +01:00
stacktrace.c
stop_machine.c
sys_ni.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2009-12-08 07:55:01 -08:00
sys.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-19 09:47:34 -08:00
sysctl_binary.c SYSCTL: Print binary sysctl warnings (nearly) only once 2009-12-23 21:00:20 +01:00
sysctl_check.c ipv4 05/05: add sysctl to accept packets with local source addresses 2009-12-03 12:14:38 -08:00
sysctl.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6 2009-12-17 16:58:26 -08:00
taskstats.c
test_kprobes.c
time.c Revert "time: Remove xtime_cache" 2009-12-22 14:10:37 -08:00
timeconst.pl
timer.c perf: Fix perf_event_do_pending() fallback callsite 2010-01-21 13:40:39 +01:00
tracepoint.c
tsacct.c
uid16.c
up.c
user_namespace.c
user-return-notifier.c core: Clean up user return notifers use of per_cpu 2009-12-02 10:22:59 +01:00
user.c uids: Prevent tear down race 2009-11-02 16:02:39 +01:00
utsname_sysctl.c sysctl kernel: Remove binary sysctl logic 2009-11-12 02:04:55 -08:00
utsname.c
wait.c
workqueue.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2009-12-10 09:35:44 -08:00