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b1cff0ad10
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Steven Rostedt b1cff0ad10 ftrace: Add internal recursive checks 
Witold reported a reboot caused by the selftests of the dynamic function
tracer. He sent me a config and I used ktest to do a config_bisect on it
(as my config did not cause the crash). It pointed out that the problem
config was CONFIG_PROVE_RCU.

What happened was that if multiple callbacks are attached to the
function tracer, we iterate a list of callbacks. Because the list is
managed by synchronize_sched() and preempt_disable, the access to the
pointers uses rcu_dereference_raw().

When PROVE_RCU is enabled, the rcu_dereference_raw() calls some
debugging functions, which happen to be traced. The tracing of the debug
function would then call rcu_dereference_raw() which would then call the
debug function and then... well you get the idea.

I first wrote two different patches to solve this bug.

1) add a __rcu_dereference_raw() that would not do any checks.
2) add notrace to the offending debug functions.

Both of these patches worked.

Talking with Paul McKenney on IRC, he suggested to add recursion
detection instead. This seemed to be a better solution, so I decided to
implement it. As the task_struct already has a trace_recursion to detect
recursion in the ring buffer, and that has a very small number it
allows, I decided to use that same variable to add flags that can detect
the recursion inside the infrastructure of the function tracer.

I plan to change it so that the task struct bit can be checked in
mcount, but as that requires changes to all archs, I will hold that off
to the next merge window.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1306348063.1465.116.camel@gandalf.stny.rr.com
Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-05-25 22:13:49 -04:00
..
debug Fix common misspellings 2011-03-31 11:26:23 -03:00
events Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 18:14:34 -07:00
gcov Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-03-20 18:14:55 -07:00
irq Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 17:30:15 -07:00
power PM: Allow drivers to allocate memory from .prepare() callbacks safely 2011-05-17 23:26:00 +02:00
time Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 17:45:08 -07:00
trace ftrace: Add internal recursive checks 2011-05-25 22:13:49 -04:00
.gitignore
acct.c
async.c
audit_tree.c Fix common misspellings 2011-03-31 11:26:23 -03:00
audit_watch.c kill path_lookup() 2011-03-14 09:15:23 -04:00
audit.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
audit.h audit: make functions static 2010-10-30 01:42:19 -04:00
auditfilter.c netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms 2011-03-03 10:55:40 -08:00
auditsc.c Fix common misspellings 2011-03-31 11:26:23 -03:00
backtracetest.c
bounds.c memcg: remove direct page_cgroup-to-page pointer 2011-03-23 19:46:28 -07:00
capability.c Cache user_ns in struct cred 2011-05-13 11:45:33 -07:00
cgroup_freezer.c cgroup_freezer: update_freezer_state() does incorrect state transitions 2010-10-27 18:03:08 -07:00
cgroup.c cgroup,rcu: convert call_rcu(__free_css_id_cb) to kfree_rcu() 2011-05-07 22:50:47 -07:00
compat.c posix-timers: Introduce a syscall for clock tuning. 2011-02-02 15:28:19 +01:00
configs.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
cpu.c Fix common misspellings 2011-03-31 11:26:23 -03:00
cpuset.c sched: Dynamic sched_domain::level 2011-04-11 14:09:32 +02:00
crash_dump.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
cred.c Cache user_ns in struct cred 2011-05-13 11:45:33 -07:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c ptrace: Prepare to fix racy accesses on task breakpoints 2011-04-25 17:28:24 +02:00
extable.c extable, core_kernel_data(): Make sure all archs define _sdata 2011-05-20 08:56:56 +02:00
fork.c sched: Remove unused parameters from sched_fork() and wake_up_new_task() 2011-05-12 09:36:37 +02:00
freezer.c Freezer: Use SMP barriers 2011-05-17 23:19:17 +02:00
futex_compat.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
futex.c futex: Set FLAGS_HAS_TIMEOUT during futex_wait restart setup 2011-04-15 16:34:32 +02:00
groups.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
hrtimer.c hrtimer: Make lookup table const 2011-05-02 21:37:57 +02:00
hung_task.c watchdog, hung_task_timeout: Add Kconfig configurable default 2011-04-28 09:13:17 +02:00
irq_work.c irq_work: Use per cpu atomics instead of regular atomics 2010-12-18 15:54:48 +01:00
itimer.c
jump_label.c jump_label: Check entries limit in __jump_label_update 2011-05-25 19:56:36 -04:00
kallsyms.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-25 17:52:22 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c PM: Remove sysdev suspend, resume and shutdown operations 2011-05-11 21:37:15 +02:00
kfifo.c kfifo: fix scatterlist usage 2010-10-01 10:50:58 -07:00
kmod.c kmod: always provide usermodehelper_disable() 2011-05-17 23:19:18 +02:00
kprobes.c Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-01-07 17:02:58 -08:00
ksysfs.c kernel/ksysfs.c: expose file_caps_enabled in sysfs 2011-04-19 16:45:51 -07:00
kthread.c Fix common misspellings 2011-03-31 11:26:23 -03:00
latencytop.c Fix common misspellings 2011-03-31 11:26:23 -03:00
lockdep_internals.h
lockdep_proc.c lockdep: Remove unused 'factor' variable from lockdep_stats_show() 2011-03-23 13:54:47 +01:00
lockdep_states.h
lockdep.c lockdep: Remove cmpxchg to update nr_chain_hlocks 2011-04-22 11:06:59 +02:00
Makefile hw breakpoints: Move to kernel/events/ 2011-05-03 15:26:43 +02:00
module.c module: Use binary search in lookup_symbol() 2011-05-19 16:55:27 +09:30
mutex-debug.c mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
mutex-debug.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
mutex.c sched: Get rid of lock_depth 2011-04-24 13:18:38 +02:00
mutex.h mutex: Use p->on_cpu for the adaptive spin 2011-04-14 08:52:33 +02:00
notifier.c
ns_cgroup.c cgroup: notify ns_cgroup deprecated 2010-10-27 18:03:09 -07:00
nsproxy.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
padata.c Fix common misspellings 2011-03-31 11:26:23 -03:00
panic.c move x86 specific oops=panic to generic code 2011-03-22 17:44:11 -07:00
params.c params.c: Use new strtobool function to process boolean inputs 2011-05-19 16:55:28 +09:30
pid_namespace.c pidns: call pid_ns_prepare_proc() from create_pid_namespace() 2011-03-23 19:46:58 -07:00
pid.c next_pidmap: fix overflow condition 2011-04-18 10:35:30 -07:00
pm_qos_params.c PM QoS: Make pm_qos settings readable 2011-03-15 00:43:18 +01:00
posix-cpu-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
posix-timers.c Fix common misspellings 2011-03-31 11:26:23 -03:00
printk.c printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig 2011-03-22 17:44:13 -07:00
profile.c profile: Use vzalloc() rather than vmalloc() & memset() 2010-10-31 09:47:26 +01:00
ptrace.c ptrace: Prepare to fix racy accesses on task breakpoints 2011-04-25 17:28:24 +02:00
range.c kernel/range.c: fix clean_sort_range() for the case of full array 2010-11-12 07:55:31 -08:00
rcupdate.c rcu: Use WARN_ON_ONCE for DEBUG_OBJECTS_RCU_HEAD warnings 2011-05-05 23:16:57 -07:00
rcutiny_plugin.h rcu: Converge TINY_RCU expedited and normal boosting 2011-05-05 23:16:58 -07:00
rcutiny.c rcu: optimize rcutiny 2011-05-05 23:16:59 -07:00
rcutorture.c rcu: mark rcutorture boosting callback as being on-stack 2011-05-05 23:16:57 -07:00
rcutree_plugin.h Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" 2011-05-19 23:25:29 +02:00
rcutree_trace.c Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" 2011-05-19 23:25:29 +02:00
rcutree.c Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" 2011-05-19 23:25:29 +02:00
rcutree.h Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" 2011-05-19 23:25:29 +02:00
relay.c Clean up relay_alloc_page_array() slightly by using vzalloc rather than vmalloc and memset 2010-11-05 08:21:34 -07:00
res_counter.c memcg: res_counter_read_u64(): fix potential races on 32-bit machines 2011-03-23 19:46:22 -07:00
resource.c resources: add arch hook for preventing allocation in reserved areas 2010-12-17 10:01:09 -08:00
rtmutex_common.h rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex-debug.h
rtmutex-tester.c rtmutex: tester: Remove the remaining BKL leftovers 2011-02-22 22:07:22 +01:00
rtmutex.c rtmutex: Simplify PI algorithm and make highest prio task get lock 2011-01-27 21:13:51 -05:00
rtmutex.h
rwsem.c
sched_autogroup.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sched_autogroup.h sched, autogroup: Stop going ahead if autogroup is disabled 2011-02-23 11:33:59 +01:00
sched_clock.c sched: Add some clock info to sched_debug 2010-11-23 10:29:08 +01:00
sched_cpupri.c
sched_cpupri.h
sched_debug.c sched: Get rid of lock_depth 2011-04-24 13:18:38 +02:00
sched_fair.c sched: Remove unused 'this_best_prio arg' from balance_tasks() 2011-05-04 09:07:21 +02:00
sched_features.h sched: Move the second half of ttwu() to the remote cpu 2011-04-14 08:52:41 +02:00
sched_idletask.c sched: Drop the rq argument to sched_class::select_task_rq() 2011-04-14 08:52:36 +02:00
sched_rt.c Merge branches 'sched-core-for-linus' and 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-05-19 17:41:22 -07:00
sched_stats.h sched_stat: Update sched_info_queue/dequeue() code comments 2010-10-24 13:29:01 +02:00
sched_stoptask.c sched: Drop the rq argument to sched_class::select_task_rq() 2011-04-14 08:52:36 +02:00
sched.c sched: Fix and optimise calculation of the weight-inverse 2011-05-16 11:01:18 +02:00
seccomp.c
semaphore.c
signal.c signal.c: fix erroneous syscall kernel-doc 2011-04-08 11:05:24 -07:00
smp.c smp: move smp setup functions to kernel/smp.c 2011-03-22 17:44:11 -07:00
softirq.c rcu: move TREE_RCU from softirq to kthread 2011-05-05 23:16:54 -07:00
spinlock.c
srcu.c rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status 2011-01-14 04:56:49 -08:00
stacktrace.c
stop_machine.c kthread: use kthread_create_on_node() 2011-03-22 17:44:01 -07:00
sys_ni.c vfs: Add open by file handle support 2011-03-15 02:21:44 -04:00
sys.c Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-05-19 18:24:11 -07:00
sysctl_binary.c open-style analog of vfs_path_lookup() 2011-03-14 09:15:28 -04:00
sysctl_check.c sysctl_check: drop dead code 2011-03-23 19:46:51 -07:00
sysctl.c watchdog: Disable watchdog when thresh is zero 2011-05-23 11:58:59 +02:00
taskstats.c taskstats: use appropriate printk priority level 2011-03-23 19:47:14 -07:00
test_kprobes.c kprobes: Fix selftest to clear flags field for reusing probes 2010-10-14 08:55:27 +02:00
time.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
timeconst.pl
timer.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 18:53:35 -07:00
tracepoint.c jump label: Introduce static_branch() interface 2011-04-04 12:48:08 -04:00
tsacct.c taskstats: use real microsecond granularity for CPU times 2010-10-27 18:03:17 -07:00
uid16.c userns: user namespaces: convert several capable() calls 2011-03-23 19:47:08 -07:00
up.c
user_namespace.c user_ns: improve the user_ns on-the-slab packaging 2011-01-13 08:03:18 -08:00
user-return-notifier.c Fix common misspellings 2011-03-31 11:26:23 -03:00
user.c userns: add a user_namespace as creator/owner of uts_namespace 2011-03-23 19:46:59 -07:00
utsname_sysctl.c
utsname.c userns: allow sethostname in a container 2011-03-23 19:47:03 -07:00
wait.c Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog.c watchdog: Fix non-standard prototype of get_softlockup_thresh() 2011-05-24 05:53:39 +02:00
workqueue_sched.h
workqueue.c workqueue: fix deadlock in worker_maybe_bind_and_lock() 2011-04-29 18:08:37 +02:00