Peter Zijlstra eced1dfcfc perf_counter: Fix /0 bug in swcounters ...

We have a race in the swcounter stuff where we can start
counting a counter that has never been enabled, this leads to a
/0 situation.

The below avoids the /0 but doesn't close the race, this would
need a new counter state.

The race is due to perf_swcounter_is_counting() which cannot
discern between disabled due to scheduled out, and disabled for
any other reason.

Such a crash has been seen by Ingo:

[  967.092372] divide error: 0000 [#1] SMP
[  967.096499] last sysfs file: /sys/devices/system/cpu/cpu15/cache/index2/shared_cpu_map
[  967.104846] CPU 5
[  967.106965] Modules linked in:
[  967.110169] Pid: 3351, comm: hackbench Not tainted 2.6.31-rc8-tip-01158-gd940a54-dirty #1568 X8DTN
[  967.119456] RIP: 0010:[<ffffffff810c0aba>]  [<ffffffff810c0aba>] perf_swcounter_ctx_event+0x127/0x1af
[  967.129137] RSP: 0018:ffff8801a95abd70  EFLAGS: 00010046
[  967.134699] RAX: 0000000000000002 RBX: ffff8801bd645c00 RCX: 0000000000000002
[  967.142162] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801bd645d40
[  967.149584] RBP: ffff8801a95abdb0 R08: 0000000000000001 R09: ffff8801a95abe00
[  967.157042] R10: 0000000000000037 R11: ffff8801aa1245f8 R12: ffff8801a95abe00
[  967.164481] R13: ffff8801a95abe00 R14: ffff8801aa1c0e78 R15: 0000000000000001
[  967.171953] FS:  0000000000000000(0000) GS:ffffc90000a00000(0063) knlGS:00000000f7f486c0
[  967.180406] CS:  0010 DS: 002b ES: 002b CR0: 000000008005003b
[  967.186374] CR2: 000000004822c0ac CR3: 00000001b19a2000 CR4: 00000000000006e0
[  967.193770] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  967.201224] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  967.208692] Process hackbench (pid: 3351, threadinfo ffff8801a95aa000, task ffff8801a96b0000)
[  967.217607] Stack:
[  967.219711]  0000000000000000 0000000000000037 0000000200000001 ffffc90000a1107c
[  967.227296] <0> ffff8801a95abe00 0000000000000001 0000000000000001 0000000000000037
[  967.235333] <0> ffff8801a95abdf0 ffffffff810c0c20 0000000200a14f30 ffff8801a95abe40
[  967.243532] Call Trace:
[  967.246103]  [<ffffffff810c0c20>] do_perf_swcounter_event+0xde/0xec
[  967.252635]  [<ffffffff810c0ca7>] perf_tpcounter_event+0x79/0x7b
[  967.258957]  [<ffffffff81037f73>] ftrace_profile_sched_switch+0xc0/0xcb
[  967.265791]  [<ffffffff8155f22d>] schedule+0x429/0x4c4
[  967.271156]  [<ffffffff8100c01e>] int_careful+0xd/0x14

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1251472247.17617.74.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2009-08-29 13:20:11 +02:00

..

gcov

gcov: enable GCOV_PROFILE_ALL for x86_64

2009-06-18 13:03:58 -07:00

irq

genirq: Wake up irq thread after action has been installed

2009-08-18 17:22:43 +02:00

power

headers: smp_lock.h redux

2009-07-12 12:22:34 -07:00

time

clockevent: Prevent dead lock on clockevents_lock

2009-08-19 18:15:10 +02:00

trace

tracing: handle broken names in ftrace filter

2009-08-18 20:39:48 -04:00

.gitignore

…

acct.c

bsdacct: fix access to invalid filp in acct_on()

2009-06-30 18:56:00 -07:00

async.c

async: Fix lack of boot-time console due to insufficient synchronization

2009-06-08 12:31:53 -07:00

audit_tree.c

Fix rule eviction order for AUDIT_DIR

2009-06-24 00:02:38 -04:00

audit_watch.c

Audit: clean up all op= output to include string quoting

2009-06-24 00:00:52 -04:00

audit.c

Fix rule eviction order for AUDIT_DIR

2009-06-24 00:02:38 -04:00

audit.h

Fix rule eviction order for AUDIT_DIR

2009-06-24 00:02:38 -04:00

auditfilter.c

Audit: clean up all op= output to include string quoting

2009-06-24 00:00:52 -04:00

auditsc.c

Fix rule eviction order for AUDIT_DIR

2009-06-24 00:02:38 -04:00

backtracetest.c

…

bounds.c

…

capability.c

…

cgroup_debug.c

debug cgroup: remove unneeded cgroup_lock

2009-04-02 19:04:54 -07:00

cgroup_freezer.c

…

cgroup.c

cgroup avoid permanent sleep at rmdir

2009-07-29 19:10:35 -07:00

compat.c

signals: implement sys_rt_tgsigqueueinfo

2009-04-30 19:24:24 +02:00

configs.c

…

cpu.c

mm/init: cpu_hotplug_init() must be initialized before SLAB

2009-06-22 21:18:12 -07:00

cpuset.c

cpuset,mm: update tasks' mems_allowed in time

2009-06-16 19:47:31 -07:00

cred-internals.h

…

cred.c

CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace

2009-05-11 08:15:36 +10:00

delayacct.c

…

dma-coherent.c

…

dma.c

…

exec_domain.c

Get rid of indirect include of fs_struct.h

2009-03-31 23:00:27 -04:00

exit.c

headers: mnt_namespace.h redux

2009-07-08 09:31:56 -07:00

extable.c

Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-04-05 11:04:19 -07:00

fork.c

clone(): fix race between copy_process() and de_thread()

2009-08-26 20:06:52 -07:00

freezer.c

sched: fix nr_uninterruptible accounting of frozen tasks really

2009-07-18 14:19:53 +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

futex.c

futex: Fix handling of bad requeue syscall pairing

2009-08-10 20:38:11 +02:00

groups.c

groups: move code to kernel/groups.c

2009-06-16 19:47:48 -07:00

hrtimer.c

hrtimer: Fix migration expiry check

2009-07-10 17:32:55 +02:00

hung_task.c

…

itimer.c

…

kallsyms.c

kernel/kallsyms.c: replace deprecated __initcall with device_initcall and fix whitespace

2009-06-09 22:37:52 +02:00

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

kernel/kfifo.c: replace conditional test with is_power_of_2()

2009-06-16 19:47:47 -07:00

kgdb.c

sysrq, intel_fb: fix sysrq g collision

2009-05-15 07:56:24 -05:00

kmod.c

headers: mnt_namespace.h redux

2009-07-08 09:31:56 -07:00

kprobes.c

kprobes: Use kernel_text_address() for checking probe address

2009-07-30 16:44:06 -07:00

ksysfs.c

…

kthread.c

update the comment in kthread_stop()

2009-07-27 12:15:46 -07:00

latencytop.c

…

lockdep_internals.h

lockdep: increase MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS

2009-05-12 19:59:52 +02:00

lockdep_proc.c

lockdep: Fix file mode of lock_stat

2009-08-07 11:58:38 +02:00

lockdep_states.h

…

lockdep.c

Merge branch 'linus' into tracing/core

2009-05-07 11:17:34 +02:00

Makefile

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-06-28 11:05:04 -07:00

marker.c

…

module.c

module: workaround duplicate section names

2009-08-27 12:33:19 -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: relax ns_can_attach checks to allow attaching to grandchild cgroups

2009-04-02 19:04:53 -07:00

nsproxy.c

nsproxy: extract create_nsproxy()

2009-06-18 13:03:56 -07:00

panic.c

trace: stop tracer in oops_enter()

2009-07-24 15:30:45 -04:00

params.c

module_param: allow 'bool' module_params to be bool, not just int.

2009-06-12 21:46:58 +09:30

perf_counter.c

perf_counter: Fix /0 bug in swcounters

2009-08-29 13:20:11 +02:00

pid_namespace.c

pidns: rewrite copy_pid_ns()

2009-06-18 13:03:55 -07:00

pid.c

kmemleak: Remove alloc_bootmem annotations introduced in the past

2009-07-09 17:07:02 +01:00

pm_qos_params.c

…

posix-cpu-timers.c

posix_cpu_timers_exit_group(): Do not use thread_group_cputimer()

2009-08-08 18:30:25 +02:00

posix-timers.c

posix-timers: Fix oops in clock_nanosleep() with CLOCK_MONOTONIC_RAW

2009-08-04 10:16:41 +02:00

printk.c

printk: Add KERN_DEFAULT printk log-level

2009-06-16 11:02:28 -07:00

profile.c

profile: suppress warning about large allocations when profile=1 is specified

2009-07-29 19:10:36 -07:00

ptrace.c

cred_guard_mutex: do not return -EINTR to user-space

2009-07-06 13:57:04 -07:00

rcuclassic.c

kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies

2009-04-03 12:23:02 +02:00

rcupdate.c

RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc

2009-04-15 13:55:14 -07:00

rcupreempt_trace.c

…

rcupreempt.c

rcu: rcu_sched_grace_period(): kill the bogus flush_signals()

2009-05-05 20:28:05 +02:00

rcutorture.c

cpumask: convert rcutorture.c

2009-03-30 22:05:16 +10:30

rcutree_trace.c

rcu: Add __rcu_pending tracing to hierarchical RCU

2009-04-14 11:33:43 +02:00

rcutree.c

rcu: Mark Hierarchical RCU no longer experimental

2009-06-24 15:02:48 +02:00

rcutree.h

kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies

2009-04-03 12:23:03 +02:00

relay.c

Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-04-05 11:04:19 -07:00

res_counter.c

memcg: add interface to reset limits

2009-06-18 13:03:48 -07:00

resource.c

kernel/resource.c: fix sign extension in reserve_setup()

2009-06-30 18:56:00 -07:00

rtmutex_common.h

rt_mutex: add proxy lock routines

2009-04-06 11:14:02 +02:00

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

…

rwsem.c

…

sched_clock.c

sched: Fix fallback sched_clock()'s offset when using jiffies

2009-05-09 10:08:19 +02:00

sched_cpupri.c

sched: Fix race in cpupri introduced by cpumask_var changes

2009-08-02 14:23:29 +02:00

sched_cpupri.h

cpumask: remove cpumask_t from core

2009-03-30 22:05:17 +10:30

sched_debug.c

sched: Hide runqueues from direct refer at source code level

2009-06-17 18:29:42 +02:00

sched_fair.c

sched: Fix latencytop and sleep profiling vs group scheduling

2009-08-02 14:10:12 +02:00

sched_features.h

Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-03-30 17:17:35 -07:00

sched_idletask.c

sched, timers: move calc_load() to scheduler

2009-05-15 15:32:45 +02:00

sched_rt.c

sched_rt: Fix overload bug on rt group scheduling

2009-07-10 10:43:29 +02:00

sched_stats.h

sched: remove unused fields from struct rq

2009-03-24 23:16:51 +01:00

sched.c

sched: fix load average accounting vs. cpu hotplug

2009-07-18 14:19:52 +02:00

seccomp.c

x86-64: seccomp: fix 32/64 syscall hole

2009-03-02 15:41:30 -08:00

semaphore.c

…

signal.c

do_sigaltstack: small cleanups

2009-08-01 11:18:56 -07:00

slow-work.c

slow-work: use round_jiffies() for thread pool's cull and OOM timers

2009-06-16 19:47:49 -07:00

smp.c

generic-ipi: fix hotplug_cfd()

2009-08-07 10:39:55 -07:00

softirq.c

softirq: introduce tasklet_hrtimer infrastructure

2009-07-22 17:01:17 +02:00

softlockup.c

…

spinlock.c

Allow rwlocks to re-enable interrupts

2009-04-02 19:05:11 -07:00

srcu.c

…

stacktrace.c

…

stop_machine.c

cpumask: remove cpumask_t from core

2009-03-30 22:05:17 +10:30

sys_ni.c

…

sys.c

groups: move code to kernel/groups.c

2009-06-16 19:47:48 -07:00

sysctl_check.c

…

sysctl.c

Security/SELinux: seperate lsm specific mmap_min_addr

2009-08-17 15:09:11 +10:00

taskstats.c

…

test_kprobes.c

…

time.c

…

timeconst.pl

…

timer.c

timer: Avoid reading uninitialized data

2009-07-18 23:11:43 +02:00

tracepoint.c

tracepoints: dont update zero-sized tracepoint sections

2009-03-18 19:55:00 +01:00

tsacct.c

Fix fixpoint divide exception in acct_update_integrals

2009-03-09 08:13:35 -07:00

uid16.c

…

up.c

…

user_namespace.c

Fix recursive lock in free_uid()/free_user_ns()

2009-02-27 16:26:21 -08:00

user.c

sched: delayed cleanup of user_struct

2009-06-15 21:30:23 -07:00

utsname_sysctl.c

proc_sysctl: use CONFIG_PROC_SYSCTL around ipc and utsname proc_handlers

2009-04-02 19:05:01 -07:00

utsname.c

utsns: extract creeate_uts_ns()

2009-06-18 13:03:55 -07:00

wait.c

locking, sched: Give waitqueue spinlocks their own lockdep classes

2009-08-10 14:43:09 +02:00

workqueue.c

ftrace, workqueuetrace: make workqueue tracepoints use TRACE_EVENT macro

2009-06-02 01:10:40 +02:00