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eced1dfcfc
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> |
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| .. | ||
| gcov | ||
| irq | ||
| power | ||
| time | ||
| trace | ||
| .gitignore | ||
| acct.c | ||
| async.c | ||
| audit.c | ||
| audit.h | ||
| audit_tree.c | ||
| audit_watch.c | ||
| auditfilter.c | ||
| auditsc.c | ||
| backtracetest.c | ||
| bounds.c | ||
| capability.c | ||
| cgroup.c | ||
| cgroup_debug.c | ||
| cgroup_freezer.c | ||
| compat.c | ||
| configs.c | ||
| cpu.c | ||
| cpuset.c | ||
| cred-internals.h | ||
| cred.c | ||
| delayacct.c | ||
| dma-coherent.c | ||
| dma.c | ||
| exec_domain.c | ||
| exit.c | ||
| extable.c | ||
| fork.c | ||
| freezer.c | ||
| futex.c | ||
| futex_compat.c | ||
| groups.c | ||
| hrtimer.c | ||
| hung_task.c | ||
| itimer.c | ||
| kallsyms.c | ||
| Kconfig.freezer | ||
| Kconfig.hz | ||
| Kconfig.preempt | ||
| kexec.c | ||
| kfifo.c | ||
| kgdb.c | ||
| kmod.c | ||
| kprobes.c | ||
| ksysfs.c | ||
| kthread.c | ||
| latencytop.c | ||
| lockdep.c | ||
| lockdep_internals.h | ||
| lockdep_proc.c | ||
| lockdep_states.h | ||
| Makefile | ||
| marker.c | ||
| module.c | ||
| mutex-debug.c | ||
| mutex-debug.h | ||
| mutex.c | ||
| mutex.h | ||
| notifier.c | ||
| ns_cgroup.c | ||
| nsproxy.c | ||
| panic.c | ||
| params.c | ||
| perf_counter.c | ||
| pid.c | ||
| pid_namespace.c | ||
| pm_qos_params.c | ||
| posix-cpu-timers.c | ||
| posix-timers.c | ||
| printk.c | ||
| profile.c | ||
| ptrace.c | ||
| rcuclassic.c | ||
| rcupdate.c | ||
| rcupreempt.c | ||
| rcupreempt_trace.c | ||
| rcutorture.c | ||
| rcutree.c | ||
| rcutree.h | ||
| rcutree_trace.c | ||
| relay.c | ||
| res_counter.c | ||
| resource.c | ||
| rtmutex-debug.c | ||
| rtmutex-debug.h | ||
| rtmutex-tester.c | ||
| rtmutex.c | ||
| rtmutex.h | ||
| rtmutex_common.h | ||
| rwsem.c | ||
| sched.c | ||
| sched_clock.c | ||
| sched_cpupri.c | ||
| sched_cpupri.h | ||
| sched_debug.c | ||
| sched_fair.c | ||
| sched_features.h | ||
| sched_idletask.c | ||
| sched_rt.c | ||
| sched_stats.h | ||
| seccomp.c | ||
| semaphore.c | ||
| signal.c | ||
| slow-work.c | ||
| smp.c | ||
| softirq.c | ||
| softlockup.c | ||
| spinlock.c | ||
| srcu.c | ||
| stacktrace.c | ||
| stop_machine.c | ||
| sys.c | ||
| sys_ni.c | ||
| sysctl.c | ||
| sysctl_check.c | ||
| taskstats.c | ||
| test_kprobes.c | ||
| time.c | ||
| timeconst.pl | ||
| timer.c | ||
| tracepoint.c | ||
| tsacct.c | ||
| uid16.c | ||
| up.c | ||
| user.c | ||
| user_namespace.c | ||
| utsname.c | ||
| utsname_sysctl.c | ||
| wait.c | ||
| workqueue.c | ||