[Bug runtime/6772] New: probing all functions of kernel/sched.c causes system crash on 2.6.27-rc1

["srinivasa at in dot ibm dot com" <sourceware-bugzilla at sourceware dot org>]

Environment: Kernel:2.6.27-rc1, systemtap:20080726 snapshot elfutils:-0.131
Arch:ppc64

Probing all functions of kernel/sched.c causes system crash on 2.6.27-rc1.

Some of the observations I made are listed below
1) I haven't seen this bug in previous kernel releases(2.6.26-rc's)
2) I tried disabling CONFIG_GROUP_SCHED, but still problem persists.
3) Iam able reproduce this bug only on ppc64 and not on other archs like x86_64.
4) Iam trying to isolate the problem to one single function in kernel/sched.c,
but Iam not successful till now.


I tried this script.
============================
./stap -vvvv -e 'probe kernel.function("*@kernel/sched.c") { printf("hello\n")}'

=======================
llm27lp1.in.ibm.com login: cpu 0x0: Vector: d00 (Single Step) at [c000000000682f50]
    pc: c00000000006e6b8: .scheduler_tick+0xf0/0x168
    lr: c00000000006e6b8: .scheduler_tick+0xf0/0x168
    sp: c0000000006831d0
   msr: 8000000040101032
  current = 0xc0000000005c3080
  paca    = 0xc0000000006f3480
    pid   = 0, comm = swapper
        ld      r2,40(r1)
enter ? for help
[c0000000006831d0] c00000000006e610 .scheduler_tick+0x48/0x168 (unreliable)
[c000000000683260] c00000000007efcc .update_process_times+0x60/0x8c
[c0000000006832f0] c000000000096f74 .tick_periodic+0xc0/0xec
[c000000000683380] c000000000096fd4 .tick_handle_periodic+0x34/0xb0
[c000000000683420] c000000000025150 .timer_interrupt+0xb0/0x104
[c0000000006834b0] c000000000003718 decrementer_common+0x118/0x180
--- Exception: 901 (Decrementer) at c00000000000bcc8
.raw_local_irq_restore+0x3c/0x40
[link register   ] d000000000835cc8 .enter_kprobe_probe+0x90/0x1948
[stap_6f5152cafd0831436846cf37ddd0b96b_34101]
[c0000000006837a0] d000000000835e48 .enter_kprobe_probe+0x210/0x1948
[stap_6f5152cafd0831436846cf37ddd0b96b_34101] (unreliable)
[c000000000683840] c000000000403424 .kprobe_exceptions_notify+0x288/0x4b4
[c0000000006838f0] c0000000004046d8 .notifier_call_chain+0x5c/0xcc
[c000000000683990] c000000000091560 .notify_die+0x3c/0x50
[c000000000683a30] c0000000004029c4 .program_check_exception+0x124/0x684
[c000000000683af0] c00000000000500c program_check_common+0x10c/0x180
--- Exception: 700 (Program Check) at c0000000003fef3c .schedule+0x0/0x8e4
[link register   ] c000000000012af8 .cpu_idle+0x1d8/0x1e0
[c000000000683de0] c000000000012a28 .cpu_idle+0x108/0x1e0 (unreliable)
[c000000000683e60] c00000000041007c
[c000000000683ee0] c000000000520bb4 .start_kernel+0x448/0x470
[c000000000683f90] c000000000008568 .start_here_common+0x3c/0x54

-- 
           Summary: probing all functions of kernel/sched.c causes system
                    crash on 2.6.27-rc1
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: runtime
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: srinivasa at in dot ibm dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6772

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