[Crash-utility] Interpreting bt

[Ahmed Al-Mehdi]

Hello,

I am using crash version: 6.0.4-2.el6 on CentOS 6.3 (kernel
2.6.32-279.el6.x86_64).  I apologize for my newbie questions, but googling
did not help much.

When analyzing a kernel dump, I am getting the following bt.

crash> bt
PID: 12663  TASK: ffff88036304f500  CPU: 0   COMMAND: "bash"
 #0 [ffff88035b949570] machine_kexec at ffffffff8103281b
 #1 [ffff88035b9495d0] crash_kexec at ffffffff810ba662
 #2 [ffff88035b9496a0] oops_end at ffffffff81501290
 #3 [ffff88035b9496d0] no_context at ffffffff81043bab
 #4 [ffff88035b949720] __bad_area_nosemaphore at ffffffff81043e35
 #5 [ffff88035b949770] bad_area at ffffffff81043f5e
 #6 [ffff88035b9497a0] __do_page_fault at ffffffff81044710
 #7 [ffff88035b9498c0] do_page_fault at ffffffff8150326e
 #8 [ffff88035b9498f0] page_fault at ffffffff81500625
    [exception RIP: ahaann+47]
    RIP: ffffffffa06ce48f  RSP: ffff88035b9499a8  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: 0000000000000000  RCX: 0000000000000000
    RDX: 0000000000000000  RSI: 0000000000000000  RDI: ffff88035daef4e0
    RBP: ffff88035b9499b8   R8: 0000000004a47daf   R9: ffffffffa06dae99
    R10: 0000000000000000  R11: 0000000000000246  R12: 0000000000000007
    R13: 00007fc82f4b8000  R14: 000000000000000a  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #9 [ffff88035b9499c0] ahaecho at ffffffffa06d2899 [ahadrv]
#10 [ffff88035b949a00] writectl at ffffffffa06c366e [ahadrv]
#11 [ffff88035b949e40] writeaha at ffffffffa06d3e7b [ahadrv]
#12 [ffff88035b949e60] proc_file_write at ffffffff811e6e44
#13 [ffff88035b949ea0] proc_reg_write at ffffffff811e0abe
#14 [ffff88035b949ef0] vfs_write at ffffffff8117b068
#15 [ffff88035b949f30] sys_write at ffffffff8117ba81
#16 [ffff88035b949f80] system_call_fastpath at ffffffff8100b0f2
    RIP: 0000003a29ada3c0  RSP: 00007ffffaec6830  RFLAGS: 00010202
    RAX: 0000000000000001  RBX: ffffffff8100b0f2  RCX: 0000000000000065
    RDX: 000000000000000a  RSI: 00007fc82f4b8000  RDI: 0000000000000001
    RBP: 00007fc82f4b8000   R8: 000000000000000a   R9: 00007fc82f4aa700
    R10: 00000000fffffff7  R11: 0000000000000246  R12: 000000000000000a
    R13: 0000003a29d8c780  R14: 000000000000000a  R15: 0000000001e18460
    ORIG_RAX: 0000000000000001  CS: 0033  SS: 002b
crash>

1. Are the hex addr in [] right before the function name the stack frame
ptr for that function?

2. I am assuming the panic occurred in function ahaann() (and not in
ahaecho() ).  Is that right?

3. What is puzzling me is why there is no frame associated with call to
ahaann().  Or is frame #8 associated to ahaann().  From the display it
seems frame #8 is associated to page_fault() since 0xffffffff81500625 is an
address in page_fault(). Or am totally misinterpreting the call stack.

crash> dis ffffffff81500625
0xffffffff81500625 <page_fault+37>:     jmpq   0xffffffff81500830

4. I can understand the value of register dump for frame #8, due to the
panic. What is the significance of the register dump for frame #16.

Appreciate any help.

Thank you,
Ahmed.
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