On 2014-09-10 18:58, Douglas Gilbert wrote:
On 14-09-10 11:41 AM, Christoph Hellwig wrote:
While it might not help with a blown stack, can you give the patch below
a try?  I tries to solve a problem where the timeout handler hits
before we've fully set up a command.  While I'd like to understand the
root cause of why we're hitting it as well, I'd also really to fix that
race. It would also be good to get a gdb listing of the exact area in
scsi_times_out listed in the oops.

RIP: 0010:[<ffffffff8127cd2e>]  [<ffffffff8127cd2e>]
scsi_times_out+0xe/0x2e0

(gdb) disassemble scsi_times_out
Dump of assembler code for function scsi_times_out:
    0xffffffff8127d030 <+0>:    push   %rbp
    0xffffffff8127d031 <+1>:    mov    $0x2007,%esi
    0xffffffff8127d036 <+6>:    push   %rbx
    0xffffffff8127d037 <+7>:    mov    0xf8(%rdi),%rbx
    0xffffffff8127d03e <+14>:    mov    (%rbx),%rax
    0xffffffff8127d041 <+17>:    mov    %rbx,%rdi
    0xffffffff8127d044 <+20>:    mov    (%rax),%rbp
    0xffffffff8127d047 <+23>:    callq  0xffffffff81277c70
<scsi_log_completion>
    0xffffffff8127d04c <+28>:    cmpl   $0xffffffff,0x154(%rbp)
    0xffffffff8127d053 <+35>:    je     0xffffffff8127d05f
<scsi_times_out+47>
...

which seems to agree 'objdump -drS scsi_error.o':

00000000000028b0 <scsi_times_out>:
     28b0:    55                       push   %rbp
     28b1:    be 07 20 00 00           mov    $0x2007,%esi
     28b6:    53                       push   %rbx
     28b7:    48 8b 9f f8 00 00 00     mov    0xf8(%rdi),%rbx
     28be:    48 8b 03                 mov    (%rbx),%rax
     28c1:    48 89 df                 mov    %rbx,%rdi
     28c4:    48 8b 28                 mov    (%rax),%rbp
     28c7:    e8 00 00 00 00           callq  28cc <scsi_times_out+0x1c>
             28c8: R_X86_64_PC32    scsi_log_completion-0x4
     28cc:    83 bd 54 01 00 00 ff     cmpl   $0xffffffff,0x154(%rbp)

This would be more useful if you had DEBUGINFO enabled. At least it would save use some time :-)


--
Jens Axboe

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