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Re: rebooting after remounting root FS - more info



mag@tech.sibal.ru wrote:

> "Federico G. Schwindt" wrote:
>
> > On Thu, Jul 04, 2002 at 07:02:18PM +0400, mag@tech.sibal.ru wrote:
> > > Hello.
> > >
> > > I recently wrote about this problem.
> > >
> > > Here is additional information.
> > >
> > > After remounting the root filesystem in multiuser mode with the command
> > >
> > >         mount -rfuv /
> > >
> > > this command completes succesfully and ddb pops up with the message:
> > >
> > >
> > > kernel: protection fault trap, code=0
> > > Stopped at      _proc_trampoline+0x12:  iret
> > > ddb>
> > >
> > >
> > > I have applied all patches and rebuilt everithing.

[cut]

> ddb trace output is empty
>
> ddb ps output:
>     PID    PPID    PGRP    UID    S    FLAGS        WAIT        COMMAND
>     10143  1        10143    0    3    0x4086       ttyin       getty
>     3353   1        3353     0    3    0x4086       ttyin       getty
>     29270  1        29270    0    3    0x4086       ttyin       getty
>     6819   1        6819     0    3    0x4086       ttyin       getty
>     31172  1        31172    0    3    0x4086       ttyin       sh
>    *14482  0        0        0    3    0x100204                 acct

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>
>     9      0        0        0    3    0x100204     usbevt      usb0
>     8      0        0        0    3    0x100204     apmev       apm0
>     7      0        0        0    3    0x100204     crypto_wa   crypto
>     6      0        0        0    3    0x100204     aiodoned    aiodoned
>     5      0        0        0    3    0x100204     syncer      update
>     4      0        0        0    3    0x100204     cleaner     cleaner
>     3      0        0        0    3    0x100204     reaper      reaper
>     2      0        0        0    3    0x100204     pgdaemon    pagedaemon
>     1      0        1        0    3    0x4084       wait        init
>     0      -1       0        0    3    0x80204      scheduler   swapper

[cut]

This ps output gave me useful information (thanks to Federico).
I found that accounting was turned on before remounting root FS.
And when I turned off accounting - my problem disappeared.


Conclusion.

I think that there is a bug somewhere in the kernel.
This bug is associated with writing process accounting
information into the file (specified by "accton <file>").
When the file for accounting becomes unavailable for
writing - DoS condition appear.


--
Alexei Malinin,
System Administrator of
Siberian Aluminium Group