Possible ufs livelock during coredump path?

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Hi,

It seems that we have a potential livelock during coredump
on 7.0-R, the
case was that two processes trying to coredump in the same
time (e.g. if
I configure kern.corefile=/var/tmp/%N.core and a lot of
instances
coredump in the same time), perhaps when paging involved
with it.  Upon
reboot, it would not recover but wait infinitely.  The box
is running
7.0-R/i386, UP (Origin = "GenuineIntel"  Id =
0xf34  Stepping = 4).

Is this an known issue?  This is my own server but I do not
have my
hands on it because it is in China, however I can provide
some help if
the experiment can be recovered with a power-cycle 

Cheers,
- --
Xin LI <delphijdelphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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> -----BEGIN PGP SIGNED MESSAGE-----
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>
> Hi,
>
> It seems that we have a potential livelock during
coredump on 7.0-R, the
> case was that two processes trying to coredump in the
same time (e.g. if
> I configure kern.corefile=/var/tmp/%N.core and a lot of
instances
> coredump in the same time), perhaps when paging
involved with it.  Upon
> reboot, it would not recover but wait infinitely.  The
box is running
> 7.0-R/i386, UP (Origin = "GenuineIntel"  Id =
0xf34  Stepping = 4).
>
> Is this an known issue?  This is my own server but I do
not have my
> hands on it because it is in China, however I can
provide some help if
> the experiment can be recovered with a power-cycle 
>

AFAIK it is an old problem. I have some test where I had to
disable core
dumps for the same reason. I seem to remember that the
problem is related
to running out of VM?

- Peter



> Cheers,
> - --
> Xin LI <delphijdelphij.net>	http://www.delphij.net/
> FreeBSD - The Power to Serve!
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>
>
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Peter Holm wrote:
| Hi,
|
| It seems that we have a potential livelock during coredump
on 7.0-R, the
| case was that two processes trying to coredump in the same
time (e.g. if
| I configure kern.corefile=/var/tmp/%N.core and a lot of
instances
| coredump in the same time), perhaps when paging involved
with it.  Upon
| reboot, it would not recover but wait infinitely.  The box
is running
| 7.0-R/i386, UP (Origin = "GenuineIntel"  Id =
0xf34  Stepping = 4).
|
| Is this an known issue?  This is my own server but I do
not have my
| hands on it because it is in China, however I can provide
some help if
| the experiment can be recovered with a power-cycle 
|
|
|> AFAIK it is an old problem. I have some test where I
had to disable core
|> dumps for the same reason. I seem to remember that the
problem is related
|> to running out of VM?

For my case it does not seem to be ran out of VM (at least
the system
did not printed out any messages, the log has a lot of
kernel: pid 27223
(httpd), uid 80: exited on signal 11 (core dumped) but not
the out of
swap one.

So, presumably we can reliably trigger this situation (or at
least your
ones ?

Cheers,
- --
Xin LI <delphijdelphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Peter Holm wrote:
> | Hi,
> |
> | It seems that we have a potential livelock during
coredump on 7.0-R, the
> | case was that two processes trying to coredump in the
same time (e.g. if
> | I configure kern.corefile=/var/tmp/%N.core and a lot
of instances
> | coredump in the same time), perhaps when paging
involved with it.  Upon
> | reboot, it would not recover but wait infinitely. 
The box is running
> | 7.0-R/i386, UP (Origin = "GenuineIntel"  Id
= 0xf34  Stepping = 4).
> |
> | Is this an known issue?  This is my own server but I
do not have my
> | hands on it because it is in China, however I can
provide some help if
> | the experiment can be recovered with a power-cycle

> |
> |
> |> AFAIK it is an old problem. I have some test
where I had to disable
> core
> |> dumps for the same reason. I seem to remember
that the problem is
> related
> |> to running out of VM?
>
> For my case it does not seem to be ran out of VM (at
least the system
> did not printed out any messages, the log has a lot of
kernel: pid 27223
> (httpd), uid 80: exited on signal 11 (core dumped) but
not the out of
> swap one.
>

Nor did I, as I remember.

> So, presumably we can reliably trigger this situation
(or at least your
> ones ?
>

It's a long time since I looked at this problem, but this
would seem to be
a good excuse to look at it again.

- Peter

> Cheers,
> - --
> Xin LI <delphijdelphij.net>	http://www.delphij.net/
> FreeBSD - The Power to Serve!
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>
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