2006-07-18 11:36:08

by Razvan Gavril

[permalink] [raw]
Subject: Buf starting 2.6.16 - rpc: bad TCP reclen

I posted on the linux kernel mailing list but got no answer till now.

I have a nfs server and some diskless computers that that have there
root mounted via nfs from the server. In certain situations the
diskless computers fail to write correctly to their nfs mounted
filesystem (some files get corrupted). Looking into the nfs server's
dmesg, i see this messages:

RPC: bad TCP reclen 0x5e9c5bec (non-terminal)
RPC: bad TCP reclen 0x29db3277 (large)
RPC: bad TCP reclen 0x698f6ccf (large)
RPC: bad TCP reclen 0x336160a9 (large)
RPC: bad TCP reclen 0x773ffdff (large)
RPC: bad TCP reclen 0x231b8d5c (non-terminal)
RPC: bad TCP reclen 0x39902af4 (large)
RPC: bad TCP reclen 0x6048d9cc (non-terminal)
RPC: bad TCP reclen 0x212f7e14 (non-terminal)

This errors start to happen when upgrading to 2.6.16 from 2.6.15 but the
problem is still present in 2.6.17 kernel. For now i tested like this:

Client - Server - State
------------------------
2.6.15 - 2.6.15 - Works
2.6.15 - 2.6.16 - Errors
2.6.16 - 2.6.16 - Errors
2.6.16 - 2.6.17 - Errors
2.6.17 - 2.6.17 - Errors

From the looks of it the problem seems to be related to the nfs server
implemetation from the kernels newer that 2.6.15.

Those corrupted writes on client + dmesg messages on the server are easy
to duplicate when using Debian on the client computers and running this
script in parallel on more that 1 client:

while /bin/true ;do
apt-get update
err=$?
[[ $err != 0 ]] && echo "Exiting $err" && exit $err

# you can replace gdb with any other package
apt-get -y install gdb
err=$?
[[ $err != 0 ]] && echo "Exiting $err" && exit $err

apt-get -y remove gdb
err=$?
[[ $err != 0 ]] && echo "Exiting $err" && exit $err

sleep $(( $RANDOM % 3 ))
done

After a couple o minutes (1-5min) apt should give a segmentation fault
because one of its state files got corrupted (/lib/dpkg/status or
other). FYI, the clients DON'T have any common files/dirs so a race
condition in apt can't be the cause. It's easy to see that for every apt
segfault on the client you'll have a rpc error message on the server.

I also tried with some different script to reproduce the problem, for
example to copy a lot of files(small, big ..) from a nfs share to
another but the md5sum reported that every time the copying was
happening without corruption so using apt is the only solution to
reproduce the bug for now.

I'm here if you need any other info related to this problem.

--
Razvan Gavril



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2006-07-19 14:46:38

by Razvan Gavril

[permalink] [raw]
Subject: Re: Bug starting 2.6.16 - rpc: bad TCP reclen

Razvan Gavril wrote:
> I posted on the linux kernel mailing list but got no answer till now.
>
> I have a nfs server and some diskless computers that that have there
> root mounted via nfs from the server. In certain situations the
> diskless computers fail to write correctly to their nfs mounted
> filesystem (some files get corrupted). Looking into the nfs server's
> dmesg, i see this messages:
>
> RPC: bad TCP reclen 0x5e9c5bec (non-terminal)
> RPC: bad TCP reclen 0x29db3277 (large)
> RPC: bad TCP reclen 0x698f6ccf (large)
> RPC: bad TCP reclen 0x336160a9 (large)
> RPC: bad TCP reclen 0x773ffdff (large)
> RPC: bad TCP reclen 0x231b8d5c (non-terminal)
> RPC: bad TCP reclen 0x39902af4 (large)
> RPC: bad TCP reclen 0x6048d9cc (non-terminal)
> RPC: bad TCP reclen 0x212f7e14 (non-terminal)
>
> This errors start to happen when upgrading to 2.6.16 from 2.6.15 but the
> problem is still present in 2.6.17 kernel. For now i tested like this:
>
> Client - Server - State
> ------------------------
> 2.6.15 - 2.6.15 - Works
> 2.6.15 - 2.6.16 - Errors
> 2.6.16 - 2.6.16 - Errors
> 2.6.16 - 2.6.17 - Errors
> 2.6.17 - 2.6.17 - Errors
>
> From the looks of it the problem seems to be related to the nfs server
> implemetation from the kernels newer that 2.6.15.
>
> Those corrupted writes on client + dmesg messages on the server are easy
> to duplicate when using Debian on the client computers and running this
> script in parallel on more that 1 client:
>
> while /bin/true ;do
> apt-get update
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> # you can replace gdb with any other package
> apt-get -y install gdb
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> apt-get -y remove gdb
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> sleep $(( $RANDOM % 3 ))
> done
>
> After a couple o minutes (1-5min) apt should give a segmentation fault
> because one of its state files got corrupted (/lib/dpkg/status or
> other). FYI, the clients DON'T have any common files/dirs so a race
> condition in apt can't be the cause. It's easy to see that for every apt
> segfault on the client you'll have a rpc error message on the server.
>
> I also tried with some different script to reproduce the problem, for
> example to copy a lot of files(small, big ..) from a nfs share to
> another but the md5sum reported that every time the copying was
> happening without corruption so using apt is the only solution to
> reproduce the bug for now.
>
> I'm here if you need any other info related to this problem.
>
> --
> Razvan Gavril
>
>
>
> -------------------------------------------------------------------------
> Take Surveys. Earn Cash. Influence the Future of IT
> Join SourceForge.net's Techsay panel and you'll get the chance to share your
> opinions on IT & business topics through brief surveys -- and earn cash
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> _______________________________________________
> NFS maillist - [email protected]
> https://lists.sourceforge.net/lists/listinfo/nfs
>
Razvan Gavril wrote:
> I posted on the linux kernel mailing list but got no answer till now.
>
> I have a nfs server and some diskless computers that that have there
> root mounted via nfs from the server. In certain situations the
> diskless computers fail to write correctly to their nfs mounted
> filesystem (some files get corrupted). Looking into the nfs server's
> dmesg, i see this messages:
>
> RPC: bad TCP reclen 0x5e9c5bec (non-terminal)
> RPC: bad TCP reclen 0x29db3277 (large)
> RPC: bad TCP reclen 0x698f6ccf (large)
> RPC: bad TCP reclen 0x336160a9 (large)
> RPC: bad TCP reclen 0x773ffdff (large)
> RPC: bad TCP reclen 0x231b8d5c (non-terminal)
> RPC: bad TCP reclen 0x39902af4 (large)
> RPC: bad TCP reclen 0x6048d9cc (non-terminal)
> RPC: bad TCP reclen 0x212f7e14 (non-terminal)
>
> This errors start to happen when upgrading to 2.6.16 from 2.6.15 but the
> problem is still present in 2.6.17 kernel. For now i tested like this:
>
> Client - Server - State
> ------------------------
> 2.6.15 - 2.6.15 - Works
> 2.6.15 - 2.6.16 - Errors
> 2.6.16 - 2.6.16 - Errors
> 2.6.16 - 2.6.17 - Errors
> 2.6.17 - 2.6.17 - Errors
>
> From the looks of it the problem seems to be related to the nfs server
> implemetation from the kernels newer that 2.6.15.
>
> Those corrupted writes on client + dmesg messages on the server are easy
> to duplicate when using Debian on the client computers and running this
> script in parallel on more that 1 client:
>
> while /bin/true ;do
> apt-get update
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> # you can replace gdb with any other package
> apt-get -y install gdb
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> apt-get -y remove gdb
> err=$?
> [[ $err != 0 ]] && echo "Exiting $err" && exit $err
>
> sleep $(( $RANDOM % 3 ))
> done
>
> After a couple o minutes (1-5min) apt should give a segmentation fault
> because one of its state files got corrupted (/lib/dpkg/status or
> other). FYI, the clients DON'T have any common files/dirs so a race
> condition in apt can't be the cause. It's easy to see that for every apt
> segfault on the client you'll have a rpc error message on the server.
>
> I also tried with some different script to reproduce the problem, for
> example to copy a lot of files(small, big ..) from a nfs share to
> another but the md5sum reported that every time the copying was
> happening without corruption so using apt is the only solution to
> reproduce the bug for now.
>
> I'm here if you need any other info related to this problem.
>
>
Can someone at least confirm this bug and give me an idea where to start
debugging ?

Thanks

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2006-07-19 15:52:28

by Razvan Gavril

[permalink] [raw]
Subject: Re: Bug starting 2.6.16 - rpc: bad TCP reclen

Chuck Lever wrote:

> I haven't seen other reports like this recently. It could be a
> hardware problem on your server or in your network (like a bad server
> NIC). A network trace would be the way to start tracking this down.
>
> sudo tcpdump -s0 -w /tmp/dump
>
> on your server. Stop the dump when the server starts reporting the
> TCP stream problems. Then take a look at the end of the dump with
> tethereal.
>

A hardware problem is almost impossible since we test it on a lot of
different computers. I'm really interested if someone can explain what
that message is meaning, it doesn't make much sense to me cause i don't
know anything about rpc.

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2006-07-19 15:31:08

by Chuck Lever

[permalink] [raw]
Subject: Re: Bug starting 2.6.16 - rpc: bad TCP reclen

On 7/19/06, Razvan Gavril <[email protected]> wrote:
> Razvan Gavril wrote:
> > I posted on the linux kernel mailing list but got no answer till now.
> >
> > I have a nfs server and some diskless computers that that have there
> > root mounted via nfs from the server. In certain situations the
> > diskless computers fail to write correctly to their nfs mounted
> > filesystem (some files get corrupted). Looking into the nfs server's
> > dmesg, i see this messages:
> >
> > RPC: bad TCP reclen 0x5e9c5bec (non-terminal)
> > RPC: bad TCP reclen 0x29db3277 (large)
> > RPC: bad TCP reclen 0x698f6ccf (large)
> > RPC: bad TCP reclen 0x336160a9 (large)
> > RPC: bad TCP reclen 0x773ffdff (large)
> > RPC: bad TCP reclen 0x231b8d5c (non-terminal)
> > RPC: bad TCP reclen 0x39902af4 (large)
> > RPC: bad TCP reclen 0x6048d9cc (non-terminal)
> > RPC: bad TCP reclen 0x212f7e14 (non-terminal)
> >
> > This errors start to happen when upgrading to 2.6.16 from 2.6.15 but the
> > problem is still present in 2.6.17 kernel. For now i tested like this:
> >
> > Client - Server - State
> > ------------------------
> > 2.6.15 - 2.6.15 - Works
> > 2.6.15 - 2.6.16 - Errors
> > 2.6.16 - 2.6.16 - Errors
> > 2.6.16 - 2.6.17 - Errors
> > 2.6.17 - 2.6.17 - Errors
> >
> > From the looks of it the problem seems to be related to the nfs server
> > implemetation from the kernels newer that 2.6.15.
> >
> > Those corrupted writes on client + dmesg messages on the server are easy
> > to duplicate when using Debian on the client computers and running this
> > script in parallel on more that 1 client:
> >
> > while /bin/true ;do
> > apt-get update
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > # you can replace gdb with any other package
> > apt-get -y install gdb
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > apt-get -y remove gdb
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > sleep $(( $RANDOM % 3 ))
> > done
> >
> > After a couple o minutes (1-5min) apt should give a segmentation fault
> > because one of its state files got corrupted (/lib/dpkg/status or
> > other). FYI, the clients DON'T have any common files/dirs so a race
> > condition in apt can't be the cause. It's easy to see that for every apt
> > segfault on the client you'll have a rpc error message on the server.
> >
> > I also tried with some different script to reproduce the problem, for
> > example to copy a lot of files(small, big ..) from a nfs share to
> > another but the md5sum reported that every time the copying was
> > happening without corruption so using apt is the only solution to
> > reproduce the bug for now.
> >
> > I'm here if you need any other info related to this problem.
> >
> > --
> > Razvan Gavril
> >
> >
> >
> > -------------------------------------------------------------------------
> > Take Surveys. Earn Cash. Influence the Future of IT
> > Join SourceForge.net's Techsay panel and you'll get the chance to share your
> > opinions on IT & business topics through brief surveys -- and earn cash
> > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
> > _______________________________________________
> > NFS maillist - [email protected]
> > https://lists.sourceforge.net/lists/listinfo/nfs
> >
> Razvan Gavril wrote:
> > I posted on the linux kernel mailing list but got no answer till now.
> >
> > I have a nfs server and some diskless computers that that have there
> > root mounted via nfs from the server. In certain situations the
> > diskless computers fail to write correctly to their nfs mounted
> > filesystem (some files get corrupted). Looking into the nfs server's
> > dmesg, i see this messages:
> >
> > RPC: bad TCP reclen 0x5e9c5bec (non-terminal)
> > RPC: bad TCP reclen 0x29db3277 (large)
> > RPC: bad TCP reclen 0x698f6ccf (large)
> > RPC: bad TCP reclen 0x336160a9 (large)
> > RPC: bad TCP reclen 0x773ffdff (large)
> > RPC: bad TCP reclen 0x231b8d5c (non-terminal)
> > RPC: bad TCP reclen 0x39902af4 (large)
> > RPC: bad TCP reclen 0x6048d9cc (non-terminal)
> > RPC: bad TCP reclen 0x212f7e14 (non-terminal)
> >
> > This errors start to happen when upgrading to 2.6.16 from 2.6.15 but the
> > problem is still present in 2.6.17 kernel. For now i tested like this:
> >
> > Client - Server - State
> > ------------------------
> > 2.6.15 - 2.6.15 - Works
> > 2.6.15 - 2.6.16 - Errors
> > 2.6.16 - 2.6.16 - Errors
> > 2.6.16 - 2.6.17 - Errors
> > 2.6.17 - 2.6.17 - Errors
> >
> > From the looks of it the problem seems to be related to the nfs server
> > implemetation from the kernels newer that 2.6.15.
> >
> > Those corrupted writes on client + dmesg messages on the server are easy
> > to duplicate when using Debian on the client computers and running this
> > script in parallel on more that 1 client:
> >
> > while /bin/true ;do
> > apt-get update
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > # you can replace gdb with any other package
> > apt-get -y install gdb
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > apt-get -y remove gdb
> > err=$?
> > [[ $err != 0 ]] && echo "Exiting $err" && exit $err
> >
> > sleep $(( $RANDOM % 3 ))
> > done
> >
> > After a couple o minutes (1-5min) apt should give a segmentation fault
> > because one of its state files got corrupted (/lib/dpkg/status or
> > other). FYI, the clients DON'T have any common files/dirs so a race
> > condition in apt can't be the cause. It's easy to see that for every apt
> > segfault on the client you'll have a rpc error message on the server.
> >
> > I also tried with some different script to reproduce the problem, for
> > example to copy a lot of files(small, big ..) from a nfs share to
> > another but the md5sum reported that every time the copying was
> > happening without corruption so using apt is the only solution to
> > reproduce the bug for now.
> >
> > I'm here if you need any other info related to this problem.
> >
> >
> Can someone at least confirm this bug and give me an idea where to start
> debugging ?

I haven't seen other reports like this recently. It could be a
hardware problem on your server or in your network (like a bad server
NIC). A network trace would be the way to start tracking this down.

sudo tcpdump -s0 -w /tmp/dump

on your server. Stop the dump when the server starts reporting the
TCP stream problems. Then take a look at the end of the dump with
tethereal.

--
"We who cut mere stones must always be envisioning cathedrals"
-- Quarry worker's creed

-------------------------------------------------------------------------
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_______________________________________________
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