Fwd: [Bug 4615] Modem connection stalls out.

Fwd: [Bug 4615] Modem connection stalls out.

[Russell King]

Anyone have any ideas on this bug?

The "No buffer space available" looks like the system is running low on
memory.  Would networking folk concur with that?

----- Forwarded message from bugme-daemon@kernel-bugs.osdl.org -----

Date: Mon, 6 Jun 2005 09:19:47 -0700
From: bugme-daemon@kernel-bugs.osdl.org
To: rmk@arm.linux.org.uk
Subject: [Bug 4615] Modem connection stalls out.

http://bugzilla.kernel.org/show_bug.cgi?id=4615





------- Additional Comments From alangrimes@starpower.net  2005-06-06 09:19 -------
The only reliable feedback I get from the bug, asside from its obvious symptoms,
is through ping... 

Here is a typical output: 

64 bytes from 10.65.28.26: icmp_seq=296 ttl=255 time=2552 ms
64 bytes from 10.65.28.26: icmp_seq=297 ttl=255 time=1561 ms
64 bytes from 10.65.28.26: icmp_seq=298 ttl=255 time=567 ms
64 bytes from 10.65.28.26: icmp_seq=299 ttl=255 time=137 ms
64 bytes from 10.65.28.26: icmp_seq=300 ttl=255 time=484 ms  # Hmm, exactly 5 
##  minutes, though I've seen it quit after only 10 seconds...) 
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
## It would have continued repeating this message indefinitely... 
## Note: many more iterations have been removed from this report!!! =P  

## Below is what happens when I manually disconnect the modem by sending 
## the break signal to the dialer. 
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable

--- 10.65.28.26 ping statistics ---
337 packets transmitted, 300 received, 10% packet loss, time 35529
5ms
rtt min/avg/max/mdev = 122.973/687.037/6298.163/1093.624 ms, pipe 
7
###################################

After power cycling the modem here's what the dialer does: 
leenooks ~ # wvdial
--> WvDial: Internet dialer version 1.54.0
--> Initializing modem.
--> Sending: ATZ
--> Sending: ATQ0
--> Re-Sending: ATZ 

### the dialer is hung and will report that the modem is not responding in a 
### few seconds...

### At this point I could ctrl-break the dialer and try again, 
### However, this would be entirely unproductive as I'd get the same mesage 
### each and every time.

### Only by allowing it to complete its cycle, will it return the modem to 
### functionality. I suspect that the dialer sends an IOCTL or something to the
### driver which clears the fault... 

--> Modem not responding.
leenooks ~ # wvdial
--> WvDial: Internet dialer version 1.54.0
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Sending: AT&F&D2&C1X4V1Q0S7=70W2\N3&K3S11=60
AT&F&D2&C1X4V1Q0S7=70W2\N3&K3S11=60
OK
--> Modem initialized.
--> Sending: ATDT7038298111
--> Waiting for carrier.
ATDT7038298111
CONNECT 49333
--> Carrier detected.  Waiting for prompt.
** Ascend TNT2.LNHVA.MD.RCN.NET Terminal Server **
Login: 
--> Looks like a login prompt.
--> Sending: alangrimes
alangrimes
Password: 
--> Looks like a password prompt.
--> Sending: (password)
    Entering PPP Session.
    IP address is 66.44.56.212
    MTU is 1006.
--> Looks like a welcome message.
--> Starting pppd at Tue Jun  7 04:58:30 2005
--> pid of pppd: 19733
--> Using interface ppp0
--> local  IP address 66.44.56.212
--> remote IP address 10.65.28.27
--> primary   DNS address 207.172.3.10
--> secondary DNS address 207.172.3.11

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----- End forwarded message -----

-- 
Russell King

Re: Fwd: [Bug 4615] Modem connection stalls out.

[Herbert Xu]

Russell King <rmk@arm.linux.org.uk> wrote:
> 
> The "No buffer space available" looks like the system is running low on
> memory.  Would networking folk concur with that?

It's probably not running low of system memory.  However, it might
be running out of things such as routing cache entries.

Check the dmesg output, it might have a clue on what went wrong.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

2.6.17-rc1: ping: sendmsg: No buffer space available

[Ville Herva]

I don't know if 
http://bugzilla.kernel.org/show_bug.cgi?id=4615
has been solved yet, but I'm seeing a similar thing with 2.6.17-rc1 and a ppp
connection over ssh.

Earlier kernels (at least linux-2.6.14-rc4) did not show this with the
exactly same settings.

How it happens: 
 - open up the ppp connection over ssh.
 - stress it a bit with samba
 - after a few minutes, pinging the remote end gives
     ping: sendmsg: No buffer space available
   and I have to re-establish the connection

The ssh connection seems solid afaict. Also, with bare ssh connetion, no
problems occur even under load. The ppp connection seems prone to hang
especially with SMB traffic (don't know why.)

In dmesg, there seems to be nothing relevant. /proc/slabinfo doesn't seem to
to have anything alerting in it.

The underlying connection is ADSL (8/1Mbit). The driver is eepro100. ppp is
ppp-2.4.3-6.2.1. 

ppp_deflate is in use:

ppp_deflate             5536  3 
zlib_deflate           18360  1 ppp_deflate
bsd_comp                5312  0 
ppp_async               9664  2 
crc_ccitt               1952  1 ppp_async
ppp_generic            20468  11 ppp_deflate,bsd_comp,ppp_async