Date: Fri, 22 Jan 1999 11:29:21 +1030 (CST) From: Greg Lehey <grog@panic.lemis.com> To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: kern/9612: NFS mounts on dual-homed server may hang Message-ID: <199901220059.LAA01868@panic.lemis.com>
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>Number: 9612
>Category: kern
>Synopsis: NFS mounts on dual-homed server may hang
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Jan 21 17:00:01 PST 1999
>Closed-Date:
>Last-Modified:
>Originator: Greg Lehey
>Release: FreeBSD 4.0-CURRENT i386
>Organization:
LEMIS
>Environment:
FreeBSD 3.0 or 4.0 system
>Description:
In this example, panic.lemis.com (192.109.197.149) attempts to
mount a file system on freebie.lemis.com, which has the
addresses 139.130.136.133 (PPP interface) and 192.109.197.137
(Ethernet). The command is:
mount freebie:/T /T
The resolution of the name `freebie' may be one of the two
addresses. If the address is 192.109.197.137, the mount
completes normally. If the address is 139.130.136.133, the
following exchange occurs:
11:14:44.568928 192.109.197.149.1709389267 > 139.130.136.133.2049: 120 getattr [|nfs]
11:14:44.569102 192.109.197.137.2049 > 192.109.197.149.1709389267: reply ok 112 read [|nfs]
11:14:44.569536 192.109.197.149 > 192.109.197.137: icmp: 192.109.197.149 udp port 1022 unreachable
11:14:44.589909 192.109.197.149.1029 > 139.130.136.133.6000: . ack 5120 win 17376 <nop,nop,timestamp 178539 117902> (DF)
11:14:45.569932 192.109.197.149.1709389267 > 139.130.136.133.2049: 120 getattr [|nfs]
11:14:45.570128 192.109.197.137.2049 > 192.109.197.149.1709389267: reply ok 112 read [|nfs]
11:14:45.570549 192.109.197.149 > 192.109.197.137: icmp: 192.109.197.149 udp port 1022 unreachable
11:14:47.579700 192.109.197.149.1709389267 > 139.130.136.133.2049: 120 getattr [|nfs]
11:14:47.579878 192.109.197.137.2049 > 192.109.197.149.1709389267: reply ok 112 read [|nfs]
11:14:47.580298 192.109.197.149 > 192.109.197.137: icmp: 192.109.197.149 udp port 1022 unreachable
Here the mount succeeds on the server side, but the reply
contains the address 192.109.197.137, not 139.130.136.133, and
is thus rejected by panic. The mount process hangs in sbwait
and is not stoppable.
0 1709 1 0 2 0 340 188 sbwait D p0 0:00.01 nfs panic:/T (mount_nfs)
This problem is made worse by the fact that there is no
possibility of retrying: any subsequent attempt to mount the
file system fails with the message
nfs: /T: Device busy
This address replacement is not always the case. For example,
a ping shows:
11:14:20.662949 192.109.197.149 > 139.130.136.133: icmp: echo request
11:14:20.663017 139.130.136.133 > 192.109.197.149: icmp: echo reply
>How-To-Repeat:
As above
>Fix:
To be investigated
>Release-Note:
>Audit-Trail:
>Unformatted:
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