Date: Tue, 23 Jun 1998 11:03:44 +0200 (CEST) From: rolfjs@ife.no To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: kern/7028: Panic in vinvalbuf when appending to and looking at tail of NFS file. Message-ID: <199806230903.LAA10674@virginis.ife.no>
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>Number: 7028
>Category: kern
>Synopsis: Panic in vinvalbuf when appending/looking at tail of NFS file.
>Confidential: yes
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Jun 23 02:10:01 PDT 1998
>Last-Modified:
>Originator: Rolf J Soedahl
>Organization:
Institute for energy technology
P.O. Box 40
N-2007 KJELLER
NORWAY
>Release: FreeBSD 2.2.6-RELEASE i386
>Environment:
NFS client: FreeBSD 2.2.6 (also FreeBSD 3.0 980222)
NFS server: FreeBSD 2.2.6 (also FreeBSD 3.0 980222 / Digital UNIX 3.2G)
>Description:
When writing to a file in a NFS-mounted directory in append mode
(using shell >> or "a" in fopen), looking at the tail of this file
on the same NFS client causes a kernel panic in vinvalbuf.
Note that both the writing and the looking (with tail) is done at
the NFS client.
I post this bug as confidential because I think a fix should
be available when users start to "investigate" this malfunction.
>How-To-Repeat:
Method 1:
This standard command sequence shows the problem:
cd Any-NFS-mounted-directory-with-write-permission
touch out
/usr/sbin/lptest 50 100000 >> out &
sleep 1
tail out
This is the output from DDB (as read and reentered by me):
panic: vinvalbuf: flush failed
Debugger("panic")
Stopped at _Debugger+0x35: movb $0,_in_Debugger.122
db>
db> ps
pid proc addr uid ppid pgrp flag stat wmesg wchan cmd
208 f0743c00 f4b44000 1000 204 204 004006 2 tail
206 f0743e00 f4b42000 1000 204 206 004006 2 lptest
204 f06ec000 f4b40000 1000 179 204 004086 3 pause f4b40128 csh
--More--
db>
db> trace
_Debugger(f0117e38) at _Debugger+0x35
_panic(f01344a0,f074b200,0,0,10) at _panic+0x5a
_vinvalbuf(f074cf00,1,f073f000,f0743e00,0,0) at _vinvalbuf+0x21c
_nfs_vinvalbuf(f074cf00,1,f073f000,f0743e00,1) at _nfs_vinvalbuf+0xf8
_nfs_write(efbffee8,f01f94d0,400,efbfff94,2) at _nfs_write+0xfa
_vn_write(f074ab00,efbfff34,f073f000,f01f94d0,f0743e00) at _vn_write+0x93
_write(f0743e00,efbfff94,efbfff84,20079060,21d4) at _write+0x97
_syscall(27,27,efbfd5bc,21d4,efbfd548) at _syscall+0x183
_Xsyscall() at _Xsyscall+0x35
---syscall 0x4, eip = 0x2006c981, esp = 0xefbfd530, ebp = 0xefbfd548 ---
Method 2:
This small C program may be used instead of lptest. It results
in a panic for N = 100 with my client and server configuration.
Smaller values of N has not crashed, I suspect there is a race
condition in the kernel.
/* Program nfstest.c. Usage: "./nfstest 100".
** If this program is executed in a NFS-mounted directory,
** the command "tail out" gives panic in vinvalbuf
** when N is large (e.g. 100). */
#include <stdlib.h>
#include <stdio.h>
#define FILENAME "out"
main(int argc, char **argv)
{
FILE *f;
int i, N;
if (argc != 2) {
fprintf(stderr, "Usage: %s N\n", argv[0]);
exit(1);
}
N = atoi(argv[1]);
printf("N = %d\n", N);
if ((f = fopen(FILENAME, "a")) == NULL) { /* Append mode !! */
fprintf(stderr, "fopen failed");
exit(1);
}
for (;;) {
for (i = 0; i < N; i++)
fprintf(f, "testing NFS in append mode\n");
sleep(1);
}
}
>Fix:
Sorry, I have no fix for this problem.
>Audit-Trail:
>Unformatted:
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