Date: Fri, 20 Sep 1996 20:24:16 +0300 (EET DST) From: sja@tekla.fi To: FreeBSD-gnats-submit@freebsd.org Subject: kern/1658: ktrace/kdump flaky - corrupted ktrace.out file Message-ID: <199609201724.UAA01147@sja.home.tekla.fi> Resent-Message-ID: <199609201730.KAA22858@freefall.freebsd.org>
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>Number: 1658
>Category: kern
>Synopsis: ktrace/kdump flaky - corrupted ktrace.out file
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Sep 20 10:30:02 PDT 1996
>Last-Modified:
>Originator: Sakari Jalovaara
>Organization:
Ministry of Information, Information Retrieval
>Release: FreeBSD 2.2-960801-SNAP i386
>Environment:
P6/200, Asus P6NP5 m/b Natoma chipset, IDE disk
>Description:
ktrace(1) or ktrace(2) acts strangely. Maybe the dump file
is not flushed to the disk?
Sometimes ktrace+kdump work ok, but a few seconds later the
dump file is spontaneously corrupted.
The corrupted dump file often has lots of NUL bytes. The scary
question is: where, if anywhere, on the disk does the real data
end up?
>How-To-Repeat:
Run ktrace + kdump several times. Trace different commands
at different times; if you trace the same command several times,
the dump file seems to "settle down"? Big dump files seem to get
trashed easier.
"ktrace -p" fails similarly.
Dump file corruption seems to be triggered by disk activity.
Get a ktrace, do something on the disk, then kdump.
~ (sja@estabur) 112> /bin/rm ktrace.out ; ktrace wc /bin/ls > /dev/null ; kdump | tail -2
998 wc RET write 33/0x21
998 wc CALL exit(0)
~ (sja@estabur) 113> kdump | tail -2
kdump: bogus length 0xe0f43d83
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
1688299074 } RET
~ (sja@estabur) 114>
~ (sja@estabur) 135> /bin/rm ktrace.out ; ktrace od -c /kernel > /dev/null ; kdump | tail -2
1055 od RET write 15694/0x3d4e
1055 od CALL exit(0)
~ (sja@estabur) 136> kdump | tail -2
1055 od RET write 15694/0x3d4e
1055 od CALL exit(0)
~ (sja@estabur) 137> cp /kernel junkfile
~ (sja@estabur) 138> kdump | tail -2
kdump: bogus length 0xc3c95f5e
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
~ (sja@estabur) 139>
>Fix:
>Audit-Trail:
>Unformatted:
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