From j@ida.interface-business.de Wed Feb 19 06:43:22 1997 Received: from innocence.interface-business.de (innocence.interface-business.de [193.101.57.202]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id GAA25958 for ; Wed, 19 Feb 1997 06:43:20 -0800 (PST) Received: from ida.interface-business.de (ida.interface-business.de [193.101.57.203]) by innocence.interface-business.de (8.6.11/8.6.9) with SMTP id PAA17105 for ; Wed, 19 Feb 1997 15:39:22 +0100 Received: (from j@localhost) by ida.interface-business.de (8.8.5/8.7.3) id PAA01363; Wed, 19 Feb 1997 15:43:12 +0100 (MET) Message-Id: <199702191443.PAA01363@ida.interface-business.de> Date: Wed, 19 Feb 1997 15:43:12 +0100 (MET) From: J Wunsch Reply-To: j@ida.interface-business.de To: FreeBSD-gnats-submit@freebsd.org Subject: ktrace(1) -i dumps corrupted trace data X-Send-Pr-Version: 3.2 >Number: 2768 >Category: kern >Synopsis: ktrace(1) -i dumps corrupted trace data >Confidential: no >Severity: non-critical >Priority: low >Responsible: gabor >State: closed >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Feb 19 06:50:02 PST 1997 >Closed-Date: Tue Jan 09 13:12:43 GMT 2007 >Last-Modified: Tue Jan 09 13:12:43 GMT 2007 >Originator: J Wunsch >Release: FreeBSD 2.2-GAMMA i386 >Organization: interface business GmbH, Dresden >Environment: FreeBSD 2.2-GAMMA, probably any other version as well. >Description: Running ktrace -i on a process that becomes a daemon and then heavily forks off children causes parts of the ktrace.out file being corrupted. In my case, the ktrace file started with 25160 NUL bytes before the first usable entry could be found, and the behaviour to sprinkle the trace file with odd numbers of NUL bytes continued throughout the entire trace. No useful pattern could be guessed where it happens, but i suspect it is related to process switching. By manually deleting the junk, i've been able to reveal some usable entries, but judging from the data contents of the dump it seems the NUL bytes have been clobbering valid entries (as opposed to being put in there in excess of the other dump data). >How-To-Repeat: Run ktrace -i on something that often forks off children. In my case, it's been syslogd with the (yet inofficial) log-to-pipe extensions, but i assume something similar would happen e.g. for inetd. A typical symptom is: j@ida 142% kdump -f /tmp/syslogd.trace 1937075797 ed kdump: Cannot allocate memory. at-7 207/udp #AppleTal@  UNKNOWN(27745) j@ida 143% >Fix: Not known. Maybe a VM problem? However, 25160 ain't a mulitple of the page size either. >Release-Note: >Audit-Trail: State-Changed-From-To: open->feedback State-Changed-By: johan State-Changed-When: Fri Oct 27 12:35:11 PDT 2000 State-Changed-Why: Hi Is this still a problem in more recent releases of FreeBSD (for example 4.1-RELEASE)? http://www.freebsd.org/cgi/query-pr.cgi?pr=2768 From: Bruce Evans To: johan@FreeBSD.ORG Cc: j@ida.interface-business.de, freebsd-gnats-submit@FreeBSD.ORG Subject: Re: kern/2768: ktrace(1) -i dumps corrupted trace data Date: Sat, 28 Oct 2000 16:39:53 +1100 (EST) > Is this still a problem in more recent releases of FreeBSD > (for example 4.1-RELEASE)? I don't know what caused it in PR 2768, but I have seen it in -current when the ktrace output is written to an nfs filesystem. It seemed to be caused by rev.1.37 of kern_ktrace.c. ktrwrite() needs to write the header and the record atomically, but doesn't. Bruce State-Changed-From-To: feedback->open State-Changed-By: johan State-Changed-When: Sat Oct 28 02:40:10 PDT 2000 State-Changed-Why: According to Bruce this is still a problem in 5-Current. http://www.freebsd.org/cgi/query-pr.cgi?pr=2768 State-Changed-From-To: open->feedback State-Changed-By: gabor State-Changed-When: Mon Dec 25 21:11:45 UTC 2006 State-Changed-Why: Dear Submitter, could you please confirm if this issue still exists in a recent FreeBSD release? Regards, Gabor Kovesdan Responsible-Changed-From-To: freebsd-bugs->gabor Responsible-Changed-By: gabor Responsible-Changed-When: Mon Dec 25 21:11:45 UTC 2006 Responsible-Changed-Why: Dear Submitter, could you please confirm if this issue still exists in a recent FreeBSD release? Regards, Gabor Kovesdan http://www.freebsd.org/cgi/query-pr.cgi?pr=2768 State-Changed-From-To: feedback->closed State-Changed-By: gabor State-Changed-When: Tue Jan 9 13:12:30 UTC 2007 State-Changed-Why: Fedback timeout. If this problem shows up again, please feel free to submit a follow-up to this PR ticket, so that we can re-open it and find a solution for the problem. Regards, Gabor Kovesdan http://www.freebsd.org/cgi/query-pr.cgi?pr=2768 >Unformatted: