Date: Fri, 29 Jul 2005 14:19:33 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-stable@freebsd.org Subject: Re: Consistent file system hang with RELENG_6 of today ... Message-ID: <20050729141816.I74149@fledge.watson.org> In-Reply-To: <20050729095407.O997@ganymede.hub.org> References: <20050728231728.E968@ganymede.hub.org> <20050729092127.V74149@fledge.watson.org> <20050729095407.O997@ganymede.hub.org>
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On Fri, 29 Jul 2005, Marc G. Fournier wrote: > Oh, before I forget ... how do you break to DDB from a serial console? > I'll be running a Portmaster for this ... Compile BREAK_TO_DEBUGGER into the kernel. Then issue a serial break and it should go into the debugger if the low-level console is set to the serial port. On my port-master, I issue a telnet break using "send break" after hitting ^] to generate a serial break for a serial port hooked up to TCP. There's also ALT_BREAK_TO_DEBUGGER, which is documented in NOTES, and provides for an alternative key sequence that doesn't use a break signal. Robert N M Watson > > On Fri, 29 Jul 2005, Robert Watson wrote: > >> >> On Thu, 28 Jul 2005, Marc G. Fournier wrote: >> >>> 'k, I'm starting to play with 6.x, for our new server ... my priority >>> right now is to just have it run the existing 'jail' environments from my >>> 4.x machine, while I work on getting all of our servers up to 6.x, and >>> then will worry about the jail's themselves ... >>> >>> When I try and startup the 4.x jail on my 6.x machine, it "hangs" the file >>> system that the jail directory hierarchy happens to be mounted on though >>> ... twice in a row so far ... >>> >>> Now, I'm suspecting (and am going to try without it) that it might be >>> because I'm mounting devfs within the 4.x jail, but even then, it >>> shouldn't hang things up, only generate a whack of errors ... >>> >>> I have a good dump (CTL-ALT-ESC -> panic), but do not have a clue what to >>> offer from within there that might be of any use ... >>> >>> If anyone is interested ... ? >> >> If you can get into DDB and have serial console output, the following would >> be useful: >> >> The output of 'show pcpu' >> >> The output of 'show pcpu X' for each present cpu, starting with 0. >> >> The output of 'ps' >> >> The output of 'trace' for the currently running thread, and each non-idle >> thread shown in the show pcpu output >> >> The output of 'show lockedvnods' >> >> It would also be useful if, relating to the startup of the jail, you can >> identify the point in the jail boot where it wedges, and if you hit Ctrl-T, >> what process is shown as running and what state it is in, and using DDB, >> trace that process. >> >> If you could show the trace output for each process listed in "show >> lockevnods". >> >> Likely, there is a leaked lock or a low buffer condition. However, once we >> have the above output we should be able to say more. The above will >> hopefully tell us whether it's a vnode deadlock, and ideally, the >> approximate source. >> >> Robert N M Watson >> >> > > ---- > Marc G. Fournier Hub.Org Networking Services (http://www.hub.org) > Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664 >
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