Date: Mon, 09 Feb 2015 10:08:40 -0700 From: Ian Lepore <ian@freebsd.org> To: Kurt Lidl <lidl@pix.net> Cc: freebsd-stable@freebsd.org Subject: Re: freebsd-update and hang during reboot Message-ID: <1423501720.16794.18.camel@freebsd.org> In-Reply-To: <54D8E341.101@pix.net> References: <2F9DC176-912C-40C0-BAB7-DB66BD572ABA@vnode.se> <54D8E341.101@pix.net>
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On Mon, 2015-02-09 at 11:41 -0500, Kurt Lidl wrote: > Joel wrote: > > Hi, > > > > Just about every machine I have seems to hang after running freebsd-update and doing a reboot. The last message on the screen is "All buffers synced¡ and it just freezes. > > > > This happens when doing a freebsd-update and going from 10.0 to 10.1, but also when doing a fresh 10.1 install and using freebsd-update to get the latest -pX security patches. As soon as I reboot the machine, it hangs. > > > > Iÿve tried it on several different HP ProLiant models, on Intel NUCs and on VMware virtual machines. Same phenomenon everywhere. Itÿs really easy to trigger: just install 10.1, use default settings everywhere, freebsd-update fetch/install, shutdown -r now and BOOM. It hangs. I think Iÿve seen it on > > > > > > > > > > 30 servers or so now. > > > > Everything works like it should after the initial hang tough - no matter how many times I reboot it completes the reboot cycle just fine. > > > > Iÿve seen several people (mostly on IRC) mention this problem, but no solution. > > > > Is anyone working on fixing this? > > I ran into this problem in spades when upgrading a set of servers from > FreeBSD 9.0 to 9.1. I happened consistently. Normal reboots worked, > but when going from 9.0 to 9.1, it *ALWAYS* hung, and it always hung > at the same place, after printing the "All buffers synced" message. > > I ultimately determined that if I did the following, rather than > just a "reboot" or "shutdown -r now 'FreeBSD 9.1-RELEASE upgrade'", > it would consistently AVOID the hang: > > sync ; sync ; sync ; shutdown -o -n -r now "FreeBSD 9.1 install" > > Your mileage may vary, but you don't have a lot to lose by trying it. > > -Kurt > That is just bad advice. sync(1) does not g'tee that all data has been written, no matter how many times you type it. shutdown -n tells the system to abandon unwritten data. All in all, this is a recipe for silent filesystem corruption. Using it after an update is just asking to have a mix of old and new files on the system after the reboot. A more robust workaround would be to "mount -r" on all filesystems before invoking the shutdown (even a shutdown -n should be safe after everything has been remounted readonly). If the mount -r hangs on one of the filesystems, then you've probably got a clue as to where a normal shutdown is hanging. -- Ian
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