Date: Fri, 1 Oct 2010 17:32:35 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: avg@icyb.net.ua Cc: stable@FreeBSD.org, sterling@camdensoftware.com, freebsd@jdc.parodius.com Subject: Re: CPU time accounting broken on 8-STABLE machine after a few hours of uptime Message-ID: <201010020032.o920WZKG028379@gw.catspoiler.org> In-Reply-To: <201009300849.o8U8nr8r081019@gw.catspoiler.org>
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On 30 Sep, Don Lewis wrote: > The silent reboots that I was seeing with WITNESS go away if I add > WITNESS_SKIPSPIN. Witness doesn't complain about anything. I've tracked down the the silent reboot problem. It happens when a userland sysctl call gets down into calcru1(), which tries to print a "calcu: .." message. Eventually sc_puts() wants to grab a spin lock, which causes a call to witness, which detects a lock order reversal. This recurses into printf(), which dives back into the console code and eventually triggers a panic. I'm still gathering the details on this and I see what I can come up with for a fix. > I tested -CURRENT and !SMP seems to work ok. One difference in terms of > hardware between the two tests is that I'm using a SATA drive when > testing -STABLE and a SCSI drive when testing -CURRENT. I'm not able to trigger the problem with -CURRENT when it is running on a SCSI drive, but I do see the freezes, long ping RTTs, and ntp insanity when running a !SMP -CURRENT kernel on my SATA drive with an 8.1-STABLE world.
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