Date: Thu, 16 Jul 2009 14:45:32 +0800 From: "C. C. Tang" <hiyorin@gmail.com> To: freebsd-stable@freebsd.org Subject: Re: 7.2-release/amd64: panic, spin lock held too long Message-ID: <4A5ECC8C.7030808@gmail.com> In-Reply-To: <3bbf2fe10907080250q35899d3dhc2f101b62c6e5306@mail.gmail.com> References: <cf9b1ee00907061812r3da70018i1c8d8d12bb038a80@mail.gmail.com> <3bbf2fe10907061818v245abd0cgc3ca5073cb93aea4@mail.gmail.com> <cf9b1ee00907061825r34165c48x6727c50b3219d5fb@mail.gmail.com> <3bbf2fe10907061827g35eaeb49g26cf6fdb64436ca7@mail.gmail.com> <cf9b1ee00907071757i169d2a82la260798f364054f9@mail.gmail.com> <cf9b1ee00907080018s3f32c8afr4f65f01ce9ff1f25@mail.gmail.com> <3bbf2fe10907080250q35899d3dhc2f101b62c6e5306@mail.gmail.com>
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Attilio Rao wrote: > 2009/7/8 Dan Naumov <dan.naumov@gmail.com>: >> On Wed, Jul 8, 2009 at 3:57 AM, Dan Naumov<dan.naumov@gmail.com> wrote: >>> On Tue, Jul 7, 2009 at 4:27 AM, Attilio Rao<attilio@freebsd.org> wrote: >>>> 2009/7/7 Dan Naumov <dan.naumov@gmail.com>: >>>>> On Tue, Jul 7, 2009 at 4:18 AM, Attilio Rao<attilio@freebsd.org> wrote: >>>>>> 2009/7/7 Dan Naumov <dan.naumov@gmail.com>: >>>>>>> I just got a panic following by a reboot a few seconds after running >>>>>>> "portsnap update", /var/log/messages shows the following: >>>>>>> >>>>>>> Jul 7 03:49:38 atom syslogd: kernel boot file is /boot/kernel/kernel >>>>>>> Jul 7 03:49:38 atom kernel: spin lock 0xffffffff80b3edc0 (sched lock >>>>>>> 1) held by 0xffffff00017d8370 (tid 100054) too long >>>>>>> Jul 7 03:49:38 atom kernel: panic: spin lock held too long >>>>>> That's a known bug, affecting -CURRENT as well. >>>>>> The cpustop IPI is handled though an NMI, which means it could >>>>>> interrupt a CPU in any moment, even while holding a spinlock, >>>>>> violating one well known FreeBSD rule. >>>>>> That means that the cpu can stop itself while the thread was holding >>>>>> the sched lock spinlock and not releasing it (there is no way, modulo >>>>>> highly hackish, to fix that). >>>>>> In the while hardclock() wants to schedule something else to run and >>>>>> got stuck on the thread lock. >>>>>> >>>>>> Ideal fix would involve not using a NMI for serving the cpustop while >>>>>> having a cheap way (not making the common path too hard) to tell >>>>>> hardclock() to avoid scheduling while cpustop is in flight. >>>>>> >>>>>> Thanks, >>>>>> Attilio >>>>> Any idea if a fix is being worked on and how unlucky must one be to >>>>> run into this issue, should I expect it to happen again? Is it >>>>> basically completely random? >>>> I'd like to work on that issue before BETA3 (and backport to >>>> STABLE_7), I'm just time-constrained right now. >>>> it is completely random. >>>> >>>> Thanks, >>>> Attilio >>> Ok, this is getting pretty bad, 23 hours later, I get the same kind of >>> panic, the only difference is that instead of "portsnap update", this >>> was triggered by "portsnap cron" which I have running between 3 and 4 >>> am every day: >>> >>> Jul 8 03:03:49 atom kernel: ssppiinn lloocckk >>> 00xxffffffffffffffff8800bb33eeddc400 ((sscchheedd lloocck k1 )0 )h >>> ehledl db yb y 0x0xfffffffffff0f00001081735339760e 0( t(itdi d >>> 10100006070)5 )t otoo ol olnogng >>> Jul 8 03:03:49 atom kernel: p >>> Jul 8 03:03:49 atom kernel: anic: spin lock held too long >>> Jul 8 03:03:49 atom kernel: cpuid = 0 >>> Jul 8 03:03:49 atom kernel: Uptime: 23h2m38s >> I have now tried repeating the problem by running "stress --cpu 8 --io >> 8 --vm 4 --vm-bytes 1024M --timeout 600s --verbose" which pushed >> system load into the 15.50 ballpark and simultaneously running >> "portsnap fetch" and "portsnap update" but I couldn't manually trigger >> the panic, it seems that this problem is indeed random (although it >> baffles me why is it specifically portsnap triggering it). I have now >> disabled powerd to check whether that makes any difference to system >> stability. > > But is that happening at reboot time? > > Thanks, > Attilio > I think I am also having similar problem on my Atom machine. (FreeBSD-7.2-Release-p1) It does not happen at boot/reboot but panic randomly. And I found that it remains stable for more than a month now after I disabled powerd... (although I want to have it enabled) -- C.C.
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