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Date: Wed, 22 Jul 2015 16:14:53 +0200 From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com> To: Florian Westphal <fw@...len.de> Cc: Frank Schreuder <fschreuder@...nsip.nl>, Johan Schuijt <johan@...nsip.nl>, Eric Dumazet <eric.dumazet@...il.com>, "nikolay@...hat.com" <nikolay@...hat.com>, "davem@...emloft.net" <davem@...emloft.net>, "chutzpah@...too.org" <chutzpah@...too.org>, Robin Geuze <robing@...nsip.nl>, netdev <netdev@...r.kernel.org> Subject: Re: reproducable panic eviction work queue On 07/22/2015 04:03 PM, Nikolay Aleksandrov wrote: > On 07/22/2015 03:58 PM, Florian Westphal wrote: >> Nikolay Aleksandrov <nikolay@...ulusnetworks.com> wrote: >>> On 07/22/2015 10:17 AM, Frank Schreuder wrote: >>>> I got some additional information from syslog: >>>> >>>> Jul 22 09:49:33 dommy0 kernel: [ 675.987890] NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [kworker/3:1:42] >>>> Jul 22 09:49:42 dommy0 kernel: [ 685.114033] INFO: rcu_sched self-detected stall on CPU { 3} (t=39918 jiffies g=988 c=987 q=23168) >>>> >>>> Thanks, >>>> Frank >>>> >>>> >>> >>> Hi, >>> It looks like it's happening because of the evict_again logic, I think we should also >>> add Florian's first suggestion about simplifying it to the patch and just skip the >>> entry if we can't delete its timer otherwise we can restart the eviction and see >>> entries that already had their timer stopped by us and can keep restarting for >>> a long time. >>> Here's an updated patch that removes the evict_again logic. >> >> Thanks Nik. I'm afraid this adds bug when netns is exiting. >> >> Currently, we wait until timer has finished, but after the change >> we might destroy percpu counter while a timer is still executing on >> another cpu. >> >> I pushed a patch series to >> https://git.breakpoint.cc/cgit/fw/net.git/log/?h=inetfrag_fixes_02 >> >> It includes this patch with a small change -- deferral of the percpu >> counter subtraction until after queue has been free'd. >> >> Frank -- it would be great if you could test with the four patches in >> that series applied. >> >> I'll then add your tested-by Tag to all of them before submitting this. >> >> Thanks again for all your help in getting this fixed! >> > > Sure, I didn't think it through, just supplied it for the test. :-) > Thanks for fixing it up! > Patches look great, even the INET_FRAG_EVICTED flag will not be accidentally cleared this way. I'll give them a try. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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