Ben RUBSON
2017-Aug-28 08:25 UTC
mlx4en, timer irq @100%... (11.0 stuck on high network load ???)
> On 16 Aug 2017, at 11:02, Ben RUBSON <ben.rubson at gmail.com> wrote: > >> On 15 Aug 2017, at 23:33, Julien Charbon <jch at freebsd.org> wrote: >> >> On 8/11/17 11:32 AM, Ben RUBSON wrote: >>>> On 08 Aug 2017, at 13:33, Julien Charbon <jch at freebsd.org> wrote: >>>> >>>> On 8/8/17 10:31 AM, Hans Petter Selasky wrote: >>>>> >>>>> Suggested fix attached. >>>> >>>> I agree we your conclusion. Just for the record, more precisely this >>>> regression seems to have been introduced with: >>>> (...) >>>> Thus good catch, and your patch looks good. I am going to just verify >>>> the other in_pcbrele_wlocked() calls in TCP stack. >>> >>> Julien, do you plan to make this fix reach 11.0-p12 ? >> >> I am checking if your issue is another flavor of the issue fixed by: >> >> https://svnweb.freebsd.org/base?view=revision&revision=307551 >> https://reviews.freebsd.org/D8211 >> >> This fix in not in 11.0 but in 11.1. Currently I did not found how an >> inp in INP_TIMEWAIT state can have been INP_FREED without having its tw >> set to NULL already except the issue fixed by r307551. >> >> Thus could you try to apply this patch: >> >> https://github.com/freebsd/freebsd/commit/acb5bfda99b753d9ead3529d04f20087c5f7d0a0.patch >> >> and see if you can still reproduce this issue? > > Thank you for your answer Julien. > Unfortunately, I'm not sure at all how to reproduce the issue. > I have other servers which are 100% identical to this one, same workload, > same some-months uptime, but they did not trigger the bug yet. > > If other network stack experts (I'm not) agree with your analysis, > we could then certainly go further with D8211 / r307551. > > One thing that perhaps might help : > # netstat -an | grep TIME_WAIT$ | wc -l > 468 > > Note that due to this running bug, sendmail has lots of difficulties to send outgoing mails. > As soon as I run the above netstat command, I receive a lot of stacked mails (more than 20 this time). > As if netstat was able to somehow help... > > Number of TIME_WAIT connections however does not decrease, but increases. > >> And in the spirit of r307551 fix and based on Hans patch I will also >> propose to add a kernel log describing the issue instead of starting an >> infinite loop when INVARIANT is not set. > > Which should then never be triggered :) > Good idea I think !What about : D8211/r307551 + Hans' patch + Julien's idea of a kernel log (sort of "We should not be here but we are") And backporting all this to 11.0 (and so to 11.1 too) ? As this bug can impact every FreeBSD machine / server, leading to an unavailable / unreachable system (this is how mine ended), sounds like it could inevitably be a good thing, for production stability purpose. Thank you very much ! Ben
Julien Charbon
2017-Aug-28 09:27 UTC
mlx4en, timer irq @100%... (11.0 stuck on high network load ???)
Hi Ben, On 8/28/17 10:25 AM, Ben RUBSON wrote:>> On 16 Aug 2017, at 11:02, Ben RUBSON <ben.rubson at gmail.com> wrote: >> >>> On 15 Aug 2017, at 23:33, Julien Charbon <jch at freebsd.org> wrote: >>> >>> On 8/11/17 11:32 AM, Ben RUBSON wrote: >>>>> On 08 Aug 2017, at 13:33, Julien Charbon <jch at freebsd.org> wrote: >>>>> >>>>> On 8/8/17 10:31 AM, Hans Petter Selasky wrote: >>>>>> >>>>>> Suggested fix attached. >>>>> >>>>> I agree we your conclusion. Just for the record, more precisely this >>>>> regression seems to have been introduced with: >>>>> (...) >>>>> Thus good catch, and your patch looks good. I am going to just verify >>>>> the other in_pcbrele_wlocked() calls in TCP stack. >>>> >>>> Julien, do you plan to make this fix reach 11.0-p12 ? >>> >>> I am checking if your issue is another flavor of the issue fixed by: >>> >>> https://svnweb.freebsd.org/base?view=revision&revision=307551 >>> https://reviews.freebsd.org/D8211 >>> >>> This fix in not in 11.0 but in 11.1. Currently I did not found how an >>> inp in INP_TIMEWAIT state can have been INP_FREED without having its tw >>> set to NULL already except the issue fixed by r307551. >>> >>> Thus could you try to apply this patch: >>> >>> https://github.com/freebsd/freebsd/commit/acb5bfda99b753d9ead3529d04f20087c5f7d0a0.patch >>> >>> and see if you can still reproduce this issue? >> >> Thank you for your answer Julien. >> Unfortunately, I'm not sure at all how to reproduce the issue. >> I have other servers which are 100% identical to this one, same workload, >> same some-months uptime, but they did not trigger the bug yet. >> >> If other network stack experts (I'm not) agree with your analysis, >> we could then certainly go further with D8211 / r307551. >> >> One thing that perhaps might help : >> # netstat -an | grep TIME_WAIT$ | wc -l >> 468 >> >> Note that due to this running bug, sendmail has lots of difficulties to send outgoing mails. >> As soon as I run the above netstat command, I receive a lot of stacked mails (more than 20 this time). >> As if netstat was able to somehow help... >> >> Number of TIME_WAIT connections however does not decrease, but increases. >> >>> And in the spirit of r307551 fix and based on Hans patch I will also >>> propose to add a kernel log describing the issue instead of starting an >>> infinite loop when INVARIANT is not set. >> >> Which should then never be triggered :) >> Good idea I think ! > > What about : > D8211/r307551 > + Hans' patch > + Julien's idea of a kernel log (sort of "We should not be here but we are")I did this change and I am testing it, on your side did you try this patch applied on 11.0? https://github.com/freebsd/freebsd/commit/acb5bfda99b753d9ead3529d04f20087c5f7d0a0.patch> And backporting all this to 11.0 (and so to 11.1 too) ? > > As this bug can impact every FreeBSD machine / server, > leading to an unavailable / unreachable system (this is how mine ended), > sounds like it could inevitably be a good thing, for production stability purpose.The main fix for your issue is (I believe): Fix a double-free when an inp transitions to INP_TIMEWAIT state after having been dropped. https://svnweb.freebsd.org/base?view=revision&revision=307551 This fix has been MFC-ed on both stable/11, stable/10 and is already included in 11.1 and will be in 10.4. To push in 11.0 release directly, I guess you have to promote this change to an Errata (never did that myself): https://www.freebsd.org/security/notices.html https://www.freebsd.org/security/security.html#reporting While waiting for this errata to be accepted better using the patch. My 2 cents. -- Julien