Messages in this thread | | | Date | Sat, 4 Jul 2009 00:56:40 +0200 | From | Jarek Poplawski <> | Subject | Re: Soft-Lockup/Race in networking in 2.6.31-rc1+195 ( possibly?caused by netem) |
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On Fri, Jul 03, 2009 at 01:22:20PM -0700, David Miller wrote: > From: Jarek Poplawski <jarkao2@gmail.com> > Date: Fri, 3 Jul 2009 12:03:01 +0000 > > > On Fri, Jul 03, 2009 at 01:26:21PM +0200, Andres Freund wrote: > >> On Friday 03 July 2009 08:12:13 Jarek Poplawski wrote: > >> > On Fri, Jul 03, 2009 at 03:31:31AM +0200, Andres Freund wrote: > >> > ... > >> > > >> > > Ok. I finally see the light. I bisected the issue down to > >> > > eea08f32adb3f97553d49a4f79a119833036000a : timers: Logic to move non > >> > > pinned timers > >> > > > >> > > Disabling timer migration like provided in the earlier commit stops the > >> > > issue from occuring. > >> > > > >> > > That it is related to timers is sensible in the light of my findings, > >> > > that I could trigger the issue only when using delay in netem - that is > >> > > the codepath using qdisc_watchdog... > >> > > >> > Andres, thanks for your work and time. It saved me a lot of searching, > >> > because I wasn't able to trigger this on my old box. > >> Thanks. It allowed me to go through some of my remaining paperwork ;-) > >> > >> Does anybody of you have an idea where the problem actually resides? > > > > Do you mean possibly broken timers are not enough? > > Well, if you look at that commit the bisect pointed to Jarek, it is a > change which starts causing a situation which never happened before. > Namely, timers added on one cpu can be migrated and fire on another. > > So this could be exposing races in the networking that technically > always existed.
I'm not sure I get your point; could you give some example? Actually, I've suspected races in timers code.
Jarek P.
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