Messages in this thread | | | Date | Mon, 21 Sep 2009 18:45:38 +0200 | From | Ingo Molnar <> | Subject | Re: [crash] kernel BUG at net/core/pktgen.c:3503! |
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* Ingo Molnar <mingo@elte.hu> wrote:
> > * David Miller <davem@davemloft.net> wrote: > > > From: Cyrill Gorcunov <gorcunov@gmail.com> > > Date: Tue, 15 Sep 2009 22:51:12 +0400 > > > > > [Ingo Molnar - Tue, Sep 15, 2009 at 08:36:47PM +0200] > > > | > > > | not sure which merge caused this, but i got this boot crash with latest > > > | -git: > > > | > > > | calling flow_cache_init+0x0/0x1b9 @ 1 > > > | initcall flow_cache_init+0x0/0x1b9 returned 0 after 64 usecs > > > | calling pg_init+0x0/0x37c @ 1 > > > | pktgen 2.72: Packet Generator for packet performance testing. > > > | ------------[ cut here ]------------ > > > | kernel BUG at net/core/pktgen.c:3503! > > > | invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > > > | last sysfs file: > > > | > > > > > > Hi Ingo, > > > > > > just curious, will the following patch fix the problem? > > > I've been fixing problem with familiar symthoms on > > > system with custome virtual cpu implementation so > > > it may not help in mainline but anyway :) > > > > Ingo, does Cyrill's patch help? > > For now i've turned pktgen off in my tests. Will check it again once > things have calmed down somewhat. > > Also, i just tried to reproduce the pktgen crash with latest -git and > the config i sent - no luck, so i cannot test Cyrill's patch either. > > Btw., we are seeing some other preempt count and task related > weirdnesses as well in other code, maybe it's related. No good pattern > yet to act upon. > > Anyway - please disregard this bugreport until i've investigated it > closer.
Update: i've further investigated it and this bug was caused by a scheduler bug introduced in this merge window, which got fixed in:
3f04e8c: sched: Re-add lost cpu_allowed check to sched_fair.c::select_task_rq_fair()
This bug caused CPU affinities to not work in essence - breaking kthread per-cpu assumptions in net/core/pktgen.c.
I've confirmed this by re-enabling pktgen in my tests and the crash has no reappeared.
Thanks,
Ingo
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