Messages in this thread | | | Date | Wed, 26 Jan 2022 09:31:17 -0600 | From | Corey Minyard <> | Subject | Re: Possible reproduction of CSD locking issue |
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On Wed, Jan 26, 2022 at 03:51:36PM +0100, Juergen Gross wrote: > On 26.01.22 14:56, Corey Minyard wrote: > > On Wed, Jan 26, 2022 at 07:08:22AM +0100, Juergen Gross wrote:
snip..
> > > > csd: cnt(63d8e1f): 0003->0037 queue > > csd: cnt(63d8e20): 0003->0037 ipi > > csd: cnt(63d8e21): 0003->0037 ping > > > > In __smp_call_single_queue_debug CPU 3 sends another message to > > CPU 55 and sends an IPI. But there should be a pinged entry > > after this. > > > > csd: cnt(63d8e22): 0003->0037 queue > > csd: cnt(63d8e23): 0003->0037 noipi > > This is interesting. Those are 5 consecutive entries without any > missing in between (see the counter values). Could it be that after > the ping there was an interrupt and the code was re-entered for > sending another IPI? This would clearly result in a hang as seen.
Since preempt is enabled, wouldn't it eventually come back to the first thread and send the IPI? Unless CPU 3 is stuck in an interrupt or interrupt storm.
-corey
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