i386 hangs during halt "vnodes remaining... 0 time out"

[Claude Buisson]

On 04/21/2018 23:09, Rick Macklem wrote:
> With a recent head/current kernel (doesn't happen when running a Dec. 2017 one),
> when I do a halt, it gets as far as:
> 
> vnodes remaining... 0 time out
> 
> and that's it (the time out appears several seconds after the first "0").
> With a Dec. 2017 kernel there would be several "0"s printed.
> It appears that it is stuck in the first iteration of the sched_sync() loop after
> it is no longer in SYNCER_RUNNING state.
> 
> Any ideas? rick
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There is a PR which seems related: 227404

I was hit by this problem when upgrading an i386 UP system from r329142 
to r332518. The culprit appears to be r329612.

I reverted 4 files:

sys/kern/vfs_bio.c -> r329187
sys/kern/vfs_subr.c -> r328643
sys/sys/buf.h -> r329078
sys/sys/bufobj.h -> r326256

rebuild the system, and the hang disappeared.

I have now 2 i386 UP and 1 amd64 MP systems running with this 
modification, and 1 RPI2 in the pipe line.

Hope it helps

Claude Buisson