Process stuck in "vnread"

Maxim Sobolev sobomax at
Tue Mar 29 08:18:19 UTC 2016

Hey Adrian, unfortunately, this is kinda our production build/test box,
it's not particularly beefy and we also run some heavily contended apps on
it too just to see how it performs on this size of machine, so we would not
really want to put any heavy debug into kernel unless it's some issue that
can be triggered quickly. This particular deadlock has been popping up
every few weeks, annoying but not severely critical to jump to guns. I
think, thanks to @kib and @avg we might be on the right track. At least
that sounds plausible and kinda fits the pattern.

On Mon, Mar 28, 2016 at 9:09 AM, Adrian Chadd <adrian.chadd at>

> Hi,
> I think a bunch of the lock order checks with witness get disabled for ZFS
> ?
> Maybe compile up a witness kernel so you can get 'show alllocks' in
> ddb. That should help narrow down exactly what's going on.
> Thanks!
> -a

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