Re: GPF on boot with devmatch

On 05.10.2020 17:20, Warner Losh wrote:
> On Mon, Oct 5, 2020 at 12:36 PM Alexander Motin <mav_at_freebsd.org
> <mailto:mav_at_freebsd.org>> wrote:
> 
>     I can add that we've received report about identical panic on FreeBSD
>     releng/12.2 of r365436, AKA TrueNAS 12.0-RC1:
>     https://jira.ixsystems.com/browse/NAS-107578 .  So it looks a) pretty
>     rate (one report from thousands of early adopters and none in our lab),
>     and b) it is in stable/12 too, not only head.
> 
> Thanks! I'll see if I can recreate here....  But we're accessing the
> sysctl tree from devmatch to get some information, which should always
> be OK (the fact that it isn't suggests either a bug in some driver
> leaving bad pointers, or some race or both)...  It would be nice to know
> which nodes they were, or to have a kernel panic I can look at...

All we have now in this case is a screenshot you may see in the ticket.
 Also previously the same user on some earlier version of stable/12
reported other very weird panics on process lock being dropped where it
can't be in some other sysctls inside kern.proc, so if we guess those
are related, I suspect there may be some kind of memory corruption
happening, but have no clue where.  Unfortunately we have only textdumps
for those.  So if Xin is able to reproduce it locally, it may be our
best chance to debug it, at least this specific issue.

-- 
Alexander Motin