Re: kern/53385 (vnconfig deadlock on fstchg)

[Brad Spencer <brad%anduin.eldar.org@localhost>]

"Greg A. Woods" <woods%planix.ca@localhost> writes:

> The following reply was made to PR kern/53385; it has been noted by GNATS.
>
> From: "Greg A. Woods" <woods%planix.ca@localhost>
> To: NetBSD GNATS <gnats-bugs%NetBSD.org@localhost>
> Cc: 
> Subject: Re: kern/53385 (vnconfig deadlock on fstchg)
> Date: Fri, 19 Feb 2021 14:07:20 -0800
>
>  > >How-To-Repeat:
>  > 	destroy a domU with 2 file-backed disks ?
>  
>  Definitely that.
>  
>  I just ran "halt -p" in just such a domU (four LVM disks and two
>  file-backed disks) and instantly everything in the dom0 got hung in
>  "fstchg", including all login shells.
>  
>  The dom0 host is running NetBSD/amd64 8.99.32 (kernel from about
>  2019/11/28).

I see this problem on a 8.99.25 NetBSD DOM0.  However, I thought I also
saw a commit where this was fixed (I may also be misremembering this)
and I may remember that it made it into 9.x.  I am not currently in a
position to try a newer DOM0 NetBSD, but it may be worth attempting that
if you can.

>  
>  (Thankfully other domUs running on the same machine appear to still be
>  running and apparently can still access their LVM-backed disks, so I
>  think I can shut them down before crashing the dom0 -- BUT the dom0 is
>  remote and I don't have easy console access!)
>  
>  > >Fix:
>  > 	workaround: make sure Xen won't call more than one vnconfig -u at
>  > 	once. But we need a fix for this.
>  
>  Seriously!
>  
>  -- 
>  					Greg A. Woods <gwoods%acm.org@localhost>
>  
>  Kelowna, BC     +1 250 762-7675           RoboHack <woods%robohack.ca@localhost>
>  Planix, Inc. <woods%planix.com@localhost>     Avoncote Farms <woods%avoncote.ca@localhost>
>  



-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org