Re: kern/54541: kernel panic using "zfs diff"

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

The following reply was made to PR kern/54541; it has been noted by GNATS.

From: Brad Spencer <brad%anduin.eldar.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
        joernc%posteo.de@localhost
Subject: Re: kern/54541: kernel panic using "zfs diff"
Date: Sat, 12 Oct 2019 07:33:14 -0400

 "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost> writes:
 
 > The following reply was made to PR kern/54541; it has been noted by GNATS.
 >
 > From: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
 > To: gnats-bugs%netbsd.org@localhost
 > Cc: 
 > Subject: Re: kern/54541: kernel panic using "zfs diff"
 > Date: Sat, 12 Oct 2019 10:02:28 +0200
 >
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 >  
 >  > On 12. Oct 2019, at 01:50, Brad Spencer <brad%anduin.eldar.org@localhost> wrote:
 >  <snip>
 >  >=20
 >  > [ 472375.2036056] panic: kernel diagnostic assertion "fdm !=3D NULL" =
 >  failed: file "/usr/src/sys/kern/vfs_trans.c", line 166 mount 0x0 invalid
 >  
 >  Sorry for being late, looks like vn_rdwr() gets called
 >  with garbage instead of a vnode.
 >  
 >  The attached diff could help to track it down.
 >  
 >  Do you have a recipe to trigger this panic?
 >  
 >  --
 >  J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig
 
 
 For me personally, it is something like this, although I don't know how
 much of this matters:
 
 sysctl -w ddb.onpanic=1
 zpool create tank xbd4d  <- 1GB presented to a DOMU
 zfs create tank/ds1
 zfs set quota=100m tank/ds1
 (fill tank/ds1 up to about 80% or so with anything, I used multiple files, but I doubt that matters)
 zfs snapshot tank/ds1@sn1
 (change tank/ds1.  Add or delete something, I think any change will work)
 You will end up with something like this:
 test3# zfs list -t all
 NAME           USED  AVAIL  REFER  MOUNTPOINT
 rstuff         264M  1.55G    23K  /rstuff
 rstuff/var     261M   139M   261M  legacy
 tank          80.8M  1.73G    23K  /tank
 tank/ds1      80.2M  19.8M  80.2M  /tank/ds1
 tank/ds1@sn1    18K      -  80.2M  -
 zfs diff tank/ds1@sn1
 panic here
 
 I applied the included patch to a test build which is building now, but
 I can't retest this for a bit.  The test DOMU that triggers this has 1GB
 of memory given to it and is running a pretty recent build.
 
 
 
 -- 
 Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org