linux-kernel - Re: PROBLEM: NULL pointer dereference in kernel 4.14.6

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Date:   Sun, 17 Dec 2017 18:48:16 +0000
From:   Bronek Kozicki <brok@...orrekt.com>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Cc:     cgroups@...r.kernel.org
Subject: Re: PROBLEM: NULL pointer dereference in kernel 4.14.6

FWIW, I can do "cat" . I get a single number seemingly followed by an
infinite stream of 0s (I tried wc -l, but did not want to wait very long
and killed it). Here is what it looks like, if limited by "head":

root@...nsk ~ # cat
'/sys/fs/cgroup/unified/machine.slice/machine-qemu\x2d1\x2dkartuzy\x2dspice.scope/cgroup.procs'
| head
10649
0
0
0
0
0
0
0
0
0
root@...nsk ~ #

PID 10649 is indeed qemu process running the virtual machine in
question:

root@...nsk ~ # ps lw 10649
F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME
COMMAND
6     0 10649     1  20   0 4815836 60252 -     Sl   ?          2:56
/usr/bin/qemu-system-x86_64 -name
guest=kartuzy-spice,process=qemu:kartuzy-spice,debug-threads=on -S
-object se

Sorry about taint by ZFS, but there is nothing I can do, it is my root
filesystem. Since I am the only user of the package in question I could
cheat and replace the license for the build of the ZFS module, but I do
not see how that might help.

B.