Hello Ken,
do you have a command to reproduce this? I would like to use it to
verify the fix.
I tired this on a Cosmic KVM allocated with 2G ram, 512MB swap, with:
* "zswap.enabled=1 zswap.zpool=z3fold zswap.max_pool_percent=5
zswap.compressor=lz4" added to the grub
* z3pool, lz4, lz4_compress module added to initramfs
and stress it with the stress command with 115% of available memory.
stress --vm-bytes $(awk '/MemAvailable/{printf "%d\n", $2 * 1.15;}' <
/proc/meminfo)k --vm-keep -m 1
All I got is a soft CPU lockup. Or should I leave it there for a while?
Thanks
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https://bugs.launchpad.net/bugs/1814874
Title:
NULL pointer dereference when using z3fold and zswap
Status in Linux:
Fix Released
Status in linux package in Ubuntu:
New
Bug description:
Under memory pressure, my VM locks up. This has been reported upstream
though I don't know how far any solution has progressed.
https://bugzilla.kernel.org/show_bug.cgi?id=201603
Feb 6 07:15:42 vps632258 kernel: [151336.450064] z3fold: unknown buddy id 0
Feb 6 07:15:42 vps632258 kernel: [151336.454450] BUG: unable to handle
kernel NULL pointer dereference at 0000000000000008
The little bit of log I managed to salvage is attached.
This has happened to two identical VMs. Unusually it has not occurred
on a third VM which is configured the same but has less RAM (fingers
crossed it won't).
Irrelevant information:
I thought the lock-ups were due to me using a BTRFS filesystem, however I
swapped over to NILFS2 and this still occurs. The only difference seems to be
that I am now able to grab some of the kernel output.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.18.0-14-generic 4.18.0-14.15~18.04.1
ProcVersionSignature: Ubuntu 4.18.0-14.15~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-14-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
Date: Wed Feb 6 10:55:05 2019
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_GB.UTF-8
SHELL=/bin/bash
SourcePackage: linux-signed-hwe
UpgradeStatus: No upgrade log present (probably fresh install)
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