#1133220 linux-image-6.12.74+deb13+1-amd64: zstd/lz4 are not activated while using zswap - there is always fallback to lzo

Package:
src:linux
Source:
src:linux
Submitter:
sergey
Date:
2026-06-17 02:23:01 UTC
Severity:
normal
#1133220#5
Date:
2026-04-11 06:48:17 UTC
From:
To:
Hi. This is my first report so do not judge strictly, please.
As always on fresh systems  with small amount RAM I configured zswap to use zstd+zsmalloc
When I've configured modules adding zstd,lz4 and rebult initramfs and rebooted I've saw that there is fallback to lzo.
It happens with both compressors zstd and lz4


Here is my config:
GRUB_CMDLINE_LINUX_DEFAULT="zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=zsmalloc"

# dmesg | grep zswap
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-6.12.74+deb13+1-amd64 root=UUID=12412ff1-8ede-4e90-bf78-c658fc1035c3 ro net.ifnames=0 biosdevname=0 rootdelay=2 root=/dev/vda1 zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=zsmalloc
[    0.044141] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-6.12.74+deb13+1-amd64 root=UUID=12412ff1-8ede-4e90-bf78-c658fc1035c3 ro net.ifnames=0 biosdevname=0 rootdelay=2 root=/dev/vda1 zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=zsmalloc
[    1.046619] zswap: compressor lz4 not available, using default lzo
[    1.047524] zswap: loaded using pool lzo/zsmalloc


# lsinitramfs /boot/initrd.img-$(uname -r) | grep -E 'zstd|zsmalloc|lz4'
usr/lib/modules/6.12.74+deb13+1-amd64/kernel/crypto/lz4.ko.xz
usr/lib/modules/6.12.74+deb13+1-amd64/kernel/crypto/zstd.ko.xz
usr/lib/modules/6.12.74+deb13+1-amd64/kernel/lib/lz4
usr/lib/modules/6.12.74+deb13+1-amd64/kernel/lib/lz4/lz4_compress.ko.xz
usr/lib/modules/6.12.74+deb13+1-amd64/kernel/lib/lz4/lz4hc_compress.ko.xz
usr/lib/x86_64-linux-gnu/libzstd.so.1
usr/lib/x86_64-linux-gnu/libzstd.so.1.5.7
#1133220#10
Date:
2026-04-16 14:05:09 UTC
From:
To:
Where does this work?  zswap is initialized before the system would be
able to load modules the normal way.

With Debian Unstable it works, not sure exactly how.

With Debian Trixie and Linux 6.19 it also does not work.

Oh, with dracut it works, what?

Sorry, I have no answer right now.  Something changed that makes it work
with the next Debian release, but not the current one.

Bastian
#1133220#15
Date:
2026-06-17 02:20:32 UTC
From:
To:
Hi, all.
Any news ?
Bug still present in 13.5.
Earlier enabling zstd and/or lz4 works perfectly with zswap in older
releases.

чт, 16 апр. 2026 г. в 14:05, Bastian Blank <waldi@debian.org>: