On Mon, Nov 07, 2022 at 10:47:33PM +0100, Petr Vorel wrote:
Hi Minchan,
On Mon, Nov 07, 2022 at 08:11:35PM +0100, Petr Vorel wrote:
Hi all,
following bug is trying to workaround an error on ppc64le, where zram01.sh LTP test (there is also kernel selftest tools/testing/selftests/zram/zram01.sh, but LTP test got further updates) has often mem_used_total 0 although zram is already filled.
Hi, Petr,
Is it happening on only ppc64le?
I haven't seen it on other archs (x86_64, aarch64).
Is it a new regression? What kernel version did you use?
Found on openSUSE kernel, which uses stable kernel releases 6.0.x. It's probably much older, first I've seen it some years ago (I'm not able to find kernel version), but it was random. Now it's much more common.
Test runs on VM (I can give qemu command or whatever you need to know about it) I'll try to verify it on some bare metal ppc64le.
Hi Petr and Martin,
Thanks for testing and meaning information.
Could you tell how I could create VM to run ppc64le and run the test? I'd like to reproduce in my local to debug it.
I suppose you don't have ppc64le bare metal machine, thus you run on x86_64.
One way would be to install on host qemu-system-ppc64, download iso image of any distro which supports ppc64le and install it with virt-manager (which would fill necessary qemu params).
Other way, which I often use is to compile system with Buildroot distribution. You can clone my Buildroot distro fork, branch debug/zram [1]. I put there in 3 commits my configuration. I added 0001-zram-Debug-mm_stat_show.patch [2] on the top of 6.0.7 with little debugging.
What is now only needed is to 1) install on host qemu-system-ppc64 (speedup build + Buildroot is configured not to compile qemu-system-ppc64), then: $ make # takes time $ ./output/images/start-qemu.sh serial-only
When I have ppc64le host with enough space, I often use rapido [3], but that crashed stable kernel (another story which I'll report soon).
Hope that helps.
Kind regards, Petr
[1] https://github.com/pevik/buildroot/commits/debug/zram [2] https://github.com/pevik/buildroot/blob/debug/zram/0001-zram-Debug-mm_stat_s... [3] https://github.com/rapido-linux/rapido