Comment # 23 on bug 1159882 from Robert Delahunt

Confirmed this bug exists in OpenSUSE LEAP 15.2.

https://forums.opensuse.org/showthread.php/544618-Hard-Disk-Activity-Memory-Hole?p=2965585#post2965585

Brand new Dell Inspiron 7591 laptop.  16GB RAM, 1TB SSD.

dd, rsync, and over operations that use lots of disk I/O result in the system
dramatically digging into swap.  Even with swappiness=1, swap use (of 1GB swap)
increased to 105 MB (10%).

Transcript of forum post:    ----- QUOTE BEGIN

I do not know where else to post this, so here goes. I have a clean basic XFCE
installation of OpenSUSE LEAP 15.2. This behavior happens on both the Asus
R541U laptop I used to have (8GB RAM, 512MB Swap) and my new Dell Inspiron 7591
(16GB RAM, 1GB swap). I would boot into OpenSUSE to do some "hard drive
wrangling", i.e. making disk images of hard drives via USB adapters (dd
if=/some/device | gzip -c > imagefile) or zeroizing old disks (dd if=/dev/zero
of=/some/device).

As soon as I begin the dd process, my RAM and swap climb through the roof.
Almost no applications are open when this occurs. For example:

1) When I was using my Asus to read the 512GB SSD via an adapter to another USB
external hard drive (BACKUP) (i.e. dd if=/dev/nvme0n1 | gzip -c >
/run/media/robert/BACKUP/Windows/dell7591.img.gz)

2) When I was backing up my files on the Asus (rsync -Hav /home/robert/
/run/media/robert/BACKUP/dell/robert/)

3) When I was copying the dd image to the new 1TB SSD upgrade for my dell
(gunzip -c /run/media/robert/BACKUP/Windows/dell7591.img.gz | dd
of=/dev/nvme0n1)

4) When I was just now zeroizing the old 512GB SSD via the same USB adapter (dd
if=/dev/zero of=/dev/sdb)

5) When I was synchronizing my incremental monthly backups (both 2TB external
USB drives running LUKS) (rsync -Hav --delete --progress
/run/media/robert/BACKUP/ /run/media/robert/BACKUP2/ )

It always seems connected to rsync/gzip/dd, i.e. heavy use of filesystems. If I
boot OpenSUSE and I am just sitting in OpenSUSE using applications, usually it
does not cause me to dig into swap.

At the height of the zeroizing action, for example, swap use (16GB RAM, 1GB
swap, new Dell Inspiron 7591) climbed to 108MB. It dropped to 11MB.

Given that I have 16GB of RAM, such behavior is absolutely unacceptable. All
the I/O should be happening on disks. I have not been able to triangulate,
using top, what process is eating RAM so much.

I am using EXT4 exclusively, no BTRFS anywhere.

I have remounted all tmpfs entries to only give them 1GB of RAM to work with,
as in the past this has prevented such excessive swappiness (believe it or not;
it's difficult to prove; older versions of OpenSUSE, etc).

I am willing to run experiments to see what's going on.

I noticed that there were some btrfs components of systemd that were installed.
I uninstalled them, but the problem remains.

I don't understand how even running something complex as rsync + gzip + dd
should need to dig into that much system RAM. I mean, I have 16GB!

Have any memory leaks been reported on OpenSUSE? ----- END QUOTE

I am very willing to provide any information to help resolve this apparent
memory hole or memory leak.