Comment 78 for bug 1833281

(In reply to Mikhail Novosyolov from comment #54)
>
> So, something was fixed in upstream, backported to LTS kernel 4.19 and to
> Ubuntu kernel. I don't know what. And that issue is 100% not in BTRFS but is
> another problem or another aspect of the problem.
>
I can suspect commit 2c012a4ad1a2cd3fb5a0f9307b9d219f84eda1fa "mm: vmscan: scan anonymous pages on file refaults"

https://github.com/torvalds/linux/commit/2c012a4ad1a2cd3fb5a0f9307b9d219f84eda1fa

It appeared in kernel 5.3 and was backported to 4.19.62 and Ubuntu kernel 4.15.0-59

(In reply to ValdikSS from comment #53)
> Recently, about since kernel 5.2.7, the issue is either gone or present to
> much less extent.
> Right now I'm running kernel 5.2.11 and finally I can keel Firefox and
> VirtualBox running at the same time, with 3G+ in swap, and the system does
> not freeze.
... and to 5.2.3

But that commit "fixes" commits from the era of kernels 3.8 and 3.9, so probably it is not the one I'm looking for.