Re: Path forward for Virtualized Swap?

[Nhat Pham]

On Tue, Sep 8, 2026 at 11:30 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
>
> On Mon, Sep 07, 2026 at 01:51:31PM +0800, Kairui Song wrote:
> > Where I've ended up is that unbounded growth is a real concern. On a
> > host with no memcg limit (root cgroup, and most desktop and embedded
> > setups), an unlimited pool means usage can keep growing, with no
> > admin visible ceiling at all. I'm not attached to xswap's percent of RAM
> > knob specifically, but I do think some kind of bound makes sense.
>
> Swap space is just process virtual address space, no?
>
> Swap entries already have one or more page table entries pointing to
> them, which in turn are managed by trees of vm_area_structs. That
> means rlimits apply, overcommit protection applies, and OOM killer
> attribution works as well (oom_badness()).

I tested this theory. I spinned up a process, and let it spam 0-filled
memory + swap these pages out continually.

As you predicted, oom-killer picked it up eventually. The host was
(and is) intact otherwise :)