From: Johannes Weiner <hannes@cmpxchg.org>
To: Kairui Song <ryncsn@gmail.com>
Cc: "Nhat Pham" <nphamcs@gmail.com>, "Chris Li" <chrisl@kernel.org>,
"Michal Hocko" <mhocko@kernel.org>,
"Roman Gushchin" <roman.gushchin@linux.dev>,
"Shakeel Butt" <shakeel.butt@linux.dev>,
"Yosry Ahmed" <yosry@kernel.org>,
"David Hildenbrand" <david@kernel.org>,
"Muchun Song" <muchun.song@linux.dev>,
"Kemeng Shi" <shikemeng@huaweicloud.com>,
"Baoquan He" <baoquan.he@linux.dev>,
"Barry Song" <baohua@kernel.org>,
"YoungJun Park" <youngjun.park@lge.com>,
"Chengming Zhou" <chengming.zhou@linux.dev>,
"Lorenzo Stoakes (Oracle)" <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
"Vlastimil Babka (SUSE)" <vbabka@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"Suren Baghdasaryan" <surenb@google.com>,
"Qi Zheng" <qi.zheng@linux.dev>,
"Axel Rasmussen" <axelrasmussen@google.com>,
"Yuanchu Xie" <yuanchu@google.com>, "Wei Xu" <weixugc@google.com>,
"Rik van Riel" <riel@surriel.com>,
"Gregory Price" <gourry@gourry.net>,
"Wenchao Hao" <haowenchao22@gmail.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Hugh Dickins" <hughd@google.com>,
"Baolin Wang" <baolin.wang@linux.alibaba.com>,
"Tejun Heo" <tj@kernel.org>, "Michal Koutný" <mkoutny@suse.com>,
"Shuah Khan" <skhan@linuxfoundation.org>,
"Kunwu Chan" <kunwu.chan@linux.dev>,
"Meta kernel team" <kernel-team@meta.com>,
"Linux Memory Management List" <linux-mm@kvack.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-doc@vger.kernel.org,
"open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)"
<cgroups@vger.kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Joshua Hahn" <joshua.hahnjy@gmail.com>
Subject: Re: Path forward for Virtualized Swap?
Date: Tue, 8 Sep 2026 14:30:11 -0400 [thread overview]
Message-ID: <aqBT_35E-eSoN_zj@cmpxchg.org> (raw)
In-Reply-To: <CAMgjq7AHRzBsbmGOx0s=TQFBwcn=DEU1naR443sO6x+pJd6hAg@mail.gmail.com>
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()).
Shmem has its own defaults and limit interface on address space.
I'm not quite seeing how the swap space needs an additional limit. How
could users break things in unique new ways without it?
It would be good to spell out that vector before discussing numbers :)
next prev parent reply other threads:[~2026-09-08 18:30 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 21:14 Nhat Pham
2026-09-07 5:51 ` Kairui Song
2026-09-08 16:36 ` Nhat Pham
2026-09-08 18:30 ` Johannes Weiner [this message]
2026-09-09 16:41 ` Nhat Pham
2026-09-09 17:47 ` Nhat Pham
2026-09-10 23:27 ` Nhat Pham
2026-09-07 11:30 ` David Hildenbrand (Arm)
2026-09-08 16:45 ` Nhat Pham
2026-09-10 10:56 ` David Hildenbrand (Arm)
2026-09-10 16:22 ` Nhat Pham
2026-09-10 17:57 ` David Hildenbrand (Arm)
2026-09-10 7:09 ` Baoquan He
2026-09-10 16:39 ` Shakeel Butt
2026-09-10 17:03 ` Johannes Weiner
2026-09-10 17:16 ` Nhat Pham
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