linux-kernel - [RFC PATCH v7 0/2] mm: Fix OOM killer inaccuracy on large many-core systems

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Message-Id: <20251031144232.15284-1-mathieu.desnoyers@efficios.com>
Date: Fri, 31 Oct 2025 10:42:30 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Mateusz Guzik <mjguzik@...il.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Sweet Tea Dorminy <sweettea@...gle.com>
Cc: linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Dennis Zhou <dennis@...nel.org>,
	Tejun Heo <tj@...nel.org>,
	Christoph Lameter <cl@...ux.com>,
	Martin Liu <liumartin@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	christian.koenig@....com,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	SeongJae Park <sj@...nel.org>,
	Michal Hocko <mhocko@...e.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R . Howlett" <liam.howlett@...cle.com>,
	Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Christian Brauner <brauner@...nel.org>,
	Wei Yang <richard.weiyang@...il.com>,
	David Hildenbrand <david@...hat.com>,
	Miaohe Lin <linmiaohe@...wei.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-mm@...ck.org,
	linux-trace-kernel@...r.kernel.org,
	Yu Zhao <yuzhao@...gle.com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Matthew Wilcox <willy@...radead.org>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	Aboorva Devarajan <aboorvad@...ux.ibm.com>
Subject: [RFC PATCH v7 0/2] mm: Fix OOM killer inaccuracy on large many-core systems

Introduce hierarchical per-cpu counters and use them for rss tracking to
fix the per-mm RSS tracking which has become too inaccurate for OOM
killer purposes on large many-core systems.

The approach proposed here is to replace this by the hierarchical
per-cpu counters, which bounds the inaccuracy based on the system
topology with O(N*logN).

Relevant delta since v6: Rebase to v6.18-rc3 and implement
get_mm_counter_sum() as percpu_counter_tree_precise_sum().

Testing and feedback are welcome!

Thanks,

Mathieu

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Dennis Zhou <dennis@...nel.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Martin Liu <liumartin@...gle.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: christian.koenig@....com
Cc: Shakeel Butt <shakeel.butt@...ux.dev>
Cc: SeongJae Park <sj@...nel.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Sweet Tea Dorminy <sweettea@...gle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: "Liam R . Howlett" <liam.howlett@...cle.com>
Cc: Mike Rapoport <rppt@...nel.org>
Cc: Suren Baghdasaryan <surenb@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Christian Brauner <brauner@...nel.org>
Cc: Wei Yang <richard.weiyang@...il.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Miaohe Lin <linmiaohe@...wei.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-mm@...ck.org
Cc: linux-trace-kernel@...r.kernel.org
Cc: Yu Zhao <yuzhao@...gle.com>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Mateusz Guzik <mjguzik@...il.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Aboorva Devarajan <aboorvad@...ux.ibm.com>

Mathieu Desnoyers (2):
  lib: Introduce hierarchical per-cpu counters
  mm: Fix OOM killer inaccuracy on large many-core systems

 include/linux/mm.h                  |  10 +-
 include/linux/mm_types.h            |   4 +-
 include/linux/percpu_counter_tree.h | 203 ++++++++++++++
 include/trace/events/kmem.h         |   2 +-
 kernel/fork.c                       |  32 ++-
 lib/Makefile                        |   1 +
 lib/percpu_counter_tree.c           | 394 ++++++++++++++++++++++++++++
 7 files changed, 627 insertions(+), 19 deletions(-)
 create mode 100644 include/linux/percpu_counter_tree.h
 create mode 100644 lib/percpu_counter_tree.c

-- 
2.39.5