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Fri, 20 Feb 2026 11:02:49 -0800 (PST) Received: from localhost ([2603:7000:c00:3a00:365a:60ff:fe62:ff29]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-5070d6df498sm488911cf.30.2026.02.20.11.02.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Feb 2026 11:02:49 -0800 (PST) Date: Fri, 20 Feb 2026 14:02:48 -0500 From: Johannes Weiner To: "JP Kobryn (Meta)" Cc: linux-mm@kvack.org, mst@redhat.com, mhocko@suse.com, vbabka@suse.cz, apopple@nvidia.com, akpm@linux-foundation.org, axelrasmussen@google.com, byungchul@sk.com, cgroups@vger.kernel.org, david@kernel.org, eperezma@redhat.com, gourry@gourry.net, jasowang@redhat.com, joshua.hahnjy@gmail.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, rppt@kernel.org, muchun.song@linux.dev, zhengqi.arch@bytedance.com, rakie.kim@sk.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, surenb@google.com, virtualization@lists.linux.dev, weixugc@google.com, xuanzhuo@linux.alibaba.com, ying.huang@linux.alibaba.com, yuanchu@google.com, ziy@nvidia.com, kernel-team@meta.com Subject: Re: [PATCH v5] mm: move pgscan, pgsteal, pgrefill to node stats Message-ID: References: <20260219235846.161910-1-jp.kobryn@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260219235846.161910-1-jp.kobryn@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 326D218000F X-Stat-Signature: 9fx3oxzzbnwjqcx8cux114kew6rej89c X-HE-Tag: 1771614171-836421 X-HE-Meta: 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 EEL+GYK4 YxFlAdID6ysRkhfnp7gJq6F7Wqz13bE3kFF4eyR40rJocUQlEm4UYpBL6C/vo7SWLeAYrIt2LbjRPEd/CSkZM9IiRoJFRvOotNltG6e//usbr+ahXMSF41pHwhcRH2Etu7pUkEjNhb7/vwoIX5psROS1UFhk4Kmx/jYx7lumykLzzob+IDD8Gq7bAZYO9fceHuWicRf3HeK38ENP7rDwJKVpnrJAD8xsb53cacckz7wfFUG1CD98akkcFBNU/hUgav0xd7Ov5LC+HggwkJIvkMjGtPuIgS2bDvl6us2PzVvlxchqZU9vp3EF7a0AOS6uTusm5kDVerspm8WyJCH53pPdpBKu1pc0AZM9D+QRv1POHdPHJCqi5o9aBsErEq1QRjE+5Mi3KwGWDRxhdJUHAb62xJMaFFrTjtRHG0EZZk40R4gcuAxtFbw2zZls0ItfeOTtxvLNIEVAUYZg15+jfxFUmqyjpTAMipRQYNfS45Te4JYM880vLFdvrR11kGwzUdliGlOHvRl0N4k3uA0kLELFyxbCApSpTFg7oxs+qPLP25rI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 19, 2026 at 03:58:46PM -0800, JP Kobryn (Meta) wrote: > There are situations where reclaim kicks in on a system with free memory. > One possible cause is a NUMA imbalance scenario where one or more nodes are > under pressure. It would help if we could easily identify such nodes. > > Move the pgscan, pgsteal, and pgrefill counters from vm_event_item to > node_stat_item to provide per-node reclaim visibility. With these counters > as node stats, the values are now displayed in the per-node section of > /proc/zoneinfo, which allows for quick identification of the affected > nodes. > > /proc/vmstat continues to report the same counters, aggregated across all > nodes. But the ordering of these items within the readout changes as they > move from the vm events section to the node stats section. > > Memcg accounting of these counters is preserved. The relocated counters > remain visible in memory.stat alongside the existing aggregate pgscan and > pgsteal counters. > > However, this change affects how the global counters are accumulated. > Previously, the global event count update was gated on !cgroup_reclaim(), > excluding memcg-based reclaim from /proc/vmstat. Now that > mod_lruvec_state() is being used to update the counters, the global > counters will include all reclaim. This is consistent with how pgdemote > counters are already tracked. > > Finally, the virtio_balloon driver is updated to use > global_node_page_state() to fetch the counters, as they are no longer > accessible through the vm_events array. > > Signed-off-by: JP Kobryn > Suggested-by: Johannes Weiner > Acked-by: Michael S. Tsirkin > Reviewed-by: Vlastimil Babka (SUSE) Acked-by: Johannes Weiner