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Mon, 19 Oct 2026 13:16:48 -0700 (PDT) Received: from localhost ([2605:8600:200:1d58:2ffc:79a5:7374:fa95]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-679b19c3933sm4507704d50.0.2026.10.19.13.16.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 13:16:47 -0700 (PDT) Date: Mon, 19 Oct 2026 22:16:45 +0200 From: Johannes Weiner To: "Gregory Price (Meta)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, david@kernel.org, mhocko@kernel.org, ljs@kernel.org, dave@stgolabs.net, roman.gushchin@linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] mm/vmscan: reclaim every zone in per-node proactive reclaim Message-ID: <20261019201645.GK371161@cmpxchg.org> References: <20261019185002.3428594-1-gourry@gourry.net> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261019185002.3428594-1-gourry@gourry.net> On Mon, Oct 19, 2026 at 02:50:02PM -0400, Gregory Price (Meta) wrote: > user_proactive_reclaim() limits per-node reclaim to > gfp_zone(GFP_KERNEL), which is ZONE_NORMAL. Proactive reclaim serves no > allocation, but that limit makes shrink_node() skip every ZONE_MOVABLE > folio, so writing to /sys/devices/system/node/nodeN/reclaim never > reclaims a node's movable memory. A movable-only node, such as dax/kmem > or hotplugged memory onlined movable, reclaims nothing and fails with > -EAGAIN. > > To reproduce, fill a movable-only node with clean page cache and write > 200M to its nodeN/reclaim: the write fails with -EAGAIN and the page > cache stays. The same write to a ZONE_NORMAL node frees 200MB. > > Scan every zone, as memory.reclaim does. > > Fixes: b980077899ea4 ("mm: introduce per-node proactive reclaim interface") > Cc: stable@vger.kernel.org > Signed-off-by: Gregory Price (Meta) Reviewed-by: Johannes Weiner