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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-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261019185002.3428594-1-gourry@gourry.net> X-Rspamd-Queue-Id: 64F30A0007 X-Rspam-User: X-Stat-Signature: 1y6kyxiwph78b7usxm4zjimmhy9xi3wg X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam03 X-HE-Tag: 1792441009-53799 X-HE-Meta: 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 XdyfOoas 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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