From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f179.google.com (mail-qk1-f179.google.com [209.85.222.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7742C4C9002 for ; Mon, 20 Jul 2026 19:35:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784576157; cv=none; b=thrRMnyp5cod/QwB8Wp4twanGOZydeNRL8Z4d4ih2jX50/B8P5ozJ0oogZLYJv0d2Rk05rHBoQDHW6HsrQ2GoSQfWtmphIAO0jjsWJOf1t98xi4MlDf+FN4OQol/NMOEla2uLMsWrc3ivPPEGxfLlY22Tz3u61mvhl/MqRDFJjI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784576157; c=relaxed/simple; bh=d6pCHtBqoNKDq4P4c/ZFNHldTuhwFRB86ulVg/xnwxw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nVR/D8qLNaciGv+P3qPYWgUabKODUH9rTh6YyPjKHXO6a9gzwB4TXsyPY88XxP+KD58easfN3gBGdNj4Md1ULWmM1VVSgzMQ/bqJHWPeNg7A3BiSLXLwOzuTsAStxj9tWAlZQ/0sKfYoyry/hfb088Ak+gKCKRUW85bGAP2kNFw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net; spf=pass smtp.mailfrom=gourry.net; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b=TiX71lti; arc=none smtp.client-ip=209.85.222.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gourry.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b="TiX71lti" Received: by mail-qk1-f179.google.com with SMTP id af79cd13be357-92e6c4a867cso465803185a.0 for ; Mon, 20 Jul 2026 12:35:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1784576151; x=1785180951; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=hwwcrXiYs5LXY1nHNJcH4eGwqAhaBzqBMJWfc0nxcvk=; b=TiX71lti/fGfGqI1Nq0o4bMWi1T16hMzawXuMTsk4cmVwvbIFFz8ekkpZXZxb/xbr1 nAi/jnDKtoKLA7CSVfizAykTJKfCQRIBv0ewKO+1KZxxSuDnVyoLw6NxsSJ99+DG9OfO hegJ0mSqZjMgU8lC15QQkKKGtJVt4kuzjAfBqhfq+0cwt4gxRms27urAw6Rbj031Ev0z TfTwbhOi2/7tbUVVolw03M4lSeXS/PCTz49fgkDcy1CNwVt4b/BHnJXKEyu2F54u1yC/ AXF0liVQ1Y/OwGGUAO3fQclDK70oGHNy4vNvzimrhP5uDYKq7Lnb1k9lVNqw7B3TEYbB NY8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784576151; x=1785180951; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=hwwcrXiYs5LXY1nHNJcH4eGwqAhaBzqBMJWfc0nxcvk=; b=Ol3/BQGEstf0PGNx2KZamY6CbMvnS7HGYNvxCgoWkbZzUVszyCrN6KoF3B6hFJ5RtX QRhUA3R1fShFMA61pj0QsjVHbi8jrRmmLT5oR9WqGnexyoA9dpDLnf9V81qKfNQ7YhkM G15108iWh2AGMTpza9JGKdXzn4RtjpL1890Kkwt15IFAUl+6ohWGWwID3QUMPFOumKJo OSCEmElQbNEzkNePBod8wXPvceQgpuD6utGrDRHJx2gLUOCm5yau1FSVmQXBnwQmqVYx 3TBI5tWB7BSgyu+fQAlO+lZKJsdSOHLlfGpeV90vt34kl+VJ6LFL8L1xlHHLbCemtpol wiZg== X-Forwarded-Encrypted: i=1; AHgh+RrqHecskXkCdueIkkz6wDtyCLKhBA/o4cn2K7pZLN0MRbZgPMK7brYgHDwUM9mjbxw+Rz+v0aE3kj3pAQ==@lists.linux.dev X-Gm-Message-State: AOJu0YyTILzSr90+tqY+50jljm7xYGbdSNNkOunnTX7vRtORTcg9HbcC sztNRTywrKfNlQlTzsmJZgvph4lLNIm6S5QnfCkK0TA4syHNAphmMS9ZsZ/tZzeOnTY= X-Gm-Gg: AfdE7ckVRwC3QDDWVB4EUMIloT8txvxJa69hbnhjbqdwZGCS1c0JrnmAMWGJNj0Vf8i 5FCt1XlwHQ5x18muixTgqEtZAeAVqB9FfbtuaDRMWPORdqTGhLztcERdqIyr6ht+HlTTGbjnZbv oOl9ExsIq4htPQHRdVF2amOzUvnI/mvGAv8wiwpHQjzzeK0oMoEPcBBDifqNQDDSPWamu4O01Cd VA2jmL9jnR+lGEGS0OSxR7VkwPXwseUkyMqPP5Q3Hc88v6R25QMnKAJ+UlCDqfOer2iKR8ciEVm DTBA7opAhOk7NHVI27+qVq2a0E4aJQ+D1AQV7uiuXECLXLMrDShy1wNFcLcuGwXynXDaTyhKhZk BINrpHUU76VZPB07Zmi8VmkvlCYxhDaRDR3khhc7zQBLVXk50g2LCFxR3ytel+fMS3vkk2oRf+4 9KYfUz6WHRLRojKnRB0BS2U7zSesbvuYoT7HdDXNFWrw2wzm6rHkJKHK5lxkBSM8Q= X-Received: by 2002:a05:620a:370e:b0:930:9a84:d90b with SMTP id af79cd13be357-930b416db01mr1583254785a.50.1784576151483; Mon, 20 Jul 2026 12:35:51 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F.lan (pool-173-79-60-52.washdc.fios.verizon.net. [173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-930b545e47bsm957792285a.35.2026.07.20.12.35.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2026 12:35:51 -0700 (PDT) From: Gregory Price To: linux-mm@kvack.org Cc: Zhigang.Luo@amd.com, arun.george@samsung.com, balbirs@nvidia.com, brendan.jackman@linux.dev, yuzenghui@huawei.com, apopple@nvidia.com, alucerop@amd.com, matthew.brost@intel.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, alison.schofield@intel.com, osandov@osandov.com, jannh@google.com, pfalcato@suse.de, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, pbonzini@redhat.com, osalvador@suse.de, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, mkoutny@suse.com, sj@kernel.org, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, usama.arif@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, driver-core@lists.linux.dev, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-debuggers@vger.kernel.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v5 28/36] mm: add NODE_PRIVATE_CAP_HOTUNPLUG for opted-in private nodes Date: Mon, 20 Jul 2026 15:34:22 -0400 Message-ID: <20260720193431.3841992-29-gourry@gourry.net> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260720193431.3841992-1-gourry@gourry.net> References: <20260720193431.3841992-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add CAP_HOTUNPLUG, which allows memory_hotplug to migrate a private node's folios for the purpose of hotunplugging memory. Without this, hotunplug fails if any folio on the node is allocated. Add node_allows_hotunplug() - which returns true for any normal node and private nodes with CAP_HOTUNPLUG. Signed-off-by: Gregory Price --- include/linux/node_private.h | 26 ++++++++++++++++++++++++++ mm/memory_hotplug.c | 4 ++-- 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/include/linux/node_private.h b/include/linux/node_private.h index 655fe9ec5cb61..7b617b1fa9c28 100644 --- a/include/linux/node_private.h +++ b/include/linux/node_private.h @@ -14,6 +14,7 @@ struct page; */ #define NODE_PRIVATE_CAP_RECLAIM (1UL << 0) /* allow mm reclaim */ #define NODE_PRIVATE_CAP_USER_NUMA (1UL << 1) /* allow mempolicy */ +#define NODE_PRIVATE_CAP_HOTUNPLUG (1UL << 2) /* allow hot-unplug */ /** * struct node_private - Per-node container for N_MEMORY_PRIVATE nodes @@ -97,6 +98,26 @@ static inline bool node_allows_user_numa(int nid) return ret; } +/** + * node_allows_hotunplug - may hot-unplug migrate this node's folios? + * @nid: the node to test + * + * True for normal nodes and private nodes opted into CAP_HOTUNPLUG. + */ +static inline bool node_allows_hotunplug(int nid) +{ + struct node_private *np; + bool ret; + + if (!node_state(nid, N_MEMORY_PRIVATE)) + return true; + rcu_read_lock(); + np = rcu_dereference(NODE_DATA(nid)->node_private); + ret = np && (np->caps & NODE_PRIVATE_CAP_HOTUNPLUG); + rcu_read_unlock(); + return ret; +} + #else /* !CONFIG_NUMA */ static inline bool folio_is_private_node(struct folio *folio) @@ -124,6 +145,11 @@ static inline bool node_allows_user_numa(int nid) return true; } +static inline bool node_allows_hotunplug(int nid) +{ + return true; +} + #endif /* CONFIG_NUMA */ #if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 1f42ed303366c..e9573f90e0dcd 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1943,8 +1943,8 @@ static int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) goto put_folio; } - /* Private node folios cannot migrate, fail outright */ - if (folio_is_private_node(folio)) { + /* Fail outright on private nodes w/o hotunplug support */ + if (!node_allows_hotunplug(folio_nid(folio))) { pr_info_ratelimited("memory offline refused: node %d pfn %lx\n", folio_nid(folio), pfn); folio_put(folio); -- 2.53.0-Meta