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imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=pXcZ+7fn; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774880427; a=rsa-sha256; cv=none; b=7/l+U0NBgMgl5Gc2ePUazYjcZakADgQne82uRw18UQm3il+VbnmHUBq94oDICDEGctEOx2 VvOXNJCec7+V5pFX62k63+36muTCbN5Ra6VxWgiTI8wEfEfa9C+GH0MyXuuZ3xdSFn18kO CP5V1CAi6jgyPvPyeb7X3eYADP8dL2M= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id DD0FA60054; Mon, 30 Mar 2026 14:20:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D420FC4CEF7; Mon, 30 Mar 2026 14:20:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774880426; bh=06bf5S3/WSaRWoCBlnC2mh9au4sOQz5mO11EQY3Buns=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pXcZ+7fncPEcnrzkSfN6YMN6OGr061xooYBr65rWkkI8sB/QKQ/qimT6UI5BQGz0r YXuf43myE3joGOPmz60hD2l8+GzzUiu85x93Cf9J2oZBZJG5h11ERYxW1+j6IeWFMv D8KERD1V78j0ECVlK0ByYkH5UkyBI5W8S77NkMVD/OVgzs7O/0S9kAUKM6oG2ArqvE eRSjC2TuVo2bykiLZmpPufFgHEvywx/YEYYj6TLH1bHsqEYAZ8CaJ9T5q7WdVlDHQR qT5gl++rEnuydu/LUPFKdINEFnkRqUgv4i7TBNDPFv/nthgbVhBI4+KrViH4VtuwAF GXMJozgEcc29g== Message-ID: <5de08585-fd2b-4395-b421-99c7b887aa8f@kernel.org> Date: Mon, 30 Mar 2026 16:20:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/memory_hotplug: maintain N_NORMAL_MEMORY during hotplug To: Hao Li , osalvador@suse.de, akpm@linux-foundation.org Cc: vbabka@suse.cz, harry.yoo@oracle.com, joshua.hahnjy@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org References: <20260330035941.518186-1-hao.li@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260330035941.518186-1-hao.li@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 64239180009 X-Stat-Signature: dyn3w98attciwqjb54cdj7cpqzi1fb7x X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1774880427-916411 X-HE-Meta: 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 smrlQsyf m2rg83bUncckxmtoV1TGVUgZymY5SWeNb32nr6YHn2x17B5M5lZKzhrC/KbF23H2pR3x02swI0mn2w4DyG0lnLEVQRMWjKiPMZ5YbPxKXamjMEQ+A8f9bzr7TUjhHn428rBifHJtFj9XijxOniFySIA+p30EOysbjezTAulY3ULsgF36g8tToB3boRwgVQdOfBkA+TDCEVjwVBvOH8dWHTNt6qAjjRdisPyPCtMltZo5NCyBtg0584tfl5g7M0b0dcA4vX5aqvL3wQFWdQrkk2B/qBLTk12faxi+Kc7HhBr51+cUDcO+MtWAMWQtYwjir2hwcfawtMgTMFFQfxE6u2qk2aTqhazD/GohNnC7psbnCDH6IgsDCjXyH5o2CIRP+6RjbBDfsY6pc/JBVnmrixp9mXIcUSj+n3cxLAHkbFpYodt8kBNsiLFqoXQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/30/26 05:57, Hao Li wrote: > N_NORMAL_MEMORY is initialized from zone population at boot, but memory > hotplug currently only updates N_MEMORY. As a result, a node that gains > normal memory via hotplug can remain invisible to users iterating over > N_NORMAL_MEMORY, while a node that loses its last normal memory can stay > incorrectly marked as such. > > Restore N_NORMAL_MEMORY maintenance directly in online_pages() and > offline_pages(). Set the bit when a node that currently lacks normal > memory onlines pages into a zone <= ZONE_NORMAL, and clear it when > offlining removes the last present pages from zones <= ZONE_NORMAL. > > This restores the intended semantics without bringing back the old > status_change_nid_normal notifier plumbing which was removed in > 8d2882a8edb8. > > Current users that benefit include list_lru, zswap, nfsd filecache, > hugetlb_cgroup, and has_normal_memory sysfs reporting. > > Fixes: 8d2882a8edb8 ("mm,memory_hotplug: remove status_change_nid_normal and update documentation") Agreed on CCing stable. > Signed-off-by: Hao Li > --- > Changes: simplify the code. (Thanks Joshua and David) > --- > mm/memory_hotplug.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index bc805029da51..05a47953ef21 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1209,6 +1209,13 @@ int online_pages(unsigned long pfn, unsigned long nr_pages, > > if (node_arg.nid >= 0) > node_set_state(nid, N_MEMORY); > + /* > + * Check whether we are adding normal memory to the node for the first > + * time. > + */ > + if (!node_state(nid, N_NORMAL_MEMORY) && zone_idx(zone) <= ZONE_NORMAL) > + node_set_state(nid, N_NORMAL_MEMORY); > + > if (need_zonelists_rebuild) > build_all_zonelists(NULL); > > @@ -1908,6 +1915,8 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages, > unsigned long flags; > char *reason; > int ret; > + unsigned long normal_pages = 0; > + enum zone_type zt; > > /* > * {on,off}lining is constrained to full memory sections (or more > @@ -2055,6 +2064,17 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages, > /* reinitialise watermarks and update pcp limits */ > init_per_zone_wmark_min(); > > + /* > + * Check whether this operation removes the last normal memory from > + * the node. We do this before clearing N_MEMORY to avoid the possible > + * transient "!N_MEMORY && N_NORMAL_MEMORY" state. > + */ > + if (zone_idx(zone) <= ZONE_NORMAL) { > + for (zt = 0; zt <= ZONE_NORMAL; zt++) > + normal_pages += pgdat->node_zones[zt].present_pages; > + if (!normal_pages) > + node_clear_state(node, N_NORMAL_MEMORY); > + } Was wondering whether we could just do an early exit, like: for (zt = 0; zt <= ZONE_NORMAL; zt++) { if (pgdat->node_zones[zt].present_pages) break; } if (zt > ZONE_NORMAL) node_clear_state(node, N_NORMAL_MEMORY); But ends up being harder to digest (incl. all variants I tried :) ), so Acked-by: David Hildenbrand (Arm) -- Cheers, David