From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A246F3019B2 for ; Fri, 6 Feb 2026 13:03:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770383024; cv=none; b=XSDZfcUvPGMaPYj5U2XoCPEpzQVi1Cm8ygF0RpDHVUoslLaqBajlhEWTTSbl1IFEyep7jWvZ1gVyWHZn9yexlcm7i3mkDp0Mt24QuBqTr6LoGpz61nmm2bC9p0HBmXPCwrlFUMCzcb9S+CBKngaSXRv6VZpfwAgvjQY1MnozsHI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770383024; c=relaxed/simple; bh=MJuM4duWRQOdgMSoWpQ5n672KHtCLpnyJV0vo6WaoLo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YZeDR5lKnaMJN58hYdMGzaaqa2vwTHOyJcNbEr98Woh1j9YbkMmu10pBPsLbimbH8M/dIFIYkB62cX7gV9iQOvLpC6ukL5zOOnmF5N9zPKmXqEvQBlexLt6zKiNFt+tANA85sQcIWgv5U0T+hoVQ1mZKTmfHY5o9Ohkgs+zqCvo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bv7EzWDi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bv7EzWDi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AA2DC116C6; Fri, 6 Feb 2026 13:03:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770383024; bh=MJuM4duWRQOdgMSoWpQ5n672KHtCLpnyJV0vo6WaoLo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=bv7EzWDiendze/cP586ru5zBpHpfCly8MOX3VxeiW381Thyq5+xgeBLPmDNR9+jdi JAOrL8xYk19kWk4srpq3Qin0GmbD6FLxg0sC+mQRf0F7UQFseVZPC0Kn0XMrkua7p+ jyuqkpfOWUKjHFO3qv4JfoGJvnaWs4NCNGAKZ0hiUqCB3t1DRiRIqviwua3mzILUne 6zqF76LQM8geG+0JjCw2KugvN9IszV9WTp3MHfeCZ0BlNIo4dsPQ4jBlrtL77nPg1f IsjOZGxkgXZ9b56jYnxu1sdNaARVf03RaHZ0K7DeEaM07nKsgcRfI00Yes63M9BMnj y2Q0UeF/w8xCQ== Message-ID: <00d07c59-e573-40b6-a096-266ef14545b9@kernel.org> Date: Fri, 6 Feb 2026 14:03:39 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/memory hotplug: Fix zone->contiguous always false when hotplug To: Tianyou Li , Oscar Salvador , Mike Rapoport , Wei Yang , Michal Hocko Cc: linux-mm@kvack.org, Yong Hu , Nanhai Zou , Yuan Liu , Tim Chen , Qiuxu Zhuo , Yu C Chen , Pan Deng , Chen Zhang , linux-kernel@vger.kernel.org References: <20260130160938.2671462-1-tianyou.li@intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/30/26 17:09, Tianyou Li wrote: > From: Yuan Liu Nit: subject should start with "mm/memory_hotplug:" > > set_zone_contiguous() uses __pageblock_pfn_to_page() to detect > pageblocks that either do not exist (hole) or that do not belong > to the same zone. > > __pageblock_pfn_to_page(), however, relies on pfn_to_online_page(), > effectively always returning NULL for memory ranges that were not > onlined yet. So when called on a range-to-be-onlined, it indicates > a memory hole to set_zone_contiguous(). > > Consequently, the set_zone_contiguous() call in move_pfn_range_to_zone(), > which happens early during memory onlining, will never detect a > zone as being contiguous. Bad: the fast path relies on the zone > contiguous state may skipped. > > To fix the issue, move the set_zone_contiguous() call to a later > stage in memory onlining, where pfn_to_online_page() will succeed: > after we mark the memory sections to be online. > > Fixes: 2d070eab2e82 ("mm: consider zone which is not fully populated to have holes") > Cc: Michal Hocko > Cc: stable@vger.kernel.org > Reviewed-by: Nanhai Zou > Signed-off-by: Yuan Liu > Signed-off-by: Tianyou Li How was Yuan Liu involved? If he is a co-author there is a Co-developed-by: Yuan Liu missing. Likely there is no resend required if you tell Andrew what to do, so he can just fixup when applying. Acked-by: David Hildenbrand (Arm) -- Cheers, David