From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B09B93D891F for ; Fri, 21 Aug 2026 09:32:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787304745; cv=none; b=FMHP7+YbWH8096pr2U5+vpkx/tHJvvGy1Y8ULIXMcKmvWIUrSF4/56CX+lImtkN9XWyy1j7s3xm44mfWoyeyMQaMyC7Yzn+xaIP7DATA7dCQslBrqkht2PVm38JRzK7UrSWMG7LzUYxV8gGOXBDdMHTS27azvRrDwg9pkxjeluc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787304745; c=relaxed/simple; bh=b0DkLuGvLKFyFXJGrZU6YeUbD4URMluIG0Ytsq3hEX0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=A5EHwkQzwm1C6umkx3KOPIWz95/qUqHxfJPlWquApQMM1wrVdyWnYeGIHDnfm5A8jpWH5mT+KBjRwN84vjsAq/hTUCW9L9OleiahxQGHM6NaAhzEZGtMtVhJYMZNxjhirSR/a0+ODP7rtT7TD83gTAjf9nYPXnecGFdICsmNH5Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CrUtN3Fi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CrUtN3Fi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 779721F000E9; Fri, 21 Aug 2026 09:32:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787304737; bh=FhFDMwjisFQlmA53RTr6EmbhwCInFJVNArYz9R9qOUQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=CrUtN3FivWiRmuwK4pcrEznRzh4JuAN8BFS8RElvfSQtHfOHcf2NtiZ0F8mwaBMjx BnSqoWrVgE9x0mJR5jzwBU3De2TaOArD3l6lcJNlHmoriW3pp0p7F4qfIMRknEZOfO Cm1spU+sKk/vZz4oNh3jPqLT/BYGxUI6YPcnOia8bY/KRxpx1PsJilmhLsp9ZGyPP/ oMXQnXnsv04vpHilaHmfIYd7Q+IXNDovrb6+NYJqJc6lFFv9QBbQ2t6sfBAd1D6hAM OogdwQbZ2KzYMn8zTdolQywifgNeOrx5LSal05zTVdZSdttiGdkMHZNPbnOjDU8miP FZQdJXT4phKgA== Message-ID: Date: Fri, 21 Aug 2026 11:32:11 +0200 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 v7 1/2] mm/memory_hotplug: make shrink_zone_span() more robust To: Wei Yang , Yuan Liu Cc: Oscar Salvador , Mike Rapoport , linux-mm@kvack.org, Nanhai Zou , Chen Zhang , Jason Zeng , Chen Yu , Pan Deng , Tianyou Li , linux-kernel@vger.kernel.org References: <20260818085702.3395529-1-yuan1.liu@intel.com> <20260818085702.3395529-2-yuan1.liu@intel.com> <20260821031427.qq6mb3j2zqtzdl3n@master> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/21/26 05:14, Wei Yang wrote: > On Tue, Aug 18, 2026 at 04:57:01AM -0400, Yuan Liu wrote: >> From: "David Hildenbrand (Arm)" >> >> Let's make shrink_zone_span() more robust by checking in >> find_smallest_section_pfn() / find_biggest_section_pfn() that the >> start and end PFNs of the subsection are within the zone. >> >> While at it, clean up the function by factoring the core check out >> into subsection_overlaps_zone(). >> >> There likely is no need to check the nid first. We require >> SPARSEMEM_VMEMMAP_ENABLE, where pfn_to_page() is cheap, and >> pfn_to_nid() on CONFIG_NUMA would call pfn_to_page() either way. >> So let's just drop that for now. >> >> Signed-off-by: David Hildenbrand (Arm) >> Tested-by: Yuan Liu >> Signed-off-by: Yuan Liu >> --- >> mm/memory_hotplug.c | 59 ++++++++++++++++++--------------------------- >> 1 file changed, 24 insertions(+), 35 deletions(-) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 7ac19fab2263..cd82e79f0782 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -422,49 +422,39 @@ int __add_pages(int nid, unsigned long pfn, unsigned long nr_pages, >> return err; >> } >> >> -/* find the smallest valid pfn in the range [start_pfn, end_pfn) */ >> -static unsigned long find_smallest_section_pfn(int nid, struct zone *zone, >> - unsigned long start_pfn, >> - unsigned long end_pfn) >> +static bool subsection_overlaps_zone(unsigned long pfn, struct zone *zone) >> { >> - for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { >> - if (unlikely(!pfn_to_online_page(start_pfn))) >> - continue; >> + const unsigned long start_pfn = ALIGN_DOWN(pfn, PAGES_PER_SUBSECTION); >> + const unsigned long end_pfn = start_pfn + PAGES_PER_SUBSECTION - 1; >> >> - if (unlikely(pfn_to_nid(start_pfn) != nid)) >> - continue; > > Would we have a memory layout with node interleave? I think core-mm is not prepared for actual overlapping zone ranges during boot. -- Cheers, David