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 4877A392838 for ; Wed, 19 Aug 2026 15:53:52 +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=1787154833; cv=none; b=BfB3aNbRUq5wDWzHBgIyIeGw9exLF9/c13Wyks0smQT0PEpHtyNFrjpKJEw50YI5g+DlyGv2eCogQgdej8oDHDhJjVwWrf+p38Zkdf+Sv+Nx0v4eDqVU8l5nWRIzEjZmLFUfWdXhRhJIs6nFm/EIxzwm2IvR1e+5WgTqaoTf2k0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787154833; c=relaxed/simple; bh=Zj1xKNoH/Px+cTHJyB24dD4tUxo3SfaCRB2exQ05rGc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=u1QFYShP/69EvNSkCWrE70ANbayP+G8QtwGxSAkJeLtSuQnh4f/LH4qQhHi9cxbVCY0bNZOKmmCNKFVa5Nz1T5WN4YGT2PZjuV0B5MUDr7wJxd/ekCglXS786gLVhGbUcANLP9mLtRueMolAWjCisznzrDdgaFzaR/WTwe/uKbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oGEaAZsL; 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="oGEaAZsL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E5631F000E9; Wed, 19 Aug 2026 15:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787154832; bh=QLHvEXhl7bh0vVvB52S7db8GJd87oXRQT+N5wVcQ1Ws=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=oGEaAZsLUiOpJaCVmkYmiTswK1xknZbj0vjIV5zZsc7E6d0UpT2EhwqajNnX9CTDx clsyRk+c5aszdB0sdGkj2MwkAj47YUPGM2xS98Vc2RAPPam+Z0GAwg/DrstZ0Kz7yX yrh41chB/jZcKZpz84nhP+H7xMDPQRAhLbToA8Ga2Gr4PRpEyfHK5W44tYLki3Ey1x AnUEUKUknX2PrTQY+fLdA1c2mnIoqTj7XuT+pRCIUNfEm2wNLJmHyO7zkxg5mF6EsG Ylkuolzme/9nR60/L4lDSzBc5S0FhBY514UPxGCxCBWMShNXgd1MTeuK6r4dWyI3MH nKuXqk3wSrTDA== Message-ID: Date: Wed, 19 Aug 2026 17:53:45 +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 2/2] mm/memory_hotplug: optimize zone contiguous check when changing pfn range To: Yuan Liu , Oscar Salvador , Mike Rapoport , Wei Yang Cc: 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> <20260818085702.3395529-3-yuan1.liu@intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit > /* > * Only struct pages that correspond to ranges defined by memblock.memory > * are zeroed and initialized by going through __init_single_page() during > @@ -822,22 +844,27 @@ void __meminit init_deferred_page(unsigned long pfn, int nid) > * zone/node above the hole except for the trailing pages in the last > * section that will be appended to the zone/node below. > */ > -static void __init init_unavailable_range(unsigned long spfn, > - unsigned long epfn, > - int zone, int node) > +static unsigned long __init init_unavailable_range(unsigned long spfn, > + unsigned long epfn, > + int zone, int node) > { > unsigned long pfn; > - u64 pgcnt = 0; > + u64 pgcnt = 0, online_pgcnt = 0; > + unsigned long last_subsection = -1; > + bool is_online = false; > > for_each_valid_pfn(pfn, spfn, epfn) { > __init_single_page(pfn_to_page(pfn), pfn, zone, node); > __SetPageReserved(pfn_to_page(pfn)); > + if (unavailable_pfn_is_online(pfn, &last_subsection, &is_online)) > + online_pgcnt++; Can we avoid these helpers? const unsigned long subsection = pfn & PAGE_SUBSECTION_MASK; /* We can have section-sized online holes with VMEMMAP. */ if (IS_ENMABLED(CONFIG_SPARSEMEM_VMEMMAP) && subsection != last_subsection) { is_online = pfn_to_online_page(pfn); last_subsection = subsection; } if (is_online) online_pgcnt++; An alternative is an inner loop that just walks in SUBSECTION chunks until epfn. That would probably be even cleaner and faster. I remember !vmemmap always only has early sections when they are actually online. We could extent the comment to clarify that. (I have patches to clean that init code up) -- Cheers, David