From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=jJTS=3Y=lists.ozlabs.org=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,
	URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no
	version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 989D7C2D0B1
	for <linuxppc-dev@archiver.kernel.org>; Tue,  4 Feb 2020 09:48:59 +0000 (UTC)
Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by mail.kernel.org (Postfix) with ESMTPS id 1928121741
	for <linuxppc-dev@archiver.kernel.org>; Tue,  4 Feb 2020 09:48:58 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1928121741
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])
	by lists.ozlabs.org (Postfix) with ESMTP id 48BfzD0TdFzDqQW
	for <linuxppc-dev@archiver.kernel.org>; Tue,  4 Feb 2020 20:48:56 +1100 (AEDT)
Authentication-Results: lists.ozlabs.org;
 spf=pass (sender SPF authorized) smtp.mailfrom=suse.de
 (client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=osalvador@suse.de;
 receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org;
 dmarc=none (p=none dis=none) header.from=suse.de
Received: from mx2.suse.de (mx2.suse.de [195.135.220.15])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 48Bfwz65vKzDqLL
 for <linuxppc-dev@lists.ozlabs.org>; Tue,  4 Feb 2020 20:46:59 +1100 (AEDT)
X-Virus-Scanned: by amavisd-new at test-mx.suse.de
Received: from relay2.suse.de (unknown [195.135.220.254])
 by mx2.suse.de (Postfix) with ESMTP id BC651ABF4;
 Tue,  4 Feb 2020 09:46:55 +0000 (UTC)
Date: Tue, 4 Feb 2020 10:46:53 +0100
From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v6 10/10] mm/memory_hotplug: Cleanup __remove_pages()
Message-ID: <20200204094652.GE6494@linux>
References: <20191006085646.5768-1-david@redhat.com>
 <20191006085646.5768-11-david@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20191006085646.5768-11-david@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: linux-s390@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
 linux-ia64@vger.kernel.org, Pavel Tatashin <pasha.tatashin@soleen.com>,
 linux-sh@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org,
 linux-mm@kvack.org, Wei Yang <richardw.yang@linux.intel.com>,
 Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org,
 Dan Williams <dan.j.williams@intel.com>, linux-arm-kernel@lists.infradead.org
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On Sun, Oct 06, 2019 at 10:56:46AM +0200, David Hildenbrand wrote:
> Let's drop the basically unused section stuff and simplify.
> 
> Also, let's use a shorter variant to calculate the number of pages to
> the next section boundary.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Wei Yang <richardw.yang@linux.intel.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

I have to confess that it took me while to wrap around my head
with the new min() change, but looks ok:

Reviewed-by: Oscar Salvador <osalvador@suse.de>

> ---
>  mm/memory_hotplug.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 843481bd507d..2275240cfa10 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -490,25 +490,20 @@ static void __remove_section(unsigned long pfn, unsigned long nr_pages,
>  void __remove_pages(unsigned long pfn, unsigned long nr_pages,
>  		    struct vmem_altmap *altmap)
>  {
> +	const unsigned long end_pfn = pfn + nr_pages;
> +	unsigned long cur_nr_pages;
>  	unsigned long map_offset = 0;
> -	unsigned long nr, start_sec, end_sec;
>  
>  	map_offset = vmem_altmap_offset(altmap);
>  
>  	if (check_pfn_span(pfn, nr_pages, "remove"))
>  		return;
>  
> -	start_sec = pfn_to_section_nr(pfn);
> -	end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
> -	for (nr = start_sec; nr <= end_sec; nr++) {
> -		unsigned long pfns;
> -
> +	for (; pfn < end_pfn; pfn += cur_nr_pages) {
>  		cond_resched();
> -		pfns = min(nr_pages, PAGES_PER_SECTION
> -				- (pfn & ~PAGE_SECTION_MASK));
> -		__remove_section(pfn, pfns, map_offset, altmap);
> -		pfn += pfns;
> -		nr_pages -= pfns;
> +		/* Select all remaining pages up to the next section boundary */
> +		cur_nr_pages = min(end_pfn - pfn, -(pfn | PAGE_SECTION_MASK));
> +		__remove_section(pfn, cur_nr_pages, map_offset, altmap);
>  		map_offset = 0;
>  	}
>  }
> -- 
> 2.21.0
> 
> 

-- 
Oscar Salvador
SUSE L3