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 6BF2241C71 for ; Mon, 23 Mar 2026 11:51:20 +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=1774266680; cv=none; b=FmX8G8eI+MqtnPHkdp30irhZzwDwOfgWyPBXa20e8Nu5h/jx/4TMPwBvyeTNkeamLqmW+IUybogGDYfym4JqQBQ9X8yfoipRu43VpVau84q76GuD7wiAsjK3Es7S+FCQbDHCENC/t0twHxjjMVufge8hwDMuPb5c8zzXbyMvKa0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774266680; c=relaxed/simple; bh=Dt+bOuxM+mfvDdyqEPo+p9Blwv4Fd6GpODUcVdZHmsg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lBt+lhHZkyJJOlW+D/MM0KRZrA5hFFNcYFhpd4OIPXrDeUcnaBp1cY569jbtMZ9s4QkRUGtGm5JkgIMv6PnwPhLliELqiGGfrTTIHmkyOmyIkBFjQIhMtckjB9lmZ8MVvm7W2z2650rGbFaynRvX1WAqEzuvR9YPoiHKCvwzsYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ShF8suCu; 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="ShF8suCu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 854F5C4CEF7; Mon, 23 Mar 2026 11:51:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774266680; bh=Dt+bOuxM+mfvDdyqEPo+p9Blwv4Fd6GpODUcVdZHmsg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ShF8suCu0EIYttE51LjmUkUNKgnfiaXhrGdhtkAuCSVDtz5eowsLmJ41LC75ubyRd j3SilNylxvIIzRO5Q/lVctIWxftc1xnyE7ZnAT1rW5SIw5Lair09qzcpDMaYIxjkFT E+mQ2cZTXx60HmOGmHkkhZoQo81EMRrc4qPp4NndJT9s1/VqIb2E6V1hicIOQsnLUK zJy89psnogeKxkdwkYQrtQBqQJQgzzLBhO9GOjRhSpwW5/j4fFCT+uPcAJDGaOAQsv 5A66hl153VQ/yRjQOlb18s5PrGG46+ENAxN5m47k/HQ4IXVk/XVOV6eISXASY7b+ZO suKNADU5PNDGQ== Date: Mon, 23 Mar 2026 13:51:11 +0200 From: Mike Rapoport To: Yuan Liu Cc: David Hildenbrand , Oscar Salvador , Wei Yang , linux-mm@kvack.org, Yong Hu , Nanhai Zou , Tim Chen , Qiuxu Zhuo , Yu C Chen , Pan Deng , Tianyou Li , Chen Zhang , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/memory hotplug/unplug: Optimize zone contiguous check when changing pfn range Message-ID: References: <20260319095622.1130380-1-yuan1.liu@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260319095622.1130380-1-yuan1.liu@intel.com> Hi, On Thu, Mar 19, 2026 at 05:56:22AM -0400, Yuan Liu wrote: ... > diff --git a/mm/mm_init.c b/mm/mm_init.c > index df34797691bd..96690e550024 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -946,6 +946,7 @@ static void __init memmap_init_zone_range(struct zone *zone, > unsigned long zone_start_pfn = zone->zone_start_pfn; > unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages; > int nid = zone_to_nid(zone), zone_id = zone_idx(zone); > + unsigned long zone_hole_start, zone_hole_end; > > start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn); > end_pfn = clamp(end_pfn, zone_start_pfn, zone_end_pfn); > @@ -957,8 +958,19 @@ static void __init memmap_init_zone_range(struct zone *zone, > zone_end_pfn, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE, > false); > > - if (*hole_pfn < start_pfn) > + WRITE_ONCE(zone->pages_with_online_memmap, > + READ_ONCE(zone->pages_with_online_memmap) + > + (end_pfn - start_pfn)); > + > + if (*hole_pfn < start_pfn) { > init_unavailable_range(*hole_pfn, start_pfn, zone_id, nid); > + zone_hole_start = clamp(*hole_pfn, zone_start_pfn, zone_end_pfn); > + zone_hole_end = clamp(start_pfn, zone_start_pfn, zone_end_pfn); > + if (zone_hole_start < zone_hole_end) > + WRITE_ONCE(zone->pages_with_online_memmap, > + READ_ONCE(zone->pages_with_online_memmap) + > + (zone_hole_end - zone_hole_start)); > + } I didn't have time to review it, but it really jumped at me. memmap_init_zone_range() runs before SMP, there is no need for WRITE_ONCE()/READ_ONCE() here. -- Sincerely yours, Mike.