From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 326A1C88E50 for ; Mon, 14 Sep 2026 07:27:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5C7796B0095; Mon, 14 Sep 2026 03:27:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 59FD06B0096; Mon, 14 Sep 2026 03:27:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4B7F26B0098; Mon, 14 Sep 2026 03:27:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 23FFA6B0095 for ; Mon, 14 Sep 2026 03:27:44 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 54645C11ED for ; Mon, 14 Sep 2026 07:27:43 +0000 (UTC) X-FDA: 85211538006.27.BF398C8 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) by imf23.hostedemail.com (Postfix) with ESMTP id 1886114000A for ; Mon, 14 Sep 2026 07:27:40 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=WSr5DlDQ; spf=pass (imf23.hostedemail.com: domain of yuan1.liu@intel.com designates 192.198.163.11 as permitted sender) smtp.mailfrom=yuan1.liu@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1789370861; b=7HLxJF1HE2O9SbJmYTQX9jfrvE00au3fR/UN3KurysmvVTLNfWg1+YocoaWjeJ+hqDwtpY 3b9tp2k+LBsusxqVfl1txm3lIzYnO9PNcxAI/NsBIieteEavhb3gC7jeoQiC1r0NL0QnYR mgl0V9jGhva91MXXm44cpnKUNOYb3ls= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=WSr5DlDQ; spf=pass (imf23.hostedemail.com: domain of yuan1.liu@intel.com designates 192.198.163.11 as permitted sender) smtp.mailfrom=yuan1.liu@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1789370861; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8f/7efMiC6ft/Zrjv2n+Em6z0opx8zWnbRPBMtnAXTM=; b=Y7zybRGKC5FHU5V3V+oP7trmJNqFlv1ccG7yg32hX1wjgD7uavZYNmFyXcDWmYixPBe/fH /JwAAv7NUZu3ZQSuiqdS5/q2u2k+zZC/hkvq4hplEiOTKxXIBcaJXO+2SSAO2+/wpPbB9P P5nDItJGOCHw2Zy6NiSlXiaA0C4/5eM= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1789370861; x=1820906861; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=HAcgfKHkNgLlXaIqIJX2qqZ64BIXaJH3XvIA/CZsUSI=; b=WSr5DlDQl+4PewdZAaJzegXGEJK+ITgJ2ZT1YbvK9RtCz3ENm8X8GfOe CH04S6yOz4RwC5PHnyzj1VkGNgL9nQe5JfnF/HmoE+Dn8jANsAWkfHEi5 PltzvzSUCOu6l5OyMI9GCVgbLRm7AVZt8Dcy81MasyG1hDXmvIe5N6zR7 zw4BZPvkw40/30hEhtZaQmLVuYM5nAxMBWRfQuwmE2Qhi7VhwizunVxls 5DKvAmR7yejNTgJUAZ7nBGbyE47D7g9fHB45Dvs41iSpSPAmr+qX0NvL2 XxvAM31DztmuvcHuzGxP1I4p9x5yBkVWije4+XQl7UFJ3ggyUgK8Sdd2c w==; X-CSE-ConnectionGUID: dWvkC699TRy0pj9/ycRlxw== X-CSE-MsgGUID: epaUFu/HR7605mn+NgkbnA== X-IronPort-AV: E=McAfee;i="6800,10657,11904"; a="100314902" X-IronPort-AV: E=Sophos;i="6.27,102,1787036400"; d="scan'208";a="100314902" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2026 00:27:39 -0700 X-CSE-ConnectionGUID: 9fWNmxtXT+O4SVTqoSzkmA== X-CSE-MsgGUID: +moyawqkRKSX0CZQCNdHZw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,102,1787036400"; d="scan'208";a="271152822" Received: from spr10.sh.intel.com (HELO localhost) ([10.239.23.75]) by orviesa010.jf.intel.com with ESMTP; 14 Sep 2026 00:26:05 -0700 From: Yuan Liu To: David Hildenbrand , Oscar Salvador , Mike Rapoport , Wei Yang Cc: linux-mm@kvack.org, Nanhai Zou , Chen Zhang , Yuan Liu , Jason Zeng , Chen Yu , Pan Deng , Tianyou Li , linux-kernel@vger.kernel.org Subject: [PATCH v9 1/2] mm/memory_hotplug: make shrink_zone_span() more robust Date: Mon, 14 Sep 2026 03:29:28 -0400 Message-ID: <20260914072929.1883794-2-yuan1.liu@intel.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260914072929.1883794-1-yuan1.liu@intel.com> References: <20260914072929.1883794-1-yuan1.liu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1886114000A X-Rspam-User: X-Stat-Signature: 5qnw8tk3w6i6ztyo9rnun9cncse14mf7 X-HE-Tag: 1789370860-547111 X-HE-Meta: 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 9Mj4xGK/ c1izl09bCsPBlXmaQNpOv7KpPnPpMWIBBPfGXnAKVktpwQwVSraZm8P2xlzJ4RgRGU+cjJ5+fiOpem4U/53cJJTOlj62ZZ7UN0Q/qn1cs/fBZwKvBhbW0Ex7g4+0seyAmveI2QHxpibugy4NNCesouo9pzUEiRBidTqgXrLsk3kemMCEMYJNNul68FHQydcdMpDSKIjiWkNXa9QC59Vw+lSHRAkJ4h+PG1mO/GJBbF8QJJOsnVj084zSt6F8QSmf3C61hNdhbl7AhXdLeUysBvCLcKAyAX/PqbIerpbBcJfmORgYIwraHZJbIBaWZwbrgJ3ItwE1k456K45zPZrR17SitLVOirH1tJkm3 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 or end PFN of the subsection is 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 Reviewed-by: Wei Yang 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 226ab9cb078a..9f19876ec3ec 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -425,49 +425,39 @@ 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; + /* All pages in a subsection are either online or offline. */ + if (unlikely(!pfn_to_online_page(start_pfn))) + return false; - if (zone != page_zone(pfn_to_page(start_pfn))) - continue; + /* Checking start+end is sufficient. */ + return zone == page_zone(pfn_to_page(start_pfn)) || + zone == page_zone(pfn_to_page(end_pfn)); +} - return start_pfn; +/* find the smallest valid pfn in the range [start_pfn, end_pfn) */ +static unsigned long find_smallest_section_pfn(struct zone *zone, + unsigned long start_pfn, unsigned long end_pfn) +{ + for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { + if (subsection_overlaps_zone(start_pfn, zone)) + return start_pfn; } - return 0; } /* find the biggest valid pfn in the range [start_pfn, end_pfn). */ -static unsigned long find_biggest_section_pfn(int nid, struct zone *zone, - unsigned long start_pfn, - unsigned long end_pfn) +static unsigned long find_biggest_section_pfn(struct zone *zone, + unsigned long start_pfn, unsigned long end_pfn) { - unsigned long pfn; - - /* pfn is the end pfn of a memory section. */ - pfn = end_pfn - 1; - for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_to_online_page(pfn))) - continue; - - if (unlikely(pfn_to_nid(pfn) != nid)) - continue; - - if (zone != page_zone(pfn_to_page(pfn))) - continue; - - return pfn; + for (; end_pfn > start_pfn; end_pfn -= PAGES_PER_SUBSECTION) { + if (subsection_overlaps_zone(end_pfn - 1, zone)) + return end_pfn - 1; } - return 0; } @@ -475,7 +465,6 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, unsigned long end_pfn) { unsigned long pfn; - int nid = zone_to_nid(zone); if (zone->zone_start_pfn == start_pfn) { /* @@ -484,7 +473,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, * In this case, we find second smallest valid mem_section * for shrinking zone. */ - pfn = find_smallest_section_pfn(nid, zone, end_pfn, + pfn = find_smallest_section_pfn(zone, end_pfn, zone_end_pfn(zone)); if (pfn) { zone->spanned_pages = zone_end_pfn(zone) - pfn; @@ -500,7 +489,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, * In this case, we find second biggest valid mem_section for * shrinking zone. */ - pfn = find_biggest_section_pfn(nid, zone, zone->zone_start_pfn, + pfn = find_biggest_section_pfn(zone, zone->zone_start_pfn, start_pfn); if (pfn) zone->spanned_pages = pfn - zone->zone_start_pfn + 1; -- 2.47.3