From nobody Fri Feb 13 14:08:36 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CDCECE7A81 for ; Mon, 25 Sep 2023 07:22:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230177AbjIYHWz (ORCPT ); Mon, 25 Sep 2023 03:22:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231896AbjIYHWl (ORCPT ); Mon, 25 Sep 2023 03:22:41 -0400 Received: from out-200.mta1.migadu.com (out-200.mta1.migadu.com [95.215.58.200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C5A619F for ; Mon, 25 Sep 2023 00:22:27 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1695626546; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u7hdNMC4UOcW2t7uwYGgTfN9WDCRbod/rNSZ3lnlhtw=; b=BXlLx+C48qOjacmeTMWRU5jZhJUdcFTtpDZuI2ajVt4e0J0SA08MBhucH4QPbVjAKyPmun h0Z0jblLvBQUT5O2gVLrp8WKrOnPSG/ynQtMXnmkDDf/KGlSUKhtGechJ/dINHbRNQC22I mgTeKnYclWq7yaIPfhAd3gFi7RMWn3E= From: Yajun Deng To: akpm@linux-foundation.org, rppt@kernel.org Cc: mike.kravetz@oracle.com, muchun.song@linux.dev, willy@infradead.org, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yajun Deng Subject: [PATCH v2 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY Date: Mon, 25 Sep 2023 15:21:50 +0800 Message-Id: <20230925072150.386880-3-yajun.deng@linux.dev> In-Reply-To: <20230925072150.386880-1-yajun.deng@linux.dev> References: <20230925072150.386880-1-yajun.deng@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" memmap_init_range() would set page count of all pages, but the free pages count would be reset in __free_pages_core(). There are opposite operations. It's unnecessary and time-consuming when it's MEMINIT_EARLY context. Init page count in reserve_bootmem_region when in MEMINIT_EARLY context, and check the page count before reset it. At the same time, the INIT_LIST_HEAD in reserve_bootmem_region isn't need, as it already done in __init_single_page. The following data was tested on an x86 machine with 190GB of RAM. before: free_low_memory_core_early() 341ms after: free_low_memory_core_early() 285ms Signed-off-by: Yajun Deng --- mm/mm_init.c | 18 +++++++++++++----- mm/page_alloc.c | 20 ++++++++++++-------- 2 files changed, 25 insertions(+), 13 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 61df37133331..64c00ebaf4ef 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -718,7 +718,7 @@ static void __meminit init_reserved_page(unsigned long = pfn, int nid) if (zone_spans_pfn(zone, pfn)) break; } - __init_single_page(pfn_to_page(pfn), pfn, zid, nid, INIT_PAGE_COUNT); + __init_single_page(pfn_to_page(pfn), pfn, zid, nid, 0); } #else static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {} @@ -756,8 +756,8 @@ void __meminit reserve_bootmem_region(phys_addr_t start, =20 init_reserved_page(start_pfn, nid); =20 - /* Avoid false-positive PageTail() */ - INIT_LIST_HEAD(&page->lru); + /* Set page count for the reserve region */ + init_page_count(page); =20 /* * no need for atomic set_bit because the struct @@ -888,9 +888,17 @@ void __meminit memmap_init_range(unsigned long size, i= nt nid, unsigned long zone } =20 page =3D pfn_to_page(pfn); - __init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT); - if (context =3D=3D MEMINIT_HOTPLUG) + + /* If the context is MEMINIT_EARLY, we will set page count and + * mark page reserved in reserve_bootmem_region, the free region + * wouldn't have page count and we will check the pages count + * in __free_pages_core. + */ + __init_single_page(page, pfn, zone, nid, 0); + if (context =3D=3D MEMINIT_HOTPLUG) { + init_page_count(page); __SetPageReserved(page); + } =20 /* * Usually, we want to mark the pageblock MIGRATE_MOVABLE, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 06be8821d833..b868caabe8dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1285,18 +1285,22 @@ void __free_pages_core(struct page *page, unsigned = int order) unsigned int loop; =20 /* - * When initializing the memmap, __init_single_page() sets the refcount - * of all pages to 1 ("allocated"/"not free"). We have to set the - * refcount of all involved pages to 0. + * When initializing the memmap, memmap_init_range sets the refcount + * of all pages to 1 ("reserved" and "free") in hotplug context. We + * have to set the refcount of all involved pages to 0. Otherwise, + * we don't do it, as reserve_bootmem_region only set the refcount on + * reserve region ("reserved") in early context. */ - prefetchw(p); - for (loop =3D 0; loop < (nr_pages - 1); loop++, p++) { - prefetchw(p + 1); + if (page_count(page)) { + prefetchw(p); + for (loop =3D 0; loop < (nr_pages - 1); loop++, p++) { + prefetchw(p + 1); + __ClearPageReserved(p); + set_page_count(p, 0); + } __ClearPageReserved(p); set_page_count(p, 0); } - __ClearPageReserved(p); - set_page_count(p, 0); =20 atomic_long_add(nr_pages, &page_zone(page)->managed_pages); =20 --=20 2.25.1