From patchwork Fri Dec 17 11:30:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 12684335 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 A8610C433F5 for ; Fri, 17 Dec 2021 11:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235448AbhLQLdh (ORCPT ); Fri, 17 Dec 2021 06:33:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:46316 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235447AbhLQLdh (ORCPT ); Fri, 17 Dec 2021 06:33:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639740816; 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=UTfvPc+jpJw3w8ga8TZ2rx5ThiRLullRxNgQNYf86dk=; b=VJYyfW2leLo9iETHR2xo07vl/elK85RGaGrQWYA9gqhq2YmfZ0eIz3ihdWb0zSRB7uTL3p SmBeARnEAv4o9PGkY4mBEqfZnOwflrEVXSGYamBzuSwTLWsd6NtDGU5GqYB2Fs0I3O9gdg hcZUCw3qQbeeL0pec2tb7HY8Jk+SUL4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-307-IqsbLDQXOCm4tMXYTw-Yaw-1; Fri, 17 Dec 2021 06:33:33 -0500 X-MC-Unique: IqsbLDQXOCm4tMXYTw-Yaw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 439AB81CCC4; Fri, 17 Dec 2021 11:33:30 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.193.204]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0D1B88CB3E; Fri, 17 Dec 2021 11:32:48 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, David Hildenbrand Subject: [PATCH v1 02/11] mm: thp: consolidate mapcount logic on THP split Date: Fri, 17 Dec 2021 12:30:40 +0100 Message-Id: <20211217113049.23850-3-david@redhat.com> In-Reply-To: <20211217113049.23850-1-david@redhat.com> References: <20211217113049.23850-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Let's consolidate the mapcount logic to make it easier to understand and to prepare for further changes. Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand Reviewed-by: Yang Shi Acked-by: Kirill A. Shutemov --- mm/huge_memory.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e5483347291c..4751d03947da 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2101,21 +2101,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, addr, pte, entry); - if (!pmd_migration) - atomic_inc(&page[i]._mapcount); pte_unmap(pte); } if (!pmd_migration) { + /* Sub-page mapcount accounting for above small mappings. */ + int val = 1; + /* * Set PG_double_map before dropping compound_mapcount to avoid * false-negative page_mapped(). + * + * The first to set PageDoubleMap() has to increment all + * sub-page mapcounts by one. */ - if (compound_mapcount(page) > 1 && - !TestSetPageDoubleMap(page)) { - for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_inc(&page[i]._mapcount); - } + if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) + val++; + + for (i = 0; i < HPAGE_PMD_NR; i++) + atomic_add(val, &page[i]._mapcount); lock_page_memcg(page); if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {