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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham 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 A9C08C11F6B for ; Thu, 1 Jul 2021 01:51:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AC1561474 for ; Thu, 1 Jul 2021 01:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238481AbhGAByZ (ORCPT ); Wed, 30 Jun 2021 21:54:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:43936 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238427AbhGAByZ (ORCPT ); Wed, 30 Jun 2021 21:54:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6802C6146D; Thu, 1 Jul 2021 01:51:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104315; bh=uANmw+e78nTpk2QCb7SCehF0iEDyB5ErkP6kLyFncNc=; h=Date:From:To:Subject:In-Reply-To:From; b=CIx1tKBzGtNTzULqGpeMh/fc9oAN6u8a9mlSlvjux/QODdy+exnsPo30KCeQ7PzIy MJxVwx542wawMebhkHYU/MjDJCdD892Oua2HQn+G7g+mb8VswMU354uXJBcjtRkgMY sWyz3vVlQZ09SIxHNrF+KT92lffKPHi8uxEJpkYw= Date: Wed, 30 Jun 2021 18:51:55 -0700 From: Andrew Morton To: akpm@linux-foundation.org, borntraeger@de.ibm.com, gerald.schaefer@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mgorman@suse.de, mhocko@suse.com, mm-commits@vger.kernel.org, shy828301@gmail.com, torvalds@linux-foundation.org, ying.huang@intel.com, ziy@nvidia.com Subject: [patch 089/192] mm: thp: skip make PMD PROT_NONE if THP migration is not supported Message-ID: <20210701015155.l-dNiqU7C%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yang Shi Subject: mm: thp: skip make PMD PROT_NONE if THP migration is not supported A quick grep shows x86_64, PowerPC (book3s), ARM64 and S390 support both NUMA balancing and THP. But S390 doesn't support THP migration so NUMA balancing actually can't migrate any misplaced pages. Skip make PMD PROT_NONE for such case otherwise CPU cycles may be wasted by pointless NUMA hinting faults on S390. Link: https://lkml.kernel.org/r/20210518200801.7413-8-shy828301@gmail.com Signed-off-by: Yang Shi Acked-by: Mel Gorman Cc: Christian Borntraeger Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huang Ying Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Michal Hocko Cc: Vasily Gorbik Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/huge_memory.c~mm-thp-skip-make-pmd-prot_none-if-thp-migration-is-not-supported +++ a/mm/huge_memory.c @@ -1742,6 +1742,7 @@ bool move_huge_pmd(struct vm_area_struct * Returns * - 0 if PMD could not be locked * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary + * or if prot_numa but THP migration is not supported * - HPAGE_PMD_NR if protections changed and TLB flush necessary */ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, @@ -1756,6 +1757,9 @@ int change_huge_pmd(struct vm_area_struc bool uffd_wp = cp_flags & MM_CP_UFFD_WP; bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + if (prot_numa && !thp_migration_supported()) + return 1; + ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; _