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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86DAEECAA24 for ; Thu, 25 Aug 2022 16:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243435AbiHYQtz (ORCPT ); Thu, 25 Aug 2022 12:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242954AbiHYQtb (ORCPT ); Thu, 25 Aug 2022 12:49:31 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A62CBFAA7 for ; Thu, 25 Aug 2022 09:47:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1661446031; 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=Q3NPvWyh2xRtoYXHMmyrsAAtGbzTeyv985JIMuXJIb4=; b=IuyWJAWMTr8eL4p1Clm+lJ6P8aG8+34RIxuK7iEslEBbAPvkDQoTrA0lp/jcp2zU9I97d6 g4Cg1uMCU0SgO1v+bm72qfEHBpOBVZ9z2N3xTv0JSXZKOREHoGDWdoxif3Q+ciC3IS5l4L PsYTTwXOVRAqwixZCDq7V4fjumRSzTA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-620-xXkhVmbBN16ANoNW0OvGkQ-1; Thu, 25 Aug 2022 12:47:09 -0400 X-MC-Unique: xXkhVmbBN16ANoNW0OvGkQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 689E6101AA45; Thu, 25 Aug 2022 16:47:09 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.192.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id CF705492CA2; Thu, 25 Aug 2022 16:47:06 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Mel Gorman , Jason Gunthorpe , John Hubbard , "Matthew Wilcox (Oracle)" , Andrea Arcangeli , Hugh Dickins , Peter Xu Subject: [PATCH v1 2/3] mm/gup: use gup_can_follow_protnone() also in GUP-fast Date: Thu, 25 Aug 2022 18:46:58 +0200 Message-Id: <20220825164659.89824-3-david@redhat.com> In-Reply-To: <20220825164659.89824-1-david@redhat.com> References: <20220825164659.89824-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There seems to be no reason why FOLL_FORCE during GUP-fast would have to fallback to the slow path when stumbling over a PROT_NONE mapped page. We only have to trigger hinting faults in case FOLL_FORCE is not set, and any kind of fault handling naturally happens from the slow path -- where NUMA hinting accounting/handling would be performed. Note that the comment regarding THP migration is outdated: commit 2b4847e73004 ("mm: numa: serialise parallel get_user_page against THP migration") described that this was required for THP due to lack of PMD migration entries. Nowadays, we do have proper PMD migration entries in place -- see set_pmd_migration_entry(), which does a proper pmdp_invalidate() when placing the migration entry. So let's just reuse gup_can_follow_protnone() here to make it consistent and drop the somewhat outdated comments. Signed-off-by: David Hildenbrand --- mm/gup.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index a1355dbd848e..dfef23071dc8 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2350,11 +2350,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, struct page *page; struct folio *folio; - /* - * Similar to the PMD case below, NUMA hinting must take slow - * path using the pte_protnone check. - */ - if (pte_protnone(pte)) + if (pte_protnone(pte) && !gup_can_follow_protnone(flags)) goto pte_unmap; if (!pte_access_permitted(pte, flags & FOLL_WRITE)) @@ -2736,12 +2732,8 @@ static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned lo if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) || pmd_devmap(pmd))) { - /* - * NUMA hinting faults need to be handled in the GUP - * slowpath for accounting purposes and so that they - * can be serialised against THP migration. - */ - if (pmd_protnone(pmd)) + if (pmd_protnone(pmd) && + !gup_can_follow_protnone(flags)) return 0; if (!gup_huge_pmd(pmd, pmdp, addr, next, flags, -- 2.37.1