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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9EB3AC5475B for ; Wed, 6 Mar 2024 10:44:14 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Tvnghwcm; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Tvnghwcm; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4TqTZP2BJyz3vX6 for ; Wed, 6 Mar 2024 21:44:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Tvnghwcm; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Tvnghwcm; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.133.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=peterx@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4TqTXD70V6z3vZD for ; Wed, 6 Mar 2024 21:42:20 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709721738; 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=3D9LYre9es5Pr/ZmF0ksBqg/v+REJVkPqwZxeVyu2sc=; b=TvnghwcmBkGaIwcP/g2BdggK67IK2QaOE+k+YdWYOVCwv+UhqVX109j3hYbtR7S1+59qDd 9HXF+BHLcbIHr9whsr2jqTQTg0bS1L6fDBDN3N26kVedjfaB6vuSywY8HqKyzbGtZG7tnV rcXHVvXjjA6PhGA8c3wm2r4aXE2Yyjc= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709721738; 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=3D9LYre9es5Pr/ZmF0ksBqg/v+REJVkPqwZxeVyu2sc=; b=TvnghwcmBkGaIwcP/g2BdggK67IK2QaOE+k+YdWYOVCwv+UhqVX109j3hYbtR7S1+59qDd 9HXF+BHLcbIHr9whsr2jqTQTg0bS1L6fDBDN3N26kVedjfaB6vuSywY8HqKyzbGtZG7tnV rcXHVvXjjA6PhGA8c3wm2r4aXE2Yyjc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-158-uC-oagQgMFWs_CgooWNVxQ-1; Wed, 06 Mar 2024 05:42:11 -0500 X-MC-Unique: uC-oagQgMFWs_CgooWNVxQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D81EA8007A2; Wed, 6 Mar 2024 10:42:10 +0000 (UTC) Received: from x1n.redhat.com (unknown [10.72.116.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id 97C19112131D; Wed, 6 Mar 2024 10:42:04 +0000 (UTC) From: peterx@redhat.com To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC 02/13] mm/gup: Cache p4d in follow_p4d_mask() Date: Wed, 6 Mar 2024 18:41:36 +0800 Message-ID: <20240306104147.193052-3-peterx@redhat.com> In-Reply-To: <20240306104147.193052-1-peterx@redhat.com> References: <20240306104147.193052-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org, x86@kernel.org, Muchun Song , peterx@redhat.com, Matthew Wilcox , Jason Gunthorpe , sparclinux@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, Mike Rapoport Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Peter Xu Add a variable to cache p4d in follow_p4d_mask(). It's a good practise to make sure all the following checks will have a consistent view of the entry. Signed-off-by: Peter Xu --- mm/gup.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index df83182ec72d..69a777f4fc5c 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -772,16 +772,17 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, unsigned int flags, struct follow_page_context *ctx) { - p4d_t *p4d; + p4d_t *p4dp, p4d; - p4d = p4d_offset(pgdp, address); - if (p4d_none(*p4d)) + p4dp = p4d_offset(pgdp, address); + p4d = READ_ONCE(*p4dp); + if (p4d_none(p4d)) return no_page_table(vma, flags); - BUILD_BUG_ON(p4d_huge(*p4d)); - if (unlikely(p4d_bad(*p4d))) + BUILD_BUG_ON(p4d_huge(p4d)); + if (unlikely(p4d_bad(p4d))) return no_page_table(vma, flags); - return follow_pud_mask(vma, address, p4d, flags, ctx); + return follow_pud_mask(vma, address, p4dp, flags, ctx); } /** -- 2.44.0