From nobody Wed Apr 8 06:39:49 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 44487C433FE for ; Sat, 22 Oct 2022 11:49:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230182AbiJVLtg (ORCPT ); Sat, 22 Oct 2022 07:49:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230024AbiJVLtA (ORCPT ); Sat, 22 Oct 2022 07:49:00 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 672C4251D7C for ; Sat, 22 Oct 2022 04:48:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=ZxLGyKaonAFGosmEJEXCJIuUc/p2pYnEnlwCFC//QMs=; b=d5RZJQiWmMamzGxaIKQnEOtUwD T9H/sWSomE2By/o8fhYFxcJnvZOZCOoyYsj4DPqrDTAEiVXHR6xyiOPOuV3LpQeQUbDuoAPcmVKGs DJSaXerbzdFXHI/CeMHGBW7cMxLNnTrKYaXjJZ3DmnuM+KA59Jo1ENMyp0WIE4NfWdcSJlN6hSA3v I0C+dfhtEKU3yRXt+wguStxjqcWSysKILzObipzuaBHkU3xB0q+bVaL3s37Udbo8ewcAHquPYv+98 QYAVXxD+sKkG/ZpZypq3uRMpr18Br1YlM8YBXYyqaiaLhGv+xeybW3Binc8LI7NIXuDe907gPs0vd qMBpHPRw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1omCzM-005XdG-1V; Sat, 22 Oct 2022 11:48:28 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id BDB6F302D82; Sat, 22 Oct 2022 13:48:26 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 33F9C28B8E514; Sat, 22 Oct 2022 13:48:26 +0200 (CEST) Message-ID: <20221022114424.906110403@infradead.org> User-Agent: quilt/0.66 Date: Sat, 22 Oct 2022 13:14:10 +0200 From: Peter Zijlstra To: x86@kernel.org, willy@infradead.org, torvalds@linux-foundation.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, linux-mm@kvack.org, aarcange@redhat.com, kirill.shutemov@linux.intel.com, jroedel@suse.de, ubizjak@gmail.com Subject: [PATCH 07/13] mm/gup: Fix the lockless PMD access References: <20221022111403.531902164@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On architectures where the PTE/PMD is larger than the native word size (i386-PAE for example), READ_ONCE() can do the wrong thing. Use pmdp_get_lockless() just like we use ptep_get_lockless(). Signed-off-by: Peter Zijlstra (Intel) --- kernel/events/core.c | 2 +- mm/gup.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7186,7 +7186,7 @@ static u64 perf_get_pgtable_size(struct return pud_leaf_size(pud); =20 pmdp =3D pmd_offset_lockless(pudp, pud, addr); - pmd =3D READ_ONCE(*pmdp); + pmd =3D pmdp_get_lockless(pmdp); if (!pmd_present(pmd)) return 0; =20 --- a/mm/gup.c +++ b/mm/gup.c @@ -2507,7 +2507,7 @@ static int gup_pmd_range(pud_t *pudp, pu =20 pmdp =3D pmd_offset_lockless(pudp, pud, addr); do { - pmd_t pmd =3D READ_ONCE(*pmdp); + pmd_t pmd =3D pmdp_get_lockless(pmdp); =20 next =3D pmd_addr_end(addr, end); if (!pmd_present(pmd))