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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 32324C43387 for ; Mon, 7 Jan 2019 19:54:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 005102173C for ; Mon, 7 Jan 2019 19:54:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728497AbfAGTyA (ORCPT ); Mon, 7 Jan 2019 14:54:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:35388 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728225AbfAGTxf (ORCPT ); Mon, 7 Jan 2019 14:53:35 -0500 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0B2D9218D9; Mon, 7 Jan 2019 19:53:35 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.91) (envelope-from ) id 1ggaxp-0000Ms-VN; Mon, 07 Jan 2019 14:53:33 -0500 Message-Id: <20190107195333.842328119@goodmis.org> User-Agent: quilt/0.65 Date: Mon, 07 Jan 2019 14:53:03 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Julia Cartwright , Daniel Wagner , tom.zanussi@linux.intel.com Subject: [PATCH RT 11/13] x86/mm/pat: disable preemption __split_large_page() after spin_lock() References: <20190107195252.599921907@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14.87-rt50-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior [ Upstream commit 45c6ff4811878e5c1c2ae31303cd95cdc6ae2ab4 ] Commit "x86/mm/pat: Disable preemption around __flush_tlb_all()" added a warning if __flush_tlb_all() is invoked in preemptible context. On !RT the warning does not trigger because a spin lock is acquired which disables preemption. On RT the spin lock does not disable preemption and so the warning is seen. Disable preemption to avoid the warning __flush_tlb_all(). Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware) --- arch/x86/mm/pageattr.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 835620ab435f..57a04ef6fe47 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -661,12 +661,18 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, pgprot_t ref_prot; spin_lock(&pgd_lock); + /* + * Keep preemption disabled after __flush_tlb_all() which expects not be + * preempted during the flush of the local TLB. + */ + preempt_disable(); /* * Check for races, another CPU might have split this page * up for us already: */ tmp = _lookup_address_cpa(cpa, address, &level); if (tmp != kpte) { + preempt_enable(); spin_unlock(&pgd_lock); return 1; } @@ -696,6 +702,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, break; default: + preempt_enable(); spin_unlock(&pgd_lock); return 1; } @@ -743,6 +750,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, * going on. */ __flush_tlb_all(); + preempt_enable(); spin_unlock(&pgd_lock); return 0; -- 2.19.2