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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 92352C5ACCC for ; Tue, 16 Oct 2018 20:25:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FD442098A for ; Tue, 16 Oct 2018 20:25:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5FD442098A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727050AbeJQERx (ORCPT ); Wed, 17 Oct 2018 00:17:53 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:58828 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726067AbeJQERw (ORCPT ); Wed, 17 Oct 2018 00:17:52 -0400 Received: from localhost ([127.0.0.1] helo=bazinga.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1gCVuR-0006PK-Rl; Tue, 16 Oct 2018 22:25:44 +0200 From: Sebastian Andrzej Siewior To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Dave Hansen , Andy Lutomirski , Peter Zijlstra , Borislav Petkov , Sebastian Andrzej Siewior Subject: [PATCH 1/3] x86/mm/pat: Disable preemption around __flush_tlb_all() Date: Tue, 16 Oct 2018 22:25:23 +0200 Message-Id: <20181016202525.29437-2-bigeasy@linutronix.de> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181016202525.29437-1-bigeasy@linutronix.de> References: <20181016202525.29437-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I've seen the WARN_ON_ONCE(__read_cr3() != build_cr3()) in switch_mm_irqs_off() every once in a while during a snapshotted system upgrade. I also saw the warning early during which was introduced in commit decab0888e6e ("x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()"). The callchain is get_page_from_freelist() -> post_alloc_hook() -> __kernel_map_pages() with CONFIG_DEBUG_PAGEALLOC enabled. Turns out, once I disable preemption around __flush_tlb_all() both warnings do not appear. Disable preemption during CR3 reset / __flush_tlb_all(). Fixes: decab0888e6e ("x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()") Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/mm/pageattr.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 51a5a69ecac9f..fe6b21f0a6631 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -2088,7 +2088,9 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) * We should perform an IPI and flush all tlbs, * but that can deadlock->flush only current cpu: */ + preempt_disable(); __flush_tlb_all(); + preempt_enable(); arch_flush_lazy_mmu_mode(); } -- 2.19.1