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=-6.8 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 AAF09C0044C for ; Mon, 29 Oct 2018 18:10:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F60B2082D for ; Mon, 29 Oct 2018 18:10:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F60B2082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com 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 S1728401AbeJ3DAg (ORCPT ); Mon, 29 Oct 2018 23:00:36 -0400 Received: from terminus.zytor.com ([198.137.202.136]:34211 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727502AbeJ3DAg (ORCPT ); Mon, 29 Oct 2018 23:00:36 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w9TIAR0h1642856 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 29 Oct 2018 11:10:27 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w9TIARc21642850; Mon, 29 Oct 2018 11:10:27 -0700 Date: Mon, 29 Oct 2018 11:10:27 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Sebastian Andrzej Siewior Message-ID: Cc: linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, peterz@infradead.org, tglx@linutronix.de, luto@kernel.org, bp@alien8.de, hpa@zytor.com, bigeasy@linutronix.de, mingo@kernel.org Reply-To: bp@alien8.de, luto@kernel.org, hpa@zytor.com, bigeasy@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, dave.hansen@linux.intel.com, tglx@linutronix.de In-Reply-To: <20181017103432.zgv46nlu3hc7k4rq@linutronix.de> References: <20181017103432.zgv46nlu3hc7k4rq@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/mm/pat: Disable preemption around __flush_tlb_all() Git-Commit-ID: f77084d96355f5fba8e2c1fb3a51a393b1570de7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f77084d96355f5fba8e2c1fb3a51a393b1570de7 Gitweb: https://git.kernel.org/tip/f77084d96355f5fba8e2c1fb3a51a393b1570de7 Author: Sebastian Andrzej Siewior AuthorDate: Wed, 17 Oct 2018 12:34:32 +0200 Committer: Thomas Gleixner CommitDate: Mon, 29 Oct 2018 19:04:31 +0100 x86/mm/pat: Disable preemption around __flush_tlb_all() The WARN_ON_ONCE(__read_cr3() != build_cr3()) in switch_mm_irqs_off() triggers every once in a while during a snapshotted system upgrade. The warning triggers since 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. Disable preemption during CR3 reset / __flush_tlb_all() and add a comment why preemption has to be disabled so it won't be removed accidentaly. Add another preemptible() check in __flush_tlb_all() to catch callers with enabled preemption when PGE is enabled, because PGE enabled does not trigger the warning in __native_flush_tlb(). Suggested by Andy Lutomirski. Fixes: decab0888e6e ("x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()") Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Dave Hansen Cc: Peter Zijlstra Cc: Borislav Petkov Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181017103432.zgv46nlu3hc7k4rq@linutronix.de --- arch/x86/include/asm/tlbflush.h | 6 ++++++ arch/x86/mm/pageattr.c | 6 +++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 323a313947e0..d760611cfc35 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -453,6 +453,12 @@ static inline void __native_flush_tlb_one_user(unsigned long addr) */ static inline void __flush_tlb_all(void) { + /* + * This is to catch users with enabled preemption and the PGE feature + * and don't trigger the warning in __native_flush_tlb(). + */ + VM_WARN_ON_ONCE(preemptible()); + if (boot_cpu_has(X86_FEATURE_PGE)) { __flush_tlb_global(); } else { diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 62bb30b4bd2a..a1004dec98ea 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -2309,9 +2309,13 @@ 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: + * but that can deadlock->flush only current cpu. + * Preemption needs to be disabled around __flush_tlb_all() due to + * CR3 reload in __native_flush_tlb(). */ + preempt_disable(); __flush_tlb_all(); + preempt_enable(); arch_flush_lazy_mmu_mode(); }