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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 07DE1C282C2 for ; Wed, 13 Feb 2019 10:36:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB25D2190A for ; Wed, 13 Feb 2019 10:36:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="jHJJNhfC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391467AbfBMKgA (ORCPT ); Wed, 13 Feb 2019 05:36:00 -0500 Received: from merlin.infradead.org ([205.233.59.134]:40974 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729719AbfBMKgA (ORCPT ); Wed, 13 Feb 2019 05:36:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=czAaUKm5d4NJqhNhwcovfXQn4SkiGplxomEQLfnJLXs=; b=jHJJNhfC68k0s+g824T+ojFF/ RyG1NGZLpeUAjfrd263UZFzBTLsa4GHWlBlybEx3lJM57Pa6fjTTkGYIdeTFFFVSwEYk4BgQnXT20 4gysr+4A+RjR11ZuH1FUUCUv2N1IPKAdHl6EYJqHZ9NvLgmsgWYGGx2hxwiHFCnruSA7AVyDYkqnp sQRJB2CY3CHasCgDslp3BlsywX/tGVTnlfey9HIqHE4EFJ73nbpLMPTI07UAVXQccISuZTaKoJH8+ vnbszb+VGF23wKB/ljdjBoJVyTpC8PCQTkJWQ3oVG0UZUQ1Zj2mT+xyoVJ/kmy22KA0NN/8A0Zrnz iFM9IkVYA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtrtT-0005FS-MI; Wed, 13 Feb 2019 10:35:55 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 06ACE20D0C1E6; Wed, 13 Feb 2019 11:35:54 +0100 (CET) Date: Wed, 13 Feb 2019 11:35:53 +0100 From: Peter Zijlstra To: Julien Thierry Cc: Ingo Molnar , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, mingo@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, james.morse@arm.com, hpa@zytor.com, valentin.schneider@arm.com Subject: Re: [PATCH v3 3/4] uaccess: Check no rescheduling function is called in unsafe region Message-ID: <20190213103553.GO32494@hirez.programming.kicks-ass.net> References: <1547560709-56207-1-git-send-email-julien.thierry@arm.com> <1547560709-56207-4-git-send-email-julien.thierry@arm.com> <20190211134527.GA121589@gmail.com> <20190211135159.GC32511@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 12, 2019 at 09:15:13AM +0000, Julien Thierry wrote: > >>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > >>> index a674c7db..b1bb7e9 100644 > >>> --- a/kernel/sched/core.c > >>> +++ b/kernel/sched/core.c > >>> @@ -3289,6 +3289,14 @@ static inline void schedule_debug(struct task_struct *prev) > >>> __schedule_bug(prev); > >>> preempt_count_set(PREEMPT_DISABLED); > >>> } > >>> + > >>> + if (IS_ENABLED(CONFIG_DEBUG_UACCESS_SLEEP) && > >>> + unlikely(unsafe_user_region_active())) { > >>> + printk(KERN_ERR "BUG: scheduling while user_access enabled: %s/%d/0x%08x\n", > >>> + prev->comm, prev->pid, preempt_count()); > >>> + dump_stack(); > >>> + } > >>> + > >>> rcu_sleep_check(); > >>> > >>> profile_hit(SCHED_PROFILING, __builtin_return_address(0)); > I guess I'll drop the might_resched() part of this patch if that sounds > alright. I'm still confused by the schedule_debug() part. How is that not broken?