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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 A7DADC43387 for ; Mon, 7 Jan 2019 19:52:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E1962070C for ; Mon, 7 Jan 2019 19:52:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DJzY1uLK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727820AbfAGTwN (ORCPT ); Mon, 7 Jan 2019 14:52:13 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:38608 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726654AbfAGTwN (ORCPT ); Mon, 7 Jan 2019 14:52:13 -0500 Received: by mail-wm1-f67.google.com with SMTP id m22so2097760wml.3 for ; Mon, 07 Jan 2019 11:52:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=4E5IVL2GoplbevTO2WqBBnn7uJ9mULKzXA9/zrnqEVE=; b=DJzY1uLKLaAIyeaoSDQN8oMLSVkWmx7A0gS1CRSEtbdTiVqez3MRGy61iz2qMHkl5W 2yxN39dld4T9wCryw7sqQQ25cLDEQ2jHfxuvF8H4C5C9QhvFGlPg75v32URela+cMMyw +3+akTL92QwszwaeINwWUmCOTDKSaGBhH1p76ZwimIQm+oUSSFzp7j5GNhey0kr/pFws nmlGJUQcD/DPB/FW6Z+rCMWbzsN+YBme2zLr0VERfmc2tRKv75U5GJJjg4RW/+JWaxz7 Euc1II3rpai5SRYMuNbWSq7w68J6rKXdSTs4N5FvhO+U+/FnowzjGF6pSDIRj0MJAO1l gTBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=4E5IVL2GoplbevTO2WqBBnn7uJ9mULKzXA9/zrnqEVE=; b=aGuKYoqXllXLEkr3/RZGqJ4a34YhgPgfrl/WdySwZbeyUnaCYIDz1PW/TEA11tj4P4 0JTTbwyhU0yoj+DqcgjeRmaizNo8rbLF3SpVG1hCQp3kOnHFcf730yGn/Q3dyQ1QyF79 FbbX8K/MYEV5oc93ptYyp6Nnf2RGAlwaHjCeqU7sqfyE9IIDDXRA7LSHGNHGIvdqoA3x E/KMuIn6OK2dy0zBAs4U5m26m26b8Zhed8bX+sBDomptMk/HtZQllPeF40yXTYFLPg9f SLFg3eor0QNxytguNm04gxn/HuMLmbWktbA7tVN7y84G2X9Bsjl3Fvv9tlA2DyzdH8a+ DVRA== X-Gm-Message-State: AJcUukfgnRo5hoBym8SI6v6YnytDLo5BHpmFJa/tXWxShddacSpgtGOy v6ufW6OKzSjd+WGsHrSkLg== X-Google-Smtp-Source: ALg8bN63S7+Rgf2lcQlpejA5c9FgzfR4k4CA3oNlPwnaTHk+I6sXElPUmoBfYtGDLmQ0BxV/ZSBl6w== X-Received: by 2002:a1c:1cf:: with SMTP id 198mr9399494wmb.5.1546890730503; Mon, 07 Jan 2019 11:52:10 -0800 (PST) Received: from localhost (host89-130-dynamic.43-79-r.retail.telecomitalia.it. [79.43.130.89]) by smtp.gmail.com with ESMTPSA id e17sm82221707wri.36.2019.01.07.11.52.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 Jan 2019 11:52:09 -0800 (PST) Date: Mon, 7 Jan 2019 20:52:09 +0100 From: Andrea Righi To: Steven Rostedt Cc: Masami Hiramatsu , Ingo Molnar , peterz@infradead.org, Mathieu Desnoyers , linux-kernel Subject: Re: [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order problem Message-ID: <20190107195209.GB5966@xps-13> References: <154686789378.15479.2886543882215785247.stgit@devbox> <20190107183444.GA5966@xps-13> <20190107142749.34231bb6@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190107142749.34231bb6@gandalf.local.home> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 07, 2019 at 02:27:49PM -0500, Steven Rostedt wrote: > On Mon, 7 Jan 2019 19:34:44 +0100 > Andrea Righi wrote: > > > On Mon, Jan 07, 2019 at 10:31:34PM +0900, Masami Hiramatsu wrote: > > ... > > > BTW, this is not all of issues. To remove CONFIG_KPROBE_EVENTS_ON_NOTRACE > > > I'm trying to find out other notrace functions which can cause > > > kernel crash by probing. Mostly done on x86, so I'll post it > > > after this series. > > > > Not sure if you found it already, but it looks like some of the > > _raw_spin_lock/unlock* functions (when they're not inlined) are causing > > the same problem (or something similar), I can deadlock the system by > > doing this for example: > > > > echo "r:event_1 __fdget" >> kprobe_events > > echo "r:event_2 _raw_spin_lock_irqsave" >> kprobe_events > > echo 1 > events/kprobes/enable > > [DEADLOCK] > > > > Sending the following just in case... > > > > Ug, kretprobe calls spinlocks in the callback? I wonder if we can > remove them. > > I'm guessing this is a different issue than the one that this patch > fixes. This sounds like we are calling kretprobe from kretprobe? > > -- Steve kretprobe_trampoline() -> trampoline_handler() -> kretprobe_hash_lock() -> raw_spin_lock_irqsave() If we put a kretprobe to raw_spin_lock_irqsave() it looks like kretprobe is going to call kretprobe... -Andrea