From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752154AbdEQBin (ORCPT ); Tue, 16 May 2017 21:38:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:36008 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342AbdEQBim (ORCPT ); Tue, 16 May 2017 21:38:42 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4755C239D0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org Date: Wed, 17 May 2017 10:38:34 +0900 From: Masami Hiramatsu To: Thomas Gleixner Cc: Steven Rostedt , LKML Subject: Re: WARNING at arch/x86/kernel/alternative.c:707 text_poke+0x25d/0x270 Message-Id: <20170517103834.5e8642a26e2e49369c88bf0d@kernel.org> In-Reply-To: References: <20170516094802.76a468bb@gandalf.local.home> <20170517001539.171b05fd39bbdd4ce36566c2@kernel.org> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 16 May 2017 23:42:58 +0200 (CEST) Thomas Gleixner wrote: > On Wed, 17 May 2017, Masami Hiramatsu wrote: > > On Tue, 16 May 2017 09:48:02 -0400 > > Steven Rostedt wrote: > > > It appears that the kprobe_optimizer work thread call happened after > > > the init pages were freed, causing alternative.c to give the above > > > warning because the text that is being unoptimized happens to no longer > > > exist. > > > > Ah, I see. I need to check that case. Actually for the module > > init text area, kill_kprobe() correctly kicks kill_optimized_kprobe() > > so it should safe. But above case is on the init-text in kernel > > itself. I guess module_notifier may not be called for that area... > > Find below the patch I'm using for now . Thank you very much! It looks good to me. Acked-by: Masami Hiramatsu > > Thanks, > > tglx > > 8<-------------------- > > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -349,6 +349,9 @@ extern int proc_kprobes_optimization_han > int write, void __user *buffer, > size_t *length, loff_t *ppos); > #endif > +extern void wait_for_kprobe_optimizer(void); > +#else > +static inline void wait_for_kprobe_optimizer(void) { } > #endif /* CONFIG_OPTPROBES */ > #ifdef CONFIG_KPROBES_ON_FTRACE > extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -595,7 +595,7 @@ static void kprobe_optimizer(struct work > } > > /* Wait for completing optimization and unoptimization */ > -static void wait_for_kprobe_optimizer(void) > +void wait_for_kprobe_optimizer(void) > { > mutex_lock(&kprobe_mutex); > > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1535,6 +1535,11 @@ static __init int kprobe_trace_self_test > > end: > release_all_trace_kprobes(); > + /* > + * Wait for the optimizer work to finish. Otherwise it might fiddle > + * with probes in already freed __init text. > + */ > + wait_for_kprobe_optimizer(); > if (warn) > pr_cont("NG: Some tests are failed. Please check them.\n"); > else -- Masami Hiramatsu