From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751357AbaDOVta (ORCPT ); Tue, 15 Apr 2014 17:49:30 -0400 Received: from www.linutronix.de ([62.245.132.108]:60581 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbaDOVt2 (ORCPT ); Tue, 15 Apr 2014 17:49:28 -0400 Date: Tue, 15 Apr 2014 23:49:39 +0200 (CEST) From: Thomas Gleixner To: Vince Weaver cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar Subject: Re: [perf] more perf_fuzzer memory corruption In-Reply-To: Message-ID: References: User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Apr 2014, Vince Weaver wrote: > > Still tracking memory corruption bugs found by the perf_fuzzer, I have > about 10 different log splats that I think might all be related to the > same underlying problem. > > Anyway I managed to trigger this using the perf_fuzzer: > > [ 221.065278] Slab corruption (Not tainted): kmalloc-2048 start=ffff8800cd15e800, len=2048 > [ 221.074062] 040: 6b 6b 6b 6b 6b 6b 6b 6b 98 72 57 cd 00 88 ff ff kkkkkkkk.rW..... > [ 221.082321] Prev obj: start=ffff8800cd15e000, len=2048 > [ 221.087933] 000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk > [ 221.096224] 010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk > > And luckily I had ftrace running at the time. > > The allocation of this block is by perf_event > > perf_fuzzer-2520 [001] 182.980563: kmalloc: (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800 bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO > perf_fuzzer-2520 [000] 183.628515: kmalloc: (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800 bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO > perf_fuzzer-2520 [000] 183.628521: kfree: (perf_event_alloc+0x2f7) call_site=ffffffff81139c57 ptr=0xffff8800cd15e800 > perf_fuzzer-2520 [000] 183.628844: kmalloc: (perf_event_alloc+0x55) call_site=ffffffff811399b5 ptr=0xffff8800cd15e800 bytes_req=1272 bytes_alloc=2048 gfp_flags=GFP_KERNEL|GFP_ZERO > ...(thousands of times of kmalloc/kfree) > > Is it worth wading through this mess to try to track down what happened? Definitely worth a try. Can you upload the trace file and provide the URL or send it offlist in private mail if you cannot provide a public URL. Thanks, tglx