Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758643Ab1ELUcd (ORCPT ); Thu, 12 May 2011 16:32:33 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:34608 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758615Ab1ELUca (ORCPT ); Thu, 12 May 2011 16:32:30 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Linus Torvalds Date: Thu, 12 May 2011 13:31:37 -0700 Message-ID: Subject: Re: [BUG] perf: bogus correlation of kernel symbols To: Stephane Eranian Cc: Arnaldo Carvalho de Melo , LKML , Ingo Molnar Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1068 Lines: 25 On Thu, May 12, 2011 at 7:48 AM, Stephane Eranian wrote: > > I think there is a serious problem with kernel symbol correlation > with the latest perf in 2.6.39-rc7-tip. Yeah. It's annoying. It's a "perf" bug, though - triggered by /proc/sys/kernel/kptr_restrict being set to 1. The bug is that perf doesn't say "I can't match kernel symbols", but instead does some crazy matching and gives total crap module information (I think it just picks the one that shows up last in /proc/kallsyms). That said, I have considered just reverting the thing that makes kptr_restrict be 1 by default. I do like the security implications of restricting visibility into kernel pointers, but I also think that security rules that make the system less usable are dubious. So I dunno. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/