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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 E1ACCC433EF for ; Fri, 24 Sep 2021 13:34:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C456261029 for ; Fri, 24 Sep 2021 13:34:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346529AbhIXNfo (ORCPT ); Fri, 24 Sep 2021 09:35:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346678AbhIXNfP (ORCPT ); Fri, 24 Sep 2021 09:35:15 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA3EBC0610D2; Fri, 24 Sep 2021 06:30:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=Io2oolRwrQOpJUWvka+JVfALnOE720dEYxe2COcajmY=; b=d0Os5iTqtYDz3iOfjSNUDNZtIc cLL9qyj0M5q5WbzkXsWtR/+itD++6KgboyCTk07uJIliFpXsqMm4nD8fDbVjg8Ga2Ts8JZDwgvQQ5 NRVV9yiGDCTFmYcPhpmkDOStf0M/t2lQ7Dgc/vnpWir3RvrzmXeFuNrUJ8o0CYYSeY3/phUUFc4kB rnbdyQ58eZ7aub3jQsytJa0FJSxoPVtTEO/SS2/wfLISw7LwSKCXaXWpRx6oAi8TWD635YoihOkBR bOE4kb4lmBcFUYLvATFfYDQhKAeYst7VXGKebA/gAF4EouUJ1iC+Qhb+0t7V+HL+/xOkH10iyDpqW kI70V3LA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mTlH6-005XRt-1O; Fri, 24 Sep 2021 13:30:00 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 22ECD30026F; Fri, 24 Sep 2021 15:29:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DC4CF2C5DFD92; Fri, 24 Sep 2021 15:29:55 +0200 (CEST) Date: Fri, 24 Sep 2021 15:29:55 +0200 From: Peter Zijlstra To: Kees Cook Cc: Thomas Gleixner , Josh Poimboeuf , Vito Caputo , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Jens Axboe , Mark Rutland , Stefan Metzmacher , Andy Lutomirski , Lai Jiangshan , Christian Brauner , Andrew Morton , "Kenta.Tada@sony.com" , Daniel Bristot de Oliveira , Michael =?iso-8859-1?Q?Wei=DF?= , Anand K Mistry , Alexey Gladkov , Michal Hocko , Helge Deller , Dave Hansen , Andrea Righi , Ohhoon Kwon , Kalesh Singh , YiFei Zhu , "Eric W. Biederman" , linux-kernel@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] proc: Disable /proc/$pid/wchan Message-ID: References: <20210923233105.4045080-1-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210923233105.4045080-1-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Thu, Sep 23, 2021 at 04:31:05PM -0700, Kees Cook wrote: > This leaves kernel/sched/fair.c as the only user of get_wchan(). But > again, since this was broken for 4 years, was this profiling logic > actually doing anything useful? Unlikely, I proposed removing the whole kernel/profile.c thing a while back, but some people complained that it would make it 'hard' to profile early boot. IMO this not actually working right seems another argument for killing that too :-)