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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 8761FC433F5 for ; Thu, 6 Sep 2018 21:41:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DE8B206BA for ; Thu, 6 Sep 2018 21:41:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SzzWPBtQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DE8B206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728538AbeIGCTA (ORCPT ); Thu, 6 Sep 2018 22:19:00 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49548 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726086AbeIGCTA (ORCPT ); Thu, 6 Sep 2018 22:19:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=meUx+c5OOhrm8NhHBdhijNt0QxOOddzH6wzatUXtTiE=; b=SzzWPBtQYSgLZaHm+RdkY0/DQe rwIiPTrRGPlwlJ9in/ZlYzr8DzWLWYMdhTYHLq9VwFNecf2Az4w/gKs8KUvWgMP/fs9OldKs6afWg sCdrLuVwxfqpNBEaWkB5ixUAXSe7+nvtgkfQZOI3OuS/hsdAWfX3/GIVP2cAfrDPPzoNWM6xaN+gg LnvM9sPKzU61Hc6KEgxz3oveZtYyS+LKUQs7iPXKgyI6azOlICe0Os8n6I+stGlW2/d8w4Js3OlEM 5ExxZyPX8Ndw+19mUzwNQWVtOail1cFDrcTYUHHlWNSOl9HvYB+068SHEeC3WevgcD6S4Db94uT+p KXKn2eaQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fy21l-00052v-8G; Thu, 06 Sep 2018 21:41:25 +0000 Received: by worktop (Postfix, from userid 1000) id 6B3B86E0AA9; Thu, 6 Sep 2018 23:41:22 +0200 (CEST) Date: Thu, 6 Sep 2018 23:41:22 +0200 From: Peter Zijlstra To: Nadav Amit Cc: Thomas Gleixner , LKML , Ingo Molnar , X86 ML , Arnd Bergmann , linux-arch , Dave Hansen , Jiri Kosina , Andy Lutomirski , Kees Cook , Dave Hansen Subject: Re: [PATCH v2 1/6] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Message-ID: <20180906214122.GG9358@worktop.programming.kicks-ass.net> References: <20180902173224.30606-1-namit@vmware.com> <20180902173224.30606-2-namit@vmware.com> <20180906194003.GD4816@worktop.programming.kicks-ass.net> <20180906195351.GB9358@worktop.programming.kicks-ass.net> <20180906202547.GC9358@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 06, 2018 at 08:57:38PM +0000, Nadav Amit wrote: > at 1:25 PM, Peter Zijlstra wrote: > > > On Thu, Sep 06, 2018 at 07:58:40PM +0000, Nadav Amit wrote: > >>> With that CR3 trickery, we can rid ourselves of the text_mutex > >>> requirement, since concurrent text_poke is 'safe'. That would clean up > >>> the kgdb code quite a bit. > >> > >> I don’t know. I’m somewhat worried with multiple mechanisms potentially > >> changing the same code at the same time - and maybe ending up with some > >> mess. > > > > kgdb only pokes INT3, that should be pretty safe. > > Maybe I misunderstand your point. If you want me to get rid of text_mutex > completely, No, just the ugly things kgdb does with it.