Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753317Ab2EaQ4c (ORCPT ); Thu, 31 May 2012 12:56:32 -0400 Received: from casper.infradead.org ([85.118.1.10]:37754 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721Ab2EaQ4b convert rfc822-to-8bit (ORCPT ); Thu, 31 May 2012 12:56:31 -0400 Message-ID: <1338483372.28384.65.camel@twins> Subject: Re: [PATCH 1/3] uprobes/core: Remove redundant lock_page/unlock_page From: Peter Zijlstra To: Srikar Dronamraju Cc: Ingo Molnar , Linus Torvalds , Ananth N Mavinakayanahalli , LKML , Oleg Nesterov , Steven Rostedt , Arnaldo Carvalho de Melo , Masami Hiramatsu , Anton Arapov Date: Thu, 31 May 2012 18:56:12 +0200 In-Reply-To: <20120531150756.GC24279@linux.vnet.ibm.com> References: <20120531114630.23691.33166.sendpatchset@srdronam.in.ibm.com> <1338465518.28384.55.camel@twins> <20120531150756.GC24279@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1281 Lines: 31 On Thu, 2012-05-31 at 20:37 +0530, Srikar Dronamraju wrote: > * Peter Zijlstra [2012-05-31 13:58:38]: > > > On Thu, 2012-05-31 at 17:16 +0530, Srikar Dronamraju wrote: > > > From: Srikar Dronamraju > > > > > > No need to lock the page when copying the opcode in read_opcode(). > > > > It would be good if the changelog said _why_ this is so :-) > > In read_opcode(), we have the reference for the page and we only are reading > from the the page. i.e we are neither modifying the page contents, not > the page attributes. Fair enough, so put that in the changelog. The changelog should explain things, not raise questions. > Existing kernel code has enough examples where we read the contents > of the page without taking the page lock. Yes, but that doesn't tell us this site is ok, doing it because others do isn't an argument. > Further this was discussed here too https://lkml.org/lkml/2012/4/17/361. That wasn't a discussion, that was two people saying they don't know. -- 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/