Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760137Ab2BJUNL (ORCPT ); Fri, 10 Feb 2012 15:13:11 -0500 Received: from mail-ee0-f46.google.com ([74.125.83.46]:48963 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760043Ab2BJUNK convert rfc822-to-8bit (ORCPT ); Fri, 10 Feb 2012 15:13:10 -0500 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes To: "Dan Smith" Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Ensure that walk_page_range()'s start and end are page-aligned References: <1328902796-30389-1-git-send-email-danms@us.ibm.com> <874nuy31hw.fsf@caffeine.danplanet.com> Date: Fri, 10 Feb 2012 21:13:07 +0100 MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT From: "Michal Nazarewicz" Message-ID: In-Reply-To: <874nuy31hw.fsf@caffeine.danplanet.com> User-Agent: Opera Mail/11.61 (Linux) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1488 Lines: 34 On Fri, 10 Feb 2012 20:57:31 +0100, Dan Smith wrote: > MN> Commit message says about walk_pte_range() but commit changes > MN> walk_page_range(). > > Yep, the issue occurs in walk_pte_range(). OK, it wasn't immediately obvious for me that while loop in walk_page_range() will actually recover if arguments are not aligned (since pgd_addr_end() caps returned value). > The goal was to ensure that > the external interface to it (which is walk_page_range()) does the check > and avoids doing the walk entirely. I think the expectation is that > walk_page_range() is used on aligned addresses. If we put the check in > walk_pte_range() then only walks with a pte_entry handler would fail on > unaligned addresses, which is potentially confusing. > > MN> So why not change the condition to addr < end? > > That would work, of course, but seems sloppier and less precise. The > existing code was clearly written expecting to walk aligned addresses. Fair enough. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +------------------ooO--(_)--Ooo-- -- 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/