From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx129.postini.com [74.125.245.129]) by kanga.kvack.org (Postfix) with SMTP id D1BFE6B002C for ; Fri, 10 Feb 2012 15:13:10 -0500 (EST) Received: by eekc13 with SMTP id c13so1232809eek.14 for ; Fri, 10 Feb 2012 12:13:09 -0800 (PST) Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes 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: Quoted-Printable From: "Michal Nazarewicz" Message-ID: In-Reply-To: <874nuy31hw.fsf@caffeine.danplanet.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Smith Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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_ra= nge() 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 che= ck > 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 o= n > 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' \,=3D./ `o ..o | Computer Science, Micha=C5=82 =E2=80=9Cmina86=E2=80=9D Nazarewicz= (o o) ooo +------------------ooO--(_)--Ooo-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org