From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932312AbVHHWha (ORCPT ); Mon, 8 Aug 2005 18:37:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932325AbVHHWha (ORCPT ); Mon, 8 Aug 2005 18:37:30 -0400 Received: from fmr23.intel.com ([143.183.121.15]:46268 "EHLO scsfmr003.sc.intel.com") by vger.kernel.org with ESMTP id S932312AbVHHWh1 (ORCPT ); Mon, 8 Aug 2005 18:37:27 -0400 Message-Id: <200508082236.j78MaXg20909@unix-os.sc.intel.com> From: "Chen, Kenneth W" To: "'Adam Litke'" Cc: , , , Subject: RE: [RFC] Demand faulting for large pages Date: Mon, 8 Aug 2005 15:36:28 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.6353 In-Reply-To: <1123539400.3122.365.camel@localhost.localdomain> Thread-Index: AcWcZ50qxctxXkp0SkmwwCcBd1IvMQAANToQ X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Adam Litke wrote on Monday, August 08, 2005 3:17 PM > The reason for the VM_FAULT_SIGBUS default return is because I thought a > fault on a pte_present hugetlb page was an invalid/unhandled fault. > I'll have another think about races to the fault handler though. Two threads fault on the same pte, one won the race, install a pte, 2nd thread then walk the page table, found the pte inserted by the first thread, exit with SIGBUS, kernel then kills the entire app with sigbus. > I've definitely been able to produce some strange behavior on 2.6.7 > relative to your post about this topic here: > http://www.ussg.iu.edu/hypermail/linux/kernel/0406.2/0234.html > I confirmed the fix in 2.6.8 and also don't see the problem when using > my demand fault patch. Do you have a copy of the program you used to > generate the Oops in the post linked above so I can use it as a test > case? I'd guess either the problem is gone entirely with demand > faulting, or just harder to trigger. Demanding paging doesn't solve this problem. It is related to how pmds are freed. - Ken