From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756566Ab1IBXEY (ORCPT ); Fri, 2 Sep 2011 19:04:24 -0400 Received: from claw.goop.org ([74.207.240.146]:45445 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756464Ab1IBXEW (ORCPT ); Fri, 2 Sep 2011 19:04:22 -0400 Message-ID: <4E6160F3.8030708@goop.org> Date: Fri, 02 Sep 2011 16:04:19 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0 MIME-Version: 1.0 To: Andrew Morton CC: David Vrabel , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , "namhyung@gmail.com" , "rientjes@google.com" , "linux-mm@kvack.org" , "xen-devel@lists.xensource.com" , "paulmck@linux.vnet.ibm.com" Subject: Re: [Revert] Re: [PATCH] mm: sync vmalloc address space page tables in alloc_vm_area() References: <1314877863-21977-1-git-send-email-david.vrabel@citrix.com> <20110901161134.GA8979@dumpdata.com> <4E5FED1A.1000300@goop.org> <20110901141754.76cef93b.akpm@linux-foundation.org> <4E60C067.4010600@citrix.com> <20110902153204.59a928c1.akpm@linux-foundation.org> In-Reply-To: <20110902153204.59a928c1.akpm@linux-foundation.org> X-Enigmail-Version: 1.3.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/02/2011 03:32 PM, Andrew Morton wrote: > On Fri, 2 Sep 2011 12:39:19 +0100 > David Vrabel wrote: > >> Xen backend drivers (e.g., blkback and netback) would sometimes fail >> to map grant pages into the vmalloc address space allocated with >> alloc_vm_area(). The GNTTABOP_map_grant_ref would fail because Xen >> could not find the page (in the L2 table) containing the PTEs it >> needed to update. >> >> (XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000 >> >> netback and blkback were making the hypercall from a kernel thread >> where task->active_mm != &init_mm and alloc_vm_area() was only >> updating the page tables for init_mm. The usual method of deferring >> the update to the page tables of other processes (i.e., after taking a >> fault) doesn't work as a fault cannot occur during the hypercall. >> >> This would work on some systems depending on what else was using >> vmalloc. >> >> Fix this by reverting ef691947d8a3d479e67652312783aedcf629320a >> (vmalloc: remove vmalloc_sync_all() from alloc_vm_area()) and add a >> comment to explain why it's needed. > oookay, I queued this for 3.1 and tagged it for a 3.0.x backport. I > *think* that's the outcome of this discussion, for the short-term? Sure, that will get things going for now. Thanks, J From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id A5FBA6B01A9 for ; Fri, 2 Sep 2011 19:04:23 -0400 (EDT) Message-ID: <4E6160F3.8030708@goop.org> Date: Fri, 02 Sep 2011 16:04:19 -0700 From: Jeremy Fitzhardinge MIME-Version: 1.0 Subject: Re: [Revert] Re: [PATCH] mm: sync vmalloc address space page tables in alloc_vm_area() References: <1314877863-21977-1-git-send-email-david.vrabel@citrix.com> <20110901161134.GA8979@dumpdata.com> <4E5FED1A.1000300@goop.org> <20110901141754.76cef93b.akpm@linux-foundation.org> <4E60C067.4010600@citrix.com> <20110902153204.59a928c1.akpm@linux-foundation.org> In-Reply-To: <20110902153204.59a928c1.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: David Vrabel , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , "namhyung@gmail.com" , "rientjes@google.com" , "linux-mm@kvack.org" , "xen-devel@lists.xensource.com" , "paulmck@linux.vnet.ibm.com" On 09/02/2011 03:32 PM, Andrew Morton wrote: > On Fri, 2 Sep 2011 12:39:19 +0100 > David Vrabel wrote: > >> Xen backend drivers (e.g., blkback and netback) would sometimes fail >> to map grant pages into the vmalloc address space allocated with >> alloc_vm_area(). The GNTTABOP_map_grant_ref would fail because Xen >> could not find the page (in the L2 table) containing the PTEs it >> needed to update. >> >> (XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000 >> >> netback and blkback were making the hypercall from a kernel thread >> where task->active_mm != &init_mm and alloc_vm_area() was only >> updating the page tables for init_mm. The usual method of deferring >> the update to the page tables of other processes (i.e., after taking a >> fault) doesn't work as a fault cannot occur during the hypercall. >> >> This would work on some systems depending on what else was using >> vmalloc. >> >> Fix this by reverting ef691947d8a3d479e67652312783aedcf629320a >> (vmalloc: remove vmalloc_sync_all() from alloc_vm_area()) and add a >> comment to explain why it's needed. > oookay, I queued this for 3.1 and tagged it for a 3.0.x backport. I > *think* that's the outcome of this discussion, for the short-term? Sure, that will get things going for now. Thanks, J -- 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