From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932873Ab2GKP04 (ORCPT ); Wed, 11 Jul 2012 11:26:56 -0400 Received: from mga12.intel.com ([143.182.124.36]:46701 "EHLO azsmga102.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932835Ab2GKP0x (ORCPT ); Wed, 11 Jul 2012 11:26:53 -0400 MIME-Version: 1.0 In-Reply-To: <20120711145412.GA2430@ram-ThinkPad-T61> References: <1341057657-7823-1-git-send-email-octavian.purdila@intel.com> <20120710143348.d977da44.akpm@linux-foundation.org> <20120711020902.GC13885@ram-ThinkPad-T61> <20120711145412.GA2430@ram-ThinkPad-T61> Date: Wed, 11 Jul 2012 18:26:49 +0300 Message-ID: Subject: Re: [PATCH] resource: make sure requested range intersects root range From: "Purdila, Octavian" To: Ram Pai Cc: Andrew Morton , "H. Peter Anvin" , linux-kernel@vger.kernel.org, Jesse Barnes Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 11, 2012 at 5:54 PM, Ram Pai wrote: > On Wed, Jul 11, 2012 at 02:06:10PM +0300, Purdila, Octavian wrote: >> On Wed, Jul 11, 2012 at 5:09 AM, Ram Pai wrote: >> >> > >> > Wait.. I am not sure this will fix the problem entirely. The above check >> > will handle the case where the range requested is entirey out of the >> > root's range. But if the requested range overlapps that of the root >> > range, we will still call __reserve_region_with_split() and end up with >> > a recursion if there is a overflow. Wont we? >> > >> >> Good catch. I will fix this as well as address Andrew's and Joe's >> comments in a new patch. The only question is how to handle the >> overlap case: >> >> (a) abort the whole request or >> >> (b) try to reserve the part that overlaps (and adjust the request to >> avoid the overflow) >> >> I think (b) is more in line with the current implementation for reservations. > > > I prefer (b). following patch should handle that. > > diff --git a/kernel/resource.c b/kernel/resource.c > index e1d2b8e..dd87fde 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -780,6 +780,10 @@ static void __init __reserve_region_with_split(struct resource *root, > > if (conflict->start > start) > __reserve_region_with_split(root, start, conflict->start-1, name); > + > + if (conflict->end == parent->end ) > + return; > + > if (conflict->end < end) > __reserve_region_with_split(root, conflict->end+1, end, name); > } > I don't think this covers all cases, e.g. if root range starts somewhere above 0 and the request is below the root start point. What about something like below? It is maybe too verbose, but it should make it easier to find the offender. diff --git a/kernel/resource.c b/kernel/resource.c index e1d2b8e..0d71983 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -788,8 +788,29 @@ void __init reserve_region_with_split(struct resource *root, resource_size_t start, resource_size_t end, const char *name) { + int abort = 0; + write_lock(&resource_lock); - __reserve_region_with_split(root, start, end, name); + if (!(root->start >= start && root->end >= end)) { + pr_err("Requested range (0x%llx-0x%llx) not in root %pr\n", + (unsigned long long)start, (unsigned long long)end, + root); + if (start > root->end || end < root->start) { + abort = 1; + pr_err("Unable to fix request, aborting\n"); + } else { + if (end > root->end) + end = root->end; + else if (start < root->start) + start = root->start; + pr_err("Request trimmed to (0x%llx-0x%llx)\n", + (unsigned long long)start, + (unsigned long long)end); + } + dump_stack(); + } + if (!abort) + __reserve_region_with_split(root, start, end, name); write_unlock(&resource_lock); }