From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp06.au.ibm.com (unknown [202.81.31.148]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp06.au.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 66A87DDF20 for ; Thu, 22 Jan 2009 19:20:29 +1100 (EST) Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.31.250]) by e23smtp06.au.ibm.com (8.13.1/8.13.1) with ESMTP id n0M8KSPR018314 for ; Thu, 22 Jan 2009 19:20:28 +1100 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id n0M8KRps303760 for ; Thu, 22 Jan 2009 19:20:28 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n0M8KRdh021122 for ; Thu, 22 Jan 2009 19:20:27 +1100 From: Chandru To: Dave Hansen Subject: Re: 2.6.28-rc9 panics with crashkernel=256M while booting Date: Thu, 22 Jan 2009 13:50:21 +0530 References: <200812241325.49404.chandru@in.ibm.com> <200901191700.03580.chandru@in.ibm.com> <1232584180.27278.86.camel@nimitz> In-Reply-To: <1232584180.27278.86.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200901221350.21601.chandru@in.ibm.com> Cc: linuxppc-dev@ozlabs.org, Andrew Morton , Paul Mackerras , linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thursday 22 January 2009 05:59:39 Dave Hansen wrote: > Let's take, for instance, a 1-byte reservation. With this code, you've > suddenly turned that into a 0-byte reservation, and that *can't* be > right. The same thing happens if you have a reservation that spans two > pages. If you unconditionally round it down, then you might miss the > part that spans a portion of the second page. > > It needs to be rounded down like you are suggesting here, but only in > the case where we've gone over the *CURRENT* node's boundary. This is > kinda what that "if (end_pfn > node_ar.end_pfn)" check is doing. But, > it evidently screws it up if the overlap isn't by an entire page or > something. I assumed the condition 'while (start_pfn < end_pfn && .. )' asks for atleast a PAGE_SIZE difference between them and hence went ahead with that patch. My guess was a 1-byte , 2-byte or a (PAGE_SIZE -1)-byte reservations may not even go into that loop. However we just need a fix for this problem. So if there is a better fix that you have please post it to lkml. Thanks, Chandru