From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758546Ab2FVSvT (ORCPT ); Fri, 22 Jun 2012 14:51:19 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:64088 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755920Ab2FVSvS (ORCPT ); Fri, 22 Jun 2012 14:51:18 -0400 Date: Fri, 22 Jun 2012 11:51:13 -0700 From: Tejun Heo To: Yinghai Lu Cc: Gavin Shan , Sasha Levin , Andrew Morton , David Miller , hpa@linux.intel.com, linux-mm , "linux-kernel@vger.kernel.org" Subject: Re: Early boot panic on machine with lots of memory Message-ID: <20120622185113.GK4642@google.com> References: <20120614032005.GC3766@dhcp-172-17-108-109.mtv.corp.google.com> <1339667440.3321.7.camel@lappy> <20120618223203.GE32733@google.com> <1340059850.3416.3.camel@lappy> <20120619041154.GA28651@shangw> <20120619212059.GJ32733@google.com> <20120619212618.GK32733@google.com> <20120621201728.GB4642@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Yinghai. On Thu, Jun 21, 2012 at 06:47:24PM -0700, Yinghai Lu wrote: > > I'm afraid this is too early.  We don't want the region to be unmapped > > yet.  This should only happen after all memblock usages are finished > > which I don't think is the case yet. > > No, it is not early. at that time memblock usage is done. > > Also I tested one system with huge memory, duplicated the problem on > KVM that Sasha met. > my patch fixes the problem. > > please check attached patch. > > Also I add another patch to double check if there is any reference > with reserved.region. > so far there is no reference found. Thanks for checking it. I was worried because of the re-reservation of reserved.regions after giving memory to the page allocator - ie. memblock_reserve_reserved_regions() call. If memblock is done at that point, there's no reason to have that call at all. It could be that that's just dead code. If so, why aren't we freeing memory.regions? Also, shouldn't we be clearing memblock.cnt/max/total_size/regions so that we know for sure that it's never used again? What am I missing? Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx124.postini.com [74.125.245.124]) by kanga.kvack.org (Postfix) with SMTP id 59FCD6B024D for ; Fri, 22 Jun 2012 14:51:18 -0400 (EDT) Received: by dakp5 with SMTP id p5so3325192dak.14 for ; Fri, 22 Jun 2012 11:51:17 -0700 (PDT) Date: Fri, 22 Jun 2012 11:51:13 -0700 From: Tejun Heo Subject: Re: Early boot panic on machine with lots of memory Message-ID: <20120622185113.GK4642@google.com> References: <20120614032005.GC3766@dhcp-172-17-108-109.mtv.corp.google.com> <1339667440.3321.7.camel@lappy> <20120618223203.GE32733@google.com> <1340059850.3416.3.camel@lappy> <20120619041154.GA28651@shangw> <20120619212059.GJ32733@google.com> <20120619212618.GK32733@google.com> <20120621201728.GB4642@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Yinghai Lu Cc: Gavin Shan , Sasha Levin , Andrew Morton , David Miller , hpa@linux.intel.com, linux-mm , "linux-kernel@vger.kernel.org" Hello, Yinghai. On Thu, Jun 21, 2012 at 06:47:24PM -0700, Yinghai Lu wrote: > > I'm afraid this is too early. We don't want the region to be unmapped > > yet. This should only happen after all memblock usages are finished > > which I don't think is the case yet. > > No, it is not early. at that time memblock usage is done. > > Also I tested one system with huge memory, duplicated the problem on > KVM that Sasha met. > my patch fixes the problem. > > please check attached patch. > > Also I add another patch to double check if there is any reference > with reserved.region. > so far there is no reference found. Thanks for checking it. I was worried because of the re-reservation of reserved.regions after giving memory to the page allocator - ie. memblock_reserve_reserved_regions() call. If memblock is done at that point, there's no reason to have that call at all. It could be that that's just dead code. If so, why aren't we freeing memory.regions? Also, shouldn't we be clearing memblock.cnt/max/total_size/regions so that we know for sure that it's never used again? What am I missing? Thanks. -- tejun -- 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/ . Don't email: email@kvack.org