Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755249AbYGIWoh (ORCPT ); Wed, 9 Jul 2008 18:44:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751574AbYGIWo3 (ORCPT ); Wed, 9 Jul 2008 18:44:29 -0400 Received: from saeurebad.de ([85.214.36.134]:44784 "EHLO saeurebad.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751076AbYGIWo3 (ORCPT ); Wed, 9 Jul 2008 18:44:29 -0400 From: Johannes Weiner To: Lee Schermerhorn Cc: Andrew Morton , linux-kernel Subject: Re: [PATCH] Fix spurious BUG_ON() in mark_bootmem() References: <1215637772.18157.6.camel@lts-notebook> Date: Thu, 10 Jul 2008 00:43:42 +0200 In-Reply-To: <1215637772.18157.6.camel@lts-notebook> (Lee Schermerhorn's message of "Wed, 09 Jul 2008 17:09:32 -0400") Message-ID: <87fxqillup.fsf@saeurebad.de> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2617 Lines: 75 Hi Lee, Lee Schermerhorn writes: > Against: 2.6.26-rc8-mm1 > > Fixes problem introduced by patches: > > bootmem-factor-out-the-marking-of-a-pfn-range.patch > bootmem-replace-node_boot_start-in-struct-bootmem_data.patch > > HP ia64 NUMA platform fails to boot 26-rc8-mm1, hitting BUG_ON() > in mm/bootmem.c:mark_bootmem(). > > After linking all bootmem chunks, the 'bdata_list' on HP ia64 numa > platforms looks something like this: > > node 4: 0x0-0x8000 > node 0: 0x1c008000-0x1c07ec00 > node 1: 0x1c800000-0x1c87f000 > node 2: 0x1d000000-0x1d07f000 > node 3: 0x1d800000-0x1d87f000 > > [Node 4 is a pseudo-node generated by the platform firmware to > contain a configurable amount of zero-based, hardware interleaved > memory. 0x8000 pages or 512M is the minimum that can be configured.] > > First call to mark_bootmem() [from free_bootmem()] called with: > > start-end: 0x1c008063-0x1c008262, reserve: 0, flags: 0 > > I.e, NOT in the first chunk of the list. > > However, the "if (pos < bdata->node_min_pfn)" in the loop fails > to test the start address of the argument range [in 'pos'] against > the end of the chunk. So, it treats the range as being in the node > 4 chunk. Second time thru' the loop, pos == 0x8000 is < > bdata->node_min_pfn and pos != start, so we trip the BUG_ON(). > > This patch enhances the if condition to skip chunks that do not > overlap the argument range, allowing 26-rc8-mm1 to boot on this > platform. > > Signed-off-by: Lee Schermerhorn > > mm/bootmem.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > Index: linux-2.6.26-rc8-mm1/mm/bootmem.c > =================================================================== > --- linux-2.6.26-rc8-mm1.orig/mm/bootmem.c 2008-07-09 16:11:23.000000000 -0400 > +++ linux-2.6.26-rc8-mm1/mm/bootmem.c 2008-07-09 16:13:46.000000000 -0400 > @@ -299,7 +299,8 @@ static int __init mark_bootmem(unsigned > int err; > unsigned long max; > > - if (pos < bdata->node_min_pfn) { > + if (pos < bdata->node_min_pfn || > + pos >= bdata->node_low_pfn) { > BUG_ON(pos != start); > continue; > } Ah, yeah, this was obviously wrong. Thanks for the fix! Acked-by: Johannes Weiner Nice to know that it boots otherwise on such a setup :) Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/