Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992539AbWJTHSz (ORCPT ); Fri, 20 Oct 2006 03:18:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992543AbWJTHSy (ORCPT ); Fri, 20 Oct 2006 03:18:54 -0400 Received: from ozlabs.org ([203.10.76.45]:15531 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S2992539AbWJTHSy (ORCPT ); Fri, 20 Oct 2006 03:18:54 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17720.30804.180390.197567@cargo.ozlabs.ibm.com> Date: Fri, 20 Oct 2006 17:18:44 +1000 From: Paul Mackerras To: Christoph Lameter Cc: Anton Blanchard , akpm@osdl.org, linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: kernel BUG in __cache_alloc_node at linux-2.6.git/mm/slab.c:3177! In-Reply-To: References: <1161026409.31903.15.camel@farscape> <1161031821.31903.28.camel@farscape> <17717.50596.248553.816155@cargo.ozlabs.ibm.com> <17718.39522.456361.987639@cargo.ozlabs.ibm.com> <17719.1849.245776.4501@cargo.ozlabs.ibm.com> <20061019163044.GB5819@krispykreme> <17719.64246.555371.701194@cargo.ozlabs.ibm.com> X-Mailer: VM 7.19 under Emacs 21.4.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2081 Lines: 46 Christoph Lameter writes: > The page allocator must be running and able to serve pages from the boot > node. This fails for some reason and the slab cannot bootstrap. The memory > not available is the first guess. Could you trace the allocation in the > page allocator (__alloc_pages) when the slab attempts to bootstrap and > figure out why exactly the allocation fails? What is happening is that all pages are getting their zone id field in their page->flags set to point to zone for node 1 by memmap_init_zone calling set_page_links (which does set_page_zone). Thus, when those pages get freed by free_all_bootmem_node, they all end up in the zone for node 1. memmap_init_zone is called (as memmap_init, since we don't have __HAVE_ARCH_MEMMAP_INIT defined) from init_currently_empty_zone, which is called from free_area_init_core. Now the thing is that memmap_init and init_currently_empty_zone are called with the node's start PFN and size in pages, *including* holes. On the partition I'm using we have these PFN ranges for the nodes: 1: 0 -> 32768 0: 32768 -> 278528 1: 278528 -> 524288 So node 0's start PFN is 32768 and its size is 245760 pages, and so we correctly set pages 32786 to 278527 to be in the zone for node 0. Then for node 1, we have the start PFN is 0 and the size is 524288, so we then go through and set *all* pages of memory to be in the zone for node 1, including the pages which are actually on node 0. That's why we can't allocate any pages on node 0, and the kmem cache bootstrapping blows up. I don't know this code well enough to know what the correct fix is. Clearly memmap_init_zone should only be touching the pages that are actually present in the zone, but I don't know exactly what data structures it should be using to know what those pages are. Paul. - 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/