From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 43AEF6B01B2 for ; Thu, 20 May 2010 16:44:06 -0400 (EDT) Date: Thu, 20 May 2010 13:43:59 -0700 From: Andrew Morton Subject: Re: [PATCH] online CPU before memory failed in pcpu_alloc_pages() Message-Id: <20100520134359.fdfb397e.akpm@linux-foundation.org> In-Reply-To: <1274163442-7081-1-git-send-email-chaohong_guo@linux.intel.com> References: <1274163442-7081-1-git-send-email-chaohong_guo@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: minskey guo Cc: linux-mm@kvack.org, prarit@redhat.com, andi.kleen@intel.com, linux-kernel@vger.kernel.org, minskey guo , Tejun Heo , stable@kernel.org List-ID: On Tue, 18 May 2010 14:17:22 +0800 minskey guo wrote: > From: minskey guo > > The operation of "enable CPU to online before memory within a node" > fails in some case according to Prarit. The warnings as follows: > > Pid: 7440, comm: bash Not tainted 2.6.32 #2 > Call Trace: > [] pcpu_alloc+0xa05/0xa70 > [] __alloc_percpu+0x10/0x20 > [] __create_workqueue_key+0x75/0x280 > [] ? __build_all_zonelists+0x0/0x5d0 > [] stop_machine_create+0x3a/0xb0 > [] stop_machine+0x27/0x60 > [] build_all_zonelists+0xd0/0x2b0 > [] cpu_up+0xb3/0xe3 > [] store_online+0x70/0xa0 > [] sysdev_store+0x20/0x30 > [] sysfs_write_file+0xe5/0x170 > [] vfs_write+0xb8/0x1a0 > [] ? audit_syscall_entry+0x252/0x280 > [] sys_write+0x51/0x90 > [] system_call_fastpath+0x16/0x1b > Built 4 zonelists in Zone order, mobility grouping on. Total pages: 12331603 > PERCPU: allocation failed, size=128 align=64, failed to populate > > With "enable CPU to online before memory" patch, when the 1st CPU of > an offlined node is being onlined, we build zonelists for that node. > If per-cpu area needs to be extended during zonelists building period, > alloc_pages_node() will be called. The routine alloc_pages_node() fails > on the node in-onlining because the node doesn't have zonelists created > yet. > > To fix this issue, we try to alloc memory from current node. How serious is this issue? Just a warning? Dead box? Because if we want to port this fix into 2.6.34.x, we have a little problem. > --- a/mm/percpu.c > +++ b/mm/percpu.c > @@ -714,13 +714,29 @@ static int pcpu_alloc_pages(struct pcpu_chunk *chunk, In linux-next, Tejun has gone and moved pcpu_alloc_pages() into the new mm/percpu-vm.c. So either a) the -stable guys will need to patch a different file or b) we apply this fix first and muck up Tejun's tree or c) the bug isn't very serious so none of this applies. > { > const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD; > unsigned int cpu; > + int nid; > int i; > > for_each_possible_cpu(cpu) { > for (i = page_start; i < page_end; i++) { > struct page **pagep = &pages[pcpu_page_idx(cpu, i)]; > > - *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0); > + nid = cpu_to_node(cpu); > + > + /* > + * It is allowable to online a CPU within a NUMA > + * node which doesn't have onlined local memory. > + * In this case, we need to create zonelists for > + * that node when cpu is being onlined. If per-cpu > + * area needs to be extended at the exact time when > + * zonelists of that node is being created, we alloc > + * memory from current node. > + */ > + if ((nid == -1) || > + !(node_zonelist(nid, GFP_KERNEL)->_zonerefs->zone)) > + nid = numa_node_id(); > + > + *pagep = alloc_pages_node(nid, gfp, 0); > if (!*pagep) { > pcpu_free_pages(chunk, pages, populated, > page_start, page_end); -- 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