From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e31.co.us.ibm.com (8.12.10/8.12.9) with ESMTP id iAIJIDCB443060 for ; Thu, 18 Nov 2004 14:18:14 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id iAIJIACQ225770 for ; Thu, 18 Nov 2004 12:18:13 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11/8.12.11) with ESMTP id iAIJIAv6017149 for ; Thu, 18 Nov 2004 12:18:10 -0700 Subject: Re: [Lhms-devel] [RFC] fix for hot-add enabled SRAT/BIOS and numa KVA areas From: keith In-Reply-To: <1100744644.17510.8.camel@localhost> References: <1100659057.26335.125.camel@knk> <1100711519.5838.2.camel@localhost> <1100743722.26335.644.camel@knk> <1100744644.17510.8.camel@localhost> Content-Type: text/plain Message-Id: <1100805488.26335.684.camel@knk> Mime-Version: 1.0 Date: Thu, 18 Nov 2004 11:18:08 -0800 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: external hotplug mem list , linux-mm , Chris McDermott List-ID: On Wed, 2004-11-17 at 18:24, Dave Hansen wrote: > On Wed, 2004-11-17 at 18:08, keith wrote: > > I am not anticipating to support hot-add without config_nonlinear or > > something similar which should provide more flexibility in allocation of > > smaller section mem_maps. This is only a issue when booted as a > > discontig system. We don't even consult the SRAT when we boot flat > > (contiguous address space) so it is a non-issue. > > Once a system has been running for any length of time, finding any > multi-order pages gets somewhat hard. For a 16M section, you're still > talking about ~128k of mem_map, which is still an order 5 allocation. > Nick's kswapd higher-order patches should help with this, though. I think it is safe to deal with this issue later. I think i386 hot add is going to be confined to a very small pool of boxes. > > Wasting 500k of lowmem for memory that "might" be there is no good. I > > don't think having to preallocate the mem_map for a hot-add is really > > that good. What if the system never adds memory? What if it only adds > > 8gig not 49g? The system is crippled because it reserves the lmem_map > > it "might" do a hot add with? > > I have the feeling we'll eventually need a boot-time option for this > reservation. Your patch, of course will work for now. Do you want me > to pick it up in my tree? I agree a boot time option to reserve a chunk of virtual address space may be the way to go for i386. I would hate to reserve too much space that ends up just being wasted. I think this can be save off for future work. I would like to get it into mm, I'll ping Andrew. > > > I forgot the mention that without this patch my system does not boot > > with the hot-add support enabled in the bios. > > Why not? I'm just curious what caused the actual failure. > > -- Dave (snip) Summit chipset: Starting Cyclone Counter. Detected 1997.351 MHz processor. Using cyclone for high-res timesource Console: colour VGA+ 80x25 Dentry cache hash table entries: 65536 (order: 6, 262144 bytes) Inode-cache hash table entries: 32768 (order: 5, 131072 bytes) Initializing HighMem for node 0 Initializing HighMem for node 1 Bad page state at free_hot_cold_page (in process 'swapper', page d8e0d000) flags:0xfffff7ff mapping:00000000 mapcount:0 count:266321921 Backtrace: [] bad_page+0x81/0xb4 [] free_hot_cold_page+0x7e/0x100 [] one_highpage_init+0xda/0x172 [] set_highmem_pages_init+0xb0/0xf5 [] _etext+0x0/0x10d5 [] mem_init+0x14f/0x2ba [] alloc_large_system_hash+0x128/0x173 [] start_kernel+0x118/0x221 [] unknown_bootoption+0x0/0x145 Trying to fix it up, but a reboot is needed Bad page state at free_hot_cold_page (in process 'swapper', page d8e0d020) flags:0xfffff7ff mapping:00000000 mapcount:0 count:-523233279 Backtrace: [] bad_page+0x81/0xb4 [] free_hot_cold_page+0x7e/0x100 [] one_highpage_init+0xda/0x172 [] set_highmem_pages_init+0xb0/0xf5 [] _etext+0x0/0x10d5 [] mem_init+0x14f/0x2ba [] alloc_large_system_hash+0x128/0x173 [] start_kernel+0x118/0x221 [] unknown_bootoption+0x0/0x145 Trying to fix it up, but a reboot is needed Bad page state at free_hot_cold_page (in process 'swapper', page d8e0d040) flags:0xfffff7ff mapping:00000000 mapcount:0 count:-523233279 Backtrace: [] bad_page+0x81/0xb4 [] free_hot_cold_page+0x7e/0x100 [] one_highpage_init+0xda/0x172 (and on and on and on) Thanks, Keith Mannthey -- 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: aart@kvack.org