From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id m9LBNqmX001968 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Tue, 21 Oct 2008 20:23:52 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id A0E002AC029 for ; Tue, 21 Oct 2008 20:23:52 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 6C51912C0AE for ; Tue, 21 Oct 2008 20:23:52 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 3B6DB1DB803E for ; Tue, 21 Oct 2008 20:23:52 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id EB4A01DB803B for ; Tue, 21 Oct 2008 20:23:51 +0900 (JST) Date: Tue, 21 Oct 2008 20:23:25 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [memcg BUG] unable to handle kernel NULL pointer derefence at 00000000 Message-Id: <20081021202325.938678c0.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20081021111951.GB4476@elte.hu> References: <20081021161621.bb51af90.kamezawa.hiroyu@jp.fujitsu.com> <48FD82E3.9050502@cn.fujitsu.com> <20081021171801.4c16c295.kamezawa.hiroyu@jp.fujitsu.com> <48FD943D.5090709@cn.fujitsu.com> <20081021175735.0c3d3534.kamezawa.hiroyu@jp.fujitsu.com> <48FD9D30.2030500@cn.fujitsu.com> <20081021182551.0158a47b.kamezawa.hiroyu@jp.fujitsu.com> <48FDA6D4.3090809@cn.fujitsu.com> <20081021191417.02ab97cc.kamezawa.hiroyu@jp.fujitsu.com> <48FDB584.7080608@cn.fujitsu.com> <20081021111951.GB4476@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: Li Zefan , balbir@linux.vnet.ibm.com, Paul Menage , Daisuke Nishimura , linux-mm@kvack.org, mel@csn.ul.ie List-ID: On Tue, 21 Oct 2008 13:19:51 +0200 Ingo Molnar wrote: > > * Li Zefan wrote: > > > > Oh! thanks...but it seems pc->page is NULL in the middle of ZONE_NORMAL.. > > > == > > > Normal 0x00001000 -> 0x000373fe > > > == > > > This is appearently in the range of page_cgroup initialization. > > > (if pgdat->node_page_cgroup is initalized correctly...) > > > > > > I think write to page_cgroup->page happens only at initialization. > > > Hmm ? not initilization failure but curruption ? > > > > > > > Yes, curruption. I didn't find informatation about initialization failure. > > > > > What happens if replacing __alloc_bootmem() with vmalloc() in page_cgroup.c init ? > > > > > > > So I did this change, and the box booted up without any problem. > > > > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > > index 5d86550..82a30b1 100644 > > --- a/mm/page_cgroup.c > > +++ b/mm/page_cgroup.c > > @@ -48,8 +48,7 @@ static int __init alloc_node_page_cgroup(int nid) > > > > table_size = sizeof(struct page_cgroup) * nr_pages; > > > > - base = __alloc_bootmem_node_nopanic(NODE_DATA(nid), > > - table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS)); > > + base = vmalloc_node(table_size, nid); > > if (!base) > > return -ENOMEM; > > i have this: > > CONFIG_FAILSLAB=y > CONFIG_FAIL_PAGE_ALLOC=y > # CONFIG_FAIL_MAKE_REQUEST is not set > CONFIG_FAIL_IO_TIMEOUT=y > > so the bug was perhaps that the __alloc_bootmem_node_nopanic() failed > and this code continued silently? vmalloc_node() probably is more > agressive about allocating memory. > Sorry. I think I cannot use alloc_bootmem() at this point because it's too late in init-path. (we can use usual page allocator) So, just replacing alloc_bootmem() with vmalloc_node() is a fix.... Thanks, -Kame -- 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