From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id E4F4C8D003A for ; Wed, 9 Feb 2011 01:46:28 -0500 (EST) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 2AA883EE0B6 for ; Wed, 9 Feb 2011 15:46:27 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 14C4145DE52 for ; Wed, 9 Feb 2011 15:46:27 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id ED07645DE50 for ; Wed, 9 Feb 2011 15:46:26 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id D01DCEF8001 for ; Wed, 9 Feb 2011 15:46:26 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 3F304EF8009 for ; Wed, 9 Feb 2011 15:46:26 +0900 (JST) Date: Wed, 9 Feb 2011 15:40:17 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [mmotm] BUG: Bad page state in process khugepaged ? Message-Id: <20110209154017.f6489f4e.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110209151036.f24a36a6.kamezawa.hiroyu@jp.fujitsu.com> References: <20110209151036.f24a36a6.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , Andrea Arcangeli , "hannes@cmpxchg.org" , "nishimura@mxp.nes.nec.co.jp" On Wed, 9 Feb 2011 15:10:36 +0900 KAMEZAWA Hiroyuki wrote: > 2nd log, "kernel BUG at include/linux/mm.h:420!" is This one. > == > static inline void __ClearPageBuddy(struct page *page) > { > VM_BUG_ON(!PageBuddy(page)); > atomic_set(&page->_mapcount, -1); > } > == > But this is just a tail of bad_page(). > == > static void bad_page(struct page *page) > { > static unsigned long resume; > static unsigned long nr_shown; > static unsigned long nr_unshown; > ... > dump_stack(); > out: > /* Leave bad fields for debug, except PageBuddy could make trouble */ > __ClearPageBuddy(page); > add_taint(TAINT_BAD_PAGE); > } > == > So, what important is bad_page(). > > BAD page says > == > BUG: Bad page state in process khugepaged pfn:1e9800 > page:ffffea0006b14000 count:0 mapcount:0 mapping: (null) index:0x2800 > page flags: 0x40000000004000(head) > pc:ffff880214a30000 pc->flags:2146246697418756 pc->mem_cgroup:ffffc9000177a000 > == > > Maybe page_mapcount(page) was > 0. and ->mapping was NULL. Sorry please ignore above. bad_page() used page_mapcount(). Regards, -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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org